Commit | Line | Data |
---|---|---|
b8d4c8d0 GM |
1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
ab422c4d PE |
3 | @c Copyright (C) 1990-1995, 1998-1999, 2001-2013 Free Software |
4 | @c Foundation, Inc. | |
b8d4c8d0 | 5 | @c See the file elisp.texi for copying conditions. |
ecc6530d | 6 | @node Windows |
b8d4c8d0 GM |
7 | @chapter Windows |
8 | ||
b33b68a3 MR |
9 | This chapter describes the functions and variables related to Emacs |
10 | windows. @xref{Frames}, for how windows are assigned an area of screen | |
11 | available for Emacs to use. @xref{Display}, for information on how text | |
12 | is displayed in windows. | |
b8d4c8d0 GM |
13 | |
14 | @menu | |
15 | * Basic Windows:: Basic information on using windows. | |
b33b68a3 MR |
16 | * Windows and Frames:: Relating windows to the frame they appear on. |
17 | * Window Sizes:: Accessing a window's size. | |
18 | * Resizing Windows:: Changing the sizes of windows. | |
fdaf534a MR |
19 | * Splitting Windows:: Creating a new window. |
20 | * Deleting Windows:: Removing a window from its frame. | |
21 | * Recombining Windows:: Preserving the frame layout when splitting and | |
22 | deleting windows. | |
b8d4c8d0 GM |
23 | * Selecting Windows:: The selected window is the one that you edit in. |
24 | * Cyclic Window Ordering:: Moving around the existing windows. | |
25 | * Buffers and Windows:: Each window displays the contents of a buffer. | |
0e406a72 | 26 | * Switching Buffers:: Higher-level functions for switching to a buffer. |
d24880de | 27 | * Choosing Window:: How to choose a window for displaying a buffer. |
9ec20d36 CY |
28 | * Display Action Functions:: Subroutines for @code{display-buffer}. |
29 | * Choosing Window Options:: Extra options affecting how buffers are displayed. | |
0e406a72 | 30 | * Window History:: Each window remembers the buffers displayed in it. |
d24880de | 31 | * Dedicated Windows:: How to avoid displaying another buffer in |
a1401ab1 | 32 | a specific window. |
c419f5cb MR |
33 | * Quitting Windows:: How to restore the state prior to displaying a |
34 | buffer. | |
b8d4c8d0 | 35 | * Window Point:: Each window has its own location of point. |
0273ca3a MR |
36 | * Window Start and End:: Buffer positions indicating which text is |
37 | on-screen in a window. | |
b8d4c8d0 GM |
38 | * Textual Scrolling:: Moving text up and down through the window. |
39 | * Vertical Scrolling:: Moving the contents up and down on the window. | |
40 | * Horizontal Scrolling:: Moving the contents sideways on the window. | |
b8d4c8d0 | 41 | * Coordinates and Windows:: Converting coordinates to windows. |
b8d4c8d0 | 42 | * Window Configurations:: Saving and restoring the state of the screen. |
0273ca3a | 43 | * Window Parameters:: Associating additional information with windows. |
b8d4c8d0 GM |
44 | * Window Hooks:: Hooks for scrolling, window size changes, |
45 | redisplay going past a certain point, | |
46 | or window configuration changes. | |
47 | @end menu | |
48 | ||
b33b68a3 | 49 | |
b8d4c8d0 GM |
50 | @node Basic Windows |
51 | @section Basic Concepts of Emacs Windows | |
52 | @cindex window | |
b8d4c8d0 | 53 | |
0d4bb04f MR |
54 | A @dfn{window} is an area of the screen that is used to display a buffer |
55 | (@pxref{Buffers}). In Emacs Lisp, windows are represented by a special | |
56 | Lisp object type. | |
b8d4c8d0 GM |
57 | |
58 | @cindex multiple windows | |
291d142b CY |
59 | Windows are grouped into frames (@pxref{Frames}). Each frame |
60 | contains at least one window; the user can subdivide it into multiple, | |
61 | non-overlapping windows to view several buffers at once. Lisp | |
62 | programs can use multiple windows for a variety of purposes. In | |
63 | Rmail, for example, you can view a summary of message titles in one | |
64 | window, and the contents of the selected message in another window. | |
b8d4c8d0 | 65 | |
b33b68a3 MR |
66 | @cindex terminal screen |
67 | @cindex screen of terminal | |
291d142b CY |
68 | Emacs uses the word ``window'' with a different meaning than in |
69 | graphical desktop environments and window systems, such as the X | |
70 | Window System. When Emacs is run on X, each of its graphical X | |
71 | windows is an Emacs frame (containing one or more Emacs windows). | |
a08a07e3 | 72 | When Emacs is run on a text terminal, the frame fills the entire |
291d142b | 73 | terminal screen. |
b8d4c8d0 | 74 | |
b8d4c8d0 | 75 | @cindex tiled windows |
291d142b CY |
76 | Unlike X windows, Emacs windows are @dfn{tiled}; they never overlap |
77 | within the area of the frame. When a window is created, resized, or | |
78 | deleted, the change in window space is taken from or given to the | |
79 | adjacent windows, so that the total area of the frame is unchanged. | |
b33b68a3 | 80 | |
291d142b CY |
81 | @defun windowp object |
82 | This function returns @code{t} if @var{object} is a window (whether or | |
3a51f0eb | 83 | not it displays a buffer). Otherwise, it returns @code{nil}. |
291d142b | 84 | @end defun |
b33b68a3 | 85 | |
3a51f0eb MR |
86 | @cindex live windows |
87 | A @dfn{live window} is one that is actually displaying a buffer in a | |
88 | frame. | |
89 | ||
b33b68a3 MR |
90 | @defun window-live-p object |
91 | This function returns @code{t} if @var{object} is a live window and | |
291d142b | 92 | @code{nil} otherwise. A live window is one that displays a buffer. |
b33b68a3 MR |
93 | @end defun |
94 | ||
3a51f0eb MR |
95 | @cindex internal windows |
96 | The windows in each frame are organized into a @dfn{window tree}. | |
97 | @xref{Windows and Frames}. The leaf nodes of each window tree are live | |
98 | windows---the ones actually displaying buffers. The internal nodes of | |
99 | the window tree are @dfn{internal windows}, which are not live. | |
100 | ||
101 | @cindex valid windows | |
102 | A @dfn{valid window} is one that is either live or internal. A valid | |
1df7defd | 103 | window can be @dfn{deleted}, i.e., removed from its frame |
3a51f0eb MR |
104 | (@pxref{Deleting Windows}); then it is no longer valid, but the Lisp |
105 | object representing it might be still referenced from other Lisp | |
106 | objects. A deleted window may be made valid again by restoring a saved | |
107 | window configuration (@pxref{Window Configurations}). | |
108 | ||
109 | You can distinguish valid windows from deleted windows with | |
291d142b CY |
110 | @code{window-valid-p}. |
111 | ||
112 | @defun window-valid-p object | |
113 | This function returns @code{t} if @var{object} is a live window, or an | |
114 | internal window in a window tree. Otherwise, it returns @code{nil}, | |
115 | including for the case where @var{object} is a deleted window. | |
b33b68a3 MR |
116 | @end defun |
117 | ||
118 | @cindex selected window | |
7bf54975 | 119 | @cindex window selected within a frame |
291d142b CY |
120 | In each frame, at any time, exactly one Emacs window is designated |
121 | as @dfn{selected within the frame}. For the selected frame, that | |
122 | window is called the @dfn{selected window}---the one in which most | |
123 | editing takes place, and in which the cursor for selected windows | |
124 | appears (@pxref{Cursor Parameters}). The selected window's buffer is | |
125 | usually also the current buffer, except when @code{set-buffer} has | |
126 | been used (@pxref{Current Buffer}). As for non-selected frames, the | |
127 | window selected within the frame becomes the selected window if the | |
128 | frame is ever selected. @xref{Selecting Windows}. | |
b33b68a3 MR |
129 | |
130 | @defun selected-window | |
291d142b CY |
131 | This function returns the selected window (which is always a live |
132 | window). | |
b33b68a3 MR |
133 | @end defun |
134 | ||
b33b68a3 MR |
135 | @node Windows and Frames |
136 | @section Windows and Frames | |
137 | ||
291d142b | 138 | Each window belongs to exactly one frame (@pxref{Frames}). |
b33b68a3 MR |
139 | |
140 | @defun window-frame window | |
291d142b CY |
141 | This function returns the frame that the window @var{window} belongs |
142 | to. If @var{window} is @code{nil}, it defaults to the selected | |
143 | window. | |
b33b68a3 MR |
144 | @end defun |
145 | ||
291d142b CY |
146 | @defun window-list &optional frame minibuffer window |
147 | This function returns a list of live windows belonging to the frame | |
148 | @var{frame}. If @var{frame} is omitted or @code{nil}, it defaults to | |
149 | the selected frame. | |
b33b68a3 | 150 | |
291d142b CY |
151 | The optional argument @var{minibuffer} specifies whether to include |
152 | the minibuffer window in the returned list. If @var{minibuffer} is | |
153 | @code{t}, the minibuffer window is included. If @var{minibuffer} is | |
154 | @code{nil} or omitted, the minibuffer window is included only if it is | |
155 | active. If @var{minibuffer} is neither @code{nil} nor @code{t}, the | |
156 | minibuffer window is never included. | |
b33b68a3 | 157 | |
90151a1e MR |
158 | The optional argument @var{window}, if non-@code{nil}, should be a live |
159 | window on the specified frame; then @var{window} will be the first | |
160 | element in the returned list. If @var{window} is omitted or @code{nil}, | |
161 | the window selected within the frame is the first element. | |
b33b68a3 MR |
162 | @end defun |
163 | ||
164 | @cindex window tree | |
291d142b CY |
165 | @cindex root window |
166 | Windows in the same frame are organized into a @dfn{window tree}, | |
167 | whose leaf nodes are the live windows. The internal nodes of a window | |
168 | tree are not live; they exist for the purpose of organizing the | |
169 | relationships between live windows. The root node of a window tree is | |
170 | called the @dfn{root window}. It can be either a live window (if the | |
171 | frame has just one window), or an internal window. | |
172 | ||
173 | A minibuffer window (@pxref{Minibuffer Windows}) is not part of its | |
174 | frame's window tree unless the frame is a minibuffer-only frame. | |
175 | Nonetheless, most of the functions in this section accept the | |
176 | minibuffer window as an argument. Also, the function | |
177 | @code{window-tree} described at the end of this section lists the | |
178 | minibuffer window alongside the actual window tree. | |
b33b68a3 MR |
179 | |
180 | @defun frame-root-window &optional frame-or-window | |
291d142b CY |
181 | This function returns the root window for @var{frame-or-window}. The |
182 | argument @var{frame-or-window} should be either a window or a frame; | |
183 | if omitted or @code{nil}, it defaults to the selected frame. If | |
184 | @var{frame-or-window} is a window, the return value is the root window | |
185 | of that window's frame. | |
b33b68a3 MR |
186 | @end defun |
187 | ||
291d142b CY |
188 | @cindex parent window |
189 | @cindex child window | |
190 | @cindex sibling window | |
191 | When a window is split, there are two live windows where previously | |
192 | there was one. One of these is represented by the same Lisp window | |
193 | object as the original window, and the other is represented by a | |
194 | newly-created Lisp window object. Both of these live windows become | |
195 | leaf nodes of the window tree, as @dfn{child windows} of a single | |
196 | internal window. If necessary, Emacs automatically creates this | |
197 | internal window, which is also called the @dfn{parent window}, and | |
198 | assigns it to the appropriate position in the window tree. A set of | |
199 | windows that share the same parent are called @dfn{siblings}. | |
b33b68a3 MR |
200 | |
201 | @cindex parent window | |
202 | @defun window-parent &optional window | |
291d142b CY |
203 | This function returns the parent window of @var{window}. If |
204 | @var{window} is omitted or @code{nil}, it defaults to the selected | |
205 | window. The return value is @code{nil} if @var{window} has no parent | |
1df7defd | 206 | (i.e., it is a minibuffer window or the root window of its frame). |
b33b68a3 MR |
207 | @end defun |
208 | ||
291d142b CY |
209 | Each internal window always has at least two child windows. If this |
210 | number falls to one as a result of window deletion, Emacs | |
211 | automatically deletes the internal window, and its sole remaining | |
212 | child window takes its place in the window tree. | |
213 | ||
214 | Each child window can be either a live window, or an internal window | |
215 | (which in turn would have its own child windows). Therefore, each | |
216 | internal window can be thought of as occupying a certain rectangular | |
217 | @dfn{screen area}---the union of the areas occupied by the live | |
218 | windows that are ultimately descended from it. | |
b33b68a3 MR |
219 | |
220 | @cindex window combination | |
221 | @cindex vertical combination | |
222 | @cindex horizontal combination | |
291d142b CY |
223 | For each internal window, the screen areas of the immediate children |
224 | are arranged either vertically or horizontally (never both). If the | |
225 | child windows are arranged one above the other, they are said to form | |
226 | a @dfn{vertical combination}; if they are arranged side by side, they | |
227 | are said to form a @dfn{horizontal combination}. Consider the | |
228 | following example: | |
b33b68a3 MR |
229 | |
230 | @smallexample | |
231 | @group | |
232 | ______________________________________ | |
233 | | ______ ____________________________ | | |
234 | || || __________________________ || | |
291d142b CY |
235 | || ||| ||| |
236 | || ||| ||| | |
237 | || ||| ||| | |
b33b68a3 MR |
238 | || |||____________W4____________||| |
239 | || || __________________________ || | |
240 | || ||| ||| | |
291d142b | 241 | || ||| ||| |
b33b68a3 MR |
242 | || |||____________W5____________||| |
243 | ||__W2__||_____________W3_____________ | | |
244 | |__________________W1__________________| | |
245 | ||
246 | @end group | |
247 | @end smallexample | |
248 | ||
291d142b | 249 | @noindent |
0d4bb04f | 250 | The root window of this frame is an internal window, @var{W1}. Its |
291d142b | 251 | child windows form a horizontal combination, consisting of the live |
0d4bb04f MR |
252 | window @var{W2} and the internal window @var{W3}. The child windows |
253 | of @var{W3} form a vertical combination, consisting of the live | |
254 | windows @var{W4} and @var{W5}. Hence, the live windows in this | |
255 | window tree are @var{W2} @var{W4}, and @var{W5}. | |
291d142b CY |
256 | |
257 | The following functions can be used to retrieve a child window of an | |
258 | internal window, and the siblings of a child window. | |
259 | ||
260 | @defun window-top-child window | |
261 | This function returns the topmost child window of @var{window}, if | |
262 | @var{window} is an internal window whose children form a vertical | |
263 | combination. For any other type of window, the return value is | |
264 | @code{nil}. | |
b33b68a3 MR |
265 | @end defun |
266 | ||
291d142b CY |
267 | @defun window-left-child window |
268 | This function returns the leftmost child window of @var{window}, if | |
269 | @var{window} is an internal window whose children form a horizontal | |
270 | combination. For any other type of window, the return value is | |
271 | @code{nil}. | |
b33b68a3 MR |
272 | @end defun |
273 | ||
274 | @defun window-child window | |
291d142b CY |
275 | This function returns the first child window of the internal window |
276 | @var{window}---the topmost child window for a vertical combination, or | |
277 | the leftmost child window for a horizontal combination. If | |
278 | @var{window} is a live window, the return value is @code{nil}. | |
b33b68a3 MR |
279 | @end defun |
280 | ||
3d8daefe | 281 | @defun window-combined-p &optional window horizontal |
291d142b CY |
282 | This function returns a non-@code{nil} value if and only if |
283 | @var{window} is part of a vertical combination. If @var{window} is | |
e7313f33 | 284 | omitted or @code{nil}, it defaults to the selected one. |
b33b68a3 | 285 | |
291d142b CY |
286 | If the optional argument @var{horizontal} is non-@code{nil}, this |
287 | means to return non-@code{nil} if and only if @var{window} is part of | |
288 | a horizontal combination. | |
b33b68a3 MR |
289 | @end defun |
290 | ||
b33b68a3 | 291 | @defun window-next-sibling &optional window |
291d142b CY |
292 | This function returns the next sibling of the window @var{window}. If |
293 | omitted or @code{nil}, @var{window} defaults to the selected window. | |
294 | The return value is @code{nil} if @var{window} is the last child of | |
295 | its parent. | |
b33b68a3 MR |
296 | @end defun |
297 | ||
298 | @defun window-prev-sibling &optional window | |
291d142b CY |
299 | This function returns the previous sibling of the window @var{window}. |
300 | If omitted or @code{nil}, @var{window} defaults to the selected | |
301 | window. The return value is @code{nil} if @var{window} is the first | |
302 | child of its parent. | |
b33b68a3 MR |
303 | @end defun |
304 | ||
291d142b CY |
305 | The functions @code{window-next-sibling} and |
306 | @code{window-prev-sibling} should not be confused with the functions | |
0b27932b GM |
307 | @code{next-window} and @code{previous-window}, which return the next |
308 | and previous window, respectively, in the cyclic ordering of windows | |
291d142b | 309 | (@pxref{Cyclic Window Ordering}). |
b33b68a3 | 310 | |
0d4bb04f MR |
311 | You can use the following functions to find the first live window on a |
312 | frame and the window nearest to a given window. | |
b33b68a3 MR |
313 | |
314 | @defun frame-first-window &optional frame-or-window | |
315 | This function returns the live window at the upper left corner of the | |
316 | frame specified by @var{frame-or-window}. The argument | |
317 | @var{frame-or-window} must denote a window or a live frame and defaults | |
318 | to the selected frame. If @var{frame-or-window} specifies a window, | |
319 | this function returns the first window on that window's frame. Under | |
320 | the assumption that the frame from our canonical example is selected | |
0d4bb04f | 321 | @code{(frame-first-window)} returns @var{W2}. |
b33b68a3 MR |
322 | @end defun |
323 | ||
0d4bb04f MR |
324 | @cindex window in direction |
325 | @defun window-in-direction direction &optional window ignore | |
326 | This function returns the nearest live window in direction | |
327 | @var{direction} as seen from the position of @code{window-point} in | |
328 | window @var{window}. The argument @var{direction} must be one of | |
329 | @code{above}, @code{below}, @code{left} or @code{right}. The optional | |
330 | argument @var{window} must denote a live window and defaults to the | |
331 | selected one. | |
332 | ||
333 | This function does not return a window whose @code{no-other-window} | |
334 | parameter is non-@code{nil} (@pxref{Window Parameters}). If the nearest | |
335 | window's @code{no-other-window} parameter is non-@code{nil}, this | |
336 | function tries to find another window in the indicated direction whose | |
337 | @code{no-other-window} parameter is @code{nil}. If the optional | |
338 | argument @var{ignore} is non-@code{nil}, a window may be returned even | |
339 | if its @code{no-other-window} parameter is non-@code{nil}. | |
340 | ||
341 | If it doesn't find a suitable window, this function returns @code{nil}. | |
342 | @end defun | |
343 | ||
344 | The following function allows to retrieve the entire window tree of a | |
345 | frame: | |
346 | ||
b33b68a3 | 347 | @defun window-tree &optional frame |
291d142b CY |
348 | This function returns a list representing the window tree for frame |
349 | @var{frame}. If @var{frame} is omitted or @code{nil}, it defaults to | |
350 | the selected frame. | |
b33b68a3 MR |
351 | |
352 | The return value is a list of the form @code{(@var{root} @var{mini})}, | |
291d142b CY |
353 | where @var{root} represents the window tree of the frame's root |
354 | window, and @var{mini} is the frame's minibuffer window. | |
b33b68a3 | 355 | |
291d142b CY |
356 | If the root window is live, @var{root} is that window itself. |
357 | Otherwise, @var{root} is a list @code{(@var{dir} @var{edges} @var{w1} | |
358 | @var{w2} ...)} where @var{dir} is @code{nil} for a horizontal | |
359 | combination and @code{t} for a vertical combination, @var{edges} gives | |
360 | the size and position of the combination, and the remaining elements | |
361 | are the child windows. Each child window may again be a window object | |
362 | (for a live window) or a list with the same format as above (for an | |
363 | internal window). The @var{edges} element is a list @code{(@var{left} | |
364 | @var{top} @var{right} @var{bottom})}, similar to the value returned by | |
365 | @code{window-edges} (@pxref{Coordinates and Windows}). | |
b33b68a3 MR |
366 | @end defun |
367 | ||
b33b68a3 MR |
368 | @node Window Sizes |
369 | @section Window Sizes | |
370 | @cindex window size | |
371 | @cindex size of window | |
372 | ||
a79db6e0 | 373 | The following schematic shows the structure of a live window: |
b33b68a3 MR |
374 | |
375 | @smallexample | |
376 | @group | |
a79db6e0 CY |
377 | _________________________________________ |
378 | ^ |______________ Header Line_______________| | |
b33b68a3 MR |
379 | | |LS|LF|LM| |RM|RF|RS| ^ |
380 | | | | | | | | | | | | |
381 | Window | | | | Text Area | | | | Window | |
382 | Total | | | | (Window Body) | | | | Body | |
383 | Height | | | | | | | | Height | |
384 | | | | | |<- Window Body Width ->| | | | | | |
385 | | |__|__|__|_______________________|__|__|__| v | |
386 | v |_______________ Mode Line _______________| | |
387 | ||
388 | <----------- Window Total Width --------> | |
389 | ||
390 | @end group | |
391 | @end smallexample | |
392 | ||
393 | @cindex window body | |
a79db6e0 | 394 | @cindex text area of a window |
b33b68a3 | 395 | @cindex body of a window |
a79db6e0 CY |
396 | At the center of the window is the @dfn{text area}, or @dfn{body}, |
397 | where the buffer text is displayed. On each side of the text area is | |
398 | a series of vertical areas; from innermost to outermost, these are the | |
399 | left and right margins, denoted by LM and RM in the schematic | |
400 | (@pxref{Display Margins}); the left and right fringes, denoted by LF | |
401 | and RF (@pxref{Fringes}); and the left or right scroll bar, only one of | |
402 | which is present at any time, denoted by LS and RS (@pxref{Scroll | |
403 | Bars}). At the top of the window is an optional header line | |
404 | (@pxref{Header Lines}), and at the bottom of the window is the mode | |
405 | line (@pxref{Mode Line Format}). | |
406 | ||
407 | Emacs provides several functions for finding the height and width of | |
1c3d7a13 | 408 | a window. Except where noted, Emacs reports window heights and widths |
0b27932b | 409 | as integer numbers of lines and columns, respectively. On a graphical |
d2ad7ee1 CY |
410 | display, each ``line'' and ``column'' actually corresponds to the |
411 | height and width of a ``default'' character specified by the frame's | |
412 | default font. Thus, if a window is displaying text with a different | |
413 | font or size, the reported height and width for that window may differ | |
414 | from the actual number of text lines or columns displayed within it. | |
b33b68a3 MR |
415 | |
416 | @cindex window height | |
b33b68a3 MR |
417 | @cindex height of a window |
418 | @cindex total height of a window | |
b33b68a3 | 419 | @cindex window width |
b33b68a3 MR |
420 | @cindex width of a window |
421 | @cindex total width of a window | |
a79db6e0 CY |
422 | The @dfn{total height} of a window is the distance between the top |
423 | and bottom of the window, including the header line (if one exists) | |
424 | and the mode line. The @dfn{total width} of a window is the distance | |
425 | between the left and right edges of the mode line. Note that the | |
426 | height of a frame is not the same as the height of its windows, since | |
427 | a frame may also contain an echo area, menu bar, and tool bar | |
428 | (@pxref{Size and Position}). | |
b33b68a3 MR |
429 | |
430 | @defun window-total-height &optional window | |
a79db6e0 CY |
431 | This function returns the total height, in lines, of the window |
432 | @var{window}. If @var{window} is omitted or @code{nil}, it defaults | |
433 | to the selected window. If @var{window} is an internal window, the | |
434 | return value is the total height occupied by its descendant windows. | |
b33b68a3 MR |
435 | @end defun |
436 | ||
437 | @defun window-total-width &optional window | |
a79db6e0 CY |
438 | This function returns the total width, in columns, of the window |
439 | @var{window}. If @var{window} is omitted or @code{nil}, it defaults | |
440 | to the selected window. If @var{window} is internal, the return value | |
441 | is the total width occupied by its descendant windows. | |
442 | @end defun | |
b33b68a3 | 443 | |
a79db6e0 CY |
444 | @defun window-total-size &optional window horizontal |
445 | This function returns either the total height or width of the window | |
446 | @var{window}. If @var{horizontal} is omitted or @code{nil}, this is | |
447 | equivalent to calling @code{window-total-height} for @var{window}; | |
448 | otherwise it is equivalent to calling @code{window-total-width} for | |
449 | @var{window}. | |
b33b68a3 MR |
450 | @end defun |
451 | ||
452 | @cindex full-width window | |
a79db6e0 CY |
453 | @cindex full-height window |
454 | The following functions can be used to determine whether a given | |
455 | window has any adjacent windows. | |
456 | ||
457 | @defun window-full-height-p &optional window | |
