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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
acaf905b | 3 | @c Copyright (C) 1990-1995, 1998-1999, 2001-2012 |
0c5413c8 | 4 | @c Free Software Foundation, Inc. |
b8d4c8d0 | 5 | @c See the file elisp.texi for copying conditions. |
6336d8c3 | 6 | @setfilename ../../info/windows |
b8d4c8d0 GM |
7 | @node Windows, Frames, Buffers, Top |
8 | @chapter Windows | |
9 | ||
b33b68a3 MR |
10 | This chapter describes the functions and variables related to Emacs |
11 | windows. @xref{Frames}, for how windows are assigned an area of screen | |
12 | available for Emacs to use. @xref{Display}, for information on how text | |
13 | is displayed in windows. | |
b8d4c8d0 GM |
14 | |
15 | @menu | |
16 | * Basic Windows:: Basic information on using windows. | |
b33b68a3 MR |
17 | * Windows and Frames:: Relating windows to the frame they appear on. |
18 | * Window Sizes:: Accessing a window's size. | |
19 | * Resizing Windows:: Changing the sizes of windows. | |
b8d4c8d0 GM |
20 | * Splitting Windows:: Splitting one window into two windows. |
21 | * Deleting Windows:: Deleting a window gives its space to other windows. | |
22 | * Selecting Windows:: The selected window is the one that you edit in. | |
23 | * Cyclic Window Ordering:: Moving around the existing windows. | |
24 | * Buffers and Windows:: Each window displays the contents of a buffer. | |
0e406a72 | 25 | * Switching Buffers:: Higher-level functions for switching to a buffer. |
d24880de | 26 | * Choosing Window:: How to choose a window for displaying a buffer. |
9ec20d36 CY |
27 | * Display Action Functions:: Subroutines for @code{display-buffer}. |
28 | * Choosing Window Options:: Extra options affecting how buffers are displayed. | |
0e406a72 | 29 | * Window History:: Each window remembers the buffers displayed in it. |
d24880de | 30 | * Dedicated Windows:: How to avoid displaying another buffer in |
a1401ab1 | 31 | a specific window. |
c419f5cb MR |
32 | * Quitting Windows:: How to restore the state prior to displaying a |
33 | buffer. | |
b8d4c8d0 | 34 | * Window Point:: Each window has its own location of point. |
0273ca3a MR |
35 | * Window Start and End:: Buffer positions indicating which text is |
36 | on-screen in a window. | |
b8d4c8d0 GM |
37 | * Textual Scrolling:: Moving text up and down through the window. |
38 | * Vertical Scrolling:: Moving the contents up and down on the window. | |
39 | * Horizontal Scrolling:: Moving the contents sideways on the window. | |
b8d4c8d0 | 40 | * Coordinates and Windows:: Converting coordinates to windows. |
b8d4c8d0 | 41 | * Window Configurations:: Saving and restoring the state of the screen. |
0273ca3a | 42 | * Window Parameters:: Associating additional information with windows. |
b8d4c8d0 GM |
43 | * Window Hooks:: Hooks for scrolling, window size changes, |
44 | redisplay going past a certain point, | |
45 | or window configuration changes. | |
46 | @end menu | |
47 | ||
b33b68a3 | 48 | |
b8d4c8d0 GM |
49 | @node Basic Windows |
50 | @section Basic Concepts of Emacs Windows | |
51 | @cindex window | |
b8d4c8d0 | 52 | |
291d142b CY |
53 | A @dfn{window} is a area of the screen which is used to display a |
54 | buffer (@pxref{Buffers}). In Emacs Lisp, windows are represented by a | |
55 | special Lisp object type. | |
b8d4c8d0 GM |
56 | |
57 | @cindex multiple windows | |
291d142b CY |
58 | Windows are grouped into frames (@pxref{Frames}). Each frame |
59 | contains at least one window; the user can subdivide it into multiple, | |
60 | non-overlapping windows to view several buffers at once. Lisp | |
61 | programs can use multiple windows for a variety of purposes. In | |
62 | Rmail, for example, you can view a summary of message titles in one | |
63 | window, and the contents of the selected message in another window. | |
b8d4c8d0 | 64 | |
b33b68a3 MR |
65 | @cindex terminal screen |
66 | @cindex screen of terminal | |
291d142b CY |
67 | Emacs uses the word ``window'' with a different meaning than in |
68 | graphical desktop environments and window systems, such as the X | |
69 | Window System. When Emacs is run on X, each of its graphical X | |
70 | windows is an Emacs frame (containing one or more Emacs windows). | |
a08a07e3 | 71 | When Emacs is run on a text terminal, the frame fills the entire |
291d142b | 72 | terminal screen. |
b8d4c8d0 | 73 | |
b8d4c8d0 | 74 | @cindex tiled windows |
291d142b CY |
75 | Unlike X windows, Emacs windows are @dfn{tiled}; they never overlap |
76 | within the area of the frame. When a window is created, resized, or | |
77 | deleted, the change in window space is taken from or given to the | |
78 | adjacent windows, so that the total area of the frame is unchanged. | |
b33b68a3 MR |
79 | |
80 | @cindex live windows | |
81 | @cindex internal windows | |
291d142b CY |
82 | A @dfn{live window} is one that is actually displaying a buffer in a |
83 | frame. Such a window can be @dfn{deleted}, i.e. removed from the | |
84 | frame (@pxref{Deleting Windows}); then it is no longer live, but the | |
85 | Lisp object representing it might be still referenced from other Lisp | |
86 | objects. A deleted window may be brought back to life by restoring a | |
87 | saved window configuration (@pxref{Window Configurations}). | |
88 | ||
89 | @defun windowp object | |
90 | This function returns @code{t} if @var{object} is a window (whether or | |
91 | not it is live). Otherwise, it returns @code{nil}. | |
92 | @end defun | |
b33b68a3 MR |
93 | |
94 | @defun window-live-p object | |
95 | This function returns @code{t} if @var{object} is a live window and | |
291d142b | 96 | @code{nil} otherwise. A live window is one that displays a buffer. |
b33b68a3 MR |
97 | @end defun |
98 | ||
291d142b CY |
99 | The windows in each frame are organized into a @dfn{window tree}. |
100 | @xref{Windows and Frames}. The leaf nodes of each window tree are | |
101 | live windows---the ones actually displaying buffers. The internal | |
102 | nodes of the window tree are internal windows, which are not live. | |
103 | You can distinguish internal windows from deleted windows with | |
104 | @code{window-valid-p}. | |
105 | ||
106 | @defun window-valid-p object | |
107 | This function returns @code{t} if @var{object} is a live window, or an | |
108 | internal window in a window tree. Otherwise, it returns @code{nil}, | |
109 | including for the case where @var{object} is a deleted window. | |
b33b68a3 MR |
110 | @end defun |
111 | ||
112 | @cindex selected window | |
7bf54975 | 113 | @cindex window selected within a frame |
291d142b CY |
114 | In each frame, at any time, exactly one Emacs window is designated |
115 | as @dfn{selected within the frame}. For the selected frame, that | |
116 | window is called the @dfn{selected window}---the one in which most | |
117 | editing takes place, and in which the cursor for selected windows | |
118 | appears (@pxref{Cursor Parameters}). The selected window's buffer is | |
119 | usually also the current buffer, except when @code{set-buffer} has | |
120 | been used (@pxref{Current Buffer}). As for non-selected frames, the | |
121 | window selected within the frame becomes the selected window if the | |
122 | frame is ever selected. @xref{Selecting Windows}. | |
b33b68a3 MR |
123 | |
124 | @defun selected-window | |
291d142b CY |
125 | This function returns the selected window (which is always a live |
126 | window). | |
b33b68a3 MR |
127 | @end defun |
128 | ||
b33b68a3 MR |
129 | @node Windows and Frames |
130 | @section Windows and Frames | |
131 | ||
291d142b | 132 | Each window belongs to exactly one frame (@pxref{Frames}). |
b33b68a3 MR |
133 | |
134 | @defun window-frame window | |
291d142b CY |
135 | This function returns the frame that the window @var{window} belongs |
136 | to. If @var{window} is @code{nil}, it defaults to the selected | |
137 | window. | |
b33b68a3 MR |
138 | @end defun |
139 | ||
291d142b CY |
140 | @defun window-list &optional frame minibuffer window |
141 | This function returns a list of live windows belonging to the frame | |
142 | @var{frame}. If @var{frame} is omitted or @code{nil}, it defaults to | |
143 | the selected frame. | |
b33b68a3 | 144 | |
291d142b CY |
145 | The optional argument @var{minibuffer} specifies whether to include |
146 | the minibuffer window in the returned list. If @var{minibuffer} is | |
147 | @code{t}, the minibuffer window is included. If @var{minibuffer} is | |
148 | @code{nil} or omitted, the minibuffer window is included only if it is | |
149 | active. If @var{minibuffer} is neither @code{nil} nor @code{t}, the | |
150 | minibuffer window is never included. | |
b33b68a3 | 151 | |
90151a1e MR |
152 | The optional argument @var{window}, if non-@code{nil}, should be a live |
153 | window on the specified frame; then @var{window} will be the first | |
154 | element in the returned list. If @var{window} is omitted or @code{nil}, | |
155 | the window selected within the frame is the first element. | |
b33b68a3 MR |
156 | @end defun |
157 | ||
158 | @cindex window tree | |
291d142b CY |
159 | @cindex root window |
160 | Windows in the same frame are organized into a @dfn{window tree}, | |
161 | whose leaf nodes are the live windows. The internal nodes of a window | |
162 | tree are not live; they exist for the purpose of organizing the | |
163 | relationships between live windows. The root node of a window tree is | |
164 | called the @dfn{root window}. It can be either a live window (if the | |
165 | frame has just one window), or an internal window. | |
166 | ||
167 | A minibuffer window (@pxref{Minibuffer Windows}) is not part of its | |
168 | frame's window tree unless the frame is a minibuffer-only frame. | |
169 | Nonetheless, most of the functions in this section accept the | |
170 | minibuffer window as an argument. Also, the function | |
171 | @code{window-tree} described at the end of this section lists the | |
172 | minibuffer window alongside the actual window tree. | |
b33b68a3 MR |
173 | |
174 | @defun frame-root-window &optional frame-or-window | |
291d142b CY |
175 | This function returns the root window for @var{frame-or-window}. The |
176 | argument @var{frame-or-window} should be either a window or a frame; | |
177 | if omitted or @code{nil}, it defaults to the selected frame. If | |
178 | @var{frame-or-window} is a window, the return value is the root window | |
179 | of that window's frame. | |
b33b68a3 MR |
180 | @end defun |
181 | ||
291d142b CY |
182 | @cindex parent window |
183 | @cindex child window | |
184 | @cindex sibling window | |
185 | When a window is split, there are two live windows where previously | |
186 | there was one. One of these is represented by the same Lisp window | |
187 | object as the original window, and the other is represented by a | |
188 | newly-created Lisp window object. Both of these live windows become | |
189 | leaf nodes of the window tree, as @dfn{child windows} of a single | |
190 | internal window. If necessary, Emacs automatically creates this | |
191 | internal window, which is also called the @dfn{parent window}, and | |
192 | assigns it to the appropriate position in the window tree. A set of | |
193 | windows that share the same parent are called @dfn{siblings}. | |
b33b68a3 MR |
194 | |
195 | @cindex parent window | |
196 | @defun window-parent &optional window | |
291d142b CY |
197 | This function returns the parent window of @var{window}. If |
198 | @var{window} is omitted or @code{nil}, it defaults to the selected | |
199 | window. The return value is @code{nil} if @var{window} has no parent | |
200 | (i.e. it is a minibuffer window or the root window of its frame). | |
b33b68a3 MR |
201 | @end defun |
202 | ||
291d142b CY |
203 | Each internal window always has at least two child windows. If this |