458 | This function returns non-@code{nil} if @var{window} has no other | |
1df7defd | 459 | window above or below it in its frame, i.e., its total height equals |
a79db6e0 CY |
460 | the total height of the root window on that frame. If @var{window} is |
461 | omitted or @code{nil}, it defaults to the selected window. | |
462 | @end defun | |
b33b68a3 MR |
463 | |
464 | @defun window-full-width-p &optional window | |
a79db6e0 | 465 | This function returns non-@code{nil} if @var{window} has no other |
1df7defd | 466 | window to the left or right in its frame, i.e., its total width equals |
a79db6e0 CY |
467 | that of the root window on that frame. If @var{window} is omitted or |
468 | @code{nil}, it defaults to the selected window. | |
b33b68a3 MR |
469 | @end defun |
470 | ||
b33b68a3 MR |
471 | @cindex window body height |
472 | @cindex body height of a window | |
b33b68a3 MR |
473 | @cindex window body width |
474 | @cindex body width of a window | |
b33b68a3 MR |
475 | @cindex body size of a window |
476 | @cindex window body size | |
a79db6e0 CY |
477 | The @dfn{body height} of a window is the height of its text area, |
478 | which does not include the mode or header line. Similarly, the | |
479 | @dfn{body width} is the width of the text area, which does not include | |
480 | the scroll bar, fringes, or margins. | |
b33b68a3 MR |
481 | |
482 | @defun window-body-height &optional window | |
a79db6e0 CY |
483 | This function returns the body height, in lines, of the window |
484 | @var{window}. If @var{window} is omitted or @code{nil}, it defaults | |
485 | to the selected window; otherwise it must be a live window. | |
b33b68a3 | 486 | |
a79db6e0 CY |
487 | If there is a partially-visible line at the bottom of the text area, |
488 | that counts as a whole line; to exclude such a partially-visible line, | |
489 | use @code{window-text-height}, below. | |
b33b68a3 MR |
490 | @end defun |
491 | ||
492 | @defun window-body-width &optional window | |
a79db6e0 CY |
493 | This function returns the body width, in columns, of the window |
494 | @var{window}. If @var{window} is omitted or @code{nil}, it defaults | |
495 | to the selected window; otherwise it must be a live window. | |
b33b68a3 MR |
496 | @end defun |
497 | ||
a79db6e0 CY |
498 | @defun window-body-size &optional window horizontal |
499 | This function returns the body height or body width of @var{window}. | |
500 | If @var{horizontal} is omitted or @code{nil}, it is equivalent to | |
501 | calling @code{window-body-height} for @var{window}; otherwise it is | |
502 | equivalent to calling @code{window-body-width}. | |
b33b68a3 MR |
503 | @end defun |
504 | ||
a79db6e0 CY |
505 | @defun window-text-height &optional window |
506 | This function is like @code{window-body-height}, except that any | |
507 | partially-visible line at the bottom of the text area is not counted. | |
b33b68a3 MR |
508 | @end defun |
509 | ||
a79db6e0 | 510 | For compatibility with previous versions of Emacs, |
182148ee | 511 | @code{window-height} is an alias for @code{window-total-height}, and |
a79db6e0 CY |
512 | @code{window-width} is an alias for @code{window-body-width}. These |
513 | aliases are considered obsolete and will be removed in the future. | |
b33b68a3 MR |
514 | |
515 | @cindex fixed-size window | |
6439ae19 GM |
516 | @vindex window-min-height |
517 | @vindex window-min-width | |
a79db6e0 CY |
518 | Commands that change the size of windows (@pxref{Resizing Windows}), |
519 | or split them (@pxref{Splitting Windows}), obey the variables | |
520 | @code{window-min-height} and @code{window-min-width}, which specify | |
521 | the smallest allowable window height and width. @xref{Change | |
522 | Window,,Deleting and Rearranging Windows, emacs, The GNU Emacs | |
523 | Manual}. They also obey the variable @code{window-size-fixed}, with | |
524 | which a window can be @dfn{fixed} in size: | |
525 | ||
b33b68a3 | 526 | @defvar window-size-fixed |
a79db6e0 CY |
527 | If this buffer-local variable is non-@code{nil}, the size of any |
528 | window displaying the buffer cannot normally be changed. Deleting a | |
529 | window or changing the frame's size may still change its size, if | |
530 | there is no choice. | |
b33b68a3 MR |
531 | |
532 | If the value is @code{height}, then only the window's height is fixed; | |
533 | if the value is @code{width}, then only the window's width is fixed. | |
534 | Any other non-@code{nil} value fixes both the width and the height. | |
b33b68a3 MR |
535 | @end defvar |
536 | ||
b33b68a3 | 537 | @defun window-size-fixed-p &optional window horizontal |
a79db6e0 CY |
538 | This function returns a non-@code{nil} value if @var{window}'s height |
539 | is fixed. If @var{window} is omitted or @code{nil}, it defaults to | |
540 | the selected window. If the optional argument @var{horizontal} is | |
541 | non-@code{nil}, the return value is non-@code{nil} if @var{window}'s | |
542 | width is fixed. | |
b33b68a3 | 543 | |
a79db6e0 CY |
544 | A @code{nil} return value does not necessarily mean that @var{window} |
545 | can be resized in the desired direction. To determine that, use the | |
546 | function @code{window-resizable}. @xref{Resizing Windows}. | |
b33b68a3 MR |
547 | @end defun |
548 | ||
1c3d7a13 CY |
549 | @xref{Coordinates and Windows}, for more functions that report the |
550 | positions of various parts of a window relative to the frame, from | |
551 | which you can calculate its size. In particular, you can use the | |
552 | functions @code{window-pixel-edges} and | |
553 | @code{window-inside-pixel-edges} to find the size in pixels, for | |
554 | graphical displays. | |
b33b68a3 MR |
555 | |
556 | @node Resizing Windows | |
557 | @section Resizing Windows | |
558 | @cindex window resizing | |
559 | @cindex resize window | |
560 | @cindex changing window size | |
561 | @cindex window size, changing | |
562 | ||
e7313f33 CY |
563 | This section describes functions for resizing a window without |
564 | changing the size of its frame. Because live windows do not overlap, | |
565 | these functions are meaningful only on frames that contain two or more | |
566 | windows: resizing a window also changes the size of a neighboring | |
567 | window. If there is just one window on a frame, its size cannot be | |
568 | changed except by resizing the frame (@pxref{Size and Position}). | |
569 | ||
570 | Except where noted, these functions also accept internal windows as | |
571 | arguments. Resizing an internal window causes its child windows to be | |
572 | resized to fit the same space. | |
b33b68a3 | 573 | |
2cffd681 | 574 | @defun window-resizable window delta &optional horizontal ignore |
b33b68a3 | 575 | This function returns @var{delta} if the size of @var{window} can be |
e7313f33 CY |
576 | changed vertically by @var{delta} lines. If the optional argument |
577 | @var{horizontal} is non-@code{nil}, it instead returns @var{delta} if | |
578 | @var{window} can be resized horizontally by @var{delta} columns. It | |
579 | does not actually change the window size. | |
580 | ||
581 | If @var{window} is @code{nil}, it defaults to the selected window. | |
582 | ||
2cffd681 MR |
583 | A positive value of @var{delta} means to check whether the window can be |
584 | enlarged by that number of lines or columns; a negative value of | |
585 | @var{delta} means to check whether the window can be shrunk by that many | |
586 | lines or columns. If @var{delta} is non-zero, a return value of 0 means | |
587 | that the window cannot be resized. | |
e7313f33 CY |
588 | |
589 | Normally, the variables @code{window-min-height} and | |
590 | @code{window-min-width} specify the smallest allowable window size. | |
591 | @xref{Change Window,, Deleting and Rearranging Windows, emacs, The GNU | |
592 | Emacs Manual}. However, if the optional argument @var{ignore} is | |
593 | non-@code{nil}, this function ignores @code{window-min-height} and | |
594 | @code{window-min-width}, as well as @code{window-size-fixed}. | |
595 | Instead, it considers the minimum-height window to be one consisting | |
596 | of a header (if any), a mode line, plus a text area one line tall; and | |
597 | a minimum-width window as one consisting of fringes, margins, and | |
598 | scroll bar (if any), plus a text area two columns wide. | |
b33b68a3 MR |
599 | @end defun |
600 | ||
b33b68a3 | 601 | @defun window-resize window delta &optional horizontal ignore |
e7313f33 CY |
602 | This function resizes @var{window} by @var{delta} increments. If |
603 | @var{horizontal} is @code{nil}, it changes the height by @var{delta} | |
604 | lines; otherwise, it changes the width by @var{delta} columns. A | |
605 | positive @var{delta} means to enlarge the window, and a negative | |
606 | @var{delta} means to shrink it. | |
607 | ||
608 | If @var{window} is @code{nil}, it defaults to the selected window. If | |
609 | the window cannot be resized as demanded, an error is signaled. | |
610 | ||
611 | The optional argument @var{ignore} has the same meaning as for the | |
612 | function @code{window-resizable} above. | |
613 | ||
b6f67890 | 614 | The choice of which window edges this function alters depends on the |
a0c2d0ae | 615 | values of the option @code{window-combination-resize} and the |
d2999b1a | 616 | combination limits of the involved windows; in some cases, it may alter |
fdaf534a | 617 | both edges. @xref{Recombining Windows}. To resize by moving only the |
d2999b1a | 618 | bottom or right edge of a window, use the function |
a0c2d0ae | 619 | @code{adjust-window-trailing-edge}, below. |
b8d4c8d0 GM |
620 | @end defun |
621 | ||
e7313f33 CY |
622 | @c The commands enlarge-window, enlarge-window-horizontally, |
623 | @c shrink-window, and shrink-window-horizontally are documented in the | |
624 | @c Emacs manual. They are not preferred for calling from Lisp. | |
b33b68a3 | 625 | |
b33b68a3 MR |
626 | @defun adjust-window-trailing-edge window delta &optional horizontal |
627 | This function moves @var{window}'s bottom edge by @var{delta} lines. | |
d2ad7ee1 CY |
628 | If optional argument @var{horizontal} is non-@code{nil}, it instead |
629 | moves the right edge by @var{delta} columns. If @var{window} is | |
630 | @code{nil}, it defaults to the selected window. | |
b33b68a3 | 631 | |
d2ad7ee1 CY |
632 | A positive @var{delta} moves the edge downwards or to the right; a |
633 | negative @var{delta} moves it upwards or to the left. If the edge | |
634 | cannot be moved as far as specified by @var{delta}, this function | |
635 | moves it as far as possible but does not signal a error. | |
b33b68a3 MR |
636 | |
637 | This function tries to resize windows adjacent to the edge that is | |
1df7defd | 638 | moved. If this is not possible for some reason (e.g., if that adjacent |
d2ad7ee1 | 639 | window is fixed-size), it may resize other windows. |
b33b68a3 MR |
640 | @end defun |
641 | ||
d2ad7ee1 CY |
642 | The following commands resize windows in more specific ways. When |
643 | called interactively, they act on the selected window. | |
644 | ||
b33b68a3 | 645 | @deffn Command fit-window-to-buffer &optional window max-height min-height override |
d2ad7ee1 CY |
646 | This command adjusts the height of @var{window} to fit the text in it. |
647 | It returns non-@code{nil} if it was able to resize @var{window}, and | |
648 | @code{nil} otherwise. If @var{window} is omitted or @code{nil}, it | |
649 | defaults to the selected window. Otherwise, it should be a live | |
650 | window. | |
651 | ||
652 | The optional argument @var{max-height}, if non-@code{nil}, specifies | |
653 | the maximum total height that this function can give @var{window}. | |
0b27932b | 654 | The optional argument @var{min-height}, if non-@code{nil}, specifies |
d2ad7ee1 CY |
655 | the minimum total height that it can give, which overrides the |
656 | variable @code{window-min-height}. | |
657 | ||
658 | If the optional argument @var{override} is non-@code{nil}, this | |
659 | function ignores any size restrictions imposed by | |
660 | @code{window-min-height} and @code{window-min-width}. | |
6439ae19 GM |
661 | |
662 | @vindex fit-frame-to-buffer | |
663 | If the option @code{fit-frame-to-buffer} is non-@code{nil}, this | |
664 | command may resize the frame to fit its contents. | |
b33b68a3 MR |
665 | @end deffn |
666 | ||
667 | @deffn Command shrink-window-if-larger-than-buffer &optional window | |
d2ad7ee1 CY |
668 | This command attempts to reduce @var{window}'s height as much as |
669 | possible while still showing its full buffer, but no less than | |
670 | @code{window-min-height} lines. The return value is non-@code{nil} if | |
671 | the window was resized, and @code{nil} otherwise. If @var{window} is | |
672 | omitted or @code{nil}, it defaults to the selected window. Otherwise, | |
673 | it should be a live window. | |
674 | ||
675 | This command does nothing if the window is already too short to | |
676 | display all of its buffer, or if any of the buffer is scrolled | |
677 | off-screen, or if the window is the only live window in its frame. | |
b33b68a3 MR |
678 | @end deffn |
679 | ||
680 | @cindex balancing window sizes | |
b33b68a3 MR |
681 | @deffn Command balance-windows &optional window-or-frame |
682 | This function balances windows in a way that gives more space to | |
683 | full-width and/or full-height windows. If @var{window-or-frame} | |
684 | specifies a frame, it balances all windows on that frame. If | |
d2ad7ee1 CY |
685 | @var{window-or-frame} specifies a window, it balances only that window |
686 | and its siblings (@pxref{Windows and Frames}). | |
b33b68a3 MR |
687 | @end deffn |
688 | ||
689 | @deffn Command balance-windows-area | |
690 | This function attempts to give all windows on the selected frame | |
d2ad7ee1 CY |
691 | approximately the same share of the screen area. Full-width or |
692 | full-height windows are not given more space than other windows. | |
b33b68a3 MR |
693 | @end deffn |
694 | ||
695 | @cindex maximizing windows | |
b33b68a3 | 696 | @deffn Command maximize-window &optional window |
d2ad7ee1 CY |
697 | This function attempts to make @var{window} as large as possible, in |
698 | both dimensions, without resizing its frame or deleting other windows. | |
699 | If @var{window} is omitted or @code{nil}, it defaults to the selected | |
700 | window. | |
b33b68a3 MR |
701 | @end deffn |
702 | ||
703 | @cindex minimizing windows | |
b33b68a3 | 704 | @deffn Command minimize-window &optional window |
d2ad7ee1 CY |
705 | This function attempts to make @var{window} as small as possible, in |
706 | both dimensions, without deleting it or resizing its frame. If | |
707 | @var{window} is omitted or @code{nil}, it defaults to the selected | |
708 | window. | |
b33b68a3 MR |
709 | @end deffn |
710 | ||
711 | ||
b8d4c8d0 GM |
712 | @node Splitting Windows |
713 | @section Splitting Windows | |
714 | @cindex splitting windows | |
715 | @cindex window splitting | |
716 | ||
f6f6d7e7 CY |
717 | This section describes functions for creating a new window by |
718 | @dfn{splitting} an existing one. | |
b8d4c8d0 | 719 | |
0aa3616e | 720 | @defun split-window &optional window size side |
f6f6d7e7 CY |
721 | This function creates a new live window next to the window |
722 | @var{window}. If @var{window} is omitted or @code{nil}, it defaults | |
723 | to the selected window. That window is ``split'', and reduced in | |
724 | size. The space is taken up by the new window, which is returned. | |
725 | ||
d2ad7ee1 | 726 | The optional second argument @var{size} determines the sizes of |
f6f6d7e7 CY |
727 | @var{window} and/or the new window. If it is omitted or @code{nil}, |
728 | both windows are given equal sizes; if there is an odd line, it is | |
729 | allocated to the new window. If @var{size} is a positive number, | |
730 | @var{window} is given @var{size} lines (or columns, depending on the | |
731 | value of @var{side}). If @var{size} is a negative number, the new | |
732 | window is given @minus{}@var{size} lines (or columns). | |
733 | ||
734 | If @var{size} is @code{nil}, this function obeys the variables | |
735 | @code{window-min-height} and @code{window-min-width}. @xref{Change | |
736 | Window,,Deleting and Rearranging Windows, emacs, The GNU Emacs | |
737 | Manual}. Thus, it signals an error if splitting would result in | |
738 | making a window smaller than those variables specify. However, a | |
739 | non-@code{nil} value for @var{size} causes those variables to be | |
740 | ignored; in that case, the smallest allowable window is considered to | |
741 | be one that has space for a text area one line tall and/or two columns | |
742 | wide. | |
743 | ||
744 | The optional third argument @var{side} determines the position of the | |
745 | new window relative to @var{window}. If it is @code{nil} or | |
746 | @code{below}, the new window is placed below @var{window}. If it is | |
747 | @code{above}, the new window is placed above @var{window}. In both | |
748 | these cases, @var{size} specifies a total window height, in lines. | |
749 | ||
750 | If @var{side} is @code{t} or @code{right}, the new window is placed on | |
751 | the right of @var{window}. If @var{side} is @code{left}, the new | |
752 | window is placed on the left of @var{window}. In both these cases, | |
753 | @var{size} specifies a total window width, in columns. | |
754 | ||
755 | If @var{window} is a live window, the new window inherits various | |
756 | properties from it, including margins and scroll bars. If | |
757 | @var{window} is an internal window, the new window inherits the | |
758 | properties of the window selected within @var{window}'s frame. | |
759 | ||
7bf54975 CY |
760 | The behavior of this function may be altered by the window parameters |
761 | of @var{window}, so long as the variable | |
0b27932b | 762 | @code{ignore-window-parameters} is @code{nil}. If the value of |
7bf54975 CY |
763 | the @code{split-window} window parameter is @code{t}, this function |
764 | ignores all other window parameters. Otherwise, if the value of the | |
765 | @code{split-window} window parameter is a function, that function is | |
766 | called with the arguments @var{window}, @var{size}, and @var{side}, in | |
767 | lieu of the usual action of @code{split-window}. Otherwise, this | |
768 | function obeys the @code{window-atom} or @code{window-side} window | |
769 | parameter, if any. @xref{Window Parameters}. | |
0aa3616e | 770 | @end defun |
b8d4c8d0 | 771 | |
7bf54975 CY |
772 | As an example, here is a sequence of @code{split-window} calls that |
773 | yields the window configuration discussed in @ref{Windows and Frames}. | |
774 | This example demonstrates splitting a live window as well as splitting | |
775 | an internal window. We begin with a frame containing a single window | |
776 | (a live root window), which we denote by @var{W4}. Calling | |
90151a1e | 777 | @code{(split-window W4)} yields this window configuration: |
b33b68a3 | 778 | |
b33b68a3 MR |
779 | @smallexample |
780 | @group | |
781 | ______________________________________ | |
782 | | ____________________________________ | | |
783 | || || | |
784 | || || | |
785 | || || | |
f6f6d7e7 CY |
786 | ||_________________W4_________________|| |
787 | | ____________________________________ | | |
b33b68a3 MR |
788 | || || |
789 | || || | |
790 | || || | |
b33b68a3 MR |
791 | ||_________________W5_________________|| |
792 | |__________________W3__________________| | |
793 | ||
794 | @end group | |
795 | @end smallexample | |
796 | ||
f6f6d7e7 CY |
797 | @noindent |
798 | The @code{split-window} call has created a new live window, denoted by | |
799 | @var{W5}. It has also created a new internal window, denoted by | |
800 | @var{W3}, which becomes the root window and the parent of both | |
801 | @var{W4} and @var{W5}. | |
b33b68a3 | 802 | |
f6f6d7e7 CY |
803 | Next, we call @code{(split-window W3 nil 'left)}, passing the |
804 | internal window @var{W3} as the argument. The result: | |
b33b68a3 | 805 | |
b33b68a3 MR |
806 | @smallexample |
807 | @group | |
808 | ______________________________________ | |
809 | | ______ ____________________________ | | |
f6f6d7e7 CY |
810 | || || __________________________ || |
811 | || ||| ||| | |
812 | || ||| ||| | |
813 | || ||| ||| | |
814 | || |||____________W4____________||| | |
815 | || || __________________________ || | |
816 | || ||| ||| | |
817 | || ||| ||| | |
818 | || |||____________W5____________||| | |
819 | ||__W2__||_____________W3_____________ | | |
b33b68a3 | 820 | |__________________W1__________________| |
b33b68a3 MR |
821 | @end group |
822 | @end smallexample | |
823 | ||
f6f6d7e7 | 824 | @noindent |
d2ad7ee1 CY |
825 | A new live window @var{W2} is created, to the left of the internal |
826 | window @var{W3}. A new internal window @var{W1} is created, becoming | |
827 | the new root window. | |
b33b68a3 | 828 | |
fdaf534a MR |
829 | For interactive use, Emacs provides two commands which always split |
830 | the selected window. These call @code{split-window} internally. | |
454592a6 | 831 | |
fdaf534a MR |
832 | @deffn Command split-window-right &optional size |
833 | This function splits the selected window into two side-by-side | |
834 | windows, putting the selected window on the left. If @var{size} is | |
835 | positive, the left window gets @var{size} columns; if @var{size} is | |
836 | negative, the right window gets @minus{}@var{size} columns. | |
837 | @end deffn | |
454592a6 | 838 | |
fdaf534a MR |
839 | @deffn Command split-window-below &optional size |
840 | This function splits the selected window into two windows, one above | |
841 | the other, leaving the upper window selected. If @var{size} is | |
842 | positive, the upper window gets @var{size} lines; if @var{size} is | |
843 | negative, the lower window gets @minus{}@var{size} lines. | |
844 | @end deffn | |
845 | ||
846 | @defopt split-window-keep-point | |
847 | If the value of this variable is non-@code{nil} (the default), | |
848 | @code{split-window-below} behaves as described above. | |
849 | ||
850 | If it is @code{nil}, @code{split-window-below} adjusts point in each | |
851 | of the two windows to minimize redisplay. (This is useful on slow | |
852 | terminals.) It selects whichever window contains the screen line that | |
853 | point was previously on. Note that this only affects | |
854 | @code{split-window-below}, not the lower-level @code{split-window} | |
855 | function. | |
89d61221 | 856 | @end defopt |
b33b68a3 | 857 | |
fdaf534a MR |
858 | @node Deleting Windows |
859 | @section Deleting Windows | |
860 | @cindex deleting windows | |
861 | ||
862 | @dfn{Deleting} a window removes it from the frame's window tree. If | |
863 | the window is a live window, it disappears from the screen. If the | |
864 | window is an internal window, its child windows are deleted too. | |
865 | ||
866 | Even after a window is deleted, it continues to exist as a Lisp | |
867 | object, until there are no more references to it. Window deletion can | |
868 | be reversed, by restoring a saved window configuration (@pxref{Window | |
869 | Configurations}). | |
870 | ||
871 | @deffn Command delete-window &optional window | |
872 | This function removes @var{window} from display and returns | |
873 | @code{nil}. If @var{window} is omitted or @code{nil}, it defaults to | |
874 | the selected window. If deleting the window would leave no more | |
1df7defd | 875 | windows in the window tree (e.g., if it is the only live window in the |
fdaf534a MR |
876 | frame), an error is signaled. |
877 | ||
878 | By default, the space taken up by @var{window} is given to one of its | |
879 | adjacent sibling windows, if any. However, if the variable | |
880 | @code{window-combination-resize} is non-@code{nil}, the space is | |
881 | proportionally distributed among any remaining windows in the window | |
882 | combination. @xref{Recombining Windows}. | |
883 | ||
884 | The behavior of this function may be altered by the window parameters | |
885 | of @var{window}, so long as the variable | |
886 | @code{ignore-window-parameters} is @code{nil}. If the value of | |
887 | the @code{delete-window} window parameter is @code{t}, this function | |
888 | ignores all other window parameters. Otherwise, if the value of the | |
889 | @code{delete-window} window parameter is a function, that function is | |
890 | called with the argument @var{window}, in lieu of the usual action of | |
891 | @code{delete-window}. Otherwise, this function obeys the | |
892 | @code{window-atom} or @code{window-side} window parameter, if any. | |
893 | @xref{Window Parameters}. | |
894 | @end deffn | |
895 | ||
896 | @deffn Command delete-other-windows &optional window | |
897 | This function makes @var{window} fill its frame, by deleting other | |
898 | windows as necessary. If @var{window} is omitted or @code{nil}, it | |
899 | defaults to the selected window. The return value is @code{nil}. | |
900 | ||
901 | The behavior of this function may be altered by the window parameters | |
902 | of @var{window}, so long as the variable | |
903 | @code{ignore-window-parameters} is @code{nil}. If the value of | |
904 | the @code{delete-other-windows} window parameter is @code{t}, this | |
905 | function ignores all other window parameters. Otherwise, if the value | |
906 | of the @code{delete-other-windows} window parameter is a function, | |
907 | that function is called with the argument @var{window}, in lieu of the | |
908 | usual action of @code{delete-other-windows}. Otherwise, this function | |
909 | obeys the @code{window-atom} or @code{window-side} window parameter, | |
910 | if any. @xref{Window Parameters}. | |
911 | @end deffn | |
912 | ||
913 | @deffn Command delete-windows-on &optional buffer-or-name frame | |
914 | This function deletes all windows showing @var{buffer-or-name}, by | |
915 | calling @code{delete-window} on those windows. @var{buffer-or-name} | |
916 | should be a buffer, or the name of a buffer; if omitted or @code{nil}, | |
917 | it defaults to the current buffer. If there are no windows showing | |
918 | the specified buffer, this function does nothing. If the specified | |
919 | buffer is a minibuffer, an error is signaled. | |
920 | ||
921 | If there is a dedicated window showing the buffer, and that window is | |
922 | the only one on its frame, this function also deletes that frame if it | |
923 | is not the only frame on the terminal. | |
924 | ||
925 | The optional argument @var{frame} specifies which frames to operate | |
926 | on: | |
927 | ||
928 | @itemize @bullet | |
929 | @item @code{nil} | |
930 | means operate on all frames. | |
931 | @item @code{t} | |
932 | means operate on the selected frame. | |
933 | @item @code{visible} | |
934 | means operate on all visible frames. | |
935 | @item @code{0} | |
936 | means operate on all visible or iconified frames. | |
937 | @item A frame | |
938 | means operate on that frame. | |
939 | @end itemize | |
940 | ||
941 | Note that this argument does not have the same meaning as in other | |
942 | functions which scan all live windows (@pxref{Cyclic Window | |
943 | Ordering}). Specifically, the meanings of @code{t} and @code{nil} here | |
944 | are the opposite of what they are in those other functions. | |
945 | @end deffn | |
946 | ||
947 | ||
948 | @node Recombining Windows | |
949 | @section Recombining Windows | |
950 | ||
0d4bb04f MR |
951 | When deleting the last sibling of a window @var{W}, its parent window |
952 | is deleted too, with @var{W} replacing it in the window tree. This | |
953 | means that @var{W} must be recombined with its parent's siblings to | |
fdaf534a MR |
954 | form a new window combination (@pxref{Windows and Frames}). In some |
955 | occasions, deleting a live window may even entail the deletion of two | |
956 | internal windows. | |
957 | ||
958 | @smallexample | |
959 | @group | |
960 | ______________________________________ | |
961 | | ______ ____________________________ | | |
962 | || || __________________________ || | |
963 | || ||| ___________ ___________ ||| | |
964 | || |||| || |||| | |
965 | || ||||____W6_____||_____W7____|||| | |
966 | || |||____________W4____________||| | |
967 | || || __________________________ || | |
968 | || ||| ||| | |
969 | || ||| ||| | |
970 | || |||____________W5____________||| | |
971 | ||__W2__||_____________W3_____________ | | |
972 | |__________________W1__________________| | |
973 | ||
974 | @end group | |
975 | @end smallexample | |
976 | ||
977 | @noindent | |
0d4bb04f MR |
978 | Deleting @var{W5} in this configuration normally causes the deletion of |
979 | @var{W3} and @var{W4}. The remaining live windows @var{W2}, | |
980 | @var{W6} and @var{W7} are recombined to form a new horizontal | |
981 | combination with parent @var{W1}. | |
fdaf534a MR |
982 | |
983 | Sometimes, however, it makes sense to not delete a parent window like | |
0d4bb04f | 984 | @var{W4}. In particular, a parent window should not be removed when it |
fdaf534a MR |
985 | was used to preserve a combination embedded in a combination of the same |
986 | type. Such embeddings make sense to assure that when you split a window | |
987 | and subsequently delete the new window, Emacs reestablishes the layout | |
988 | of the associated frame as it existed before the splitting. | |
989 | ||
0d4bb04f MR |
990 | Consider a scenario starting with two live windows @var{W2} and |
991 | @var{W3} and their parent @var{W1}. | |
7bf54975 | 992 | |
b33b68a3 MR |
993 | @smallexample |
994 | @group | |
995 | ______________________________________ | |
996 | | ____________________________________ | | |
997 | || || | |
998 | || || | |
999 | || || | |
1000 | || || | |
b33b68a3 MR |
1001 | || || |
1002 | || || | |
fdaf534a MR |
1003 | ||_________________W2_________________|| |
1004 | | ____________________________________ | | |
b33b68a3 MR |
1005 | || || |
1006 | || || | |
1007 | ||_________________W3_________________|| | |
1008 | |__________________W1__________________| | |
1009 | ||
1010 | @end group | |
1011 | @end smallexample | |
1012 | ||
7bf54975 | 1013 | @noindent |
0d4bb04f | 1014 | Split @var{W2} to make a new window @var{W4} as follows. |
7bf54975 | 1015 | |
b33b68a3 MR |
1016 | @smallexample |
1017 | @group | |
1018 | ______________________________________ | |
1019 | | ____________________________________ | | |
1020 | || || | |
1021 | || || | |
b33b68a3 MR |
1022 | ||_________________W2_________________|| |
1023 | | ____________________________________ | | |
1024 | || || | |
b33b68a3 MR |
1025 | || || |
1026 | ||_________________W4_________________|| | |
fdaf534a MR |
1027 | | ____________________________________ | |
1028 | || || | |
1029 | || || | |
1030 | ||_________________W3_________________|| | |
b33b68a3 MR |
1031 | |__________________W1__________________| |
1032 | ||
1033 | @end group | |
1034 | @end smallexample | |
1035 | ||
7bf54975 | 1036 | @noindent |
fdaf534a MR |
1037 | Now, when enlarging a window vertically, Emacs tries to obtain the |
1038 | corresponding space from its lower sibling, provided such a window | |
0d4bb04f MR |
1039 | exists. In our scenario, enlarging @var{W4} will steal space from |
1040 | @var{W3}. | |
7bf54975 | 1041 | |
b33b68a3 MR |
1042 | @smallexample |
1043 | @group | |
1044 | ______________________________________ | |
1045 | | ____________________________________ | | |
1046 | || || | |
1047 | || || | |
1048 | ||_________________W2_________________|| | |
1049 | | ____________________________________ | | |
1050 | || || | |
1051 | || || | |
fdaf534a MR |
1052 | || || |
1053 | || || | |
1054 | ||_________________W4_________________|| | |
1055 | | ____________________________________ | | |
b33b68a3 | 1056 | ||_________________W3_________________|| |
fdaf534a MR |
1057 | |__________________W1__________________| |
1058 | ||
1059 | @end group | |
1060 | @end smallexample | |
1061 | ||
1062 | @noindent | |
0d4bb04f MR |
1063 | Deleting @var{W4} will now give its entire space to @var{W2}, |
1064 | including the space earlier stolen from @var{W3}. | |
fdaf534a MR |
1065 | |
1066 | @smallexample | |
1067 | @group | |
1068 | ______________________________________ | |
b33b68a3 MR |
1069 | | ____________________________________ | |
1070 | || || | |
1071 | || || | |
fdaf534a MR |
1072 | || || |
1073 | || || | |
1074 | || || | |
1075 | || || | |
1076 | || || | |
1077 | || || | |
1078 | ||_________________W2_________________|| | |
1079 | | ____________________________________ | | |
1080 | ||_________________W3_________________|| | |
b33b68a3 MR |
1081 | |__________________W1__________________| |
1082 | ||
1083 | @end group | |
1084 | @end smallexample | |
1085 | ||
fdaf534a | 1086 | @noindent |
d125ca15 | 1087 | This can be counterintuitive, in particular if @var{W4} were used for |
fdaf534a MR |
1088 | displaying a buffer only temporarily (@pxref{Temporary Displays}), and |
1089 | you want to continue working with the initial layout. | |
1090 | ||
1091 | The behavior can be fixed by making a new parent window when splitting | |
0d4bb04f | 1092 | @var{W2}. The variable described next allows to do that. |
fdaf534a | 1093 | |
b6f67890 | 1094 | @defopt window-combination-limit |
fdaf534a MR |
1095 | This variable controls whether splitting a window shall make a new |
1096 | parent window. The following values are recognized: | |
1097 | ||
1098 | @table @code | |
1099 | @item nil | |
1100 | This means that the new live window is allowed to share the existing | |
7bf54975 | 1101 | parent window, if one exists, provided the split occurs in the same |
fdaf534a MR |
1102 | direction as the existing window combination (otherwise, a new internal |
1103 | window is created anyway). | |
1104 | ||
1105 | @item window-size | |
1106 | In this case @code{display-buffer} makes a new parent window if it is | |
1107 | passed a @code{window-height} or @code{window-width} entry in the | |
1108 | @var{alist} argument (@pxref{Display Action Functions}). | |
1109 | ||
1110 | @item temp-buffer | |
1111 | This value causes the creation of a new parent window when a window is | |
1112 | split for showing a temporary buffer (@pxref{Temporary Displays}) only. | |
1113 | ||
1114 | @item display-buffer | |
1115 | This means that when @code{display-buffer} (@pxref{Choosing Window}) | |
1116 | splits a window it always makes a new parent window. | |
1117 | ||
1118 | @item t | |
1119 | In this case a new parent window is always created when splitting a | |
1120 | window. Thus, if the value of this variable is at all times @code{t}, | |
1121 | then at all times every window tree is a binary tree (a tree where each | |
1122 | window except the root window has exactly one sibling). | |
1123 | @end table | |
1124 | ||
1125 | The default is @code{nil}. Other values are reserved for future use. | |
1126 | ||
1127 | If, as a consequence of this variable's setting, @code{split-window} | |
1128 | makes a new parent window, it also calls | |
1129 | @code{set-window-combination-limit} (see below) on the newly-created | |
1130 | internal window. This affects how the window tree is rearranged when | |
1131 | the child windows are deleted (see below). | |
b33b68a3 MR |
1132 | @end defopt |
1133 | ||
0d4bb04f | 1134 | If @code{window-combination-limit} is @code{t}, splitting @var{W2} in |
fdaf534a MR |
1135 | the initial configuration of our scenario would have produced this: |
1136 | ||
1137 | @smallexample | |
1138 | @group | |
1139 | ______________________________________ | |
1140 | | ____________________________________ | | |
1141 | || __________________________________ || | |
1142 | ||| ||| | |
1143 | |||________________W2________________||| | |
1144 | || __________________________________ || | |
1145 | ||| ||| | |
1146 | |||________________W4________________||| | |
1147 | ||_________________W5_________________|| | |
1148 | | ____________________________________ | | |
1149 | || || | |
1150 | || || | |
1151 | ||_________________W3_________________|| | |
1152 | |__________________W1__________________| | |
1153 | ||
1154 | @end group | |
1155 | @end smallexample | |
1156 | ||
1157 | @noindent | |
0d4bb04f MR |
1158 | A new internal window @var{W5} has been created; its children are |
1159 | @var{W2} and the new live window @var{W4}. Now, @var{W2} is the only | |
1160 | sibling of @var{W4}, so enlarging @var{W4} will try to shrink | |
1161 | @var{W2}, leaving @var{W3} unaffected. Observe that @var{W5} | |
fdaf534a | 1162 | represents a vertical combination of two windows embedded in the |
0d4bb04f | 1163 | vertical combination @var{W1}. |
fdaf534a | 1164 | |
7bf54975 | 1165 | @cindex window combination limit |
d2999b1a | 1166 | @defun set-window-combination-limit window limit |
7bf54975 | 1167 | This functions sets the @dfn{combination limit} of the window |
d2999b1a | 1168 | @var{window} to @var{limit}. This value can be retrieved via the |
7bf54975 CY |
1169 | function @code{window-combination-limit}. See below for its effects; |
1170 | note that it is only meaningful for internal windows. The | |
d2999b1a | 1171 | @code{split-window} function automatically calls this function, passing |
fdaf534a MR |
1172 | it @code{t} as @var{limit}, provided the value of the variable |
1173 | @code{window-combination-limit} is @code{t} when it is called. | |
b33b68a3 MR |
1174 | @end defun |
1175 | ||
7bf54975 CY |
1176 | @defun window-combination-limit window |
1177 | This function returns the combination limit for @var{window}. | |
1178 | ||
fdaf534a MR |
1179 | The combination limit is meaningful only for an internal window. If it |
1180 | is @code{nil}, then Emacs is allowed to automatically delete | |
7bf54975 | 1181 | @var{window}, in response to a window deletion, in order to group the |
a9b9b7f5 CY |
1182 | child windows of @var{window} with its sibling windows to form a new |
1183 | window combination. If the combination limit is @code{t}, the child | |
fdaf534a | 1184 | windows of @var{window} are never automatically recombined with its |
a9b9b7f5 | 1185 | siblings. |
fdaf534a MR |
1186 | |
1187 | If, in the configuration shown at the beginning of this section, the | |
0d4bb04f MR |
1188 | combination limit of @var{W4} (the parent window of @var{W6} and |
1189 | @var{W7}) is @code{t}, deleting @var{W5} will not implicitly delete | |
1190 | @var{W4} too. | |
b33b68a3 MR |
1191 | @end defun |
1192 | ||
fdaf534a MR |
1193 | Alternatively, the problems sketched above can be avoided by always |
1194 | resizing all windows in the same combination whenever one of its windows | |
1195 | is split or deleted. This also permits to split windows that would be | |
1196 | otherwise too small for such an operation. | |
1197 | ||
1198 | @defopt window-combination-resize | |
1199 | If this variable is @code{nil}, @code{split-window} can only split a | |
1200 | window (denoted by @var{window}) if @var{window}'s screen area is large | |
1201 | enough to accommodate both itself and the new window. | |
1202 | ||
1203 | If this variable is @code{t}, @code{split-window} tries to resize all | |
1204 | windows that are part of the same combination as @var{window}, in order | |
1205 | to accommodate the new window. In particular, this may allow | |
1206 | @code{split-window} to succeed even if @var{window} is a fixed-size | |
1207 | window or too small to ordinarily split. Furthermore, subsequently | |
1208 | resizing or deleting @var{window} may resize all other windows in its | |
1209 | combination. | |
1210 | ||
1211 | The default is @code{nil}. Other values are reserved for future use. | |
1212 | The value of this variable is ignored when | |
1213 | @code{window-combination-limit} is non-@code{nil}. | |
1214 | @end defopt | |
1215 | ||
1216 | To illustrate the effect of @code{window-combination-resize}, consider | |
1217 | the following frame layout. | |
7bf54975 | 1218 | |
b33b68a3 MR |
1219 | @smallexample |
1220 | @group | |
1221 | ______________________________________ | |
1222 | | ____________________________________ | | |
1223 | || || | |
1224 | || || | |
1225 | || || | |
1226 | || || | |
b33b68a3 MR |
1227 | ||_________________W2_________________|| |
1228 | | ____________________________________ | | |
1229 | || || | |
1230 | || || | |
fdaf534a MR |
1231 | || || |
1232 | || || | |
b33b68a3 MR |
1233 | ||_________________W3_________________|| |
1234 | |__________________W1__________________| | |
1235 | ||
1236 | @end group | |
1237 | @end smallexample | |
1238 | ||
7bf54975 | 1239 | @noindent |
fdaf534a | 1240 | If @code{window-combination-resize} is @code{nil}, splitting window |
0d4bb04f | 1241 | @var{W3} leaves the size of @var{W2} unchanged: |
b33b68a3 | 1242 | |
b33b68a3 MR |
1243 | @smallexample |
1244 | @group | |
1245 | ______________________________________ | |
1246 | | ____________________________________ | | |
1247 | || || | |
1248 | || || | |
b33b68a3 MR |
1249 | || || |
1250 | || || | |
fdaf534a | 1251 | ||_________________W2_________________|| |
b33b68a3 MR |
1252 | | ____________________________________ | |
1253 | || || | |
1254 | ||_________________W3_________________|| | |
fdaf534a MR |
1255 | | ____________________________________ | |
1256 | || || | |
1257 | ||_________________W4_________________|| | |
b33b68a3 MR |
1258 | |__________________W1__________________| |
1259 | ||
1260 | @end group | |
1261 | @end smallexample | |
1262 | ||
7bf54975 | 1263 | @noindent |
0d4bb04f | 1264 | If @code{window-combination-resize} is @code{t}, splitting @var{W3} |
fdaf534a MR |
1265 | instead leaves all three live windows with approximately the same |
1266 | height: | |
b33b68a3 | 1267 | |
b33b68a3 MR |
1268 | @smallexample |
1269 | @group | |
1270 | ______________________________________ | |
1271 | | ____________________________________ | | |
fdaf534a MR |
1272 | || || |
1273 | || || | |
1274 | ||_________________W2_________________|| | |
b33b68a3 MR |
1275 | | ____________________________________ | |
1276 | || || | |
1277 | || || | |
1278 | ||_________________W3_________________|| | |
fdaf534a MR |
1279 | | ____________________________________ | |
1280 | || || | |
1281 | || || | |
1282 | ||_________________W4_________________|| | |
b33b68a3 MR |
1283 | |__________________W1__________________| |
1284 | ||
1285 | @end group | |
1286 | @end smallexample | |
1287 | ||
7bf54975 | 1288 | @noindent |
0d4bb04f | 1289 | Deleting any of the live windows @var{W2}, @var{W3} or @var{W4} will |
fdaf534a MR |
1290 | distribute its space proportionally among the two remaining live |
1291 | windows. | |
b8d4c8d0 | 1292 | |
b33b68a3 | 1293 | |
b8d4c8d0 GM |
1294 | @node Selecting Windows |
1295 | @section Selecting Windows | |
1296 | @cindex selecting a window | |
1297 | ||
b8d4c8d0 | 1298 | @defun select-window window &optional norecord |
94900bfe MR |
1299 | This function makes @var{window} the selected window and the window |
1300 | selected within its frame (@pxref{Basic Windows}) and selects that | |
1301 | frame. @var{window} must be a live window. This function also makes | |
1302 | @var{window}'s buffer (@pxref{Buffers and Windows}) current and sets | |
1303 | that buffer's value of @code{point} to the value of @code{window-point} | |
1304 | (@pxref{Window Point}) in @var{window}. The return value is | |
342dac71 MR |
1305 | @var{window}. |
1306 | ||
1307 | By default, this function also moves @var{window}'s buffer to the front | |
1308 | of the buffer list (@pxref{The Buffer List}), and makes @var{window} the | |
1309 | most recently selected window. However, if the optional argument | |
1310 | @var{norecord} is non-@code{nil}, these additional actions are omitted. | |
b8d4c8d0 GM |
1311 | @end defun |
1312 | ||
b33b68a3 | 1313 | @cindex most recently selected windows |
7bf54975 | 1314 | The sequence of calls to @code{select-window} with a non-@code{nil} |
b33b68a3 MR |
1315 | @var{norecord} argument determines an ordering of windows by their |
1316 | selection time. The function @code{get-lru-window} can be used to | |
7bf54975 CY |
1317 | retrieve the least recently selected live window (@pxref{Cyclic Window |
1318 | Ordering}). | |
b33b68a3 | 1319 | |
b8d4c8d0 GM |
1320 | @defmac save-selected-window forms@dots{} |
1321 | This macro records the selected frame, as well as the selected window | |
1322 | of each frame, executes @var{forms} in sequence, then restores the | |
1323 | earlier selected frame and windows. It also saves and restores the | |
1324 | current buffer. It returns the value of the last form in @var{forms}. | |
1325 | ||
1326 | This macro does not save or restore anything about the sizes, | |
a1401ab1 | 1327 | arrangement or contents of windows; therefore, if @var{forms} change |
0273ca3a MR |
1328 | them, the change persists. If the previously selected window of some |
1329 | frame is no longer live at the time of exit from @var{forms}, that | |
1330 | frame's selected window is left alone. If the previously selected | |
1331 | window is no longer live, then whatever window is selected at the end of | |
1332 | @var{forms} remains selected. The current buffer is restored if and | |
1333 | only if it is still live when exiting @var{forms}. | |
1334 | ||
1335 | This macro changes neither the ordering of recently selected windows nor | |
1336 | the buffer list. | |
b8d4c8d0 GM |
1337 | @end defmac |
1338 | ||
1339 | @defmac with-selected-window window forms@dots{} | |
0273ca3a MR |
1340 | This macro selects @var{window}, executes @var{forms} in sequence, then |
1341 | restores the previously selected window and current buffer. The ordering | |
1342 | of recently selected windows and the buffer list remain unchanged unless | |
0b27932b | 1343 | you deliberately change them within @var{forms}; for example, by calling |
b8766179 | 1344 | @code{select-window} with argument @var{norecord} @code{nil}. |
b8d4c8d0 | 1345 | |
0b27932b GM |
1346 | This macro does not change the order of recently selected windows or |
1347 | the buffer list. | |
b33b68a3 | 1348 | @end defmac |
b8d4c8d0 | 1349 | |
7bf54975 CY |
1350 | @defun frame-selected-window &optional frame |
1351 | This function returns the window on @var{frame} that is selected | |
1352 | within that frame. @var{frame} should be a live frame; if omitted or | |
1353 | @code{nil}, it defaults to the selected frame. | |
b8d4c8d0 GM |
1354 | @end defun |
1355 | ||
b33b68a3 | 1356 | @defun set-frame-selected-window frame window &optional norecord |
0b27932b | 1357 | This function makes @var{window} the window selected within the frame |
e6c005c5 XF |
1358 | @var{frame}. @var{frame} should be a live frame; if @code{nil}, it |
1359 | defaults to the selected frame. @var{window} should be a live window; | |
1360 | if @code{nil}, it defaults to the selected window. | |
b33b68a3 | 1361 | |
7bf54975 CY |
1362 | If @var{frame} is the selected frame, this makes @var{window} the |
1363 | selected window. | |
b8d4c8d0 | 1364 | |
7bf54975 CY |
1365 | If the optional argument @var{norecord} is non-@code{nil}, this |
1366 | function does not alter the list of most recently selected windows, | |
1367 | nor the buffer list. | |
1368 | @end defun | |
b8d4c8d0 GM |
1369 | |
1370 | @node Cyclic Window Ordering | |
b8d4c8d0 GM |
1371 | @section Cyclic Ordering of Windows |
1372 | @cindex cyclic ordering of windows | |
1373 | @cindex ordering of windows, cyclic | |
1374 | @cindex window ordering, cyclic | |
1375 | ||
a9b9b7f5 | 1376 | When you use the command @kbd{C-x o} (@code{other-window}) to select |
b33b68a3 | 1377 | some other window, it moves through live windows in a specific order. |
a9b9b7f5 CY |
1378 | For any given configuration of windows, this order never varies. It |
1379 | is called the @dfn{cyclic ordering of windows}. | |
b8d4c8d0 | 1380 | |
a9b9b7f5 CY |
1381 | The ordering is determined by a depth-first traversal of the frame's |
1382 | window tree, retrieving the live windows which are the leaf nodes of | |
1383 | the tree (@pxref{Windows and Frames}). If the minibuffer is active, | |
1384 | the minibuffer window is included too. The ordering is cyclic, so the | |
1385 | last window in the sequence is followed by the first one. | |
b8d4c8d0 | 1386 | |
5854c267 | 1387 | @defun next-window &optional window minibuf all-frames |
b8d4c8d0 | 1388 | @cindex minibuffer window, and @code{next-window} |
a9b9b7f5 CY |
1389 | This function returns a live window, the one following @var{window} in |
1390 | the cyclic ordering of windows. @var{window} should be a live window; | |
1391 | if omitted or @code{nil}, it defaults to the selected window. | |
b8d4c8d0 | 1392 | |
b33b68a3 | 1393 | The optional argument @var{minibuf} specifies whether minibuffer windows |
e78d873d | 1394 | should be included in the cyclic ordering. Normally, when @var{minibuf} |
b33b68a3 MR |
1395 | is @code{nil}, a minibuffer window is included only if it is currently |
1396 | ``active''; this matches the behavior of @kbd{C-x o}. (Note that a | |
1397 | minibuffer window is active as long as its minibuffer is in use; see | |
1398 | @ref{Minibuffers}). | |
b8d4c8d0 | 1399 | |
b33b68a3 MR |
1400 | If @var{minibuf} is @code{t}, the cyclic ordering includes all |
1401 | minibuffer windows. If @var{minibuf} is neither @code{t} nor | |
1402 | @code{nil}, minibuffer windows are not included even if they are active. | |
b8d4c8d0 | 1403 | |
aeeedf76 | 1404 | The optional argument @var{all-frames} specifies which frames to |
a9b9b7f5 | 1405 | consider: |
b8d4c8d0 | 1406 | |
b33b68a3 | 1407 | @itemize @bullet |
b8d4c8d0 | 1408 | @item @code{nil} |
a9b9b7f5 CY |
1409 | means to consider windows on @var{window}'s frame. If the minibuffer |
1410 | window is considered (as specified by the @var{minibuf} argument), | |
1411 | then frames that share the minibuffer window are considered too. | |
b8d4c8d0 GM |
1412 | |
1413 | @item @code{t} | |
a9b9b7f5 | 1414 | means to consider windows on all existing frames. |
b8d4c8d0 GM |
1415 | |
1416 | @item @code{visible} | |
a9b9b7f5 | 1417 | means to consider windows on all visible frames. |
b8d4c8d0 GM |
1418 | |
1419 | @item 0 | |
a9b9b7f5 | 1420 | means to consider windows on all visible or iconified frames. |
b8d4c8d0 | 1421 | |
b33b68a3 | 1422 | @item A frame |
a9b9b7f5 | 1423 | means to consider windows on that specific frame. |
b8d4c8d0 | 1424 | |
b33b68a3 | 1425 | @item Anything else |
a9b9b7f5 | 1426 | means to consider windows on @var{window}'s frame, and no others. |
b33b68a3 | 1427 | @end itemize |
b8d4c8d0 | 1428 | |
a9b9b7f5 CY |
1429 | If more than one frame is considered, the cyclic ordering is obtained |
1430 | by appending the orderings for those frames, in the same order as the | |
1431 | list of all live frames (@pxref{Finding All Frames}). | |
5854c267 | 1432 | @end defun |
b8d4c8d0 | 1433 | |
5854c267 | 1434 | @defun previous-window &optional window minibuf all-frames |
a9b9b7f5 CY |
1435 | This function returns a live window, the one preceding @var{window} in |
1436 | the cyclic ordering of windows. The other arguments are handled like | |
1437 | in @code{next-window}. | |
5854c267 | 1438 | @end defun |
b8d4c8d0 GM |