204 | number falls to one as a result of window deletion, Emacs | |
205 | automatically deletes the internal window, and its sole remaining | |
206 | child window takes its place in the window tree. | |
207 | ||
208 | Each child window can be either a live window, or an internal window | |
209 | (which in turn would have its own child windows). Therefore, each | |
210 | internal window can be thought of as occupying a certain rectangular | |
211 | @dfn{screen area}---the union of the areas occupied by the live | |
212 | windows that are ultimately descended from it. | |
b33b68a3 MR |
213 | |
214 | @cindex window combination | |
215 | @cindex vertical combination | |
216 | @cindex horizontal combination | |
291d142b CY |
217 | For each internal window, the screen areas of the immediate children |
218 | are arranged either vertically or horizontally (never both). If the | |
219 | child windows are arranged one above the other, they are said to form | |
220 | a @dfn{vertical combination}; if they are arranged side by side, they | |
221 | are said to form a @dfn{horizontal combination}. Consider the | |
222 | following example: | |
b33b68a3 MR |
223 | |
224 | @smallexample | |
225 | @group | |
226 | ______________________________________ | |
227 | | ______ ____________________________ | | |
228 | || || __________________________ || | |
291d142b CY |
229 | || ||| ||| |
230 | || ||| ||| | |
231 | || ||| ||| | |
b33b68a3 MR |
232 | || |||____________W4____________||| |
233 | || || __________________________ || | |
234 | || ||| ||| | |
291d142b | 235 | || ||| ||| |
b33b68a3 MR |
236 | || |||____________W5____________||| |
237 | ||__W2__||_____________W3_____________ | | |
238 | |__________________W1__________________| | |
239 | ||
240 | @end group | |
241 | @end smallexample | |
242 | ||
291d142b CY |
243 | @noindent |
244 | The root window of this frame is an internal window, @code{W1}. Its | |
245 | child windows form a horizontal combination, consisting of the live | |
246 | window @code{W2} and the internal window @code{W3}. The child windows | |
247 | of @code{W3} form a vertical combination, consisting of the live | |
248 | windows @code{W4} and @code{W5}. Hence, the live windows in this | |
249 | window tree are @code{W2} @code{W4}, and @code{W5}. | |
250 | ||
251 | The following functions can be used to retrieve a child window of an | |
252 | internal window, and the siblings of a child window. | |
253 | ||
254 | @defun window-top-child window | |
255 | This function returns the topmost child window of @var{window}, if | |
256 | @var{window} is an internal window whose children form a vertical | |
257 | combination. For any other type of window, the return value is | |
258 | @code{nil}. | |
b33b68a3 MR |
259 | @end defun |
260 | ||
291d142b CY |
261 | @defun window-left-child window |
262 | This function returns the leftmost child window of @var{window}, if | |
263 | @var{window} is an internal window whose children form a horizontal | |
264 | combination. For any other type of window, the return value is | |
265 | @code{nil}. | |
b33b68a3 MR |
266 | @end defun |
267 | ||
268 | @defun window-child window | |
291d142b CY |
269 | This function returns the first child window of the internal window |
270 | @var{window}---the topmost child window for a vertical combination, or | |
271 | the leftmost child window for a horizontal combination. If | |
272 | @var{window} is a live window, the return value is @code{nil}. | |
b33b68a3 MR |
273 | @end defun |
274 | ||
3d8daefe | 275 | @defun window-combined-p &optional window horizontal |
291d142b CY |
276 | This function returns a non-@code{nil} value if and only if |
277 | @var{window} is part of a vertical combination. If @var{window} is | |
e7313f33 | 278 | omitted or @code{nil}, it defaults to the selected one. |
b33b68a3 | 279 | |
291d142b CY |
280 | If the optional argument @var{horizontal} is non-@code{nil}, this |
281 | means to return non-@code{nil} if and only if @var{window} is part of | |
282 | a horizontal combination. | |
b33b68a3 MR |
283 | @end defun |
284 | ||
b33b68a3 | 285 | @defun window-next-sibling &optional window |
291d142b CY |
286 | This function returns the next sibling of the window @var{window}. If |
287 | omitted or @code{nil}, @var{window} defaults to the selected window. | |
288 | The return value is @code{nil} if @var{window} is the last child of | |
289 | its parent. | |
b33b68a3 MR |
290 | @end defun |
291 | ||
292 | @defun window-prev-sibling &optional window | |
291d142b CY |
293 | This function returns the previous sibling of the window @var{window}. |
294 | If omitted or @code{nil}, @var{window} defaults to the selected | |
295 | window. The return value is @code{nil} if @var{window} is the first | |
296 | child of its parent. | |
b33b68a3 MR |
297 | @end defun |
298 | ||
291d142b CY |
299 | The functions @code{window-next-sibling} and |
300 | @code{window-prev-sibling} should not be confused with the functions | |
301 | @code{next-window} and @code{previous-window} which respectively | |
302 | return the next and previous window in the cyclic ordering of windows | |
303 | (@pxref{Cyclic Window Ordering}). | |
b33b68a3 | 304 | |
291d142b CY |
305 | You can use the following functions to find the first live window on |
306 | a frame, and to retrieve the entire window tree of a frame: | |
b33b68a3 MR |
307 | |
308 | @defun frame-first-window &optional frame-or-window | |
309 | This function returns the live window at the upper left corner of the | |
310 | frame specified by @var{frame-or-window}. The argument | |
311 | @var{frame-or-window} must denote a window or a live frame and defaults | |
312 | to the selected frame. If @var{frame-or-window} specifies a window, | |
313 | this function returns the first window on that window's frame. Under | |
314 | the assumption that the frame from our canonical example is selected | |
315 | @code{(frame-first-window)} returns @code{W2}. | |
316 | @end defun | |
317 | ||
b33b68a3 | 318 | @defun window-tree &optional frame |
291d142b CY |
319 | This function returns a list representing the window tree for frame |
320 | @var{frame}. If @var{frame} is omitted or @code{nil}, it defaults to | |
321 | the selected frame. | |
b33b68a3 MR |
322 | |
323 | The return value is a list of the form @code{(@var{root} @var{mini})}, | |
291d142b CY |
324 | where @var{root} represents the window tree of the frame's root |
325 | window, and @var{mini} is the frame's minibuffer window. | |
b33b68a3 | 326 | |
291d142b CY |
327 | If the root window is live, @var{root} is that window itself. |
328 | Otherwise, @var{root} is a list @code{(@var{dir} @var{edges} @var{w1} | |
329 | @var{w2} ...)} where @var{dir} is @code{nil} for a horizontal | |
330 | combination and @code{t} for a vertical combination, @var{edges} gives | |
331 | the size and position of the combination, and the remaining elements | |
332 | are the child windows. Each child window may again be a window object | |
333 | (for a live window) or a list with the same format as above (for an | |
334 | internal window). The @var{edges} element is a list @code{(@var{left} | |
335 | @var{top} @var{right} @var{bottom})}, similar to the value returned by | |
336 | @code{window-edges} (@pxref{Coordinates and Windows}). | |
b33b68a3 MR |
337 | @end defun |
338 | ||
b33b68a3 MR |
339 | @node Window Sizes |
340 | @section Window Sizes | |
341 | @cindex window size | |
342 | @cindex size of window | |
343 | ||
a79db6e0 | 344 | The following schematic shows the structure of a live window: |
b33b68a3 MR |
345 | |
346 | @smallexample | |
347 | @group | |
a79db6e0 CY |
348 | _________________________________________ |
349 | ^ |______________ Header Line_______________| | |
b33b68a3 MR |
350 | | |LS|LF|LM| |RM|RF|RS| ^ |
351 | | | | | | | | | | | | |
352 | Window | | | | Text Area | | | | Window | |
353 | Total | | | | (Window Body) | | | | Body | |
354 | Height | | | | | | | | Height | |
355 | | | | | |<- Window Body Width ->| | | | | | |
356 | | |__|__|__|_______________________|__|__|__| v | |
357 | v |_______________ Mode Line _______________| | |
358 | ||
359 | <----------- Window Total Width --------> | |
360 | ||
361 | @end group | |
362 | @end smallexample | |
363 | ||
364 | @cindex window body | |
a79db6e0 | 365 | @cindex text area of a window |
b33b68a3 | 366 | @cindex body of a window |
a79db6e0 CY |
367 | At the center of the window is the @dfn{text area}, or @dfn{body}, |
368 | where the buffer text is displayed. On each side of the text area is | |
369 | a series of vertical areas; from innermost to outermost, these are the | |
370 | left and right margins, denoted by LM and RM in the schematic | |
371 | (@pxref{Display Margins}); the left and right fringes, denoted by LF | |
372 | and RF (@pxref{Fringes}); and the left or right scroll bar, only one of | |
373 | which is present at any time, denoted by LS and RS (@pxref{Scroll | |
374 | Bars}). At the top of the window is an optional header line | |
375 | (@pxref{Header Lines}), and at the bottom of the window is the mode | |
376 | line (@pxref{Mode Line Format}). | |
377 | ||
378 | Emacs provides several functions for finding the height and width of | |
1c3d7a13 | 379 | a window. Except where noted, Emacs reports window heights and widths |
d2ad7ee1 CY |
380 | as integer numbers of lines and columns respectively. On a graphical |
381 | display, each ``line'' and ``column'' actually corresponds to the | |
382 | height and width of a ``default'' character specified by the frame's | |
383 | default font. Thus, if a window is displaying text with a different | |
384 | font or size, the reported height and width for that window may differ | |
385 | from the actual number of text lines or columns displayed within it. | |
b33b68a3 MR |
386 | |
387 | @cindex window height | |
b33b68a3 MR |
388 | @cindex height of a window |
389 | @cindex total height of a window | |
b33b68a3 | 390 | @cindex window width |
b33b68a3 MR |
391 | @cindex width of a window |
392 | @cindex total width of a window | |
a79db6e0 CY |
393 | The @dfn{total height} of a window is the distance between the top |
394 | and bottom of the window, including the header line (if one exists) | |
395 | and the mode line. The @dfn{total width} of a window is the distance | |
396 | between the left and right edges of the mode line. Note that the | |
397 | height of a frame is not the same as the height of its windows, since | |
398 | a frame may also contain an echo area, menu bar, and tool bar | |
399 | (@pxref{Size and Position}). | |
b33b68a3 MR |
400 | |
401 | @defun window-total-height &optional window | |
a79db6e0 CY |
402 | This function returns the total height, in lines, of the window |
403 | @var{window}. If @var{window} is omitted or @code{nil}, it defaults | |
404 | to the selected window. If @var{window} is an internal window, the | |
405 | return value is the total height occupied by its descendant windows. | |
b33b68a3 MR |
406 | @end defun |
407 | ||
408 | @defun window-total-width &optional window | |
a79db6e0 CY |
409 | This function returns the total width, in columns, of the window |
410 | @var{window}. If @var{window} is omitted or @code{nil}, it defaults | |
411 | to the selected window. If @var{window} is internal, the return value | |
412 | is the total width occupied by its descendant windows. | |
413 | @end defun | |
b33b68a3 | 414 | |
a79db6e0 CY |
415 | @defun window-total-size &optional window horizontal |
416 | This function returns either the total height or width of the window | |
417 | @var{window}. If @var{horizontal} is omitted or @code{nil}, this is | |
418 | equivalent to calling @code{window-total-height} for @var{window}; | |
419 | otherwise it is equivalent to calling @code{window-total-width} for | |
420 | @var{window}. | |
b33b68a3 MR |
421 | @end defun |
422 | ||
423 | @cindex full-width window | |
a79db6e0 CY |
424 | @cindex full-height window |
425 | The following functions can be used to determine whether a given | |
426 | window has any adjacent windows. | |
427 | ||
428 | @defun window-full-height-p &optional window | |
429 | This function returns non-@code{nil} if @var{window} has no other | |
430 | window above or below it in its frame, i.e. its total height equals | |
431 | the total height of the root window on that frame. If @var{window} is | |
432 | omitted or @code{nil}, it defaults to the selected window. | |
433 | @end defun | |
b33b68a3 MR |
434 | |
435 | @defun window-full-width-p &optional window | |
a79db6e0 CY |
436 | This function returns non-@code{nil} if @var{window} has no other |
437 | window to the left or right in its frame, i.e. its total width equals | |
438 | that of the root window on that frame. If @var{window} is omitted or | |
439 | @code{nil}, it defaults to the selected window. | |
b33b68a3 MR |
440 | @end defun |
441 | ||
b33b68a3 MR |
442 | @cindex window body height |
443 | @cindex body height of a window | |
b33b68a3 MR |
444 | @cindex window body width |
445 | @cindex body width of a window | |
b33b68a3 MR |
446 | @cindex body size of a window |
447 | @cindex window body size | |
a79db6e0 CY |
448 | The @dfn{body height} of a window is the height of its text area, |
449 | which does not include the mode or header line. Similarly, the | |
450 | @dfn{body width} is the width of the text area, which does not include | |
451 | the scroll bar, fringes, or margins. | |
b33b68a3 MR |
452 | |
453 | @defun window-body-height &optional window | |
a79db6e0 CY |
454 | This function returns the body height, in lines, of the window |
455 | @var{window}. If @var{window} is omitted or @code{nil}, it defaults | |
456 | to the selected window; otherwise it must be a live window. | |
b33b68a3 | 457 | |
a79db6e0 CY |
458 | If there is a partially-visible line at the bottom of the text area, |
459 | that counts as a whole line; to exclude such a partially-visible line, | |
460 | use @code{window-text-height}, below. | |
b33b68a3 MR |
461 | @end defun |
462 | ||
463 | @defun window-body-width &optional window | |
a79db6e0 CY |
464 | This function returns the body width, in columns, of the window |
465 | @var{window}. If @var{window} is omitted or @code{nil}, it defaults | |
466 | to the selected window; otherwise it must be a live window. | |
b33b68a3 MR |
467 | @end defun |
468 | ||
a79db6e0 CY |
469 | @defun window-body-size &optional window horizontal |
470 | This function returns the body height or body width of @var{window}. | |
471 | If @var{horizontal} is omitted or @code{nil}, it is equivalent to | |
472 | calling @code{window-body-height} for @var{window}; otherwise it is | |
473 | equivalent to calling @code{window-body-width}. | |
b33b68a3 MR |
474 | @end defun |
475 | ||
a79db6e0 CY |
476 | @defun window-text-height &optional window |
477 | This function is like @code{window-body-height}, except that any | |
478 | partially-visible line at the bottom of the text area is not counted. | |
b33b68a3 MR |
479 | @end defun |
480 | ||
a79db6e0 | 481 | For compatibility with previous versions of Emacs, |
182148ee | 482 | @code{window-height} is an alias for @code{window-total-height}, and |
a79db6e0 CY |
483 | @code{window-width} is an alias for @code{window-body-width}. These |
484 | aliases are considered obsolete and will be removed in the future. | |
b33b68a3 MR |
485 | |
486 | @cindex fixed-size window | |
a79db6e0 CY |
487 | Commands that change the size of windows (@pxref{Resizing Windows}), |
488 | or split them (@pxref{Splitting Windows}), obey the variables | |
489 | @code{window-min-height} and @code{window-min-width}, which specify | |
490 | the smallest allowable window height and width. @xref{Change | |
491 | Window,,Deleting and Rearranging Windows, emacs, The GNU Emacs | |
492 | Manual}. They also obey the variable @code{window-size-fixed}, with | |
493 | which a window can be @dfn{fixed} in size: | |
494 | ||
b33b68a3 | 495 | @defvar window-size-fixed |
a79db6e0 CY |
496 | If this buffer-local variable is non-@code{nil}, the size of any |
497 | window displaying the buffer cannot normally be changed. Deleting a | |
498 | window or changing the frame's size may still change its size, if | |
499 | there is no choice. | |
b33b68a3 MR |
500 | |
501 | If the value is @code{height}, then only the window's height is fixed; | |
502 | if the value is @code{width}, then only the window's width is fixed. | |
503 | Any other non-@code{nil} value fixes both the width and the height. | |
b33b68a3 MR |
504 | @end defvar |
505 | ||
b33b68a3 | 506 | @defun window-size-fixed-p &optional window horizontal |
a79db6e0 CY |
507 | This function returns a non-@code{nil} value if @var{window}'s height |
508 | is fixed. If @var{window} is omitted or @code{nil}, it defaults to | |
509 | the selected window. If the optional argument @var{horizontal} is | |
510 | non-@code{nil}, the return value is non-@code{nil} if @var{window}'s | |
511 | width is fixed. | |
b33b68a3 | 512 | |
a79db6e0 CY |
513 | A @code{nil} return value does not necessarily mean that @var{window} |
514 | can be resized in the desired direction. To determine that, use the | |
515 | function @code{window-resizable}. @xref{Resizing Windows}. | |
b33b68a3 MR |
516 | @end defun |
517 | ||
1c3d7a13 CY |
518 | @xref{Coordinates and Windows}, for more functions that report the |
519 | positions of various parts of a window relative to the frame, from | |
520 | which you can calculate its size. In particular, you can use the | |
521 | functions @code{window-pixel-edges} and | |
522 | @code{window-inside-pixel-edges} to find the size in pixels, for | |
523 | graphical displays. | |
b33b68a3 MR |
524 | |
525 | @node Resizing Windows | |
526 | @section Resizing Windows | |
527 | @cindex window resizing | |
528 | @cindex resize window | |
529 | @cindex changing window size | |
530 | @cindex window size, changing | |
531 | ||
e7313f33 CY |
532 | This section describes functions for resizing a window without |
533 | changing the size of its frame. Because live windows do not overlap, | |
534 | these functions are meaningful only on frames that contain two or more | |
535 | windows: resizing a window also changes the size of a neighboring | |
536 | window. If there is just one window on a frame, its size cannot be | |
537 | changed except by resizing the frame (@pxref{Size and Position}). | |
538 | ||
539 | Except where noted, these functions also accept internal windows as | |
540 | arguments. Resizing an internal window causes its child windows to be | |
541 | resized to fit the same space. | |
b33b68a3 | 542 | |
2cffd681 | 543 | @defun window-resizable window delta &optional horizontal ignore |
b33b68a3 | 544 | This function returns @var{delta} if the size of @var{window} can be |
e7313f33 CY |
545 | changed vertically by @var{delta} lines. If the optional argument |
546 | @var{horizontal} is non-@code{nil}, it instead returns @var{delta} if | |
547 | @var{window} can be resized horizontally by @var{delta} columns. It | |
548 | does not actually change the window size. | |
549 | ||
550 | If @var{window} is @code{nil}, it defaults to the selected window. | |
551 | ||
2cffd681 MR |
552 | A positive value of @var{delta} means to check whether the window can be |
553 | enlarged by that number of lines or columns; a negative value of | |
554 | @var{delta} means to check whether the window can be shrunk by that many | |
555 | lines or columns. If @var{delta} is non-zero, a return value of 0 means | |
556 | that the window cannot be resized. | |
e7313f33 CY |
557 | |
558 | Normally, the variables @code{window-min-height} and | |
559 | @code{window-min-width} specify the smallest allowable window size. | |
560 | @xref{Change Window,, Deleting and Rearranging Windows, emacs, The GNU | |
561 | Emacs Manual}. However, if the optional argument @var{ignore} is | |
562 | non-@code{nil}, this function ignores @code{window-min-height} and | |
563 | @code{window-min-width}, as well as @code{window-size-fixed}. | |
564 | Instead, it considers the minimum-height window to be one consisting | |
565 | of a header (if any), a mode line, plus a text area one line tall; and | |
566 | a minimum-width window as one consisting of fringes, margins, and | |
567 | scroll bar (if any), plus a text area two columns wide. | |
b33b68a3 MR |
568 | @end defun |
569 | ||
b33b68a3 | 570 | @defun window-resize window delta &optional horizontal ignore |
e7313f33 CY |
571 | This function resizes @var{window} by @var{delta} increments. If |
572 | @var{horizontal} is @code{nil}, it changes the height by @var{delta} | |
573 | lines; otherwise, it changes the width by @var{delta} columns. A | |
574 | positive @var{delta} means to enlarge the window, and a negative | |
575 | @var{delta} means to shrink it. | |
576 | ||
577 | If @var{window} is @code{nil}, it defaults to the selected window. If | |
578 | the window cannot be resized as demanded, an error is signaled. | |
579 | ||
580 | The optional argument @var{ignore} has the same meaning as for the | |
581 | function @code{window-resizable} above. | |
582 | ||
b6f67890 | 583 | The choice of which window edges this function alters depends on the |
a0c2d0ae | 584 | values of the option @code{window-combination-resize} and the |
d2999b1a MR |
585 | combination limits of the involved windows; in some cases, it may alter |
586 | both edges. @xref{Splitting Windows}. To resize by moving only the | |
587 | bottom or right edge of a window, use the function | |
a0c2d0ae | 588 | @code{adjust-window-trailing-edge}, below. |
b8d4c8d0 GM |
589 | @end defun |
590 | ||
e7313f33 CY |
591 | @c The commands enlarge-window, enlarge-window-horizontally, |
592 | @c shrink-window, and shrink-window-horizontally are documented in the | |
593 | @c Emacs manual. They are not preferred for calling from Lisp. | |
b33b68a3 | 594 | |
b33b68a3 MR |
595 | @defun adjust-window-trailing-edge window delta &optional horizontal |
596 | This function moves @var{window}'s bottom edge by @var{delta} lines. | |
d2ad7ee1 CY |
597 | If optional argument @var{horizontal} is non-@code{nil}, it instead |
598 | moves the right edge by @var{delta} columns. If @var{window} is | |
599 | @code{nil}, it defaults to the selected window. | |
b33b68a3 | 600 | |
d2ad7ee1 CY |
601 | A positive @var{delta} moves the edge downwards or to the right; a |
602 | negative @var{delta} moves it upwards or to the left. If the edge | |
603 | cannot be moved as far as specified by @var{delta}, this function | |
604 | moves it as far as possible but does not signal a error. | |
b33b68a3 MR |
605 | |
606 | This function tries to resize windows adjacent to the edge that is | |
d2ad7ee1 CY |
607 | moved. If this is not possible for some reason (e.g. if that adjacent |
608 | window is fixed-size), it may resize other windows. | |
b33b68a3 MR |
609 | @end defun |
610 | ||
d2ad7ee1 CY |
611 | The following commands resize windows in more specific ways. When |
612 | called interactively, they act on the selected window. | |
613 | ||
b33b68a3 | 614 | @deffn Command fit-window-to-buffer &optional window max-height min-height override |
d2ad7ee1 CY |
615 | This command adjusts the height of @var{window} to fit the text in it. |
616 | It returns non-@code{nil} if it was able to resize @var{window}, and | |
617 | @code{nil} otherwise. If @var{window} is omitted or @code{nil}, it | |
618 | defaults to the selected window. Otherwise, it should be a live | |
619 | window. | |
620 | ||
621 | The optional argument @var{max-height}, if non-@code{nil}, specifies | |
622 | the maximum total height that this function can give @var{window}. | |