1439 | |
1440 | @deffn Command other-window count &optional all-frames | |
a9b9b7f5 CY |
1441 | This function selects a live window, one @var{count} places from the |
1442 | selected window in the cyclic ordering of windows. If @var{count} is | |
1443 | a positive number, it skips @var{count} windows forwards; if | |
1444 | @var{count} is negative, it skips @minus{}@var{count} windows | |
1445 | backwards; if @var{count} is zero, that simply re-selects the selected | |
1446 | window. When called interactively, @var{count} is the numeric prefix | |
1447 | argument. | |
b8d4c8d0 | 1448 | |
aeeedf76 | 1449 | The optional argument @var{all-frames} has the same meaning as in |
a9b9b7f5 CY |
1450 | @code{next-window}, like a @code{nil} @var{minibuf} argument to |
1451 | @code{next-window}. | |
b33b68a3 MR |
1452 | |
1453 | This function does not select a window that has a non-@code{nil} | |
1454 | @code{no-other-window} window parameter (@pxref{Window Parameters}). | |
b8d4c8d0 GM |
1455 | @end deffn |
1456 | ||
a9b9b7f5 CY |
1457 | @defun walk-windows fun &optional minibuf all-frames |
1458 | This function calls the function @var{fun} once for each live window, | |
1459 | with the window as the argument. | |
b33b68a3 | 1460 | |
a9b9b7f5 CY |
1461 | It follows the cyclic ordering of windows. The optional arguments |
1462 | @var{minibuf} and @var{all-frames} specify the set of windows | |
1463 | included; these have the same arguments as in @code{next-window}. If | |
1464 | @var{all-frames} specifies a frame, the first window walked is the | |
1465 | first window on that frame (the one returned by | |
1466 | @code{frame-first-window}), not necessarily the selected window. | |
b33b68a3 | 1467 | |
a9b9b7f5 CY |
1468 | If @var{fun} changes the window configuration by splitting or deleting |
1469 | windows, that does not alter the set of windows walked, which is | |
1470 | determined prior to calling @var{fun} for the first time. | |
b33b68a3 MR |
1471 | @end defun |
1472 | ||
b33b68a3 | 1473 | @defun one-window-p &optional no-mini all-frames |
a9b9b7f5 CY |
1474 | This function returns @code{t} if the selected window is the only live |
1475 | window, and @code{nil} otherwise. | |
1476 | ||
1477 | If the minibuffer window is active, it is normally considered (so that | |
1478 | this function returns @code{nil}). However, if the optional argument | |
1479 | @var{no-mini} is non-@code{nil}, the minibuffer window is ignored even | |
1480 | if active. The optional argument @var{all-frames} has the same | |
1481 | meaning as for @code{next-window}. | |
b33b68a3 MR |
1482 | @end defun |
1483 | ||
1484 | @cindex finding windows | |
a9b9b7f5 CY |
1485 | The following functions return a window which satisfies some |
1486 | criterion, without selecting it: | |
b33b68a3 MR |
1487 | |
1488 | @cindex least recently used window | |
3a51f0eb | 1489 | @defun get-lru-window &optional all-frames dedicated not-selected |
a9b9b7f5 CY |
1490 | This function returns a live window which is heuristically the ``least |
1491 | recently used'' window. The optional argument @var{all-frames} has | |
1492 | the same meaning as in @code{next-window}. | |
1493 | ||
1494 | If any full-width windows are present, only those windows are | |
3a51f0eb MR |
1495 | considered. A minibuffer window is never a candidate. A dedicated |
1496 | window (@pxref{Dedicated Windows}) is never a candidate unless the | |
1497 | optional argument @var{dedicated} is non-@code{nil}. The selected | |
1498 | window is never returned, unless it is the only candidate. However, if | |
1499 | the optional argument @var{not-selected} is non-@code{nil}, this | |
1500 | function returns @code{nil} in that case. | |
b33b68a3 MR |
1501 | @end defun |
1502 | ||
1503 | @cindex largest window | |
3a51f0eb | 1504 | @defun get-largest-window &optional all-frames dedicated not-selected |
b33b68a3 | 1505 | This function returns the window with the largest area (height times |
3a51f0eb MR |
1506 | width). The optional argument @var{all-frames} specifies the windows to |
1507 | search, and has the same meaning as in @code{next-window}. | |
1508 | ||
1509 | A minibuffer window is never a candidate. A dedicated window | |
b33b68a3 | 1510 | (@pxref{Dedicated Windows}) is never a candidate unless the optional |
3a51f0eb MR |
1511 | argument @var{dedicated} is non-@code{nil}. The selected window is not |
1512 | a candidate if the optional argument @var{not-selected} is | |
1513 | non-@code{nil}. If the optional argument @var{not-selected} is | |
1514 | non-@code{nil} and the selected window is the only candidate, this | |
1515 | function returns @code{nil}. | |
b8d4c8d0 | 1516 | |
b33b68a3 MR |
1517 | If there are two candidate windows of the same size, this function |
1518 | prefers the one that comes first in the cyclic ordering of windows, | |
1519 | starting from the selected window. | |
b8d4c8d0 GM |
1520 | @end defun |
1521 | ||
b33b68a3 MR |
1522 | @cindex window that satisfies a predicate |
1523 | @cindex conditional selection of windows | |
1524 | @defun get-window-with-predicate predicate &optional minibuf all-frames default | |
a9b9b7f5 CY |
1525 | This function calls the function @var{predicate} for each of the |
1526 | windows in the cyclic order of windows in turn, passing it the window | |
1527 | as an argument. If the predicate returns non-@code{nil} for any | |
1528 | window, this function stops and returns that window. If no such | |
1529 | window is found, the return value is @var{default} (which defaults to | |
1530 | @code{nil}). | |
b8d4c8d0 | 1531 | |
b33b68a3 | 1532 | The optional arguments @var{minibuf} and @var{all-frames} specify the |
a9b9b7f5 CY |
1533 | windows to search, and have the same meanings as in |
1534 | @code{next-window}. | |
b8d4c8d0 GM |
1535 | @end defun |
1536 | ||
3a51f0eb | 1537 | |
b8d4c8d0 GM |
1538 | @node Buffers and Windows |
1539 | @section Buffers and Windows | |
1540 | @cindex examining windows | |
1541 | @cindex windows, controlling precisely | |
1542 | @cindex buffers, controlled in windows | |
1543 | ||
a9b9b7f5 CY |
1544 | This section describes low-level functions for examining and setting |
1545 | the contents of windows. @xref{Switching Buffers}, for higher-level | |
1546 | functions for displaying a specific buffer in a window. | |
b8d4c8d0 | 1547 | |
b33b68a3 | 1548 | @defun window-buffer &optional window |
a9b9b7f5 CY |
1549 | This function returns the buffer that @var{window} is displaying. If |
1550 | @var{window} is omitted or @code{nil} it defaults to the selected | |
1551 | window. If @var{window} is an internal window, this function returns | |
b33b68a3 MR |
1552 | @code{nil}. |
1553 | @end defun | |
aeeedf76 | 1554 | |
b33b68a3 | 1555 | @defun set-window-buffer window buffer-or-name &optional keep-margins |
a9b9b7f5 CY |
1556 | This function makes @var{window} display @var{buffer-or-name}. |
1557 | @var{window} should be a live window; if @code{nil}, it defaults to | |
1558 | the selected window. @var{buffer-or-name} should be a buffer, or the | |
1559 | name of an existing buffer. This function does not change which | |
1560 | window is selected, nor does it directly change which buffer is | |
1561 | current (@pxref{Current Buffer}). Its return value is @code{nil}. | |
1562 | ||
1563 | If @var{window} is @dfn{strongly dedicated} to a buffer and | |
1564 | @var{buffer-or-name} does not specify that buffer, this function | |
1565 | signals an error. @xref{Dedicated Windows}. | |
1566 | ||
1567 | By default, this function resets @var{window}'s position, display | |
1568 | margins, fringe widths, and scroll bar settings, based on the local | |
1569 | variables in the specified buffer. However, if the optional argument | |
1570 | @var{keep-margins} is non-@code{nil}, it leaves the display margins | |
1571 | and fringe widths unchanged. | |
1572 | ||
1573 | When writing an application, you should normally use the higher-level | |
1574 | functions described in @ref{Switching Buffers}, instead of calling | |
1575 | @code{set-window-buffer} directly. | |
1576 | ||
84f4a531 | 1577 | This runs @code{window-scroll-functions}, followed by |
a9b9b7f5 | 1578 | @code{window-configuration-change-hook}. @xref{Window Hooks}. |
b8d4c8d0 GM |
1579 | @end defun |
1580 | ||
1581 | @defvar buffer-display-count | |
0273ca3a | 1582 | This buffer-local variable records the number of times a buffer has been |
b8d4c8d0 GM |
1583 | displayed in a window. It is incremented each time |
1584 | @code{set-window-buffer} is called for the buffer. | |
1585 | @end defvar | |
1586 | ||
b33b68a3 | 1587 | @defvar buffer-display-time |
a9b9b7f5 CY |
1588 | This buffer-local variable records the time at which a buffer was last |
1589 | displayed in a window. The value is @code{nil} if the buffer has | |
1590 | never been displayed. It is updated each time | |
1591 | @code{set-window-buffer} is called for the buffer, with the value | |
1592 | returned by @code{current-time} (@pxref{Time of Day}). | |
b33b68a3 | 1593 | @end defvar |
b8d4c8d0 | 1594 | |
520b29e7 | 1595 | @defun get-buffer-window &optional buffer-or-name all-frames |
a9b9b7f5 CY |
1596 | This function returns the first window displaying @var{buffer-or-name} |
1597 | in the cyclic ordering of windows, starting from the selected window | |
1598 | (@pxref{Cyclic Window Ordering}). If no such window exists, the | |
1599 | return value is @code{nil}. | |
b8d4c8d0 | 1600 | |
a9b9b7f5 CY |
1601 | @var{buffer-or-name} should be a buffer or the name of a buffer; if |
1602 | omitted or @code{nil}, it defaults to the current buffer. The | |
1603 | optional argument @var{all-frames} specifies which windows to | |
1604 | consider: | |
b8d4c8d0 GM |
1605 | |
1606 | @itemize @bullet | |
1607 | @item | |
0273ca3a | 1608 | @code{t} means consider windows on all existing frames. |
b8d4c8d0 | 1609 | @item |
0273ca3a | 1610 | @code{visible} means consider windows on all visible frames. |
b8d4c8d0 | 1611 | @item |
0273ca3a | 1612 | 0 means consider windows on all visible or iconified frames. |
b8d4c8d0 | 1613 | @item |
0273ca3a | 1614 | A frame means consider windows on that frame only. |
a9b9b7f5 CY |
1615 | @item |
1616 | Any other value means consider windows on the selected frame. | |
b8d4c8d0 | 1617 | @end itemize |
0273ca3a | 1618 | |
a9b9b7f5 CY |
1619 | Note that these meanings differ slightly from those of the |
1620 | @var{all-frames} argument to @code{next-window} (@pxref{Cyclic Window | |
1621 | Ordering}). This function may be changed in a future version of Emacs | |
1622 | to eliminate this discrepancy. | |
b8d4c8d0 GM |
1623 | @end defun |
1624 | ||
520b29e7 MR |
1625 | @defun get-buffer-window-list &optional buffer-or-name minibuf all-frames |
1626 | This function returns a list of all windows currently displaying | |
a9b9b7f5 CY |
1627 | @var{buffer-or-name}. @var{buffer-or-name} should be a buffer or the |
1628 | name of an existing buffer. If omitted or @code{nil}, it defaults to | |
1629 | the current buffer. | |
1630 | ||
1631 | The arguments @var{minibuf} and @var{all-frames} have the same | |
1632 | meanings as in the function @code{next-window} (@pxref{Cyclic Window | |
1633 | Ordering}). Note that the @var{all-frames} argument does @emph{not} | |
1634 | behave exactly like in @code{get-buffer-window}. | |
b8d4c8d0 GM |
1635 | @end defun |
1636 | ||
b33b68a3 | 1637 | @deffn Command replace-buffer-in-windows &optional buffer-or-name |
0e406a72 | 1638 | This command replaces @var{buffer-or-name} with some other buffer, in |
0d4bb04f MR |
1639 | all windows displaying it. @var{buffer-or-name} should be a buffer, or |
1640 | the name of an existing buffer; if omitted or @code{nil}, it defaults to | |
1641 | the current buffer. | |
a9b9b7f5 CY |
1642 | |
1643 | The replacement buffer in each window is chosen via | |
1644 | @code{switch-to-prev-buffer} (@pxref{Window History}). Any dedicated | |
0d4bb04f MR |
1645 | window displaying @var{buffer-or-name} is deleted if possible |
1646 | (@pxref{Dedicated Windows}). If such a window is the only window on its | |
1647 | frame and there are other frames on the same terminal, the frame is | |
1648 | deleted as well. If the dedicated window is the only window on the only | |
1649 | frame on its terminal, the buffer is replaced anyway. | |
b33b68a3 MR |
1650 | @end deffn |
1651 | ||
0d4bb04f | 1652 | |
0e406a72 CY |
1653 | @node Switching Buffers |
1654 | @section Switching to a Buffer in a Window | |
b8d4c8d0 GM |
1655 | @cindex switching to a buffer |
1656 | @cindex displaying a buffer | |
1657 | ||
0d4bb04f MR |
1658 | This section describes high-level functions for switching to a specified |
1659 | buffer in some window. In general, ``switching to a buffer'' means to | |
1660 | (1) show the buffer in some window, (2) make that window the selected | |
1661 | window (and its frame the selected frame), and (3) make the buffer the | |
1662 | current buffer. | |
0e406a72 CY |
1663 | |
1664 | Do @emph{not} use these functions to make a buffer temporarily | |
9ec20d36 CY |
1665 | current just so a Lisp program can access or modify it. They have |
1666 | side-effects, such as changing window histories (@pxref{Window | |
1667 | History}), which will surprise the user if used that way. If you want | |
1668 | to make a buffer current to modify it in Lisp, use | |
0e406a72 | 1669 | @code{with-current-buffer}, @code{save-current-buffer}, or |
9ec20d36 | 1670 | @code{set-buffer}. @xref{Current Buffer}. |
0e406a72 CY |
1671 | |
1672 | @deffn Command switch-to-buffer buffer-or-name &optional norecord force-same-window | |
cee2e90d | 1673 | This command attempts to display @var{buffer-or-name} in the selected |
0d4bb04f MR |
1674 | window and make it the current buffer. It is often used interactively |
1675 | (as the binding of @kbd{C-x b}), as well as in Lisp programs. The | |
1676 | return value is the buffer switched to. | |
0e406a72 CY |
1677 | |
1678 | If @var{buffer-or-name} is @code{nil}, it defaults to the buffer | |
1679 | returned by @code{other-buffer} (@pxref{The Buffer List}). If | |
1680 | @var{buffer-or-name} is a string that is not the name of any existing | |
1681 | buffer, this function creates a new buffer with that name; the new | |
1682 | buffer's major mode is determined by the variable @code{major-mode} | |
1683 | (@pxref{Major Modes}). | |
1684 | ||
cee2e90d | 1685 | Normally, the specified buffer is put at the front of the buffer |
0e406a72 CY |
1686 | list---both the global buffer list and the selected frame's buffer |
1687 | list (@pxref{The Buffer List}). However, this is not done if the | |
1688 | optional argument @var{norecord} is non-@code{nil}. | |
1689 | ||
cee2e90d CY |
1690 | Sometimes, @code{switch-to-buffer} may be unable to display the buffer |
1691 | in the selected window. This happens if the selected window is a | |
1692 | minibuffer window, or if the selected window is strongly dedicated to | |
1693 | its buffer (@pxref{Dedicated Windows}). In that case, the command | |
1694 | normally tries to display the buffer in some other window, by invoking | |
1695 | @code{pop-to-buffer} (see below). However, if the optional argument | |
1696 | @var{force-same-window} is non-@code{nil}, it signals an error | |
0e406a72 | 1697 | instead. |
b8d4c8d0 GM |
1698 | @end deffn |
1699 | ||
0d4bb04f MR |
1700 | By default, @code{switch-to-buffer} shows the buffer at its position of |
1701 | @code{point}. This behavior can be tuned using the following option. | |
43bcfda6 MR |
1702 | |
1703 | @defopt switch-to-buffer-preserve-window-point | |
1704 | If this variable is @code{nil}, @code{switch-to-buffer} displays the | |
1705 | buffer specified by @var{buffer-or-name} at the position of that | |
1706 | buffer's @code{point}. If this variable is @code{already-displayed}, it | |
1707 | tries to display the buffer at its previous position in the selected | |
1708 | window, provided the buffer is currently displayed in some other window | |
1709 | on any visible or iconified frame. If this variable is @code{t}, | |
1710 | @code{switch-to-buffer} unconditionally tries to display the buffer at | |
1711 | its previous position in the selected window. | |
1712 | ||
1713 | This variable is ignored if the buffer is already displayed in the | |
1714 | selected window or never appeared in it before, or if | |
1715 | @code{switch-to-buffer} calls @code{pop-to-buffer} to display the | |
1716 | buffer. | |
1717 | @end defopt | |
1718 | ||
0d4bb04f MR |
1719 | The next two commands are similar to @code{switch-to-buffer}, except for |
1720 | the described features. | |
b8d4c8d0 GM |
1721 | |
1722 | @deffn Command switch-to-buffer-other-window buffer-or-name &optional norecord | |
0d4bb04f MR |
1723 | This function displays the buffer specified by @var{buffer-or-name} in |
1724 | some window other than the selected window. It uses the function | |
1725 | @code{pop-to-buffer} internally (see below). | |
b8d4c8d0 | 1726 | |
0e406a72 | 1727 | If the selected window already displays the specified buffer, it |
b8766179 | 1728 | continues to do so, but another window is nonetheless found to display |
0e406a72 | 1729 | it as well. |
b8d4c8d0 | 1730 | |
0e406a72 CY |
1731 | The @var{buffer-or-name} and @var{norecord} arguments have the same |
1732 | meanings as in @code{switch-to-buffer}. | |
b8d4c8d0 GM |
1733 | @end deffn |
1734 | ||
0e406a72 | 1735 | @deffn Command switch-to-buffer-other-frame buffer-or-name &optional norecord |
0d4bb04f MR |
1736 | This function displays the buffer specified by @var{buffer-or-name} in a |
1737 | new frame. It uses the function @code{pop-to-buffer} internally (see | |
1738 | below). | |
0e406a72 CY |
1739 | |
1740 | If the specified buffer is already displayed in another window, in any | |
1741 | frame on the current terminal, this switches to that window instead of | |
1742 | creating a new frame. However, the selected window is never used for | |
1743 | this. | |
1744 | ||
1745 | The @var{buffer-or-name} and @var{norecord} arguments have the same | |
1746 | meanings as in @code{switch-to-buffer}. | |
1747 | @end deffn | |
1748 | ||
a9b9b7f5 CY |
1749 | The above commands use the function @code{pop-to-buffer}, which |
1750 | flexibly displays a buffer in some window and selects that window for | |
1751 | editing. In turn, @code{pop-to-buffer} uses @code{display-buffer} for | |
1752 | displaying the buffer. Hence, all the variables affecting | |
1753 | @code{display-buffer} will affect it as well. @xref{Choosing Window}, | |
1754 | for the documentation of @code{display-buffer}. | |
0e406a72 | 1755 | |
0b128ac4 | 1756 | @deffn Command pop-to-buffer buffer-or-name &optional action norecord |
0e406a72 CY |
1757 | This function makes @var{buffer-or-name} the current buffer and |
1758 | displays it in some window, preferably not the window previously | |
1759 | selected. It then selects the displaying window. If that window is | |
1760 | on a different graphical frame, that frame is given input focus if | |
1761 | possible (@pxref{Input Focus}). The return value is the buffer that | |
1762 | was switched to. | |
1763 | ||
0e406a72 CY |
1764 | If @var{buffer-or-name} is @code{nil}, it defaults to the buffer |
1765 | returned by @code{other-buffer} (@pxref{The Buffer List}). If | |
1766 | @var{buffer-or-name} is a string that is not the name of any existing | |
1767 | buffer, this function creates a new buffer with that name; the new | |
1768 | buffer's major mode is determined by the variable @code{major-mode} | |
1769 | (@pxref{Major Modes}). | |
1770 | ||
1771 | If @var{action} is non-@code{nil}, it should be a display action to | |
1772 | pass to @code{display-buffer} (@pxref{Choosing Window}). | |
1773 | Alternatively, a non-@code{nil}, non-list value means to pop to a | |
1774 | window other than the selected one---even if the buffer is already | |
1775 | displayed in the selected window. | |
1776 | ||
1777 | Like @code{switch-to-buffer}, this function updates the buffer list | |
b8d4c8d0 | 1778 | unless @var{norecord} is non-@code{nil}. |
0b128ac4 | 1779 | @end deffn |
b8d4c8d0 | 1780 | |
0ff7851c | 1781 | |
0e406a72 CY |
1782 | @node Choosing Window |
1783 | @section Choosing a Window for Display | |
b8d4c8d0 | 1784 | |
0e406a72 CY |
1785 | The command @code{display-buffer} flexibly chooses a window for |
1786 | display, and displays a specified buffer in that window. It can be | |
441950c7 | 1787 | called interactively, via the key binding @kbd{C-x 4 C-o}. It is also |
0e406a72 CY |
1788 | used as a subroutine by many functions and commands, including |
1789 | @code{switch-to-buffer} and @code{pop-to-buffer} (@pxref{Switching | |
1790 | Buffers}). | |
1791 | ||
1792 | @cindex display action | |
a9b9b7f5 CY |
1793 | @cindex action function, for @code{display-buffer} |
1794 | @cindex action alist, for @code{display-buffer} | |
0e406a72 CY |
1795 | This command performs several complex steps to find a window to |
1796 | display in. These steps are described by means of @dfn{display | |
1797 | actions}, which have the form @code{(@var{function} . @var{alist})}. | |
1798 | Here, @var{function} is either a function or a list of functions, | |
9ec20d36 CY |
1799 | which we refer to as @dfn{action functions}; @var{alist} is an |
1800 | association list, which we refer to as @dfn{action alists}. | |
1801 | ||
1802 | An action function accepts two arguments: the buffer to display and | |
1803 | an action alist. It attempts to display the buffer in some window, | |
1804 | picking or creating a window according to its own criteria. If | |
1805 | successful, it returns the window; otherwise, it returns @code{nil}. | |
1806 | @xref{Display Action Functions}, for a list of predefined action | |
1807 | functions. | |
0e406a72 CY |
1808 | |
1809 | @code{display-buffer} works by combining display actions from | |
9ec20d36 CY |
1810 | several sources, and calling the action functions in turn, until one |
1811 | of them manages to display the buffer and returns a non-@code{nil} | |
0e406a72 CY |
1812 | value. |
1813 | ||
1814 | @deffn Command display-buffer buffer-or-name &optional action frame | |
1815 | This command makes @var{buffer-or-name} appear in some window, without | |
1816 | selecting the window or making the buffer current. The argument | |
1817 | @var{buffer-or-name} must be a buffer or the name of an existing | |
1818 | buffer. The return value is the window chosen to display the buffer. | |
1819 | ||
1820 | The optional argument @var{action}, if non-@code{nil}, should normally | |
1821 | be a display action (described above). @code{display-buffer} builds a | |
1822 | list of action functions and an action alist, by consolidating display | |
1823 | actions from the following sources (in order): | |
1824 | ||
1825 | @itemize | |
1826 | @item | |
1827 | The variable @code{display-buffer-overriding-action}. | |
520b29e7 | 1828 | |
0e406a72 CY |
1829 | @item |
1830 | The user option @code{display-buffer-alist}. | |
250959e0 | 1831 | |
0e406a72 CY |
1832 | @item |
1833 | The @var{action} argument. | |
b8d4c8d0 | 1834 | |
0e406a72 CY |
1835 | @item |
1836 | The user option @code{display-buffer-base-action}. | |
1837 | ||
1838 | @item | |
9ec20d36 | 1839 | The constant @code{display-buffer-fallback-action}. |
0e406a72 | 1840 | @end itemize |
b8d4c8d0 | 1841 | |
0e406a72 CY |
1842 | @noindent |
1843 | Each action function is called in turn, passing the buffer as the | |
1844 | first argument and the combined action alist as the second argument, | |
f0cfa5fe LL |
1845 | until one of the functions returns non-@code{nil}. The caller can |
1846 | pass @code{(no-display-ok . t)} as an element of the action alist to | |
1847 | indicate its readiness to handle the case of not displaying the | |
1848 | buffer. | |
0e406a72 CY |
1849 | |
1850 | The argument @var{action} can also have a non-@code{nil}, non-list | |
1851 | value. This has the special meaning that the buffer should be | |
1852 | displayed in a window other than the selected one, even if the | |
1853 | selected window is already displaying it. If called interactively | |
1854 | with a prefix argument, @var{action} is @code{t}. | |
1855 | ||
1856 | The optional argument @var{frame}, if non-@code{nil}, specifies which | |
1857 | frames to check when deciding whether the buffer is already displayed. | |
9ec20d36 CY |
1858 | It is equivalent to adding an element @code{(reusable-frames |
1859 | . @var{frame})} to the action alist of @var{action}. @xref{Display | |
1860 | Action Functions}. | |
1861 | @end deffn | |
1862 | ||
1863 | @defvar display-buffer-overriding-action | |
1864 | The value of this variable should be a display action, which is | |
1865 | treated with the highest priority by @code{display-buffer}. The | |
1df7defd | 1866 | default value is empty, i.e., @code{(nil . nil)}. |
9ec20d36 CY |
1867 | @end defvar |
1868 | ||
1869 | @defopt display-buffer-alist | |
0ff7851c MR |
1870 | The value of this option is an alist mapping conditions to display |
1871 | actions. Each condition may be either a regular expression matching a | |
f99f1641 | 1872 | buffer name or a function that takes two arguments: a buffer name and |
0ff7851c MR |
1873 | the @var{action} argument passed to @code{display-buffer}. If the name |
1874 | of the buffer passed to @code{display-buffer} either matches a regular | |
1875 | expression in this alist or the function specified by a condition | |
1876 | returns non-@code{nil}, then @code{display-buffer} uses the | |
1877 | corresponding display action to display the buffer. | |