623 | The optional argument @var{min-height}, if no-@code{nil}, specifies | |
624 | the minimum total height that it can give, which overrides the | |
625 | variable @code{window-min-height}. | |
626 | ||
627 | If the optional argument @var{override} is non-@code{nil}, this | |
628 | function ignores any size restrictions imposed by | |
629 | @code{window-min-height} and @code{window-min-width}. | |
b33b68a3 MR |
630 | @end deffn |
631 | ||
632 | @deffn Command shrink-window-if-larger-than-buffer &optional window | |
d2ad7ee1 CY |
633 | This command attempts to reduce @var{window}'s height as much as |
634 | possible while still showing its full buffer, but no less than | |
635 | @code{window-min-height} lines. The return value is non-@code{nil} if | |
636 | the window was resized, and @code{nil} otherwise. If @var{window} is | |
637 | omitted or @code{nil}, it defaults to the selected window. Otherwise, | |
638 | it should be a live window. | |
639 | ||
640 | This command does nothing if the window is already too short to | |
641 | display all of its buffer, or if any of the buffer is scrolled | |
642 | off-screen, or if the window is the only live window in its frame. | |
b33b68a3 MR |
643 | @end deffn |
644 | ||
645 | @cindex balancing window sizes | |
b33b68a3 MR |
646 | @deffn Command balance-windows &optional window-or-frame |
647 | This function balances windows in a way that gives more space to | |
648 | full-width and/or full-height windows. If @var{window-or-frame} | |
649 | specifies a frame, it balances all windows on that frame. If | |
d2ad7ee1 CY |
650 | @var{window-or-frame} specifies a window, it balances only that window |
651 | and its siblings (@pxref{Windows and Frames}). | |
b33b68a3 MR |
652 | @end deffn |
653 | ||
654 | @deffn Command balance-windows-area | |
655 | This function attempts to give all windows on the selected frame | |
d2ad7ee1 CY |
656 | approximately the same share of the screen area. Full-width or |
657 | full-height windows are not given more space than other windows. | |
b33b68a3 MR |
658 | @end deffn |
659 | ||
660 | @cindex maximizing windows | |
b33b68a3 | 661 | @deffn Command maximize-window &optional window |
d2ad7ee1 CY |
662 | This function attempts to make @var{window} as large as possible, in |
663 | both dimensions, without resizing its frame or deleting other windows. | |
664 | If @var{window} is omitted or @code{nil}, it defaults to the selected | |
665 | window. | |
b33b68a3 MR |
666 | @end deffn |
667 | ||
668 | @cindex minimizing windows | |
b33b68a3 | 669 | @deffn Command minimize-window &optional window |
d2ad7ee1 CY |
670 | This function attempts to make @var{window} as small as possible, in |
671 | both dimensions, without deleting it or resizing its frame. If | |
672 | @var{window} is omitted or @code{nil}, it defaults to the selected | |
673 | window. | |
b33b68a3 MR |
674 | @end deffn |
675 | ||
676 | ||
b8d4c8d0 GM |
677 | @node Splitting Windows |
678 | @section Splitting Windows | |
679 | @cindex splitting windows | |
680 | @cindex window splitting | |
681 | ||
f6f6d7e7 CY |
682 | This section describes functions for creating a new window by |
683 | @dfn{splitting} an existing one. | |
b8d4c8d0 | 684 | |
b33b68a3 | 685 | @deffn Command split-window &optional window size side |
f6f6d7e7 CY |
686 | This function creates a new live window next to the window |
687 | @var{window}. If @var{window} is omitted or @code{nil}, it defaults | |
688 | to the selected window. That window is ``split'', and reduced in | |
689 | size. The space is taken up by the new window, which is returned. | |
690 | ||
d2ad7ee1 | 691 | The optional second argument @var{size} determines the sizes of |
f6f6d7e7 CY |
692 | @var{window} and/or the new window. If it is omitted or @code{nil}, |
693 | both windows are given equal sizes; if there is an odd line, it is | |
694 | allocated to the new window. If @var{size} is a positive number, | |
695 | @var{window} is given @var{size} lines (or columns, depending on the | |
696 | value of @var{side}). If @var{size} is a negative number, the new | |
697 | window is given @minus{}@var{size} lines (or columns). | |
698 | ||
699 | If @var{size} is @code{nil}, this function obeys the variables | |
700 | @code{window-min-height} and @code{window-min-width}. @xref{Change | |
701 | Window,,Deleting and Rearranging Windows, emacs, The GNU Emacs | |
702 | Manual}. Thus, it signals an error if splitting would result in | |
703 | making a window smaller than those variables specify. However, a | |
704 | non-@code{nil} value for @var{size} causes those variables to be | |
705 | ignored; in that case, the smallest allowable window is considered to | |
706 | be one that has space for a text area one line tall and/or two columns | |
707 | wide. | |
708 | ||
709 | The optional third argument @var{side} determines the position of the | |
710 | new window relative to @var{window}. If it is @code{nil} or | |
711 | @code{below}, the new window is placed below @var{window}. If it is | |
712 | @code{above}, the new window is placed above @var{window}. In both | |
713 | these cases, @var{size} specifies a total window height, in lines. | |
714 | ||
715 | If @var{side} is @code{t} or @code{right}, the new window is placed on | |
716 | the right of @var{window}. If @var{side} is @code{left}, the new | |
717 | window is placed on the left of @var{window}. In both these cases, | |
718 | @var{size} specifies a total window width, in columns. | |
719 | ||
720 | If @var{window} is a live window, the new window inherits various | |
721 | properties from it, including margins and scroll bars. If | |
722 | @var{window} is an internal window, the new window inherits the | |
723 | properties of the window selected within @var{window}'s frame. | |
724 | ||
7bf54975 CY |
725 | The behavior of this function may be altered by the window parameters |
726 | of @var{window}, so long as the variable | |
727 | @code{ignore-window-parameters} is non-@code{nil}. If the value of | |
728 | the @code{split-window} window parameter is @code{t}, this function | |
729 | ignores all other window parameters. Otherwise, if the value of the | |
730 | @code{split-window} window parameter is a function, that function is | |
731 | called with the arguments @var{window}, @var{size}, and @var{side}, in | |
732 | lieu of the usual action of @code{split-window}. Otherwise, this | |
733 | function obeys the @code{window-atom} or @code{window-side} window | |
734 | parameter, if any. @xref{Window Parameters}. | |
b33b68a3 | 735 | @end deffn |
b8d4c8d0 | 736 | |
7bf54975 CY |
737 | As an example, here is a sequence of @code{split-window} calls that |
738 | yields the window configuration discussed in @ref{Windows and Frames}. | |
739 | This example demonstrates splitting a live window as well as splitting | |
740 | an internal window. We begin with a frame containing a single window | |
741 | (a live root window), which we denote by @var{W4}. Calling | |
90151a1e | 742 | @code{(split-window W4)} yields this window configuration: |
b33b68a3 | 743 | |
b33b68a3 MR |
744 | @smallexample |
745 | @group | |
746 | ______________________________________ | |
747 | | ____________________________________ | | |
748 | || || | |
749 | || || | |
750 | || || | |
f6f6d7e7 CY |
751 | ||_________________W4_________________|| |
752 | | ____________________________________ | | |
b33b68a3 MR |
753 | || || |
754 | || || | |
755 | || || | |
b33b68a3 MR |
756 | ||_________________W5_________________|| |
757 | |__________________W3__________________| | |
758 | ||
759 | @end group | |
760 | @end smallexample | |
761 | ||
f6f6d7e7 CY |
762 | @noindent |
763 | The @code{split-window} call has created a new live window, denoted by | |
764 | @var{W5}. It has also created a new internal window, denoted by | |
765 | @var{W3}, which becomes the root window and the parent of both | |
766 | @var{W4} and @var{W5}. | |
b33b68a3 | 767 | |
f6f6d7e7 CY |
768 | Next, we call @code{(split-window W3 nil 'left)}, passing the |
769 | internal window @var{W3} as the argument. The result: | |
b33b68a3 | 770 | |
b33b68a3 MR |
771 | @smallexample |
772 | @group | |
773 | ______________________________________ | |
774 | | ______ ____________________________ | | |
f6f6d7e7 CY |
775 | || || __________________________ || |
776 | || ||| ||| | |
777 | || ||| ||| | |
778 | || ||| ||| | |
779 | || |||____________W4____________||| | |
780 | || || __________________________ || | |
781 | || ||| ||| | |
782 | || ||| ||| | |
783 | || |||____________W5____________||| | |
784 | ||__W2__||_____________W3_____________ | | |
b33b68a3 | 785 | |__________________W1__________________| |
b33b68a3 MR |
786 | @end group |
787 | @end smallexample | |
788 | ||
f6f6d7e7 | 789 | @noindent |
d2ad7ee1 CY |
790 | A new live window @var{W2} is created, to the left of the internal |
791 | window @var{W3}. A new internal window @var{W1} is created, becoming | |
792 | the new root window. | |
b33b68a3 | 793 | |
a0c2d0ae | 794 | @defopt window-combination-resize |
f6f6d7e7 | 795 | If this variable is @code{nil}, @code{split-window} can only split a |
454592a6 MR |
796 | window (denoted by @var{window}) if @var{window}'s screen area is large |
797 | enough to accommodate both itself and the new window. | |
798 | ||
799 | If this variable is @code{t}, @code{split-window} tries to resize all | |
800 | windows that are part of the same combination as @var{window}, in order | |
801 | to accommodate the new window. In particular, this may allow | |
802 | @code{split-window} to succeed even if @var{window} is a fixed-size | |
803 | window or too small to ordinarily split. Furthermore, subsequently | |
804 | resizing or deleting @var{window} may resize all other windows in its | |
805 | combination. | |
806 | ||
807 | The default is @code{nil}. Other values are reserved for future use. | |
808 | The value of this variable is ignored when | |
809 | @code{window-combination-limit} is non-@code{nil} (see below). | |
89d61221 | 810 | @end defopt |
b33b68a3 | 811 | |
7bf54975 CY |
812 | To illustrate the effect of @code{window-combination-resize}, |
813 | consider the following window configuration: | |
814 | ||
b33b68a3 MR |
815 | @smallexample |
816 | @group | |
817 | ______________________________________ | |
818 | | ____________________________________ | | |
819 | || || | |
820 | || || | |
821 | || || | |
822 | || || | |
823 | ||_________________W2_________________|| | |
824 | | ____________________________________ | | |
825 | || || | |
826 | || || | |
827 | || || | |
828 | || || | |
829 | ||_________________W3_________________|| | |
830 | |__________________W1__________________| | |
831 | ||
832 | @end group | |
833 | @end smallexample | |
834 | ||
7bf54975 CY |
835 | @noindent |
836 | If @code{window-combination-resize} is @code{nil}, splitting window | |
837 | @code{W3} leaves the size of @code{W2} unchanged: | |
838 | ||
b33b68a3 MR |
839 | @smallexample |
840 | @group | |
841 | ______________________________________ | |
842 | | ____________________________________ | | |
843 | || || | |
844 | || || | |
845 | || || | |
846 | || || | |
847 | ||_________________W2_________________|| | |
848 | | ____________________________________ | | |
849 | || || | |
850 | ||_________________W3_________________|| | |
851 | | ____________________________________ | | |
852 | || || | |
853 | ||_________________W4_________________|| | |
854 | |__________________W1__________________| | |
855 | ||
856 | @end group | |
857 | @end smallexample | |
858 | ||
7bf54975 | 859 | @noindent |
454592a6 MR |
860 | If @code{window-combination-resize} is @code{t}, splitting @code{W3} |
861 | instead leaves all three live windows with approximately the same | |
862 | height: | |
7bf54975 | 863 | |
b33b68a3 MR |
864 | @smallexample |
865 | @group | |
866 | ______________________________________ | |
867 | | ____________________________________ | | |
868 | || || | |
869 | || || | |
870 | ||_________________W2_________________|| | |
871 | | ____________________________________ | | |
872 | || || | |
873 | || || | |
874 | ||_________________W3_________________|| | |
875 | | ____________________________________ | | |
876 | || || | |
877 | || || | |
878 | ||_________________W4_________________|| | |
879 | |__________________W1__________________| | |
880 | ||
881 | @end group | |
882 | @end smallexample | |
883 | ||
b6f67890 | 884 | @defopt window-combination-limit |
7bf54975 CY |
885 | If the value of this variable is @code{t}, the @code{split-window} |
886 | function always creates a new internal window. If the value is | |
887 | @code{nil}, the new live window is allowed to share the existing | |
888 | parent window, if one exists, provided the split occurs in the same | |
889 | direction as the existing window combination (otherwise, a new | |
890 | internal window is created anyway). The default is @code{nil}. Other | |
891 | values are reserved for future use. | |
892 | ||
94af99a4 MR |
893 | Thus, if the value of this variable is at all times @code{t}, then at |
894 | all times every window tree is a binary tree (a tree where each window | |
895 | except the root window has exactly one sibling). | |
7bf54975 CY |
896 | |
897 | Furthermore, @code{split-window} calls | |
898 | @code{set-window-combination-limit} on the newly-created internal | |
899 | window, recording the current value of this variable. This affects | |
900 | how the window tree is rearranged when the child windows are deleted | |
901 | (see below). | |
b33b68a3 MR |
902 | @end defopt |
903 | ||
7bf54975 | 904 | @cindex window combination limit |
d2999b1a | 905 | @defun set-window-combination-limit window limit |
7bf54975 | 906 | This functions sets the @dfn{combination limit} of the window |
d2999b1a | 907 | @var{window} to @var{limit}. This value can be retrieved via the |
7bf54975 CY |
908 | function @code{window-combination-limit}. See below for its effects; |
909 | note that it is only meaningful for internal windows. The | |
d2999b1a MR |
910 | @code{split-window} function automatically calls this function, passing |
911 | the value of the variable @code{window-combination-limit} as | |
912 | @var{limit}. | |
b33b68a3 MR |
913 | @end defun |
914 | ||
7bf54975 CY |
915 | @defun window-combination-limit window |
916 | This function returns the combination limit for @var{window}. | |
917 | ||
918 | The combination limit is meaningful only for an internal window. If | |
919 | it is @code{nil}, then Emacs is allowed to automatically delete | |
920 | @var{window}, in response to a window deletion, in order to group the | |
a9b9b7f5 CY |
921 | child windows of @var{window} with its sibling windows to form a new |
922 | window combination. If the combination limit is @code{t}, the child | |
923 | windows of @var{window} are never automatically re-combined with its | |
924 | siblings. | |
b33b68a3 MR |
925 | @end defun |
926 | ||
7bf54975 CY |
927 | To illustrate the effect of @code{window-combination-limit}, |
928 | consider the following configuration (throughout this example, we will | |
929 | assume that @code{window-combination-resize} is @code{nil}): | |
930 | ||
b33b68a3 MR |
931 | @smallexample |
932 | @group | |
933 | ______________________________________ | |
934 | | ____________________________________ | | |
935 | || || | |
936 | || || | |
937 | || || | |
938 | || || | |
939 | || || | |
940 | || || | |
941 | ||_________________W2_________________|| | |
942 | | ____________________________________ | | |
943 | || || | |
944 | || || | |
945 | ||_________________W3_________________|| | |
946 | |__________________W1__________________| | |
947 | ||
948 | @end group | |
949 | @end smallexample | |
950 | ||
7bf54975 CY |
951 | @noindent |
952 | If @code{window-combination-limit} is @code{nil}, splitting @code{W2} | |
953 | into two windows, one above the other, yields | |
b33b68a3 | 954 | |
b33b68a3 MR |
955 | @smallexample |
956 | @group | |
957 | ______________________________________ | |
958 | | ____________________________________ | | |
959 | || || | |
960 | || || | |
961 | ||_________________W2_________________|| | |
962 | | ____________________________________ | | |
963 | || || | |
964 | || || | |
b33b68a3 MR |
965 | ||_________________W4_________________|| |
966 | | ____________________________________ | | |
967 | || || | |
7bf54975 | 968 | || || |
b33b68a3 MR |
969 | ||_________________W3_________________|| |
970 | |__________________W1__________________| | |
971 | ||
972 | @end group | |
973 | @end smallexample | |
974 | ||
7bf54975 CY |
975 | @noindent |
976 | The newly-created window, @code{W4}, shares the same internal window | |
977 | @code{W1}. If @code{W4} is resized, it is allowed to resize the other | |
978 | live window, @code{W3}. | |
b33b68a3 | 979 | |
7bf54975 CY |
980 | If @code{window-combination-limit} is @code{t}, splitting @code{W2} |
981 | in the initial configuration would instead have produced this: | |
b33b68a3 | 982 | |
b33b68a3 MR |
983 | @smallexample |
984 | @group | |
985 | ______________________________________ | |
986 | | ____________________________________ | | |
987 | || __________________________________ || | |
988 | ||| ||| | |
989 | |||________________W2________________||| | |
990 | || __________________________________ || | |
991 | ||| ||| | |
992 | |||________________W4________________||| | |
993 | ||_________________W5_________________|| | |
994 | | ____________________________________ | | |
995 | || || | |
996 | || || | |
997 | ||_________________W3_________________|| | |
998 | |__________________W1__________________| | |
999 | ||
1000 | @end group | |
1001 | @end smallexample | |
1002 | ||
7bf54975 CY |
1003 | @noindent |
1004 | A new internal window @code{W5} has been created; its children are | |
1005 | @code{W2} and the new live window @code{W4}. Now, @code{W2} is the | |
1006 | only sibling of @code{W4}, so resizing @code{W4} will resize | |
1007 | @code{W2}, leaving @code{W3} unaffected. | |
b33b68a3 | 1008 | |
7bf54975 CY |
1009 | For interactive use, Emacs provides two commands which always split |
1010 | the selected window. These call @code{split-window} internally. | |
b33b68a3 | 1011 | |
7bf54975 CY |
1012 | @deffn Command split-window-right &optional size |
1013 | This function splits the selected window into two side-by-side | |
1014 | windows, putting the selected window on the left. If @var{size} is | |
1015 | positive, the left window gets @var{size} columns; if @var{size} is | |
1016 | negative, the right window gets @minus{}@var{size} columns. | |
1017 | @end deffn | |
b33b68a3 | 1018 | |
291d142b | 1019 | @deffn Command split-window-below &optional size |
7bf54975 CY |
1020 | This function splits the selected window into two windows, one above |
1021 | the other, leaving the upper window selected. If @var{size} is | |
1022 | positive, the upper window gets @var{size} lines; if @var{size} is | |
1023 | negative, the lower window gets @minus{}@var{size} lines. | |
b8d4c8d0 GM |
1024 | @end deffn |
1025 | ||
1026 | @defopt split-window-keep-point | |
7bf54975 | 1027 | If the value of this variable is non-@code{nil} (the default), |
291d142b | 1028 | @code{split-window-below} behaves as described above. |
b8d4c8d0 | 1029 | |
7bf54975 CY |
1030 | If it is @code{nil}, @code{split-window-below} adjusts point in each |
1031 | of the two windows to minimize redisplay. (This is useful on slow | |
1032 | terminals.) It selects whichever window contains the screen line that | |
1033 | point was previously on. Note that this only affects | |
1034 | @code{split-window-below}, not the lower-level @code{split-window} | |
1035 | function. | |
b8d4c8d0 GM |
1036 | @end defopt |
1037 | ||
b8d4c8d0 GM |
1038 | @node Deleting Windows |
1039 | @section Deleting Windows | |
1040 | @cindex deleting windows | |
1041 | ||
7bf54975 CY |
1042 | @dfn{Deleting} a window removes it from the frame's window tree. If |
1043 | the window is a live window, it disappears from the screen. If the | |
1044 | window is an internal window, its child windows are deleted too. | |
1045 | ||
1046 | Even after a window is deleted, it continues to exist as a Lisp | |
1047 | object, until there are no more references to it. Window deletion can | |
1048 | be reversed, by restoring a saved window configuration (@pxref{Window | |
1049 | Configurations}). | |
b8d4c8d0 GM |
1050 | |
1051 | @deffn Command delete-window &optional window | |
7bf54975 CY |
1052 | This function removes @var{window} from display and returns |
1053 | @code{nil}. If @var{window} is omitted or @code{nil}, it defaults to | |
1054 | the selected window. If deleting the window would leave no more | |
1055 | windows in the window tree (e.g. if it is the only live window in the | |
1056 | frame), an error is signaled. | |
1057 | ||
1058 | By default, the space taken up by @var{window} is given to one of its | |
1059 | adjacent sibling windows, if any. However, if the variable | |
1060 | @code{window-combination-resize} is non-@code{nil}, the space is | |
1061 | proportionally distributed among any remaining windows in the window | |
1062 | combination. @xref{Splitting Windows}. | |
1063 | ||
1064 | The behavior of this function may be altered by the window parameters | |
1065 | of @var{window}, so long as the variable | |
1066 | @code{ignore-window-parameters} is non-@code{nil}. If the value of | |
1067 | the @code{delete-window} window parameter is @code{t}, this function | |
1068 | ignores all other window parameters. Otherwise, if the value of the | |
1069 | @code{delete-window} window parameter is a function, that function is | |
1070 | called with the argument @var{window}, in lieu of the usual action of | |
1071 | @code{delete-window}. Otherwise, this function obeys the | |
1072 | @code{window-atom} or @code{window-side} window parameter, if any. | |
1073 | @xref{Window Parameters}. | |
b8d4c8d0 GM |
1074 | @end deffn |
1075 | ||
1076 | @deffn Command delete-other-windows &optional window | |
7bf54975 CY |
1077 | This function makes @var{window} fill its frame, by deleting other |
1078 | windows as necessary. If @var{window} is omitted or @code{nil}, it | |
1079 | defaults to the selected window. The return value is @code{nil}. | |
1080 | ||
1081 | The behavior of this function may be altered by the window parameters | |
1082 | of @var{window}, so long as the variable | |
1083 | @code{ignore-window-parameters} is non-@code{nil}. If the value of | |
1084 | the @code{delete-other-windows} window parameter is @code{t}, this | |
1085 | function ignores all other window parameters. Otherwise, if the value | |
1086 | of the @code{delete-other-windows} window parameter is a function, | |
1087 | that function is called with the argument @var{window}, in lieu of the | |
1088 | usual action of @code{delete-other-windows}. Otherwise, this function | |
1089 | obeys the @code{window-atom} or @code{window-side} window parameter, | |
1090 | if any. @xref{Window Parameters}. | |
b8d4c8d0 GM |
1091 | @end deffn |
1092 | ||
520b29e7 | 1093 | @deffn Command delete-windows-on &optional buffer-or-name frame |
7bf54975 CY |
1094 | This function deletes all windows showing @var{buffer-or-name}, by |
1095 | calling @code{delete-window} on those windows. @var{buffer-or-name} | |
1096 | should be a buffer, or the name of a buffer; if omitted or @code{nil}, | |
1097 | it defaults to the current buffer. If there are no windows showing | |
1098 | the specified buffer, this function does nothing. If the specified | |
1099 | buffer is a minibuffer, an error is signaled. | |
1100 | ||