9ec20d36 CY |
1878 | @end defopt |
1879 | ||
1880 | @defopt display-buffer-base-action | |
1881 | The value of this option should be a display action. This option can | |
1882 | be used to define a ``standard'' display action for calls to | |
1883 | @code{display-buffer}. | |
1884 | @end defopt | |
1885 | ||
1886 | @defvr Constant display-buffer-fallback-action | |
1887 | This display action specifies the fallback behavior for | |
1888 | @code{display-buffer} if no other display actions are given. | |
1889 | @end defvr | |
1890 | ||
0ff7851c | 1891 | |
9ec20d36 CY |
1892 | @node Display Action Functions |
1893 | @section Action Functions for @code{display-buffer} | |
1894 | ||
1895 | The following basic action functions are defined in Emacs. Each of | |
1896 | these functions takes two arguments: @var{buffer}, the buffer to | |
1897 | display, and @var{alist}, an action alist. Each action function | |
1898 | returns the window if it succeeds, and @code{nil} if it fails. | |
1899 | ||
1900 | @defun display-buffer-same-window buffer alist | |
1901 | This function tries to display @var{buffer} in the selected window. | |
1902 | It fails if the selected window is a minibuffer window or is dedicated | |
1903 | to another buffer (@pxref{Dedicated Windows}). It also fails if | |
e7313f33 | 1904 | @var{alist} has a non-@code{nil} @code{inhibit-same-window} entry. |
9ec20d36 CY |
1905 | @end defun |
1906 | ||
1907 | @defun display-buffer-reuse-window buffer alist | |
1908 | This function tries to ``display'' @var{buffer} by finding a window | |
1909 | that is already displaying it. | |
1910 | ||
1911 | If @var{alist} has a non-@code{nil} @code{inhibit-same-window} entry, | |
a9b9b7f5 CY |
1912 | the selected window is not eligible for reuse. If @var{alist} |
1913 | contains a @code{reusable-frames} entry, its value determines which | |
1914 | frames to search for a reusable window: | |
b8d4c8d0 GM |
1915 | |
1916 | @itemize @bullet | |
1917 | @item | |
0273ca3a | 1918 | @code{nil} means consider windows on the selected frame. |
b8d4c8d0 GM |
1919 | (Actually, the last non-minibuffer frame.) |
1920 | @item | |
0273ca3a | 1921 | @code{t} means consider windows on all frames. |
b8d4c8d0 | 1922 | @item |
0273ca3a | 1923 | @code{visible} means consider windows on all visible frames. |
b8d4c8d0 | 1924 | @item |
0273ca3a | 1925 | 0 means consider windows on all visible or iconified frames. |
b8d4c8d0 | 1926 | @item |
0273ca3a | 1927 | A frame means consider windows on that frame only. |
b8d4c8d0 GM |
1928 | @end itemize |
1929 | ||
ac446ed8 XF |
1930 | Note that these meanings differ slightly from those of the |
1931 | @var{all-frames} argument to @code{next-window} (@pxref{Cyclic Window | |
1932 | Ordering}). | |
1933 | ||
9ec20d36 | 1934 | If @var{alist} contains no @code{reusable-frames} entry, this function |
14ba4cf3 | 1935 | normally searches just the selected frame; however, if the variable |
9ec20d36 CY |
1936 | @code{pop-up-frames} is non-@code{nil}, it searches all frames on the |
1937 | current terminal. @xref{Choosing Window Options}. | |
a9b9b7f5 | 1938 | |
0ff7851c MR |
1939 | If this function chooses a window on another frame, it makes that frame |
1940 | visible and, unless @var{alist} contains an @code{inhibit-switch-frame} | |
1941 | entry (@pxref{Choosing Window Options}), raises that frame if necessary. | |
9ec20d36 CY |
1942 | @end defun |
1943 | ||
1944 | @defun display-buffer-pop-up-frame buffer alist | |
1945 | This function creates a new frame, and displays the buffer in that | |
a9b9b7f5 CY |
1946 | frame's window. It actually performs the frame creation by calling |
1947 | the function specified in @code{pop-up-frame-function} | |
2279276c GM |
1948 | (@pxref{Choosing Window Options}). If @var{alist} contains a |
1949 | @code{pop-up-frame-parameters} entry, the associated value | |
1950 | is added to the newly created frame's parameters. | |
9ec20d36 CY |
1951 | @end defun |
1952 | ||
1953 | @defun display-buffer-pop-up-window buffer alist | |
717a1362 | 1954 | This function tries to display @var{buffer} by splitting the largest |
a9b9b7f5 CY |
1955 | or least recently-used window (typically one on the selected frame). |
1956 | It actually performs the split by calling the function specified in | |
1957 | @code{split-window-preferred-function} (@pxref{Choosing Window | |
1958 | Options}). | |
1959 | ||
43bcfda6 MR |
1960 | The size of the new window can be adjusted by supplying |
1961 | @code{window-height} and @code{window-width} entries in @var{alist}. To | |
1962 | adjust the window's height, use an entry whose @sc{car} is | |
1963 | @code{window-height} and whose @sc{cdr} is one of: | |
1964 | ||
1965 | @itemize @bullet | |
1966 | @item | |
1967 | @code{nil} means to leave the height of the new window alone. | |
1968 | ||
1969 | @item | |
1970 | A number specifies the desired height of the new window. An integer | |
1971 | number specifies the number of lines of the window. A floating point | |
1972 | number gives the fraction of the window's height with respect to the | |
1973 | height of the frame's root window. | |
1974 | ||
1975 | @item | |
1976 | If the @sc{cdr} specifies a function, that function is called with one | |
f99f1641 | 1977 | argument: the new window. The function is supposed to adjust the |
43bcfda6 MR |
1978 | height of the window; its return value is ignored. Suitable functions |
1979 | are @code{shrink-window-if-larger-than-buffer} and | |
1980 | @code{fit-window-to-buffer}, see @ref{Resizing Windows}. | |
1981 | @end itemize | |
1982 | ||
1983 | To adjust the window's width, use an entry whose @sc{car} is | |
1984 | @code{window-width} and whose @sc{cdr} is one of: | |
1985 | ||
1986 | @itemize @bullet | |
1987 | @item | |
1988 | @code{nil} means to leave the width of the new window alone. | |
1989 | ||
1990 | @item | |
1991 | A number specifies the desired width of the new window. An integer | |
1992 | number specifies the number of columns of the window. A floating point | |
1993 | number gives the fraction of the window's width with respect to the | |
1994 | width of the frame's root window. | |
1995 | ||
1996 | @item | |
1997 | If the @sc{cdr} specifies a function, that function is called with one | |
f99f1641 | 1998 | argument: the new window. The function is supposed to adjust the width |
43bcfda6 MR |
1999 | of the window; its return value is ignored. |
2000 | @end itemize | |
2001 | ||
2002 | This function can fail if no window splitting can be performed for some | |
1df7defd | 2003 | reason (e.g., if the selected frame has an @code{unsplittable} frame |
0d4bb04f | 2004 | parameter; @pxref{Buffer Parameters}). |
9ec20d36 CY |
2005 | @end defun |
2006 | ||
43bcfda6 MR |
2007 | @defun display-buffer-below-selected buffer alist |
2008 | This function tries to display @var{buffer} in a window below the | |
0ff7851c MR |
2009 | selected window. This means to either split the selected window or use |
2010 | the window below the selected one. If it does create a new window, it | |
2011 | will also adjust its size provided @var{alist} contains a suitable | |
2012 | @code{window-height} or @code{window-width} entry, see above. | |
43bcfda6 MR |
2013 | @end defun |
2014 | ||
2015 | @defun display-buffer-in-previous-window buffer alist | |
2016 | This function tries to display @var{buffer} in a window previously | |
2017 | showing it. If @var{alist} has a non-@code{nil} | |
2018 | @code{inhibit-same-window} entry, the selected window is not eligible | |
2019 | for reuse. If @var{alist} contains a @code{reusable-frames} entry, its | |
2020 | value determines which frames to search for a suitable window as with | |
2021 | @code{display-buffer-reuse-window}. | |
2022 | ||
2023 | If @var{alist} has a @code{previous-window} entry, the window | |
2024 | specified by that entry will override any other window found by the | |
2025 | methods above, even if that window never showed @var{buffer} before. | |
2026 | @end defun | |
2027 | ||
0ff7851c MR |
2028 | @defun display-buffer-use-some-window buffer alist |
2029 | This function tries to display @var{buffer} by choosing an existing | |
2030 | window and displaying the buffer in that window. It can fail if all | |
2031 | windows are dedicated to another buffer (@pxref{Dedicated Windows}). | |
2032 | @end defun | |
2033 | ||
2034 | To illustrate the use of action functions, consider the following | |
2035 | example. | |
2036 | ||
2037 | @example | |
2038 | @group | |
2039 | (display-buffer | |
2040 | (get-buffer-create "*foo*") | |
2041 | '((display-buffer-reuse-window | |
2042 | display-buffer-pop-up-window | |
2043 | display-buffer-pop-up-frame) | |
2044 | (reusable-frames . 0) | |
2045 | (window-height . 10) (window-width . 40))) | |
2046 | @end group | |
2047 | @end example | |
2048 | ||
2049 | @noindent | |
2050 | Evaluating the form above will cause @code{display-buffer} to proceed as | |
0d4bb04f MR |
2051 | follows: If a buffer called *foo* already appears on a visible or |
2052 | iconified frame, it will reuse its window. Otherwise, it will try to | |
2053 | pop up a new window or, if that is impossible, a new frame and show the | |
2054 | buffer there. If all these steps fail, it will proceed using whatever | |
2055 | @code{display-buffer-base-action} and | |
66c466d4 | 2056 | @code{display-buffer-fallback-action} prescribe. |
0ff7851c MR |
2057 | |
2058 | Furthermore, @code{display-buffer} will try to adjust a reused window | |
0d4bb04f | 2059 | (provided *foo* was put by @code{display-buffer} there before) or a |
0ff7851c MR |
2060 | popped-up window as follows: If the window is part of a vertical |
2061 | combination, it will set its height to ten lines. Note that if, instead | |
2062 | of the number ``10'', we specified the function | |
2063 | @code{fit-window-to-buffer}, @code{display-buffer} would come up with a | |
2064 | one-line window to fit the empty buffer. If the window is part of a | |
2065 | horizontal combination, it sets its width to 40 columns. Whether a new | |
2066 | window is vertically or horizontally combined depends on the shape of | |
2067 | the window split and the values of | |
2068 | @code{split-window-preferred-function}, @code{split-height-threshold} | |
2069 | and @code{split-width-threshold} (@pxref{Choosing Window Options}). | |
2070 | ||
2071 | Now suppose we combine this call with a preexisting setup for | |
2072 | `display-buffer-alist' as follows. | |
2073 | ||
2074 | @example | |
2075 | @group | |
2076 | (let ((display-buffer-alist | |
2077 | (cons | |
2078 | '("\\*foo\\*" | |
2079 | (display-buffer-reuse-window display-buffer-below-selected) | |
2080 | (reusable-frames) | |
2081 | (window-height . 5)) | |
2082 | display-buffer-alist))) | |
2083 | (display-buffer | |
2084 | (get-buffer-create "*foo*") | |
2085 | '((display-buffer-reuse-window | |
2086 | display-buffer-pop-up-window | |
2087 | display-buffer-pop-up-frame) | |
2088 | (reusable-frames . 0) | |
2089 | (window-height . 10) (window-width . 40)))) | |
2090 | @end group | |
2091 | @end example | |
2092 | ||
2093 | @noindent | |
0d4bb04f MR |
2094 | This form will have @code{display-buffer} first try reusing a window |
2095 | that shows *foo* on the selected frame. If there's no such window, it | |
2096 | will try to split the selected window or, if that is impossible, use the | |
2097 | window below the selected window. | |
0ff7851c MR |
2098 | |
2099 | If there's no window below the selected one, or the window below the | |
2100 | selected one is dedicated to its buffer, @code{display-buffer} will | |
2101 | proceed as described in the previous example. Note, however, that when | |
2102 | it tries to adjust the height of any reused or popped-up window, it will | |
2103 | in any case try to set its number of lines to ``5'' since that value | |
2104 | overrides the corresponding specification in the @var{action} argument | |
2105 | of @code{display-buffer}. | |
2106 | ||
43bcfda6 | 2107 | |
9ec20d36 CY |
2108 | @node Choosing Window Options |
2109 | @section Additional Options for Displaying Buffers | |
2110 | ||
2111 | The behavior of the standard display actions of @code{display-buffer} | |
2112 | (@pxref{Choosing Window}) can be modified by a variety of user | |
2113 | options. | |
b8d4c8d0 | 2114 | |
52a94b85 | 2115 | @defopt pop-up-windows |
a9b9b7f5 CY |
2116 | If the value of this variable is non-@code{nil}, @code{display-buffer} |
2117 | is allowed to split an existing window to make a new window for | |
2118 | displaying in. This is the default. | |
2119 | ||
2120 | This variable is provided mainly for backward compatibility. It is | |
2121 | obeyed by @code{display-buffer} via a special mechanism in | |
2122 | @code{display-buffer-fallback-action}, which only calls the action | |
2123 | function @code{display-buffer-pop-up-window} (@pxref{Display Action | |
2124 | Functions}) when the value is @code{nil}. It is not consulted by | |
2125 | @code{display-buffer-pop-up-window} itself, which the user may specify | |
2126 | directly in @code{display-buffer-alist} etc. | |
52a94b85 MR |
2127 | @end defopt |
2128 | ||
01f17ae2 | 2129 | @defopt split-window-preferred-function |
a9b9b7f5 CY |
2130 | This variable specifies a function for splitting a window, in order to |
2131 | make a new window for displaying a buffer. It is used by the | |
2132 | @code{display-buffer-pop-up-window} action function to actually split | |
2133 | the window (@pxref{Display Action Functions}). | |
2134 | ||
2135 | The default value is @code{split-window-sensibly}, which is documented | |
0d4bb04f MR |
2136 | below. The value must be a function that takes one argument, a window, |
2137 | and return either a new window (which will be used to display the | |
a9b9b7f5 | 2138 | desired buffer) or @code{nil} (which means the splitting failed). |
01f17ae2 | 2139 | @end defopt |
43c59a3d | 2140 | |
714c3541 | 2141 | @defun split-window-sensibly window |
0b27932b GM |
2142 | This function tries to split @var{window}, and return the newly |
2143 | created window. If @var{window} cannot be split, it returns | |
a9b9b7f5 CY |
2144 | @code{nil}. |
2145 | ||
2146 | This function obeys the usual rules that determine when a window may | |
2147 | be split (@pxref{Splitting Windows}). It first tries to split by | |
2148 | placing the new window below, subject to the restriction imposed by | |
0b27932b | 2149 | @code{split-height-threshold} (see below), in addition to any other |
a9b9b7f5 CY |
2150 | restrictions. If that fails, it tries to split by placing the new |
2151 | window to the right, subject to @code{split-width-threshold} (see | |
2152 | below). If that fails, and the window is the only window on its | |
2153 | frame, this function again tries to split and place the new window | |
2154 | below, disregarding @code{split-height-threshold}. If this fails as | |
2155 | well, this function gives up and returns @code{nil}. | |
d3c0c321 MR |
2156 | @end defun |
2157 | ||
b8d4c8d0 | 2158 | @defopt split-height-threshold |
a9b9b7f5 CY |
2159 | This variable, used by @code{split-window-sensibly}, specifies whether |
2160 | to split the window placing the new window below. If it is an | |
2161 | integer, that means to split only if the original window has at least | |
2162 | that many lines. If it is @code{nil}, that means not to split this | |
2163 | way. | |
43c59a3d EZ |
2164 | @end defopt |
2165 | ||
2166 | @defopt split-width-threshold | |
a9b9b7f5 CY |
2167 | This variable, used by @code{split-window-sensibly}, specifies whether |
2168 | to split the window placing the new window to the right. If the value | |
2169 | is an integer, that means to split only if the original window has at | |
2170 | least that many columns. If the value is @code{nil}, that means not | |
2171 | to split this way. | |
b8d4c8d0 GM |
2172 | @end defopt |
2173 | ||
b8d4c8d0 | 2174 | @defopt pop-up-frames |
a9b9b7f5 CY |
2175 | If the value of this variable is non-@code{nil}, that means |
2176 | @code{display-buffer} may display buffers by making new frames. The | |
2177 | default is @code{nil}. | |
2178 | ||
2179 | A non-@code{nil} value also means that when @code{display-buffer} is | |
2180 | looking for a window already displaying @var{buffer-or-name}, it can | |
2181 | search any visible or iconified frame, not just the selected frame. | |
2182 | ||
2183 | This variable is provided mainly for backward compatibility. It is | |
2184 | obeyed by @code{display-buffer} via a special mechanism in | |
2185 | @code{display-buffer-fallback-action}, which calls the action function | |
2186 | @code{display-buffer-pop-up-frame} (@pxref{Display Action Functions}) | |
2187 | if the value is non-@code{nil}. (This is done before attempting to | |
2188 | split a window.) This variable is not consulted by | |
2189 | @code{display-buffer-pop-up-frame} itself, which the user may specify | |
2190 | directly in @code{display-buffer-alist} etc. | |
b8d4c8d0 GM |
2191 | @end defopt |
2192 | ||
b8d4c8d0 | 2193 | @defopt pop-up-frame-function |
a9b9b7f5 CY |
2194 | This variable specifies a function for creating a new frame, in order |
2195 | to make a new window for displaying a buffer. It is used by the | |
2196 | @code{display-buffer-pop-up-frame} action function (@pxref{Display | |
2197 | Action Functions}). | |
2198 | ||
2199 | The value should be a function that takes no arguments and returns a | |
2200 | frame, or @code{nil} if no frame could be created. The default value | |
2201 | is a function that creates a frame using the parameters specified by | |
2202 | @code{pop-up-frame-alist} (see below). | |
b8d4c8d0 GM |
2203 | @end defopt |
2204 | ||
2205 | @defopt pop-up-frame-alist | |
a9b9b7f5 CY |
2206 | This variable holds an alist of frame parameters (@pxref{Frame |
2207 | Parameters}), which is used by the default function in | |
2208 | @code{pop-up-frame-function} to make a new frame. The default is | |
2209 | @code{nil}. | |
b8d4c8d0 GM |
2210 | @end defopt |
2211 | ||
b8d4c8d0 GM |
2212 | @defopt same-window-buffer-names |
2213 | A list of buffer names for buffers that should be displayed in the | |
0b27932b | 2214 | selected window. If a buffer's name is in this list, |
0d4bb04f MR |
2215 | @code{display-buffer} handles the buffer by showing it in the selected |
2216 | window. | |
b8d4c8d0 GM |
2217 | @end defopt |
2218 | ||
2219 | @defopt same-window-regexps | |
2220 | A list of regular expressions that specify buffers that should be | |
2221 | displayed in the selected window. If the buffer's name matches any of | |
2222 | the regular expressions in this list, @code{display-buffer} handles the | |
0d4bb04f | 2223 | buffer by showing it in the selected window. |
b8d4c8d0 GM |
2224 | @end defopt |
2225 | ||
2226 | @defun same-window-p buffer-name | |
2227 | This function returns @code{t} if displaying a buffer | |
2228 | named @var{buffer-name} with @code{display-buffer} would | |
2229 | put it in the selected window. | |
2230 | @end defun | |
2231 | ||
0e406a72 CY |
2232 | @node Window History |
2233 | @section Window History | |
2234 | @cindex window history | |
2235 | ||
0d4bb04f MR |
2236 | Each window remembers in a list the buffers it has previously displayed, |
2237 | and the order in which these buffers were removed from it. This history | |
2238 | is used, for example, by @code{replace-buffer-in-windows} | |
2239 | (@pxref{Buffers and Windows}). The list is automatically maintained by | |
2240 | Emacs, but you can use the following functions to explicitly inspect or | |
2241 | alter it: | |
0e406a72 CY |
2242 | |
2243 | @defun window-prev-buffers &optional window | |
2244 | This function returns a list specifying the previous contents of | |
0d4bb04f MR |
2245 | @var{window}. The optional argument @var{window} should be a live |
2246 | window and defaults to the selected one. | |
0e406a72 CY |
2247 | |
2248 | Each list element has the form @code{(@var{buffer} @var{window-start} | |
2249 | @var{window-pos})}, where @var{buffer} is a buffer previously shown in | |
3cd51eaa XF |
2250 | the window, @var{window-start} is the window start position |
2251 | (@pxref{Window Start and End}) when that buffer was last shown, and | |
2252 | @var{window-pos} is the point position (@pxref{Window Point}) when | |
0d4bb04f | 2253 | that buffer was last shown in @var{window}. |
0e406a72 CY |
2254 | |
2255 | The list is ordered so that earlier elements correspond to more | |
590c056d | 2256 | recently-shown buffers, and the first element usually corresponds to the |
0e406a72 CY |
2257 | buffer most recently removed from the window. |
2258 | @end defun | |
2259 | ||
2260 | @defun set-window-prev-buffers window prev-buffers | |
2261 | This function sets @var{window}'s previous buffers to the value of | |
2262 | @var{prev-buffers}. The argument @var{window} must be a live window | |
2263 | and defaults to the selected one. The argument @var{prev-buffers} | |
2264 | should be a list of the same form as that returned by | |
2265 | @code{window-prev-buffers}. | |
2266 | @end defun | |
2267 | ||
2268 | In addition, each buffer maintains a list of @dfn{next buffers}, which | |
2269 | is a list of buffers re-shown by @code{switch-to-prev-buffer} (see | |
2270 | below). This list is mainly used by @code{switch-to-prev-buffer} and | |
2271 | @code{switch-to-next-buffer} for choosing buffers to switch to. | |
2272 | ||
2273 | @defun window-next-buffers &optional window | |
2274 | This function returns the list of buffers recently re-shown in | |
590c056d MR |
2275 | @var{window} via @code{switch-to-prev-buffer}. The @var{window} |
2276 | argument must denote a live window or @code{nil} (meaning the selected | |
2277 | window). | |
0e406a72 CY |
2278 | @end defun |
2279 | ||
2280 | @defun set-window-next-buffers window next-buffers | |
2281 | This function sets the next buffer list of @var{window} to | |
2282 | @var{next-buffers}. The @var{window} argument should be a live window | |
2283 | or @code{nil} (meaning the selected window). The argument | |
2284 | @var{next-buffers} should be a list of buffers. | |
2285 | @end defun | |
2286 | ||
2287 | The following commands can be used to cycle through the global buffer | |
2288 | list, much like @code{bury-buffer} and @code{unbury-buffer}. However, | |
2289 | they cycle according to the specified window's history list, rather | |
2290 | than the global buffer list. In addition, they restore | |
2291 | window-specific window start and point positions, and may show a | |
2292 | buffer even if it is already shown in another window. The | |
2293 | @code{switch-to-prev-buffer} command, in particular, is used by | |
2294 | @code{replace-buffer-in-windows}, @code{bury-buffer} and | |
2295 | @code{quit-window} to find a replacement buffer for a window. | |
2296 | ||
2297 | @deffn Command switch-to-prev-buffer &optional window bury-or-kill | |
2298 | This command displays the previous buffer in @var{window}. The | |
2299 | argument @var{window} should be a live window or @code{nil} (meaning | |
2300 | the selected window). If the optional argument @var{bury-or-kill} is | |
2301 | non-@code{nil}, this means that the buffer currently shown in | |
e78d873d | 2302 | @var{window} is about to be buried or killed and consequently should |
0e406a72 CY |
2303 | not be switched to in future invocations of this command. |
2304 | ||
2305 | The previous buffer is usually the buffer shown before the buffer | |
2306 | currently shown in @var{window}. However, a buffer that has been buried | |
e78d873d GM |
2307 | or killed, or has been already shown by a recent invocation of |
2308 | @code{switch-to-prev-buffer}, does not qualify as previous buffer. | |
0e406a72 CY |
2309 | |
2310 | If repeated invocations of this command have already shown all buffers | |
2311 | previously shown in @var{window}, further invocations will show buffers | |
590c056d | 2312 | from the buffer list of the frame @var{window} appears on (@pxref{The |
e78d873d | 2313 | Buffer List}), trying to skip buffers that are already shown in another |
dcb6e7b3 | 2314 | window on that frame. |
0e406a72 CY |
2315 | @end deffn |
2316 | ||
2317 | @deffn Command switch-to-next-buffer &optional window | |
e78d873d | 2318 | This command switches to the next buffer in @var{window}, thus undoing |
0e406a72 CY |
2319 | the effect of the last @code{switch-to-prev-buffer} command in |
2320 | @var{window}. The argument @var{window} must be a live window and | |
2321 | defaults to the selected one. | |
2322 | ||
e78d873d | 2323 | If there is no recent invocation of @code{switch-to-prev-buffer} that |
590c056d MR |
2324 | can be undone, this function tries to show a buffer from the buffer list |
2325 | of the frame @var{window} appears on (@pxref{The Buffer List}). | |
0e406a72 CY |
2326 | @end deffn |
2327 | ||
dcb6e7b3 MR |
2328 | By default @code{switch-to-prev-buffer} and @code{switch-to-next-buffer} |
2329 | can switch to a buffer that is already shown in another window on the | |
e78d873d | 2330 | same frame. The following option can be used to override this behavior. |
dcb6e7b3 MR |
2331 | |
2332 | @defopt switch-to-visible-buffer | |
2333 | If this variable is non-@code{nil}, @code{switch-to-prev-buffer} and | |
2334 | @code{switch-to-next-buffer} may switch to a buffer that is already | |
39e8fb76 XF |
2335 | visible on the same frame, provided the buffer was shown in the |
2336 | relevant window before. If it is @code{nil}, | |
2337 | @code{switch-to-prev-buffer} and @code{switch-to-next-buffer} always | |