1101 | If there is a dedicated window showing the buffer, and that window is | |
1102 | the only one on its frame, this function also deletes that frame if it | |
1103 | is not the only frame on the terminal. | |
1104 | ||
1105 | The optional argument @var{frame} specifies which frames to operate | |
1106 | on: | |
b8d4c8d0 GM |
1107 | |
1108 | @itemize @bullet | |
b33b68a3 MR |
1109 | @item @code{nil} |
1110 | means operate on all frames. | |
1111 | @item @code{t} | |
1112 | means operate on the selected frame. | |
1113 | @item @code{visible} | |
1114 | means operate on all visible frames. | |
1115 | @item @code{0} | |
1116 | means operate on all visible or iconified frames. | |
1117 | @item A frame | |
1118 | means operate on that frame. | |
b8d4c8d0 | 1119 | @end itemize |
b8d4c8d0 | 1120 | |
7bf54975 CY |
1121 | Note that this argument does not have the same meaning as in other |
1122 | functions which scan all live windows (@pxref{Cyclic Window | |
1123 | Ordering}). Specifically, the values @code{t} and @code{nil} have the | |
1124 | opposite of their meanings in those other functions. | |
1125 | @end deffn | |
b33b68a3 | 1126 | |
b8d4c8d0 GM |
1127 | @node Selecting Windows |
1128 | @section Selecting Windows | |
1129 | @cindex selecting a window | |
1130 | ||
b8d4c8d0 | 1131 | @defun select-window window &optional norecord |
7bf54975 CY |
1132 | This function makes @var{window} the selected window, as well as the |
1133 | window selected within its frame (@pxref{Basic Windows}). | |
a9b9b7f5 | 1134 | @var{window} must be a live window. Unless @var{window} already is the |
7bf54975 CY |
1135 | selected window, its buffer becomes the current buffer (@pxref{Buffers |
1136 | and Windows}). The return value is @var{window}. | |
1137 | ||
1138 | By default, this function also moves @var{window}'s selected buffer to | |
1139 | the front of the buffer list (@pxref{The Buffer List}), and makes | |
1140 | @var{window} the most recently selected window. However, if the | |
1141 | optional argument @var{norecord} is non-@code{nil}, these additional | |
1142 | actions are omitted. | |
b8d4c8d0 GM |
1143 | @end defun |
1144 | ||
b33b68a3 | 1145 | @cindex most recently selected windows |
7bf54975 | 1146 | The sequence of calls to @code{select-window} with a non-@code{nil} |
b33b68a3 MR |
1147 | @var{norecord} argument determines an ordering of windows by their |
1148 | selection time. The function @code{get-lru-window} can be used to | |
7bf54975 CY |
1149 | retrieve the least recently selected live window (@pxref{Cyclic Window |
1150 | Ordering}). | |
b33b68a3 | 1151 | |
b8d4c8d0 GM |
1152 | @defmac save-selected-window forms@dots{} |
1153 | This macro records the selected frame, as well as the selected window | |
1154 | of each frame, executes @var{forms} in sequence, then restores the | |
1155 | earlier selected frame and windows. It also saves and restores the | |
1156 | current buffer. It returns the value of the last form in @var{forms}. | |
1157 | ||
1158 | This macro does not save or restore anything about the sizes, | |
a1401ab1 | 1159 | arrangement or contents of windows; therefore, if @var{forms} change |
0273ca3a MR |
1160 | them, the change persists. If the previously selected window of some |
1161 | frame is no longer live at the time of exit from @var{forms}, that | |
1162 | frame's selected window is left alone. If the previously selected | |
1163 | window is no longer live, then whatever window is selected at the end of | |
1164 | @var{forms} remains selected. The current buffer is restored if and | |
1165 | only if it is still live when exiting @var{forms}. | |
1166 | ||
1167 | This macro changes neither the ordering of recently selected windows nor | |
1168 | the buffer list. | |
b8d4c8d0 GM |
1169 | @end defmac |
1170 | ||
1171 | @defmac with-selected-window window forms@dots{} | |
0273ca3a MR |
1172 | This macro selects @var{window}, executes @var{forms} in sequence, then |
1173 | restores the previously selected window and current buffer. The ordering | |
1174 | of recently selected windows and the buffer list remain unchanged unless | |
1175 | you deliberately change them within @var{forms}, for example, by calling | |
b8766179 | 1176 | @code{select-window} with argument @var{norecord} @code{nil}. |
b8d4c8d0 | 1177 | |
b33b68a3 MR |
1178 | The order of recently selected windows and the buffer list are not |
1179 | changed by this macro. | |
1180 | @end defmac | |
b8d4c8d0 | 1181 | |
7bf54975 CY |
1182 | @defun frame-selected-window &optional frame |
1183 | This function returns the window on @var{frame} that is selected | |
1184 | within that frame. @var{frame} should be a live frame; if omitted or | |
1185 | @code{nil}, it defaults to the selected frame. | |
b8d4c8d0 GM |
1186 | @end defun |
1187 | ||
b33b68a3 | 1188 | @defun set-frame-selected-window frame window &optional norecord |
7bf54975 CY |
1189 | This function makes @code{window} the window selected within the frame |
1190 | @var{frame}. @var{frame} should be a live frame; if omitted or | |
1191 | @code{nil}, it defaults to the selected frame. @var{window} should be | |
1192 | a live window; if omitted or @code{nil}, it defaults to the selected | |
1193 | window. | |
b33b68a3 | 1194 | |
7bf54975 CY |
1195 | If @var{frame} is the selected frame, this makes @var{window} the |
1196 | selected window. | |
b8d4c8d0 | 1197 | |
7bf54975 CY |
1198 | If the optional argument @var{norecord} is non-@code{nil}, this |
1199 | function does not alter the list of most recently selected windows, | |
1200 | nor the buffer list. | |
1201 | @end defun | |
b8d4c8d0 GM |
1202 | |
1203 | @node Cyclic Window Ordering | |
b8d4c8d0 GM |
1204 | @section Cyclic Ordering of Windows |
1205 | @cindex cyclic ordering of windows | |
1206 | @cindex ordering of windows, cyclic | |
1207 | @cindex window ordering, cyclic | |
1208 | ||
a9b9b7f5 | 1209 | When you use the command @kbd{C-x o} (@code{other-window}) to select |
b33b68a3 | 1210 | some other window, it moves through live windows in a specific order. |
a9b9b7f5 CY |
1211 | For any given configuration of windows, this order never varies. It |
1212 | is called the @dfn{cyclic ordering of windows}. | |
b8d4c8d0 | 1213 | |
a9b9b7f5 CY |
1214 | The ordering is determined by a depth-first traversal of the frame's |
1215 | window tree, retrieving the live windows which are the leaf nodes of | |
1216 | the tree (@pxref{Windows and Frames}). If the minibuffer is active, | |
1217 | the minibuffer window is included too. The ordering is cyclic, so the | |
1218 | last window in the sequence is followed by the first one. | |
b8d4c8d0 | 1219 | |
5854c267 | 1220 | @defun next-window &optional window minibuf all-frames |
b8d4c8d0 | 1221 | @cindex minibuffer window, and @code{next-window} |
a9b9b7f5 CY |
1222 | This function returns a live window, the one following @var{window} in |
1223 | the cyclic ordering of windows. @var{window} should be a live window; | |
1224 | if omitted or @code{nil}, it defaults to the selected window. | |
b8d4c8d0 | 1225 | |
b33b68a3 MR |
1226 | The optional argument @var{minibuf} specifies whether minibuffer windows |
1227 | shall be included in the cyclic ordering. Normally, when @var{minibuf} | |
1228 | is @code{nil}, a minibuffer window is included only if it is currently | |
1229 | ``active''; this matches the behavior of @kbd{C-x o}. (Note that a | |
1230 | minibuffer window is active as long as its minibuffer is in use; see | |
1231 | @ref{Minibuffers}). | |
b8d4c8d0 | 1232 | |
b33b68a3 MR |
1233 | If @var{minibuf} is @code{t}, the cyclic ordering includes all |
1234 | minibuffer windows. If @var{minibuf} is neither @code{t} nor | |
1235 | @code{nil}, minibuffer windows are not included even if they are active. | |
b8d4c8d0 | 1236 | |
aeeedf76 | 1237 | The optional argument @var{all-frames} specifies which frames to |
a9b9b7f5 | 1238 | consider: |
b8d4c8d0 | 1239 | |
b33b68a3 | 1240 | @itemize @bullet |
b8d4c8d0 | 1241 | @item @code{nil} |
a9b9b7f5 CY |
1242 | means to consider windows on @var{window}'s frame. If the minibuffer |
1243 | window is considered (as specified by the @var{minibuf} argument), | |
1244 | then frames that share the minibuffer window are considered too. | |
b8d4c8d0 GM |
1245 | |
1246 | @item @code{t} | |
a9b9b7f5 | 1247 | means to consider windows on all existing frames. |
b8d4c8d0 GM |
1248 | |
1249 | @item @code{visible} | |
a9b9b7f5 | 1250 | means to consider windows on all visible frames. |
b8d4c8d0 GM |
1251 | |
1252 | @item 0 | |
a9b9b7f5 | 1253 | means to consider windows on all visible or iconified frames. |
b8d4c8d0 | 1254 | |
b33b68a3 | 1255 | @item A frame |
a9b9b7f5 | 1256 | means to consider windows on that specific frame. |
b8d4c8d0 | 1257 | |
b33b68a3 | 1258 | @item Anything else |
a9b9b7f5 | 1259 | means to consider windows on @var{window}'s frame, and no others. |
b33b68a3 | 1260 | @end itemize |
b8d4c8d0 | 1261 | |
a9b9b7f5 CY |
1262 | If more than one frame is considered, the cyclic ordering is obtained |
1263 | by appending the orderings for those frames, in the same order as the | |
1264 | list of all live frames (@pxref{Finding All Frames}). | |
5854c267 | 1265 | @end defun |
b8d4c8d0 | 1266 | |
5854c267 | 1267 | @defun previous-window &optional window minibuf all-frames |
a9b9b7f5 CY |
1268 | This function returns a live window, the one preceding @var{window} in |
1269 | the cyclic ordering of windows. The other arguments are handled like | |
1270 | in @code{next-window}. | |
5854c267 | 1271 | @end defun |
b8d4c8d0 GM |
1272 | |
1273 | @deffn Command other-window count &optional all-frames | |
a9b9b7f5 CY |
1274 | This function selects a live window, one @var{count} places from the |
1275 | selected window in the cyclic ordering of windows. If @var{count} is | |
1276 | a positive number, it skips @var{count} windows forwards; if | |
1277 | @var{count} is negative, it skips @minus{}@var{count} windows | |
1278 | backwards; if @var{count} is zero, that simply re-selects the selected | |
1279 | window. When called interactively, @var{count} is the numeric prefix | |
1280 | argument. | |
b8d4c8d0 | 1281 | |
aeeedf76 | 1282 | The optional argument @var{all-frames} has the same meaning as in |
a9b9b7f5 CY |
1283 | @code{next-window}, like a @code{nil} @var{minibuf} argument to |
1284 | @code{next-window}. | |
b33b68a3 MR |
1285 | |
1286 | This function does not select a window that has a non-@code{nil} | |
1287 | @code{no-other-window} window parameter (@pxref{Window Parameters}). | |
b8d4c8d0 GM |
1288 | @end deffn |
1289 | ||
a9b9b7f5 CY |
1290 | @defun walk-windows fun &optional minibuf all-frames |
1291 | This function calls the function @var{fun} once for each live window, | |
1292 | with the window as the argument. | |
b33b68a3 | 1293 | |
a9b9b7f5 CY |
1294 | It follows the cyclic ordering of windows. The optional arguments |
1295 | @var{minibuf} and @var{all-frames} specify the set of windows | |
1296 | included; these have the same arguments as in @code{next-window}. If | |
1297 | @var{all-frames} specifies a frame, the first window walked is the | |
1298 | first window on that frame (the one returned by | |
1299 | @code{frame-first-window}), not necessarily the selected window. | |
b33b68a3 | 1300 | |
a9b9b7f5 CY |
1301 | If @var{fun} changes the window configuration by splitting or deleting |
1302 | windows, that does not alter the set of windows walked, which is | |
1303 | determined prior to calling @var{fun} for the first time. | |
b33b68a3 MR |
1304 | @end defun |
1305 | ||
b33b68a3 | 1306 | @defun one-window-p &optional no-mini all-frames |
a9b9b7f5 CY |
1307 | This function returns @code{t} if the selected window is the only live |
1308 | window, and @code{nil} otherwise. | |
1309 | ||
1310 | If the minibuffer window is active, it is normally considered (so that | |
1311 | this function returns @code{nil}). However, if the optional argument | |
1312 | @var{no-mini} is non-@code{nil}, the minibuffer window is ignored even | |
1313 | if active. The optional argument @var{all-frames} has the same | |
1314 | meaning as for @code{next-window}. | |
b33b68a3 MR |
1315 | @end defun |
1316 | ||
1317 | @cindex finding windows | |
a9b9b7f5 CY |
1318 | The following functions return a window which satisfies some |
1319 | criterion, without selecting it: | |
b33b68a3 MR |
1320 | |
1321 | @cindex least recently used window | |
1322 | @defun get-lru-window &optional all-frames dedicated | |
a9b9b7f5 CY |
1323 | This function returns a live window which is heuristically the ``least |
1324 | recently used'' window. The optional argument @var{all-frames} has | |
1325 | the same meaning as in @code{next-window}. | |
1326 | ||
1327 | If any full-width windows are present, only those windows are | |
1328 | considered. The selected window is never returned, unless it is the | |
1329 | only candidate. A minibuffer window is never a candidate. A | |
1330 | dedicated window (@pxref{Dedicated Windows}) is never a candidate | |
1331 | unless the optional argument @var{dedicated} is non-@code{nil}. | |
b33b68a3 MR |
1332 | @end defun |
1333 | ||
1334 | @cindex largest window | |
1335 | @defun get-largest-window &optional all-frames dedicated | |
1336 | This function returns the window with the largest area (height times | |
1337 | width). A minibuffer window is never a candidate. A dedicated window | |
1338 | (@pxref{Dedicated Windows}) is never a candidate unless the optional | |
1339 | argument @var{dedicated} is non-@code{nil}. | |
b8d4c8d0 | 1340 | |
b33b68a3 MR |
1341 | If there are two candidate windows of the same size, this function |
1342 | prefers the one that comes first in the cyclic ordering of windows, | |
1343 | starting from the selected window. | |
1344 | ||
a9b9b7f5 CY |
1345 | The optional argument @var{all-frames} specifies the windows to |
1346 | search, and has the same meaning as in @code{next-window}. | |
b8d4c8d0 GM |
1347 | @end defun |
1348 | ||
b33b68a3 MR |
1349 | @cindex window that satisfies a predicate |
1350 | @cindex conditional selection of windows | |
1351 | @defun get-window-with-predicate predicate &optional minibuf all-frames default | |
a9b9b7f5 CY |
1352 | This function calls the function @var{predicate} for each of the |
1353 | windows in the cyclic order of windows in turn, passing it the window | |
1354 | as an argument. If the predicate returns non-@code{nil} for any | |
1355 | window, this function stops and returns that window. If no such | |
1356 | window is found, the return value is @var{default} (which defaults to | |
1357 | @code{nil}). | |
b8d4c8d0 | 1358 | |
b33b68a3 | 1359 | The optional arguments @var{minibuf} and @var{all-frames} specify the |
a9b9b7f5 CY |
1360 | windows to search, and have the same meanings as in |
1361 | @code{next-window}. | |
b8d4c8d0 GM |
1362 | @end defun |
1363 | ||
1364 | @node Buffers and Windows | |
1365 | @section Buffers and Windows | |
1366 | @cindex examining windows | |
1367 | @cindex windows, controlling precisely | |
1368 | @cindex buffers, controlled in windows | |
1369 | ||
a9b9b7f5 CY |
1370 | This section describes low-level functions for examining and setting |
1371 | the contents of windows. @xref{Switching Buffers}, for higher-level | |
1372 | functions for displaying a specific buffer in a window. | |
b8d4c8d0 | 1373 | |
b33b68a3 | 1374 | @defun window-buffer &optional window |
a9b9b7f5 CY |
1375 | This function returns the buffer that @var{window} is displaying. If |
1376 | @var{window} is omitted or @code{nil} it defaults to the selected | |
1377 | window. If @var{window} is an internal window, this function returns | |
b33b68a3 MR |
1378 | @code{nil}. |
1379 | @end defun | |
aeeedf76 | 1380 | |
b33b68a3 | 1381 | @defun set-window-buffer window buffer-or-name &optional keep-margins |
a9b9b7f5 CY |
1382 | This function makes @var{window} display @var{buffer-or-name}. |
1383 | @var{window} should be a live window; if @code{nil}, it defaults to | |
1384 | the selected window. @var{buffer-or-name} should be a buffer, or the | |
1385 | name of an existing buffer. This function does not change which | |
1386 | window is selected, nor does it directly change which buffer is | |
1387 | current (@pxref{Current Buffer}). Its return value is @code{nil}. | |
1388 | ||
1389 | If @var{window} is @dfn{strongly dedicated} to a buffer and | |
1390 | @var{buffer-or-name} does not specify that buffer, this function | |
1391 | signals an error. @xref{Dedicated Windows}. | |
1392 | ||
1393 | By default, this function resets @var{window}'s position, display | |
1394 | margins, fringe widths, and scroll bar settings, based on the local | |
1395 | variables in the specified buffer. However, if the optional argument | |
1396 | @var{keep-margins} is non-@code{nil}, it leaves the display margins | |
1397 | and fringe widths unchanged. | |
1398 | ||
1399 | When writing an application, you should normally use the higher-level | |
1400 | functions described in @ref{Switching Buffers}, instead of calling | |
1401 | @code{set-window-buffer} directly. | |
1402 | ||
1403 | This function runs @code{window-scroll-functions}, followed by | |
1404 | @code{window-configuration-change-hook}. @xref{Window Hooks}. | |
b8d4c8d0 GM |
1405 | @end defun |
1406 | ||
1407 | @defvar buffer-display-count | |
0273ca3a | 1408 | This buffer-local variable records the number of times a buffer has been |
b8d4c8d0 GM |
1409 | displayed in a window. It is incremented each time |
1410 | @code{set-window-buffer} is called for the buffer. | |
1411 | @end defvar | |
1412 | ||
b33b68a3 | 1413 | @defvar buffer-display-time |
a9b9b7f5 CY |
1414 | This buffer-local variable records the time at which a buffer was last |
1415 | displayed in a window. The value is @code{nil} if the buffer has | |
1416 | never been displayed. It is updated each time | |
1417 | @code{set-window-buffer} is called for the buffer, with the value | |
1418 | returned by @code{current-time} (@pxref{Time of Day}). | |
b33b68a3 | 1419 | @end defvar |
b8d4c8d0 | 1420 | |
520b29e7 | 1421 | @defun get-buffer-window &optional buffer-or-name all-frames |
a9b9b7f5 CY |
1422 | This function returns the first window displaying @var{buffer-or-name} |
1423 | in the cyclic ordering of windows, starting from the selected window | |
1424 | (@pxref{Cyclic Window Ordering}). If no such window exists, the | |
1425 | return value is @code{nil}. | |
b8d4c8d0 | 1426 | |
a9b9b7f5 CY |
1427 | @var{buffer-or-name} should be a buffer or the name of a buffer; if |
1428 | omitted or @code{nil}, it defaults to the current buffer. The | |
1429 | optional argument @var{all-frames} specifies which windows to | |
1430 | consider: | |
b8d4c8d0 GM |
1431 | |
1432 | @itemize @bullet | |
1433 | @item | |
0273ca3a | 1434 | @code{t} means consider windows on all existing frames. |
b8d4c8d0 | 1435 | @item |
0273ca3a | 1436 | @code{visible} means consider windows on all visible frames. |
b8d4c8d0 | 1437 | @item |
0273ca3a | 1438 | 0 means consider windows on all visible or iconified frames. |
b8d4c8d0 | 1439 | @item |
0273ca3a | 1440 | A frame means consider windows on that frame only. |
a9b9b7f5 CY |
1441 | @item |
1442 | Any other value means consider windows on the selected frame. | |
b8d4c8d0 | 1443 | @end itemize |
0273ca3a | 1444 | |
a9b9b7f5 CY |
1445 | Note that these meanings differ slightly from those of the |
1446 | @var{all-frames} argument to @code{next-window} (@pxref{Cyclic Window | |
1447 | Ordering}). This function may be changed in a future version of Emacs | |
1448 | to eliminate this discrepancy. | |
b8d4c8d0 GM |
1449 | @end defun |
1450 | ||
520b29e7 MR |
1451 | @defun get-buffer-window-list &optional buffer-or-name minibuf all-frames |
1452 | This function returns a list of all windows currently displaying | |
a9b9b7f5 CY |
1453 | @var{buffer-or-name}. @var{buffer-or-name} should be a buffer or the |
1454 | name of an existing buffer. If omitted or @code{nil}, it defaults to | |
1455 | the current buffer. | |
1456 | ||
1457 | The arguments @var{minibuf} and @var{all-frames} have the same | |
1458 | meanings as in the function @code{next-window} (@pxref{Cyclic Window | |
1459 | Ordering}). Note that the @var{all-frames} argument does @emph{not} | |
1460 | behave exactly like in @code{get-buffer-window}. | |
b8d4c8d0 GM |
1461 | @end defun |
1462 | ||
b33b68a3 | 1463 | @deffn Command replace-buffer-in-windows &optional buffer-or-name |
0e406a72 | 1464 | This command replaces @var{buffer-or-name} with some other buffer, in |
a9b9b7f5 CY |
1465 | all windows displaying it. @var{buffer-or-name} should be a buffer, |
1466 | or the name of an existing buffer; if omitted or @code{nil}, it | |
1467 | defaults to the current buffer. | |
1468 | ||
1469 | The replacement buffer in each window is chosen via | |
1470 | @code{switch-to-prev-buffer} (@pxref{Window History}). Any dedicated | |
1471 | window displaying @var{buffer-or-name} is deleted (@pxref{Dedicated | |
1472 | Windows}), unless it is the only window on its frame---if it is the | |
1473 | only window, and that frame is not the only frame on its terminal, the | |
1474 | frame is ``dismissed'' by calling the function specified by | |
1475 | @code{frame-auto-hide-function} (@pxref{Quitting Windows}). If the | |
1476 | dedicated window is the only window on the only frame on its terminal, | |
1477 | the buffer is replaced anyway. | |
b33b68a3 MR |
1478 | @end deffn |
1479 | ||
0e406a72 CY |
1480 | @node Switching Buffers |
1481 | @section Switching to a Buffer in a Window | |
b8d4c8d0 GM |
1482 | @cindex switching to a buffer |
1483 | @cindex displaying a buffer | |
1484 | ||
0e406a72 CY |
1485 | This section describes high-level functions for switching to a |
1486 | specified buffer in some window. | |
1487 | ||
1488 | Do @emph{not} use these functions to make a buffer temporarily | |
9ec20d36 CY |
1489 | current just so a Lisp program can access or modify it. They have |
1490 | side-effects, such as changing window histories (@pxref{Window | |
1491 | History}), which will surprise the user if used that way. If you want | |
1492 | to make a buffer current to modify it in Lisp, use | |
0e406a72 | 1493 | @code{with-current-buffer}, @code{save-current-buffer}, or |
9ec20d36 | 1494 | @code{set-buffer}. @xref{Current Buffer}. |
0e406a72 CY |
1495 | |
1496 | @deffn Command switch-to-buffer buffer-or-name &optional norecord force-same-window | |
1497 | This function displays @var{buffer-or-name} in the selected window, | |
1498 | and makes it the current buffer. (In contrast, @code{set-buffer} | |
1499 | makes the buffer current but does not display it; @pxref{Current | |
1500 | Buffer}). It is often used interactively (as the binding of @kbd{C-x | |
1501 | b}), as well as in Lisp programs. The return value is the buffer | |
1502 | switched to. | |
1503 | ||
1504 | If @var{buffer-or-name} is @code{nil}, it defaults to the buffer | |
1505 | returned by @code{other-buffer} (@pxref{The Buffer List}). If | |
1506 | @var{buffer-or-name} is a string that is not the name of any existing | |
1507 | buffer, this function creates a new buffer with that name; the new | |
1508 | buffer's major mode is determined by the variable @code{major-mode} | |
1509 | (@pxref{Major Modes}). | |
1510 | ||
1511 | Normally the specified buffer is put at the front of the buffer | |
1512 | list---both the global buffer list and the selected frame's buffer | |
1513 | list (@pxref{The Buffer List}). However, this is not done if the | |
1514 | optional argument @var{norecord} is non-@code{nil}. | |
1515 | ||
590c056d MR |
1516 | If this function is unable to display the buffer in the selected |