2338 | try to avoid switching to a buffer that is already visible in another | |
2339 | window on the same frame. The default is @code{t}. | |
dcb6e7b3 MR |
2340 | @end defopt |
2341 | ||
590c056d | 2342 | |
0273ca3a MR |
2343 | @node Dedicated Windows |
2344 | @section Dedicated Windows | |
2345 | @cindex dedicated window | |
2346 | ||
2347 | Functions for displaying a buffer can be told to not use specific | |
df006536 | 2348 | windows by marking these windows as @dfn{dedicated} to their buffers. |
0273ca3a MR |
2349 | @code{display-buffer} (@pxref{Choosing Window}) never uses a dedicated |
2350 | window for displaying another buffer in it. @code{get-lru-window} and | |
0d4bb04f MR |
2351 | @code{get-largest-window} (@pxref{Cyclic Window Ordering}) do not |
2352 | consider dedicated windows as candidates when their @var{dedicated} | |
2353 | argument is non-@code{nil}. The behavior of @code{set-window-buffer} | |
0273ca3a MR |
2354 | (@pxref{Buffers and Windows}) with respect to dedicated windows is |
2355 | slightly different, see below. | |
2356 | ||
0d4bb04f MR |
2357 | Functions supposed to remove a buffer from a window or a window from |
2358 | a frame can behave specially when a window they operate on is dedicated. | |
2359 | We will distinguish three basic cases, namely where (1) the window is | |
2360 | not the only window on its frame, (2) the window is the only window on | |
2361 | its frame but there are other frames on the same terminal left, and (3) | |
2362 | the window is the only window on the only frame on the same terminal. | |
2363 | ||
2364 | In particular, @code{delete-windows-on} (@pxref{Deleting Windows}) | |
2365 | handles case (2) by deleting the associated frame and case (3) by | |
2366 | showing another buffer in that frame's only window. The function | |
2367 | @code{replace-buffer-in-windows} (@pxref{Buffers and Windows}) which is | |
2368 | called when a buffer gets killed, deletes the window in case (1) and | |
2369 | behaves like @code{delete-windows-on} otherwise. | |
3cd51eaa | 2370 | @c FIXME: Does replace-buffer-in-windows _delete_ a window in case (1)? |
0d4bb04f MR |
2371 | |
2372 | When @code{bury-buffer} (@pxref{The Buffer List}) operates on the | |
2373 | selected window (which shows the buffer that shall be buried), it | |
2374 | handles case (2) by calling @code{frame-auto-hide-function} | |
2375 | (@pxref{Quitting Windows}) to deal with the selected frame. The other | |
2376 | two cases are handled as with @code{replace-buffer-in-windows}. | |
250959e0 MR |
2377 | |
2378 | @defun window-dedicated-p &optional window | |
52a94b85 MR |
2379 | This function returns non-@code{nil} if @var{window} is dedicated to its |
2380 | buffer and @code{nil} otherwise. More precisely, the return value is | |
2381 | the value assigned by the last call of @code{set-window-dedicated-p} for | |
e78d873d | 2382 | @var{window}, or @code{nil} if that function was never called with |
aeeedf76 MR |
2383 | @var{window} as its argument. The default for @var{window} is the |
2384 | selected window. | |
b8d4c8d0 GM |
2385 | @end defun |
2386 | ||
2387 | @defun set-window-dedicated-p window flag | |
52a94b85 MR |
2388 | This function marks @var{window} as dedicated to its buffer if |
2389 | @var{flag} is non-@code{nil}, and non-dedicated otherwise. | |
52a94b85 | 2390 | |
0273ca3a MR |
2391 | As a special case, if @var{flag} is @code{t}, @var{window} becomes |
2392 | @dfn{strongly} dedicated to its buffer. @code{set-window-buffer} | |
2393 | signals an error when the window it acts upon is strongly dedicated to | |
2394 | its buffer and does not already display the buffer it is asked to | |
b8766179 MR |
2395 | display. Other functions do not treat @code{t} differently from any |
2396 | non-@code{nil} value. | |
0273ca3a | 2397 | @end defun |
52a94b85 | 2398 | |
c419f5cb MR |
2399 | |
2400 | @node Quitting Windows | |
2401 | @section Quitting Windows | |
2402 | ||
e78d873d | 2403 | When you want to get rid of a window used for displaying a buffer, you |
d83dc65b MR |
2404 | can call @code{delete-window} or @code{delete-windows-on} |
2405 | (@pxref{Deleting Windows}) to remove that window from its frame. If the | |
2406 | buffer is shown on a separate frame, you might want to call | |
2407 | @code{delete-frame} (@pxref{Deleting Frames}) instead. If, on the other | |
2408 | hand, a window has been reused for displaying the buffer, you might | |
e78d873d | 2409 | prefer showing the buffer previously shown in that window, by calling the |
d83dc65b MR |
2410 | function @code{switch-to-prev-buffer} (@pxref{Window History}). |
2411 | Finally, you might want to either bury (@pxref{The Buffer List}) or kill | |
c419f5cb MR |
2412 | (@pxref{Killing Buffers}) the window's buffer. |
2413 | ||
43bcfda6 MR |
2414 | The following command uses information on how the window for |
2415 | displaying the buffer was obtained in the first place, thus attempting | |
2416 | to automate the above decisions for you. | |
c419f5cb MR |
2417 | |
2418 | @deffn Command quit-window &optional kill window | |
2419 | This command quits @var{window} and buries its buffer. The argument | |
2420 | @var{window} must be a live window and defaults to the selected one. | |
2421 | With prefix argument @var{kill} non-@code{nil}, it kills the buffer | |
43bcfda6 MR |
2422 | instead of burying it. It calls the function @code{quit-restore-window} |
2423 | described next to deal with the window and its buffer. | |
c419f5cb MR |
2424 | @end deffn |
2425 | ||
43bcfda6 MR |
2426 | @defun quit-restore-window &optional window bury-or-kill |
2427 | This function tries to restore the state of @var{window} that existed | |
2428 | before its buffer was displayed in it. The optional argument | |
2429 | @var{window} must be a live window and defaults to the selected one. | |
2430 | ||
2431 | If @var{window} was created specially for displaying its buffer, this | |
2432 | function deletes @var{window} provided its frame contains at least one | |
2433 | other live window. If @var{window} is the only window on its frame and | |
2434 | there are other frames on the frame's terminal, the value of the | |
2435 | optional argument @var{bury-or-kill} determines how to proceed with the | |
2436 | window. If @var{bury-or-kill} equals @code{kill}, the frame is deleted | |
2437 | unconditionally. Otherwise, the fate of the frame is determined by | |
2438 | calling @code{frame-auto-hide-function} (see below) with that frame as | |
2439 | sole argument. | |
2440 | ||
2441 | Otherwise, this function tries to redisplay the buffer previously shown | |
2442 | in @var{window}. It also tries to restore the window start | |
2443 | (@pxref{Window Start and End}) and point (@pxref{Window Point}) | |
2444 | positions of the previously shown buffer. If, in addition, | |
2445 | @var{window}'s buffer was temporarily resized, this function will also | |
2446 | try to restore the original height of @var{window}. | |
2447 | ||
2448 | The cases described so far require that the buffer shown in @var{window} | |
2449 | is still the buffer displayed by the last buffer display function for | |
2450 | this window. If another buffer has been shown in the meantime, or the | |
2451 | buffer previously shown no longer exists, this function calls | |
2452 | @code{switch-to-prev-buffer} (@pxref{Window History}) to show some other | |
2453 | buffer instead. | |
2454 | ||
7831fb1b | 2455 | The optional argument @var{bury-or-kill} specifies how to deal with |
43bcfda6 MR |
2456 | @var{window}'s buffer. The following values are handled: |
2457 | ||
2458 | @table @code | |
2459 | @item nil | |
2460 | This means to not deal with the buffer in any particular way. As a | |
2461 | consequence, if @var{window} is not deleted, invoking | |
2462 | @code{switch-to-prev-buffer} will usually show the buffer again. | |
2463 | ||
2464 | @item append | |
2465 | This means that if @var{window} is not deleted, its buffer is moved to | |
2466 | the end of @var{window}'s list of previous buffers, so it's less likely | |
2467 | that a future invocation of @code{switch-to-prev-buffer} will switch to | |
2468 | it. Also, it moves the buffer to the end of the frame's buffer list. | |
2469 | ||
2470 | @item bury | |
2471 | This means that if @var{window} is not deleted, its buffer is removed | |
2472 | from @var{window}'s list of previous buffers. Also, it moves the buffer | |
2473 | to the end of the frame's buffer list. This value provides the most | |
2474 | reliable remedy to not have @code{switch-to-prev-buffer} switch to this | |
2475 | buffer again without killing the buffer. | |
2476 | ||
2477 | @item kill | |
2478 | This means to kill @var{window}'s buffer. | |
2479 | @end table | |
2480 | ||
2481 | @code{quit-restore-window} bases its decisions on information stored in | |
2482 | @var{window}'s @code{quit-restore} window parameter (@pxref{Window | |
2483 | Parameters}), and resets that parameter to @code{nil} after it's done. | |
2484 | @end defun | |
c419f5cb | 2485 | |
d83dc65b | 2486 | The following option specifies how to deal with a frame containing just |
e78d873d | 2487 | one window that should be either quit, or whose buffer should be buried. |
d83dc65b MR |
2488 | |
2489 | @defopt frame-auto-hide-function | |
2490 | The function specified by this option is called to automatically hide | |
e78d873d | 2491 | frames. This function is called with one argument---a frame. |
d83dc65b MR |
2492 | |
2493 | The function specified here is called by @code{bury-buffer} (@pxref{The | |
2494 | Buffer List}) when the selected window is dedicated and shows the buffer | |
43bcfda6 MR |
2495 | to bury. It is also called by @code{quit-restore-window} (see above) |
2496 | when the frame of the window to quit has been specially created for | |
2497 | displaying that window's buffer and the buffer is not killed. | |
d83dc65b MR |
2498 | |
2499 | The default is to call @code{iconify-frame} (@pxref{Visibility of | |
e78d873d | 2500 | Frames}). Alternatively, you may specify either @code{delete-frame} |
d83dc65b MR |
2501 | (@pxref{Deleting Frames}) to remove the frame from its display, |
2502 | @code{ignore} to leave the frame unchanged, or any other function that | |
2503 | can take a frame as its sole argument. | |
2504 | ||
43bcfda6 MR |
2505 | Note that the function specified by this option is called only if the |
2506 | specified frame contains just one live window and there is at least one | |
2507 | other frame on the same terminal. | |
d83dc65b MR |
2508 | @end defopt |
2509 | ||
c419f5cb | 2510 | |
b8d4c8d0 GM |
2511 | @node Window Point |
2512 | @section Windows and Point | |
2513 | @cindex window position | |
2514 | @cindex window point | |
2515 | @cindex position in window | |
2516 | @cindex point in window | |
2517 | ||
0273ca3a MR |
2518 | Each window has its own value of point (@pxref{Point}), independent of |
2519 | the value of point in other windows displaying the same buffer. This | |
2520 | makes it useful to have multiple windows showing one buffer. | |
b8d4c8d0 GM |
2521 | |
2522 | @itemize @bullet | |
2523 | @item | |
2524 | The window point is established when a window is first created; it is | |
2525 | initialized from the buffer's point, or from the window point of another | |
2526 | window opened on the buffer if such a window exists. | |
2527 | ||
2528 | @item | |
2529 | Selecting a window sets the value of point in its buffer from the | |
2530 | window's value of point. Conversely, deselecting a window sets the | |
2531 | window's value of point from that of the buffer. Thus, when you switch | |
2532 | between windows that display a given buffer, the point value for the | |
2533 | selected window is in effect in the buffer, while the point values for | |
2534 | the other windows are stored in those windows. | |
2535 | ||
2536 | @item | |
2537 | As long as the selected window displays the current buffer, the window's | |
2538 | point and the buffer's point always move together; they remain equal. | |
2539 | @end itemize | |
2540 | ||
b8d4c8d0 | 2541 | @cindex cursor |
af1a5cd5 | 2542 | As far as the user is concerned, point is where the cursor is, and |
b8d4c8d0 GM |
2543 | when the user switches to another buffer, the cursor jumps to the |
2544 | position of point in that buffer. | |
2545 | ||
2546 | @defun window-point &optional window | |
2547 | This function returns the current position of point in @var{window}. | |
2548 | For a nonselected window, this is the value point would have (in that | |
aeeedf76 MR |
2549 | window's buffer) if that window were selected. The default for |
2550 | @var{window} is the selected window. | |
b8d4c8d0 | 2551 | |
342dac71 MR |
2552 | When @var{window} is the selected window, the value returned is the |
2553 | value of point in that window's buffer. Strictly speaking, it would be | |
2554 | more correct to return the ``top-level'' value of point, outside of any | |
2555 | @code{save-excursion} forms. But that value is hard to find. | |
b8d4c8d0 GM |
2556 | @end defun |
2557 | ||
2558 | @defun set-window-point window position | |
2559 | This function positions point in @var{window} at position | |
2560 | @var{position} in @var{window}'s buffer. It returns @var{position}. | |
2561 | ||
342dac71 MR |
2562 | If @var{window} is selected, this simply does @code{goto-char} in |
2563 | @var{window}'s buffer. | |
b8d4c8d0 GM |
2564 | @end defun |
2565 | ||
86ab855a MR |
2566 | @defvar window-point-insertion-type |
2567 | This variable specifies the marker insertion type (@pxref{Marker | |
2568 | Insertion Types}) of @code{window-point}. The default is @code{nil}, | |
2569 | so @code{window-point} will stay behind text inserted there. | |
2570 | @end defvar | |
2571 | ||
0273ca3a MR |
2572 | @node Window Start and End |
2573 | @section The Window Start and End Positions | |
b8d4c8d0 | 2574 | @cindex window start position |
123ff297 | 2575 | @cindex display-start position |
b8d4c8d0 | 2576 | |
0273ca3a | 2577 | Each window maintains a marker used to keep track of a buffer position |
b8d4c8d0 GM |
2578 | that specifies where in the buffer display should start. This position |
2579 | is called the @dfn{display-start} position of the window (or just the | |
2580 | @dfn{start}). The character after this position is the one that appears | |
2581 | at the upper left corner of the window. It is usually, but not | |
2582 | inevitably, at the beginning of a text line. | |
2583 | ||
431b78c9 RS |
2584 | After switching windows or buffers, and in some other cases, if the |
2585 | window start is in the middle of a line, Emacs adjusts the window | |
2586 | start to the start of a line. This prevents certain operations from | |
2587 | leaving the window start at a meaningless point within a line. This | |
2588 | feature may interfere with testing some Lisp code by executing it | |
2589 | using the commands of Lisp mode, because they trigger this | |
2590 | readjustment. To test such code, put it into a command and bind the | |
2591 | command to a key. | |
2592 | ||
b8d4c8d0 GM |
2593 | @defun window-start &optional window |
2594 | @cindex window top line | |
2595 | This function returns the display-start position of window | |
2596 | @var{window}. If @var{window} is @code{nil}, the selected window is | |
e78d873d | 2597 | used. |
b8d4c8d0 GM |
2598 | |
2599 | When you create a window, or display a different buffer in it, the | |
2600 | display-start position is set to a display-start position recently used | |
0273ca3a MR |
2601 | for the same buffer, or to @code{point-min} if the buffer doesn't have |
2602 | any. | |
b8d4c8d0 GM |
2603 | |
2604 | Redisplay updates the window-start position (if you have not specified | |
0273ca3a MR |
2605 | it explicitly since the previous redisplay)---to make sure point appears |
2606 | on the screen. Nothing except redisplay automatically changes the | |
2607 | window-start position; if you move point, do not expect the window-start | |
2608 | position to change in response until after the next redisplay. | |
b8d4c8d0 GM |
2609 | @end defun |
2610 | ||
0273ca3a | 2611 | @cindex window end position |
b8d4c8d0 | 2612 | @defun window-end &optional window update |
0273ca3a | 2613 | This function returns the position where display of its buffer ends in |
aeeedf76 | 2614 | @var{window}. The default for @var{window} is the selected window. |
b8d4c8d0 GM |
2615 | |
2616 | Simply changing the buffer text or moving point does not update the | |
2617 | value that @code{window-end} returns. The value is updated only when | |
2618 | Emacs redisplays and redisplay completes without being preempted. | |
2619 | ||
2620 | If the last redisplay of @var{window} was preempted, and did not finish, | |
2621 | Emacs does not know the position of the end of display in that window. | |
2622 | In that case, this function returns @code{nil}. | |
2623 | ||
2624 | If @var{update} is non-@code{nil}, @code{window-end} always returns an | |
0273ca3a MR |
2625 | up-to-date value for where display ends, based on the current |
2626 | @code{window-start} value. If a previously saved value of that position | |
2627 | is still valid, @code{window-end} returns that value; otherwise it | |
2628 | computes the correct value by scanning the buffer text. | |
b8d4c8d0 GM |
2629 | |
2630 | Even if @var{update} is non-@code{nil}, @code{window-end} does not | |
2631 | attempt to scroll the display if point has moved off the screen, the | |
2632 | way real redisplay would do. It does not alter the | |
2633 | @code{window-start} value. In effect, it reports where the displayed | |
2634 | text will end if scrolling is not required. | |
2635 | @end defun | |
2636 | ||
2637 | @defun set-window-start window position &optional noforce | |
2638 | This function sets the display-start position of @var{window} to | |
2639 | @var{position} in @var{window}'s buffer. It returns @var{position}. | |
2640 | ||
2641 | The display routines insist that the position of point be visible when a | |
2642 | buffer is displayed. Normally, they change the display-start position | |
2643 | (that is, scroll the window) whenever necessary to make point visible. | |
2644 | However, if you specify the start position with this function using | |
2645 | @code{nil} for @var{noforce}, it means you want display to start at | |
2646 | @var{position} even if that would put the location of point off the | |
2647 | screen. If this does place point off screen, the display routines move | |
2648 | point to the left margin on the middle line in the window. | |
2649 | ||
431b78c9 RS |
2650 | For example, if point @w{is 1} and you set the start of the window |
2651 | @w{to 37}, the start of the next line, point will be ``above'' the top | |
2652 | of the window. The display routines will automatically move point if | |
2653 | it is still 1 when redisplay occurs. Here is an example: | |
b8d4c8d0 GM |
2654 | |
2655 | @example | |
2656 | @group | |
2657 | ;; @r{Here is what @samp{foo} looks like before executing} | |
2658 | ;; @r{the @code{set-window-start} expression.} | |
2659 | @end group | |
2660 | ||
2661 | @group | |
2662 | ---------- Buffer: foo ---------- | |
2663 | @point{}This is the contents of buffer foo. | |
2664 | 2 | |
2665 | 3 | |
2666 | 4 | |
2667 | 5 | |
2668 | 6 | |
2669 | ---------- Buffer: foo ---------- | |
2670 | @end group | |
2671 | ||
2672 | @group | |
2673 | (set-window-start | |
2674 | (selected-window) | |
431b78c9 RS |
2675 | (save-excursion |
2676 | (goto-char 1) | |
2677 | (forward-line 1) | |
2678 | (point))) | |
2679 | @result{} 37 | |
b8d4c8d0 GM |
2680 | @end group |
2681 | ||
2682 | @group | |
2683 | ;; @r{Here is what @samp{foo} looks like after executing} | |
2684 | ;; @r{the @code{set-window-start} expression.} | |
2685 | ---------- Buffer: foo ---------- | |
b8d4c8d0 GM |
2686 | 2 |
2687 | 3 | |
2688 | @point{}4 | |
2689 | 5 | |
2690 | 6 | |
2691 | ---------- Buffer: foo ---------- | |
2692 | @end group | |
2693 | @end example | |
2694 | ||
2695 | If @var{noforce} is non-@code{nil}, and @var{position} would place point | |
2696 | off screen at the next redisplay, then redisplay computes a new window-start | |
2697 | position that works well with point, and thus @var{position} is not used. | |
2698 | @end defun | |
2699 | ||
2700 | @defun pos-visible-in-window-p &optional position window partially | |
2701 | This function returns non-@code{nil} if @var{position} is within the | |
2702 | range of text currently visible on the screen in @var{window}. It | |
0273ca3a MR |
2703 | returns @code{nil} if @var{position} is scrolled vertically out of view. |
2704 | Locations that are partially obscured are not considered visible unless | |
2705 | @var{partially} is non-@code{nil}. The argument @var{position} defaults | |
2706 | to the current position of point in @var{window}; @var{window}, to the | |
2707 | selected window. If @var{position} is @code{t}, that means to check the | |
2708 | last visible position in @var{window}. | |
b8d4c8d0 | 2709 | |
049bcbcb CY |
2710 | This function considers only vertical scrolling. If @var{position} is |
2711 | out of view only because @var{window} has been scrolled horizontally, | |
2712 | @code{pos-visible-in-window-p} returns non-@code{nil} anyway. | |
2713 | @xref{Horizontal Scrolling}. | |
b8d4c8d0 GM |
2714 | |
2715 | If @var{position} is visible, @code{pos-visible-in-window-p} returns | |
2716 | @code{t} if @var{partially} is @code{nil}; if @var{partially} is | |
0273ca3a | 2717 | non-@code{nil}, and the character following @var{position} is fully |
b8d4c8d0 GM |
2718 | visible, it returns a list of the form @code{(@var{x} @var{y})}, where |
2719 | @var{x} and @var{y} are the pixel coordinates relative to the top left | |
0273ca3a MR |
2720 | corner of the window; otherwise it returns an extended list of the form |
2721 | @code{(@var{x} @var{y} @var{rtop} @var{rbot} @var{rowh} @var{vpos})}, | |
2722 | where @var{rtop} and @var{rbot} specify the number of off-window pixels | |
2723 | at the top and bottom of the row at @var{position}, @var{rowh} specifies | |
2724 | the visible height of that row, and @var{vpos} specifies the vertical | |
2725 | position (zero-based row number) of that row. | |
b8d4c8d0 GM |
2726 | |
2727 | Here is an example: | |
2728 | ||
2729 | @example | |
2730 | @group | |
2731 | ;; @r{If point is off the screen now, recenter it now.} | |
2732 | (or (pos-visible-in-window-p | |
2733 | (point) (selected-window)) | |
2734 | (recenter 0)) | |
2735 | @end group | |
2736 | @end example | |
2737 | @end defun | |
2738 | ||
2739 | @defun window-line-height &optional line window | |
aeeedf76 MR |
2740 | This function returns the height of text line @var{line} in |
2741 | @var{window}. If @var{line} is one of @code{header-line} or | |
2742 | @code{mode-line}, @code{window-line-height} returns information about | |
2743 | the corresponding line of the window. Otherwise, @var{line} is a text | |
2744 | line number starting from 0. A negative number counts from the end of | |
2745 | the window. The default for @var{line} is the current line in | |
2746 | @var{window}; the default for @var{window} is the selected window. | |
b8d4c8d0 GM |
2747 | |
2748 | If the display is not up to date, @code{window-line-height} returns | |
2749 | @code{nil}. In that case, @code{pos-visible-in-window-p} may be used | |
2750 | to obtain related information. | |
2751 | ||
2752 | If there is no line corresponding to the specified @var{line}, | |
2753 | @code{window-line-height} returns @code{nil}. Otherwise, it returns | |
2754 | a list @code{(@var{height} @var{vpos} @var{ypos} @var{offbot})}, | |
2755 | where @var{height} is the height in pixels of the visible part of the | |
2756 | line, @var{vpos} and @var{ypos} are the vertical position in lines and | |
2757 | pixels of the line relative to the top of the first text line, and | |
2758 | @var{offbot} is the number of off-window pixels at the bottom of the | |
2759 | text line. If there are off-window pixels at the top of the (first) | |
2760 | text line, @var{ypos} is negative. | |
2761 | @end defun | |
2762 | ||
2763 | @node Textual Scrolling | |
2764 | @section Textual Scrolling | |
2765 | @cindex textual scrolling | |
2766 | @cindex scrolling textually | |
2767 | ||
2768 | @dfn{Textual scrolling} means moving the text up or down through a | |
550f41cd CY |
2769 | window. It works by changing the window's display-start location. It |
2770 | may also change the value of @code{window-point} to keep point on the | |
2771 | screen (@pxref{Window Point}). | |
2772 | ||
2773 | The basic textual scrolling functions are @code{scroll-up} (which | |
2774 | scrolls forward) and @code{scroll-down} (which scrolls backward). In | |
2775 | these function names, ``up'' and ``down'' refer to the direction of | |
2776 | motion of the buffer text relative to the window. Imagine that the | |
2777 | text is written on a long roll of paper and that the scrolling | |
2778 | commands move the paper up and down. Thus, if you are looking at the | |
2779 | middle of a buffer and repeatedly call @code{scroll-down}, you will | |
2780 | eventually see the beginning of the buffer. | |
b8d4c8d0 | 2781 | |
09ebefe1 GM |
2782 | Unfortunately, this sometimes causes confusion, because some people |
2783 | tend to think in terms of the opposite convention: they | |
550f41cd CY |
2784 | imagine the window moving over text that remains in place, so that |
2785 | ``down'' commands take you to the end of the buffer. This convention | |
2786 | is consistent with fact that such a command is bound to a key named | |
09ebefe1 GM |
2787 | @key{PageDown} on modern keyboards. |
2788 | @ignore | |
2789 | We have not switched to this convention as that is likely to break | |
2790 | existing Emacs Lisp code. | |
2791 | @end ignore | |
550f41cd CY |
2792 | |
2793 | Textual scrolling functions (aside from @code{scroll-other-window}) | |
2794 | have unpredictable results if the current buffer is not the one | |
2795 | displayed in the selected window. @xref{Current Buffer}. | |
2796 | ||
2797 | If the window contains a row taller than the height of the window | |
2798 | (for example in the presence of a large image), the scroll functions | |
2799 | will adjust the window's vertical scroll position to scroll the | |
2800 | partially visible row. Lisp callers can disable this feature by | |
2801 | binding the variable @code{auto-window-vscroll} to @code{nil} | |
2802 | (@pxref{Vertical Scrolling}). | |
b8d4c8d0 GM |
2803 | |
2804 | @deffn Command scroll-up &optional count | |
550f41cd CY |
2805 | This function scrolls forward by @var{count} lines in the selected |
2806 | window. | |
b8d4c8d0 | 2807 | |
550f41cd CY |
2808 | If @var{count} is negative, it scrolls backward instead. If |
2809 | @var{count} is @code{nil} (or omitted), the distance scrolled is | |
2810 | @code{next-screen-context-lines} lines less than the height of the | |
2811 | window's text area. | |
b8d4c8d0 | 2812 | |
550f41cd CY |
2813 | If the selected window cannot be scrolled any further, this function |
2814 | signals an error. Otherwise, it returns @code{nil}. | |
b8d4c8d0 GM |
2815 | @end deffn |
2816 | ||
2817 | @deffn Command scroll-down &optional count | |
550f41cd CY |
2818 | This function scrolls backward by @var{count} lines in the selected |
2819 | window. | |
2820 | ||
09ebefe1 GM |
2821 | If @var{count} is negative, it scrolls forward instead. In other |
2822 | respects, it behaves the same way as @code{scroll-up} does. | |
550f41cd CY |
2823 | @end deffn |
2824 | ||
2825 | @deffn Command scroll-up-command &optional count | |
2826 | This behaves like @code{scroll-up}, except that if the selected window | |
2827 | cannot be scrolled any further and the value of the variable | |
2828 | @code{scroll-error-top-bottom} is @code{t}, it tries to move to the | |
2829 | end of the buffer instead. If point is already there, it signals an | |
2830 | error. | |
2831 | @end deffn | |
b8d4c8d0 | 2832 | |
550f41cd CY |
2833 | @deffn Command scroll-down-command &optional count |
2834 | This behaves like @code{scroll-down}, except that if the selected | |
2835 | window cannot be scrolled any further and the value of the variable | |
2836 | @code{scroll-error-top-bottom} is @code{t}, it tries to move to the | |
2837 | beginning of the buffer instead. If point is already there, it | |
2838 | signals an error. | |
b8d4c8d0 GM |
2839 | @end deffn |
2840 | ||
2841 | @deffn Command scroll-other-window &optional count | |
2842 | This function scrolls the text in another window upward @var{count} | |
2843 | lines. Negative values of @var{count}, or @code{nil}, are handled | |
2844 | as in @code{scroll-up}. | |
2845 | ||
2846 | You can specify which buffer to scroll by setting the variable | |
2847 | @code{other-window-scroll-buffer} to a buffer. If that buffer isn't | |
2848 | already displayed, @code{scroll-other-window} displays it in some | |
2849 | window. | |
2850 | ||
2851 | When the selected window is the minibuffer, the next window is normally | |
09ebefe1 GM |
2852 | the leftmost one immediately above it. You can specify a different |
2853 | window to scroll, when the minibuffer is selected, by setting the variable | |
b8d4c8d0 GM |
2854 | @code{minibuffer-scroll-window}. This variable has no effect when any |
2855 | other window is selected. When it is non-@code{nil} and the | |
2856 | minibuffer is selected, it takes precedence over | |
2857 | @code{other-window-scroll-buffer}. @xref{Definition of | |
2858 | minibuffer-scroll-window}. | |
2859 | ||
2860 | When the minibuffer is active, it is the next window if the selected | |
2861 | window is the one at the bottom right corner. In this case, | |
2862 | @code{scroll-other-window} attempts to scroll the minibuffer. If the | |
2863 | minibuffer contains just one line, it has nowhere to scroll to, so the | |
2864 | line reappears after the echo area momentarily displays the message | |
09ebefe1 | 2865 | @samp{End of buffer}. |
b8d4c8d0 GM |
2866 | @end deffn |
2867 | ||
b8d4c8d0 GM |
2868 | @defvar other-window-scroll-buffer |
2869 | If this variable is non-@code{nil}, it tells @code{scroll-other-window} | |
0273ca3a | 2870 | which buffer's window to scroll. |
b8d4c8d0 GM |
2871 | @end defvar |
2872 | ||
2873 | @defopt scroll-margin | |
2874 | This option specifies the size of the scroll margin---a minimum number | |
2875 | of lines between point and the top or bottom of a window. Whenever | |
2876 | point gets within this many lines of the top or bottom of the window, | |
2877 | redisplay scrolls the text automatically (if possible) to move point | |
2878 | out of the margin, closer to the center of the window. | |
2879 | @end defopt | |
2880 | ||
2881 | @defopt scroll-conservatively | |
2882 | This variable controls how scrolling is done automatically when point | |
2883 | moves off the screen (or into the scroll margin). If the value is a | |
2884 | positive integer @var{n}, then redisplay scrolls the text up to | |
2885 | @var{n} lines in either direction, if that will bring point back into | |
0273ca3a | 2886 | proper view. This behavior is called @dfn{conservative scrolling}. |
b8d4c8d0 GM |
2887 | Otherwise, scrolling happens in the usual way, under the control of |
2888 | other variables such as @code{scroll-up-aggressively} and | |
2889 | @code{scroll-down-aggressively}. | |
2890 | ||
2891 | The default value is zero, which means that conservative scrolling | |
2892 | never happens. | |
2893 | @end defopt | |
2894 | ||
2895 | @defopt scroll-down-aggressively | |
2896 | The value of this variable should be either @code{nil} or a fraction | |
2897 | @var{f} between 0 and 1. If it is a fraction, that specifies where on | |
2898 | the screen to put point when scrolling down. More precisely, when a | |
2899 | window scrolls down because point is above the window start, the new | |
2900 | start position is chosen to put point @var{f} part of the window | |
2901 | height from the top. The larger @var{f}, the more aggressive the | |
2902 | scrolling. | |
2903 | ||
2904 | A value of @code{nil} is equivalent to .5, since its effect is to center | |
2905 | point. This variable automatically becomes buffer-local when set in any | |
2906 | fashion. | |
2907 | @end defopt | |
2908 | ||
2909 | @defopt scroll-up-aggressively | |
2910 | Likewise, for scrolling up. The value, @var{f}, specifies how far | |
2911 | point should be placed from the bottom of the window; thus, as with | |
2912 | @code{scroll-up-aggressively}, a larger value scrolls more aggressively. | |
2913 | @end defopt | |
2914 | ||
2915 | @defopt scroll-step | |
da0bbbc4 CY |
2916 | This variable is an older variant of @code{scroll-conservatively}. |
2917 | The difference is that if its value is @var{n}, that permits scrolling | |
b8d4c8d0 GM |
2918 | only by precisely @var{n} lines, not a smaller number. This feature |
2919 | does not work with @code{scroll-margin}. The default value is zero. | |
2920 | @end defopt | |
2921 | ||
550f41cd | 2922 | @cindex @code{scroll-command} property |
b8d4c8d0 | 2923 | @defopt scroll-preserve-screen-position |
550f41cd CY |
2924 | If this option is @code{t}, whenever a scrolling command moves point |
2925 | off-window, Emacs tries to adjust point to keep the cursor at its old | |
2926 | vertical position in the window, rather than the window edge. | |
2927 | ||
2928 | If the value is non-@code{nil} and not @code{t}, Emacs adjusts point | |
2929 | to keep the cursor at the same vertical position, even if the | |
2930 | scrolling command didn't move point off-window. | |
b8d4c8d0 | 2931 | |
550f41cd CY |
2932 | This option affects all scroll commands that have a non-@code{nil} |
2933 | @code{scroll-command} symbol property. | |
b8d4c8d0 GM |
2934 | @end defopt |
2935 | ||
2936 | @defopt next-screen-context-lines | |
2937 | The value of this variable is the number of lines of continuity to | |
2938 | retain when scrolling by full screens. For example, @code{scroll-up} | |
2939 | with an argument of @code{nil} scrolls so that this many lines at the | |
2940 | bottom of the window appear instead at the top. The default value is | |
2941 | @code{2}. | |
2942 | @end defopt | |
2943 | ||
550f41cd CY |
2944 | @defopt scroll-error-top-bottom |
2945 | If this option is @code{nil} (the default), @code{scroll-up-command} | |
2946 | and @code{scroll-down-command} simply signal an error when no more | |
2947 | scrolling is possible. | |
2948 | ||
2949 | If the value is @code{t}, these commands instead move point to the | |
2950 | beginning or end of the buffer (depending on scrolling direction); | |
2951 | only if point is already on that position do they signal an error. | |
2952 | @end defopt | |
2953 | ||
b8d4c8d0 GM |
2954 | @deffn Command recenter &optional count |
2955 | @cindex centering point | |
2956 | This function scrolls the text in the selected window so that point is | |
2957 | displayed at a specified vertical position within the window. It does | |
2958 | not ``move point'' with respect to the text. | |
2959 | ||
a79db6e0 | 2960 | If @var{count} is a non-negative number, that puts the line containing |
b8d4c8d0 GM |
2961 | point @var{count} lines down from the top of the window. If |
2962 | @var{count} is a negative number, then it counts upward from the | |
2963 | bottom of the window, so that @minus{}1 stands for the last usable | |
09ebefe1 | 2964 | line in the window. |
b8d4c8d0 | 2965 | |
09ebefe1 GM |
2966 | If @var{count} is @code{nil} (or a non-@code{nil} list), |
2967 | @code{recenter} puts the line containing point in the middle of the | |
2968 | window. If @var{count} is @code{nil}, this function may redraw the | |
2969 | frame, according to the value of @code{recenter-redisplay}. | |
b8d4c8d0 GM |
2970 | |
2971 | When @code{recenter} is called interactively, @var{count} is the raw | |
2972 | prefix argument. Thus, typing @kbd{C-u} as the prefix sets the | |
2973 | @var{count} to a non-@code{nil} list, while typing @kbd{C-u 4} sets | |
2974 | @var{count} to 4, which positions the current line four lines from the | |
2975 | top. | |
2976 | ||
2977 | With an argument of zero, @code{recenter} positions the current line at | |
09ebefe1 GM |
2978 | the top of the window. The command @code{recenter-top-bottom} offers |
2979 | a more convenient way to achieve this. | |
2980 | @end deffn | |
b8d4c8d0 | 2981 | |
09ebefe1 GM |
2982 | @defopt recenter-redisplay |
2983 | If this variable is non-@code{nil}, calling @code{recenter} with a | |
2984 | @code{nil} argument redraws the frame. The default value is | |
2985 | @code{tty}, which means only redraw the frame if it is a tty frame. | |
2986 | @end defopt | |
b8d4c8d0 | 2987 | |
09ebefe1 GM |
2988 | @deffn Command recenter-top-bottom &optional count |
2989 | This command, which is the default binding for @kbd{C-l}, acts like | |
2990 | @code{recenter}, except if called with no argument. In that case, | |
2991 | successive calls place point according to the cycling order defined | |
2992 | by the variable @code{recenter-positions}. | |
b8d4c8d0 GM |
2993 | @end deffn |
2994 | ||
09ebefe1 GM |
2995 | @defopt recenter-positions |
2996 | This variable controls how @code{recenter-top-bottom} behaves when | |
2997 | called with no argument. The default value is @code{(middle top | |
2998 | bottom)}, which means that successive calls of | |
2999 | @code{recenter-top-bottom} with no argument cycle between placing | |
3000 | point at the middle, top, and bottom of the window. | |
3001 | @end defopt | |
3002 | ||
3003 | ||
b8d4c8d0 GM |
3004 | @node Vertical Scrolling |
3005 | @section Vertical Fractional Scrolling | |
3006 | @cindex vertical fractional scrolling | |
0273ca3a | 3007 | @cindex vertical scroll position |
b8d4c8d0 | 3008 | |
af1a5cd5 MR |
3009 | @dfn{Vertical fractional scrolling} means shifting text in a window |
3010 | up or down by a specified multiple or fraction of a line. Each window | |
3011 | has a @dfn{vertical scroll position}, which is a number, never less than | |
0273ca3a MR |
3012 | zero. It specifies how far to raise the contents of the window. |
3013 | Raising the window contents generally makes all or part of some lines | |
3014 | disappear off the top, and all or part of some other lines appear at the | |
3015 | bottom. The usual value is zero. | |
b8d4c8d0 | 3016 | |
af1a5cd5 | 3017 | The vertical scroll position is measured in units of the normal line |
b8d4c8d0 GM |
3018 | height, which is the height of the default font. Thus, if the value is |
3019 | .5, that means the window contents are scrolled up half the normal line | |
3020 | height. If it is 3.3, that means the window contents are scrolled up | |
3021 | somewhat over three times the normal line height. | |
3022 | ||
af1a5cd5 | 3023 | What fraction of a line the vertical scrolling covers, or how many |
b8d4c8d0 GM |
3024 | lines, depends on what the lines contain. A value of .5 could scroll a |
3025 | line whose height is very short off the screen, while a value of 3.3 | |
3026 | could scroll just part of the way through a tall line or an image. | |
3027 | ||
3028 | @defun window-vscroll &optional window pixels-p | |
3029 | This function returns the current vertical scroll position of | |
aeeedf76 MR |
3030 | @var{window}. The default for @var{window} is the selected window. |
3031 | If @var{pixels-p} is non-@code{nil}, the return value is measured in | |
0273ca3a | 3032 | pixels, rather than in units of the normal line height. |
b8d4c8d0 GM |
3033 | |
3034 | @example | |
3035 | @group | |
3036 | (window-vscroll) | |
3037 | @result{} 0 | |
3038 | @end group | |
3039 | @end example | |
3040 | @end defun | |
3041 | ||
3042 | @defun set-window-vscroll window lines &optional pixels-p | |
3043 | This function sets @var{window}'s vertical scroll position to | |
0273ca3a MR |
3044 | @var{lines}. If @var{window} is @code{nil}, the selected window is |
3045 | used. The argument @var{lines} should be zero or positive; if not, it | |
3046 | is taken as zero. | |
b8d4c8d0 | 3047 | |
b8d4c8d0 GM |
3048 | |
3049 | The actual vertical scroll position must always correspond | |
3050 | to an integral number of pixels, so the value you specify | |
3051 | is rounded accordingly. | |
3052 | ||
3053 | The return value is the result of this rounding. | |
3054 | ||
3055 | @example | |
3056 | @group | |
3057 | (set-window-vscroll (selected-window) 1.2) | |
3058 | @result{} 1.13 | |
3059 | @end group | |
3060 | @end example | |
3061 | ||
3062 | If @var{pixels-p} is non-@code{nil}, @var{lines} specifies a number of | |
3063 | pixels. In this case, the return value is @var{lines}. | |
3064 | @end defun | |
3065 | ||
3066 | @defvar auto-window-vscroll | |
04c48b14 CY |
3067 | If this variable is non-@code{nil}, the @code{line-move}, |
3068 | @code{scroll-up}, and @code{scroll-down} functions will automatically | |
3069 | modify the vertical scroll position to scroll through display rows | |
3070 | that are taller than the height of the window, for example in the | |
3071 | presence of large images. | |
b8d4c8d0 GM |
3072 | @end defvar |
3073 | ||
3074 | @node Horizontal Scrolling | |
3075 | @section Horizontal Scrolling | |
3076 | @cindex horizontal scrolling | |
3077 | ||
3078 | @dfn{Horizontal scrolling} means shifting the image in the window left | |
3079 | or right by a specified multiple of the normal character width. Each | |
3080 | window has a @dfn{horizontal scroll position}, which is a number, never | |
3081 | less than zero. It specifies how far to shift the contents left. | |
3082 | Shifting the window contents left generally makes all or part of some | |
3083 | characters disappear off the left, and all or part of some other | |
3084 | characters appear at the right. The usual value is zero. | |
3085 | ||
3086 | The horizontal scroll position is measured in units of the normal | |
3087 | character width, which is the width of space in the default font. Thus, | |
3088 | if the value is 5, that means the window contents are scrolled left by 5 | |
3089 | times the normal character width. How many characters actually | |
3090 | disappear off to the left depends on their width, and could vary from | |
3091 | line to line. | |
3092 | ||
0b27932b GM |
3093 | Because we read from side to side in the ``inner loop'', and from top |
3094 | to bottom in the ``outer loop'', the effect of horizontal scrolling is | |
b8d4c8d0 GM |
3095 | not like that of textual or vertical scrolling. Textual scrolling |
3096 | involves selection of a portion of text to display, and vertical | |
3097 | scrolling moves the window contents contiguously; but horizontal | |
3098 | scrolling causes part of @emph{each line} to go off screen. | |
3099 | ||
3100 | Usually, no horizontal scrolling is in effect; then the leftmost | |
3101 | column is at the left edge of the window. In this state, scrolling to | |
3102 | the right is meaningless, since there is no data to the left of the edge | |
3103 | to be revealed by it; so this is not allowed. Scrolling to the left is | |
3104 | allowed; it scrolls the first columns of text off the edge of the window | |
3105 | and can reveal additional columns on the right that were truncated | |
3106 | before. Once a window has a nonzero amount of leftward horizontal | |
3107 | scrolling, you can scroll it back to the right, but only so far as to | |
3108 | reduce the net horizontal scroll to zero. There is no limit to how far | |
3109 | left you can scroll, but eventually all the text will disappear off the | |
3110 | left edge. | |
3111 | ||
3112 | @vindex auto-hscroll-mode | |
3113 | If @code{auto-hscroll-mode} is set, redisplay automatically alters | |
3114 | the horizontal scrolling of a window as necessary to ensure that point | |
3115 | is always visible. However, you can still set the horizontal | |
3116 | scrolling value explicitly. The value you specify serves as a lower | |
1df7defd | 3117 | bound for automatic scrolling, i.e., automatic scrolling will not |
b8d4c8d0 GM |
3118 | scroll a window to a column less than the specified one. |
3119 | ||
3120 | @deffn Command scroll-left &optional count set-minimum | |
3121 | This function scrolls the selected window @var{count} columns to the | |
3122 | left (or to the right if @var{count} is negative). The default | |
3123 | for @var{count} is the window width, minus 2. | |
3124 | ||
3125 | The return value is the total amount of leftward horizontal scrolling in | |
3126 | effect after the change---just like the value returned by | |
3127 | @code{window-hscroll} (below). | |
3128 | ||
3129 | Once you scroll a window as far right as it can go, back to its normal | |
3130 | position where the total leftward scrolling is zero, attempts to scroll | |
3131 | any farther right have no effect. | |
3132 | ||
3133 | If @var{set-minimum} is non-@code{nil}, the new scroll amount becomes | |
3134 | the lower bound for automatic scrolling; that is, automatic scrolling | |
3135 | will not scroll a window to a column less than the value returned by | |
3136 | this function. Interactive calls pass non-@code{nil} for | |
3137 | @var{set-minimum}. | |
3138 | @end deffn | |
3139 | ||
3140 | @deffn Command scroll-right &optional count set-minimum | |
3141 | This function scrolls the selected window @var{count} columns to the | |
3142 | right (or to the left if @var{count} is negative). The default | |
3143 | for @var{count} is the window width, minus 2. Aside from the direction | |
3144 | of scrolling, this works just like @code{scroll-left}. | |
3145 | @end deffn | |
3146 | ||
3147 | @defun window-hscroll &optional window | |
3148 | This function returns the total leftward horizontal scrolling of | |
3149 | @var{window}---the number of columns by which the text in @var{window} | |
aeeedf76 MR |
3150 | is scrolled left past the left margin. The default for |
3151 | @var{window} is the selected window. | |
b8d4c8d0 | 3152 | |
0273ca3a MR |
3153 | The return value is never negative. It is zero when no horizontal |
3154 | scrolling has been done in @var{window} (which is usually the case). | |
b8d4c8d0 | 3155 | |
b8d4c8d0 GM |
3156 | |
3157 | @example | |
3158 | @group | |
3159 | (window-hscroll) | |
3160 | @result{} 0 | |
3161 | @end group | |
3162 | @group | |
3163 | (scroll-left 5) | |
3164 | @result{} 5 | |
3165 | @end group | |
3166 | @group | |
3167 | (window-hscroll) | |
3168 | @result{} 5 | |
3169 | @end group | |
3170 | @end example | |
3171 | @end defun | |
3172 | ||
3173 | @defun set-window-hscroll window columns | |
3174 | This function sets horizontal scrolling of @var{window}. The value of | |
3175 | @var{columns} specifies the amount of scrolling, in terms of columns | |
3176 | from the left margin. The argument @var{columns} should be zero or | |
3177 | positive; if not, it is taken as zero. Fractional values of | |
3178 | @var{columns} are not supported at present. | |
3179 | ||
3180 | Note that @code{set-window-hscroll} may appear not to work if you test | |
3181 | it by evaluating a call with @kbd{M-:} in a simple way. What happens | |
3182 | is that the function sets the horizontal scroll value and returns, but | |
3183 | then redisplay adjusts the horizontal scrolling to make point visible, | |
3184 | and this overrides what the function did. You can observe the | |
3185 | function's effect if you call it while point is sufficiently far from | |
3186 | the left margin that it will remain visible. | |
3187 | ||
3188 | The value returned is @var{columns}. | |
3189 | ||
3190 | @example | |
3191 | @group | |
3192 | (set-window-hscroll (selected-window) 10) | |
3193 | @result{} 10 | |
3194 | @end group | |
3195 | @end example | |
3196 | @end defun | |
3197 | ||
af1a5cd5 MR |
3198 | Here is how you can determine whether a given position @var{position} |
3199 | is off the screen due to horizontal scrolling: | |
b8d4c8d0 | 3200 | |
123ff297 | 3201 | @c FIXME: Maybe hscroll-on-screen-p is a better name? |
b8d4c8d0 GM |
3202 | @example |
3203 | @group | |
3204 | (defun hscroll-on-screen (window position) | |
3205 | (save-excursion | |
3206 | (goto-char position) | |
3207 | (and | |
3208 | (>= (- (current-column) (window-hscroll window)) 0) | |
3209 | (< (- (current-column) (window-hscroll window)) | |
3210 | (window-width window))))) | |
3211 | @end group | |
3212 | @end example | |
3213 | ||
b8d4c8d0 GM |
3214 | @node Coordinates and Windows |
3215 | @section Coordinates and Windows | |
1c3d7a13 CY |
3216 | @cindex frame-relative coordinate |
3217 | @cindex coordinate, relative to frame | |
3218 | @cindex window position | |
b8d4c8d0 | 3219 | |
1c3d7a13 CY |
3220 | This section describes functions that report the position of a |
3221 | window. Most of these functions report positions relative to the | |
3222 | window's frame. In this case, the coordinate origin @samp{(0,0)} lies | |
3223 | near the upper left corner of the frame. For technical reasons, on | |
3224 | graphical displays the origin is not located at the exact corner of | |
3225 | the graphical window as it appears on the screen. If Emacs is built | |
3226 | with the GTK+ toolkit, the origin is at the upper left corner of the | |
3227 | frame area used for displaying Emacs windows, below the title-bar, | |
3228 | GTK+ menu bar, and tool bar (since these are drawn by the window | |
3229 | manager and/or GTK+, not by Emacs). But if Emacs is not built with | |
3230 | GTK+, the origin is at the upper left corner of the tool bar (since in | |
3231 | this case Emacs itself draws the tool bar). In both cases, the X and | |
3232 | Y coordinates increase rightward and downward respectively. | |
3233 | ||
3234 | Except where noted, X and Y coordinates are reported in integer | |
1df7defd | 3235 | character units, i.e., numbers of lines and columns respectively. On a |
1c3d7a13 CY |
3236 | graphical display, each ``line'' and ``column'' corresponds to the |
3237 | height and width of a default character specified by the frame's | |
3238 | default font. | |
3239 | ||
3240 | @defun window-edges &optional window | |
3241 | This function returns a list of the edge coordinates of @var{window}. | |
3242 | If @var{window} is omitted or @code{nil}, it defaults to the selected | |
3243 | window. | |
b8d4c8d0 | 3244 | |
1c3d7a13 CY |
3245 | The return value has the form @code{(@var{left} @var{top} @var{right} |
3246 | @var{bottom})}. These list elements are, respectively, the X | |
3247 | coordinate of the leftmost column occupied by the window, the Y | |
3248 | coordinate of the topmost row, the X coordinate one column to the | |
3249 | right of the rightmost column, and the Y coordinate one row down from | |
3250 | the bottommost row. | |
b8d4c8d0 | 3251 | |
1c3d7a13 CY |
3252 | Note that these are the actual outer edges of the window, including |
3253 | any header line, mode line, scroll bar, fringes, and display margins. | |
a08a07e3 CY |
3254 | On a text terminal, if the window has a neighbor on its right, its |
3255 | right edge includes the separator line between the window and its | |
1c3d7a13 | 3256 | neighbor. |
b8d4c8d0 GM |
3257 | @end defun |
3258 | ||
1c3d7a13 CY |
3259 | @defun window-inside-edges &optional window |
3260 | This function is similar to @code{window-edges}, but the returned edge | |
3261 | values are for the text area of the window. They exclude any header | |
3262 | line, mode line, scroll bar, fringes, display margins, and vertical | |
3263 | separator. | |
3264 | @end defun | |
3265 | ||
3266 | @defun window-top-line &optional window | |
3267 | This function returns the Y coordinate of the topmost row of | |
3268 | @var{window}, equivalent to the @var{top} entry in the list returned | |
3269 | by @code{window-edges}. | |
3270 | @end defun | |
3271 | ||
3272 | @defun window-left-column &optional window | |
3273 | This function returns the X coordinate of the leftmost column of | |
3274 | @var{window}, equivalent to the @var{left} entry in the list returned | |
3275 | by @code{window-edges}. | |
3276 | @end defun | |
b8d4c8d0 | 3277 | |
1c3d7a13 CY |
3278 | The following functions can be used to relate a set of |
3279 | frame-relative coordinates to a window: | |
b8d4c8d0 | 3280 | |
1c3d7a13 CY |
3281 | @defun window-at x y &optional frame |
3282 | This function returns the live window at the frame-relative | |
3283 | coordinates @var{x} and @var{y}, on frame @var{frame}. If there is no | |
3284 | window at that position, the return value is @code{nil}. If | |
3285 | @var{frame} is omitted or @code{nil}, it defaults to the selected | |
3286 | frame. | |
3287 | @end defun | |
3288 | ||
3289 | @defun coordinates-in-window-p coordinates window | |
3290 | This function checks whether a window @var{window} occupies the | |
09ebefe1 | 3291 | frame-relative coordinates @var{coordinates}, and if so, which part of |
1c3d7a13 CY |
3292 | the window that is. @var{window} should be a live window. |
3293 | @var{coordinates} should be a cons cell of the form @code{(@var{x} | |
3294 | . @var{y})}, where @var{x} and @var{y} are frame-relative coordinates. | |
3295 | ||
3296 | If there is no window at the specified position, the return value is | |
3297 | @code{nil} . Otherwise, the return value is one of the following: | |
b8d4c8d0 GM |
3298 | |
3299 | @table @code | |
3300 | @item (@var{relx} . @var{rely}) | |
3301 | The coordinates are inside @var{window}. The numbers @var{relx} and | |
3302 | @var{rely} are the equivalent window-relative coordinates for the | |
3303 | specified position, counting from 0 at the top left corner of the | |
3304 | window. | |
3305 | ||
3306 | @item mode-line | |
3307 | The coordinates are in the mode line of @var{window}. | |
3308 | ||
3309 | @item header-line | |
3310 | The coordinates are in the header line of @var{window}. | |
3311 | ||
3312 | @item vertical-line | |
3313 | The coordinates are in the vertical line between @var{window} and its | |
3314 | neighbor to the right. This value occurs only if the window doesn't | |
3315 | have a scroll bar; positions in a scroll bar are considered outside the | |
3316 | window for these purposes. | |
3317 | ||
3318 | @item left-fringe | |
3319 | @itemx right-fringe | |
3320 | The coordinates are in the left or right fringe of the window. | |
3321 | ||
3322 | @item left-margin | |
3323 | @itemx right-margin | |
3324 | The coordinates are in the left or right margin of the window. | |
3325 | ||
3326 | @item nil | |
3327 | The coordinates are not in any part of @var{window}. | |
3328 | @end table | |
3329 | ||
3330 | The function @code{coordinates-in-window-p} does not require a frame as | |
3331 | argument because it always uses the frame that @var{window} is on. | |
3332 | @end defun | |
3333 | ||
1c3d7a13 CY |
3334 | The following functions return window positions in pixels, rather |
3335 | than character units. Though mostly useful on graphical displays, | |
a08a07e3 CY |
3336 | they can also be called on text terminals, where the screen area of |
3337 | each text character is taken to be ``one pixel''. | |
1c3d7a13 CY |
3338 | |
3339 | @defun window-pixel-edges &optional window | |
3340 | This function returns a list of pixel coordinates for the edges of | |
3341 | @var{window}. If @var{window} is omitted or @code{nil}, it defaults | |
3342 | to the selected window. | |
3343 | ||
3344 | The return value has the form @code{(@var{left} @var{top} @var{right} | |
3345 | @var{bottom})}. The list elements are, respectively, the X pixel | |
3346 | coordinate of the left window edge, the Y pixel coordinate of the top | |
3347 | edge, one more than the X pixel coordinate of the right edge, and one | |
3348 | more than the Y pixel coordinate of the bottom edge. | |
3349 | @end defun | |
3350 | ||
3351 | @defun window-inside-pixel-edges &optional window | |
3352 | This function is like @code{window-pixel-edges}, except that it | |
3353 | returns the pixel coordinates for the edges of the window's text area, | |
3354 | rather than the pixel coordinates for the edges of the window itself. | |
3355 | @var{window} must specify a live window. | |
3356 | @end defun | |
3357 | ||
3358 | The following functions return window positions in pixels, relative | |
3359 | to the display screen rather than the frame: | |
3360 | ||
3361 | @defun window-absolute-pixel-edges &optional window | |
3362 | This function is like @code{window-pixel-edges}, except that it | |
3363 | returns the edge pixel coordinates relative to the top left corner of | |
3364 | the display screen. | |
3365 | @end defun | |
3366 | ||
3367 | @defun window-inside-absolute-pixel-edges &optional window | |
3368 | This function is like @code{window-inside-pixel-edges}, except that it | |
3369 | returns the edge pixel coordinates relative to the top left corner of | |
3370 | the display screen. @var{window} must specify a live window. | |
3371 | @end defun | |
b8d4c8d0 GM |
3372 | |
3373 | @node Window Configurations | |
3374 | @section Window Configurations | |
3375 | @cindex window configurations | |
3376 | @cindex saving window information | |
3377 | ||
c419f5cb | 3378 | A @dfn{window configuration} records the entire layout of one |
0273ca3a MR |
3379 | frame---all windows, their sizes, which buffers they contain, how those |
3380 | buffers are scrolled, and their values of point and the mark; also their | |
3381 | fringes, margins, and scroll bar settings. It also includes the value | |
3382 | of @code{minibuffer-scroll-window}. As a special exception, the window | |
3383 | configuration does not record the value of point in the selected window | |
c419f5cb | 3384 | for the current buffer. |
0273ca3a | 3385 | |
a1401ab1 EZ |
3386 | You can bring back an entire frame layout by restoring a previously |
3387 | saved window configuration. If you want to record the layout of all | |
0273ca3a | 3388 | frames instead of just one, use a frame configuration instead of a |
09ebefe1 | 3389 | window configuration. @xref{Frame Configurations}. |
b8d4c8d0 GM |
3390 | |
3391 | @defun current-window-configuration &optional frame | |
3392 | This function returns a new object representing @var{frame}'s current | |
aeeedf76 | 3393 | window configuration. The default for @var{frame} is the selected |
34a02f46 | 3394 | frame. The variable @code{window-persistent-parameters} specifies |
09ebefe1 GM |
3395 | which window parameters (if any) are saved by this function. |
3396 | @xref{Window Parameters}. | |
b8d4c8d0 GM |
3397 | @end defun |
3398 | ||
3399 | @defun set-window-configuration configuration | |
3400 | This function restores the configuration of windows and buffers as | |
3401 | specified by @var{configuration}, for the frame that @var{configuration} | |
3402 | was created for. | |
3403 | ||
3404 | The argument @var{configuration} must be a value that was previously | |
0273ca3a | 3405 | returned by @code{current-window-configuration}. The configuration is |
b8d4c8d0 GM |
3406 | restored in the frame from which @var{configuration} was made, whether |
3407 | that frame is selected or not. This always counts as a window size | |
3408 | change and triggers execution of the @code{window-size-change-functions} | |
3409 | (@pxref{Window Hooks}), because @code{set-window-configuration} doesn't | |
3410 | know how to tell whether the new configuration actually differs from the | |
3411 | old one. | |
3412 | ||
09ebefe1 | 3413 | If the frame from which @var{configuration} was saved is dead, all this |
b8d4c8d0 | 3414 | function does is restore the three variables @code{window-min-height}, |
0b27932b | 3415 | @code{window-min-width} and @code{minibuffer-scroll-window}. In this |
b8d4c8d0 GM |
3416 | case, the function returns @code{nil}. Otherwise, it returns @code{t}. |
3417 | ||
3418 | Here is a way of using this function to get the same effect | |
3419 | as @code{save-window-excursion}: | |
3420 | ||
3421 | @example | |
3422 | @group | |
3423 | (let ((config (current-window-configuration))) | |
3424 | (unwind-protect | |
291d142b | 3425 | (progn (split-window-below nil) |
b8d4c8d0 GM |
3426 | @dots{}) |
3427 | (set-window-configuration config))) | |
3428 | @end group | |
3429 | @end example | |
3430 | @end defun | |
3431 | ||
2cc775f9 | 3432 | @defmac save-window-excursion forms@dots{} |
6a787d9a CY |
3433 | This macro records the window configuration of the selected frame, |
3434 | executes @var{forms} in sequence, then restores the earlier window | |
3435 | configuration. The return value is the value of the final form in | |
3436 | @var{forms}. | |
3437 | ||
3438 | Most Lisp code should not use this macro; @code{save-selected-window} | |
3439 | is typically sufficient. In particular, this macro cannot reliably | |
3440 | prevent the code in @var{forms} from opening new windows, because new | |
3441 | windows might be opened in other frames (@pxref{Choosing Window}), and | |
3442 | @code{save-window-excursion} only saves and restores the window | |
3443 | configuration on the current frame. | |
3444 | ||
3445 | Do not use this macro in @code{window-size-change-functions}; exiting | |
3446 | the macro triggers execution of @code{window-size-change-functions}, | |
3447 | leading to an endless loop. | |
2cc775f9 | 3448 | @end defmac |
b8d4c8d0 GM |
3449 | |
3450 | @defun window-configuration-p object | |
3451 | This function returns @code{t} if @var{object} is a window configuration. | |
3452 | @end defun | |
3453 | ||
3454 | @defun compare-window-configurations config1 config2 | |
3455 | This function compares two window configurations as regards the | |
3456 | structure of windows, but ignores the values of point and mark and the | |
3457 | saved scrolling positions---it can return @code{t} even if those | |
3458 | aspects differ. | |
3459 | ||
3460 | The function @code{equal} can also compare two window configurations; it | |
3461 | regards configurations as unequal if they differ in any respect, even a | |
3462 | saved point or mark. | |
3463 | @end defun | |
3464 | ||
3465 | @defun window-configuration-frame config | |
3466 | This function returns the frame for which the window configuration | |
3467 | @var{config} was made. | |
3468 | @end defun | |
3469 | ||
3470 | Other primitives to look inside of window configurations would make | |
3471 | sense, but are not implemented because we did not need them. See the | |
3472 | file @file{winner.el} for some more operations on windows | |
3473 | configurations. | |
3474 | ||
c419f5cb MR |
3475 | The objects returned by @code{current-window-configuration} die |
3476 | together with the Emacs process. In order to store a window | |
09ebefe1 GM |
3477 | configuration on disk and read it back in another Emacs session, you |
3478 | can use the functions described next. These functions are also useful | |
6a6ee00d MR |
3479 | to clone the state of a frame into an arbitrary live window |
3480 | (@code{set-window-configuration} effectively clones the windows of a | |
3481 | frame into the root window of that very frame only). | |
c419f5cb | 3482 | |
34a02f46 | 3483 | @defun window-state-get &optional window writable |
c419f5cb | 3484 | This function returns the state of @var{window} as a Lisp object. The |
43bcfda6 MR |
3485 | argument @var{window} must be a valid window and defaults to the root |
3486 | window of the selected frame. | |
c419f5cb | 3487 | |
34a02f46 | 3488 | If the optional argument @var{writable} is non-@code{nil}, this means to |
6a6ee00d MR |
3489 | not use markers for sampling positions like @code{window-point} or |
3490 | @code{window-start}. This argument should be non-@code{nil} when the | |
e78d873d | 3491 | state will be written to disk and read back in another session. |
6a6ee00d | 3492 | |
34a02f46 MR |
3493 | Together, the argument @var{writable} and the variable |
3494 | @code{window-persistent-parameters} specify which window parameters are | |
09ebefe1 | 3495 | saved by this function. @xref{Window Parameters}. |
c419f5cb MR |
3496 | @end defun |
3497 | ||
34a02f46 MR |
3498 | The value returned by @code{window-state-get} can be used in the same |
3499 | session to make a clone of a window in another window. It can be also | |
3500 | written to disk and read back in another session. In either case, use | |
09ebefe1 | 3501 | the following function to restore the state of the window. |
c419f5cb MR |
3502 | |
3503 | @defun window-state-put state &optional window ignore | |
3504 | This function puts the window state @var{state} into @var{window}. The | |
3505 | argument @var{state} should be the state of a window returned by an | |
3506 | earlier invocation of @code{window-state-get}, see above. The optional | |
3507 | argument @var{window} must specify a live window and defaults to the | |
3508 | selected one. | |
3509 | ||
09ebefe1 GM |
3510 | If the optional argument @var{ignore} is non-@code{nil}, it means to ignore |
3511 | minimum window sizes and fixed-size restrictions. If @var{ignore} | |
3512 | is @code{safe}, this means windows can get as small as one line | |
c419f5cb MR |
3513 | and/or two columns. |
3514 | @end defun | |
3515 | ||
3516 | ||
0273ca3a MR |
3517 | @node Window Parameters |
3518 | @section Window Parameters | |
3519 | @cindex window parameters | |
3520 | ||
c419f5cb | 3521 | This section describes how window parameters can be used to associate |
0273ca3a MR |
3522 | additional information with windows. |
3523 | ||
3524 | @defun window-parameter window parameter | |
aeeedf76 | 3525 | This function returns @var{window}'s value for @var{parameter}. The |
c419f5cb MR |
3526 | default for @var{window} is the selected window. If @var{window} has no |
3527 | setting for @var{parameter}, this function returns @code{nil}. | |
0273ca3a MR |
3528 | @end defun |
3529 | ||
a1401ab1 | 3530 | @defun window-parameters &optional window |
0273ca3a | 3531 | This function returns all parameters of @var{window} and their values. |
09ebefe1 GM |
3532 | The default for @var{window} is the selected window. The return value |
3533 | is either @code{nil}, or an association list whose elements have the form | |
c419f5cb | 3534 | @code{(@var{parameter} . @var{value})}. |
0273ca3a MR |
3535 | @end defun |
3536 | ||
3537 | @defun set-window-parameter window parameter value | |
3538 | This function sets @var{window}'s value of @var{parameter} to | |
aeeedf76 MR |
3539 | @var{value} and returns @var{value}. The default for @var{window} |
3540 | is the selected window. | |
0273ca3a MR |
3541 | @end defun |
3542 | ||
09ebefe1 | 3543 | By default, the functions that save and restore window configurations or the |
f5064cae | 3544 | states of windows (@pxref{Window Configurations}) do not care about |
09ebefe1 | 3545 | window parameters. This means that when you change the value of a |
6a6ee00d | 3546 | parameter within the body of a @code{save-window-excursion}, the |
09ebefe1 | 3547 | previous value is not restored when that macro exits. It also means |
34a02f46 MR |
3548 | that when you restore via @code{window-state-put} a window state saved |
3549 | earlier by @code{window-state-get}, all cloned windows have their | |
09ebefe1 GM |
3550 | parameters reset to @code{nil}. The following variable allows you to |
3551 | override the standard behavior: | |
6a6ee00d MR |
3552 | |
3553 | @defvar window-persistent-parameters | |
3554 | This variable is an alist specifying which parameters get saved by | |
09ebefe1 | 3555 | @code{current-window-configuration} and @code{window-state-get}, and |
6a6ee00d | 3556 | subsequently restored by @code{set-window-configuration} and |
09ebefe1 | 3557 | @code{window-state-put}. @xref{Window Configurations}. |
6a6ee00d | 3558 | |
09ebefe1 | 3559 | The @sc{car} of each entry of this alist is a symbol specifying the |
34a02f46 | 3560 | parameter. The @sc{cdr} should be one of the following: |
6a6ee00d MR |
3561 | |
3562 | @table @asis | |
6a6ee00d | 3563 | @item @code{nil} |
09ebefe1 | 3564 | This value means the parameter is saved neither by |
34a02f46 MR |
3565 | @code{window-state-get} nor by @code{current-window-configuration}. |
3566 | ||
3567 | @item @code{t} | |
6a6ee00d | 3568 | This value specifies that the parameter is saved by |
09ebefe1 GM |
3569 | @code{current-window-configuration} and (provided its @var{writable} |
3570 | argument is @code{nil}) by @code{window-state-get}. | |
6a6ee00d | 3571 | |
34a02f46 | 3572 | @item @code{writable} |
6a6ee00d MR |
3573 | This means that the parameter is saved unconditionally by both |
3574 | @code{current-window-configuration} and @code{window-state-get}. This | |
3575 | value should not be used for parameters whose values do not have a read | |
3576 | syntax. Otherwise, invoking @code{window-state-put} in another session | |
3577 | may fail with an @code{invalid-read-syntax} error. | |
3578 | @end table | |
6a6ee00d MR |
3579 | @end defvar |
3580 | ||
09ebefe1 GM |
3581 | Some functions (notably @code{delete-window}, |
3582 | @code{delete-other-windows} and @code{split-window}), may behave specially | |
c419f5cb MR |
3583 | when their @var{window} argument has a parameter set. You can override |
3584 | such special behavior by binding the following variable to a | |
3585 | non-@code{nil} value: | |
3586 | ||
3587 | @defvar ignore-window-parameters | |
3588 | If this variable is non-@code{nil}, some standard functions do not | |
3589 | process window parameters. The functions currently affected by this are | |
09ebefe1 | 3590 | @code{split-window}, @code{delete-window}, @code{delete-other-windows}, |
c419f5cb MR |
3591 | and @code{other-window}. |
3592 | ||
3593 | An application can bind this variable to a non-@code{nil} value around | |
3594 | calls to these functions. If it does so, the application is fully | |
3595 | responsible for correctly assigning the parameters of all involved | |
3596 | windows when exiting that function. | |
3597 | @end defvar | |
3598 | ||
3599 | The following parameters are currently used by the window management | |
6a6ee00d | 3600 | code: |
c419f5cb MR |
3601 | |
3602 | @table @asis | |
3603 | @item @code{delete-window} | |
3604 | This parameter affects the execution of @code{delete-window} | |
3605 | (@pxref{Deleting Windows}). | |
3606 | ||
3607 | @item @code{delete-other-windows} | |
3608 | This parameter affects the execution of @code{delete-other-windows} | |
3609 | (@pxref{Deleting Windows}). | |
3610 | ||
3611 | @item @code{split-window} | |
3612 | This parameter affects the execution of @code{split-window} | |
3613 | (@pxref{Splitting Windows}). | |
3614 | ||
3615 | @item @code{other-window} | |
3616 | This parameter affects the execution of @code{other-window} | |
3617 | (@pxref{Cyclic Window Ordering}). | |
3618 | ||
3619 | @item @code{no-other-window} | |
3620 | This parameter marks the window as not selectable by @code{other-window} | |
3621 | (@pxref{Cyclic Window Ordering}). | |
6a6ee00d MR |
3622 | |
3623 | @item @code{clone-of} | |
09ebefe1 GM |
3624 | This parameter specifies the window that this one has been cloned |
3625 | from. It is installed by @code{window-state-get} (@pxref{Window | |
3626 | Configurations}). | |
6a6ee00d MR |
3627 | |
3628 | @item @code{quit-restore} | |
43bcfda6 MR |
3629 | This parameter is installed by the buffer display functions |
3630 | (@pxref{Choosing Window}) and consulted by @code{quit-restore-window} | |
3631 | (@pxref{Quitting Windows}). It contains four elements: | |
3632 | ||
f99f1641 PE |
3633 | The first element is one of the symbols @code{window}, meaning that the |
3634 | window has been specially created by @code{display-buffer}; @code{frame}, | |
3635 | a separate frame has been created; @code{same}, the window has | |
3636 | displayed the same buffer before; or @code{other}, the window showed | |
43bcfda6 MR |
3637 | another buffer before. |
3638 | ||
3639 | The second element is either one of the symbols @code{window} or | |
3640 | @code{frame}, or a list whose elements are the buffer shown in the | |
3641 | window before, that buffer's window start and window point positions, | |
3642 | and the window's height at that time. | |
3643 | ||
3644 | The third element is the window selected at the time the parameter was | |
3645 | created. The function @code{quit-restore-window} tries to reselect that | |
3646 | window when it deletes the window passed to it as argument. | |
3647 | ||
3648 | The fourth element is the buffer whose display caused the creation of | |
3649 | this parameter. @code{quit-restore-window} deletes the specified window | |
3650 | only if it still shows that buffer. | |
c419f5cb MR |
3651 | @end table |
3652 | ||
09ebefe1 GM |
3653 | There are additional parameters @code{window-atom} and @code{window-side}; |
3654 | these are reserved and should not be used by applications. | |
c419f5cb | 3655 | |
0273ca3a | 3656 | |
b8d4c8d0 GM |
3657 | @node Window Hooks |
3658 | @section Hooks for Window Scrolling and Changes | |
3659 | @cindex hooks for window operations | |
3660 | ||
3661 | This section describes how a Lisp program can take action whenever a | |
3662 | window displays a different part of its buffer or a different buffer. | |
3663 | There are three actions that can change this: scrolling the window, | |
3664 | switching buffers in the window, and changing the size of the window. | |
3665 | The first two actions run @code{window-scroll-functions}; the last runs | |
3666 | @code{window-size-change-functions}. | |
3667 | ||
3668 | @defvar window-scroll-functions | |
3669 | This variable holds a list of functions that Emacs should call before | |
0273ca3a MR |
3670 | redisplaying a window with scrolling. Displaying a different buffer in |
3671 | the window also runs these functions. | |
b8d4c8d0 | 3672 | |
0273ca3a MR |
3673 | This variable is not a normal hook, because each function is called with |
3674 | two arguments: the window, and its new display-start position. | |
b8d4c8d0 | 3675 | |
09ebefe1 | 3676 | These functions must take care when using @code{window-end} |
0273ca3a MR |
3677 | (@pxref{Window Start and End}); if you need an up-to-date value, you |
3678 | must use the @var{update} argument to ensure you get it. | |
b8d4c8d0 GM |
3679 | |
3680 | @strong{Warning:} don't use this feature to alter the way the window | |
3681 | is scrolled. It's not designed for that, and such use probably won't | |
3682 | work. | |
3683 | @end defvar | |
3684 | ||
3685 | @defvar window-size-change-functions | |
3686 | This variable holds a list of functions to be called if the size of any | |
3687 | window changes for any reason. The functions are called just once per | |
3688 | redisplay, and just once for each frame on which size changes have | |
3689 | occurred. | |
3690 | ||
3691 | Each function receives the frame as its sole argument. There is no | |
3692 | direct way to find out which windows on that frame have changed size, or | |
3693 | precisely how. However, if a size-change function records, at each | |
3694 | call, the existing windows and their sizes, it can also compare the | |
3695 | present sizes and the previous sizes. | |
3696 | ||
3697 | Creating or deleting windows counts as a size change, and therefore | |
3698 | causes these functions to be called. Changing the frame size also | |
3699 | counts, because it changes the sizes of the existing windows. | |
3700 | ||
6a787d9a CY |
3701 | You may use @code{save-selected-window} in these functions |
3702 | (@pxref{Selecting Windows}). However, do not use | |
3703 | @code{save-window-excursion} (@pxref{Window Configurations}); exiting | |
3704 | that macro counts as a size change, which would cause these functions | |
3705 | to be called over and over. | |
b8d4c8d0 GM |
3706 | @end defvar |
3707 | ||
b8d4c8d0 GM |
3708 | @defvar window-configuration-change-hook |
3709 | A normal hook that is run every time you change the window configuration | |
3710 | of an existing frame. This includes splitting or deleting windows, | |
3711 | changing the sizes of windows, or displaying a different buffer in a | |
0273ca3a MR |
3712 | window. |
3713 | ||
09ebefe1 | 3714 | The buffer-local part of this hook is run once for each window on the |
0273ca3a MR |
3715 | affected frame, with the relevant window selected and its buffer |
3716 | current. The global part is run once for the modified frame, with that | |
3717 | frame selected. | |
b8d4c8d0 GM |
3718 | @end defvar |
3719 | ||
38b1d346 | 3720 | In addition, you can use @code{jit-lock-register} to register a Font |
b8766179 MR |
3721 | Lock fontification function, which will be called whenever parts of a |
3722 | buffer are (re)fontified because a window was scrolled or its size | |
3723 | changed. @xref{Other Font Lock Variables}. |