1517 | window---usually because the selected window is a minibuffer window or | |
1518 | is strongly dedicated to its buffer (@pxref{Dedicated Windows})---then | |
1519 | it normally tries to display the buffer in some other window, in the | |
1520 | manner of @code{pop-to-buffer} (see below). However, if the optional | |
1521 | argument @var{force-same-window} is non-@code{nil}, it signals an error | |
0e406a72 | 1522 | instead. |
b8d4c8d0 GM |
1523 | @end deffn |
1524 | ||
1525 | The next two functions are similar to @code{switch-to-buffer}, except | |
1526 | for the described features. | |
1527 | ||
1528 | @deffn Command switch-to-buffer-other-window buffer-or-name &optional norecord | |
0e406a72 CY |
1529 | This function makes the buffer specified by @var{buffer-or-name} |
1530 | current and displays it in some window other than the selected window. | |
1531 | It uses the function @code{pop-to-buffer} internally (see below). | |
b8d4c8d0 | 1532 | |
0e406a72 | 1533 | If the selected window already displays the specified buffer, it |
b8766179 | 1534 | continues to do so, but another window is nonetheless found to display |
0e406a72 | 1535 | it as well. |
b8d4c8d0 | 1536 | |
0e406a72 CY |
1537 | The @var{buffer-or-name} and @var{norecord} arguments have the same |
1538 | meanings as in @code{switch-to-buffer}. | |
b8d4c8d0 GM |
1539 | @end deffn |
1540 | ||
0e406a72 CY |
1541 | @deffn Command switch-to-buffer-other-frame buffer-or-name &optional norecord |
1542 | This function makes the buffer specified by @var{buffer-or-name} | |
1543 | current and displays it, usually in a new frame. It uses the function | |
1544 | @code{pop-to-buffer} (see below). | |
1545 | ||
1546 | If the specified buffer is already displayed in another window, in any | |
1547 | frame on the current terminal, this switches to that window instead of | |
1548 | creating a new frame. However, the selected window is never used for | |
1549 | this. | |
1550 | ||
1551 | The @var{buffer-or-name} and @var{norecord} arguments have the same | |
1552 | meanings as in @code{switch-to-buffer}. | |
1553 | @end deffn | |
1554 | ||
a9b9b7f5 CY |
1555 | The above commands use the function @code{pop-to-buffer}, which |
1556 | flexibly displays a buffer in some window and selects that window for | |
1557 | editing. In turn, @code{pop-to-buffer} uses @code{display-buffer} for | |
1558 | displaying the buffer. Hence, all the variables affecting | |
1559 | @code{display-buffer} will affect it as well. @xref{Choosing Window}, | |
1560 | for the documentation of @code{display-buffer}. | |
0e406a72 CY |
1561 | |
1562 | @defun pop-to-buffer buffer-or-name &optional action norecord | |
1563 | This function makes @var{buffer-or-name} the current buffer and | |
1564 | displays it in some window, preferably not the window previously | |
1565 | selected. It then selects the displaying window. If that window is | |
1566 | on a different graphical frame, that frame is given input focus if | |
1567 | possible (@pxref{Input Focus}). The return value is the buffer that | |
1568 | was switched to. | |
1569 | ||
0e406a72 CY |
1570 | If @var{buffer-or-name} is @code{nil}, it defaults to the buffer |
1571 | returned by @code{other-buffer} (@pxref{The Buffer List}). If | |
1572 | @var{buffer-or-name} is a string that is not the name of any existing | |
1573 | buffer, this function creates a new buffer with that name; the new | |
1574 | buffer's major mode is determined by the variable @code{major-mode} | |
1575 | (@pxref{Major Modes}). | |
1576 | ||
1577 | If @var{action} is non-@code{nil}, it should be a display action to | |
1578 | pass to @code{display-buffer} (@pxref{Choosing Window}). | |
1579 | Alternatively, a non-@code{nil}, non-list value means to pop to a | |
1580 | window other than the selected one---even if the buffer is already | |
1581 | displayed in the selected window. | |
1582 | ||
1583 | Like @code{switch-to-buffer}, this function updates the buffer list | |
b8d4c8d0 | 1584 | unless @var{norecord} is non-@code{nil}. |
35a30759 | 1585 | @end defun |
b8d4c8d0 | 1586 | |
0e406a72 CY |
1587 | @node Choosing Window |
1588 | @section Choosing a Window for Display | |
b8d4c8d0 | 1589 | |
0e406a72 CY |
1590 | The command @code{display-buffer} flexibly chooses a window for |
1591 | display, and displays a specified buffer in that window. It can be | |
441950c7 | 1592 | called interactively, via the key binding @kbd{C-x 4 C-o}. It is also |
0e406a72 CY |
1593 | used as a subroutine by many functions and commands, including |
1594 | @code{switch-to-buffer} and @code{pop-to-buffer} (@pxref{Switching | |
1595 | Buffers}). | |
1596 | ||
1597 | @cindex display action | |
a9b9b7f5 CY |
1598 | @cindex action function, for @code{display-buffer} |
1599 | @cindex action alist, for @code{display-buffer} | |
0e406a72 CY |
1600 | This command performs several complex steps to find a window to |
1601 | display in. These steps are described by means of @dfn{display | |
1602 | actions}, which have the form @code{(@var{function} . @var{alist})}. | |
1603 | Here, @var{function} is either a function or a list of functions, | |
9ec20d36 CY |
1604 | which we refer to as @dfn{action functions}; @var{alist} is an |
1605 | association list, which we refer to as @dfn{action alists}. | |
1606 | ||
1607 | An action function accepts two arguments: the buffer to display and | |
1608 | an action alist. It attempts to display the buffer in some window, | |
1609 | picking or creating a window according to its own criteria. If | |
1610 | successful, it returns the window; otherwise, it returns @code{nil}. | |
1611 | @xref{Display Action Functions}, for a list of predefined action | |
1612 | functions. | |
0e406a72 CY |
1613 | |
1614 | @code{display-buffer} works by combining display actions from | |
9ec20d36 CY |
1615 | several sources, and calling the action functions in turn, until one |
1616 | of them manages to display the buffer and returns a non-@code{nil} | |
0e406a72 CY |
1617 | value. |
1618 | ||
1619 | @deffn Command display-buffer buffer-or-name &optional action frame | |
1620 | This command makes @var{buffer-or-name} appear in some window, without | |
1621 | selecting the window or making the buffer current. The argument | |
1622 | @var{buffer-or-name} must be a buffer or the name of an existing | |
1623 | buffer. The return value is the window chosen to display the buffer. | |
1624 | ||
1625 | The optional argument @var{action}, if non-@code{nil}, should normally | |
1626 | be a display action (described above). @code{display-buffer} builds a | |
1627 | list of action functions and an action alist, by consolidating display | |
1628 | actions from the following sources (in order): | |
1629 | ||
1630 | @itemize | |
1631 | @item | |
1632 | The variable @code{display-buffer-overriding-action}. | |
520b29e7 | 1633 | |
0e406a72 CY |
1634 | @item |
1635 | The user option @code{display-buffer-alist}. | |
250959e0 | 1636 | |
a9b9b7f5 CY |
1637 | @item |
1638 | A special action for handling @code{special-display-buffer-names} and | |
1639 | @code{special-display-regexps}, if either of those variables is | |
1640 | non-@code{nil}. @xref{Choosing Window Options}. | |
1641 | ||
0e406a72 CY |
1642 | @item |
1643 | The @var{action} argument. | |
b8d4c8d0 | 1644 | |
0e406a72 CY |
1645 | @item |
1646 | The user option @code{display-buffer-base-action}. | |
1647 | ||
1648 | @item | |
9ec20d36 | 1649 | The constant @code{display-buffer-fallback-action}. |
0e406a72 | 1650 | @end itemize |
b8d4c8d0 | 1651 | |
0e406a72 CY |
1652 | @noindent |
1653 | Each action function is called in turn, passing the buffer as the | |
1654 | first argument and the combined action alist as the second argument, | |
e7313f33 | 1655 | until one of the functions returns non-@code{nil}. |
0e406a72 CY |
1656 | |
1657 | The argument @var{action} can also have a non-@code{nil}, non-list | |
1658 | value. This has the special meaning that the buffer should be | |
1659 | displayed in a window other than the selected one, even if the | |
1660 | selected window is already displaying it. If called interactively | |
1661 | with a prefix argument, @var{action} is @code{t}. | |
1662 | ||
1663 | The optional argument @var{frame}, if non-@code{nil}, specifies which | |
1664 | frames to check when deciding whether the buffer is already displayed. | |
9ec20d36 CY |
1665 | It is equivalent to adding an element @code{(reusable-frames |
1666 | . @var{frame})} to the action alist of @var{action}. @xref{Display | |
1667 | Action Functions}. | |
1668 | @end deffn | |
1669 | ||
1670 | @defvar display-buffer-overriding-action | |
1671 | The value of this variable should be a display action, which is | |
1672 | treated with the highest priority by @code{display-buffer}. The | |
1673 | default value is empty, i.e. @code{(nil . nil)}. | |
1674 | @end defvar | |
1675 | ||
1676 | @defopt display-buffer-alist | |
1677 | The value of this option is an alist mapping regular expressions to | |
1678 | display actions. If the name of the buffer passed to | |
1679 | @code{display-buffer} matches a regular expression in this alist, then | |
1680 | @code{display-buffer} uses the corresponding display action. | |
1681 | @end defopt | |
1682 | ||
1683 | @defopt display-buffer-base-action | |
1684 | The value of this option should be a display action. This option can | |
1685 | be used to define a ``standard'' display action for calls to | |
1686 | @code{display-buffer}. | |
1687 | @end defopt | |
1688 | ||
1689 | @defvr Constant display-buffer-fallback-action | |
1690 | This display action specifies the fallback behavior for | |
1691 | @code{display-buffer} if no other display actions are given. | |
1692 | @end defvr | |
1693 | ||
1694 | @node Display Action Functions | |
1695 | @section Action Functions for @code{display-buffer} | |
1696 | ||
1697 | The following basic action functions are defined in Emacs. Each of | |
1698 | these functions takes two arguments: @var{buffer}, the buffer to | |
1699 | display, and @var{alist}, an action alist. Each action function | |
1700 | returns the window if it succeeds, and @code{nil} if it fails. | |
1701 | ||
1702 | @defun display-buffer-same-window buffer alist | |
1703 | This function tries to display @var{buffer} in the selected window. | |
1704 | It fails if the selected window is a minibuffer window or is dedicated | |
1705 | to another buffer (@pxref{Dedicated Windows}). It also fails if | |
e7313f33 | 1706 | @var{alist} has a non-@code{nil} @code{inhibit-same-window} entry. |
9ec20d36 CY |
1707 | @end defun |
1708 | ||
1709 | @defun display-buffer-reuse-window buffer alist | |
1710 | This function tries to ``display'' @var{buffer} by finding a window | |
1711 | that is already displaying it. | |
1712 | ||
1713 | If @var{alist} has a non-@code{nil} @code{inhibit-same-window} entry, | |
a9b9b7f5 CY |
1714 | the selected window is not eligible for reuse. If @var{alist} |
1715 | contains a @code{reusable-frames} entry, its value determines which | |
1716 | frames to search for a reusable window: | |
b8d4c8d0 GM |
1717 | |
1718 | @itemize @bullet | |
1719 | @item | |
0273ca3a | 1720 | @code{nil} means consider windows on the selected frame. |
b8d4c8d0 GM |
1721 | (Actually, the last non-minibuffer frame.) |
1722 | @item | |
0273ca3a | 1723 | @code{t} means consider windows on all frames. |
b8d4c8d0 | 1724 | @item |
0273ca3a | 1725 | @code{visible} means consider windows on all visible frames. |
b8d4c8d0 | 1726 | @item |
0273ca3a | 1727 | 0 means consider windows on all visible or iconified frames. |
b8d4c8d0 | 1728 | @item |
0273ca3a | 1729 | A frame means consider windows on that frame only. |
b8d4c8d0 GM |
1730 | @end itemize |
1731 | ||
9ec20d36 CY |
1732 | If @var{alist} contains no @code{reusable-frames} entry, this function |
1733 | normally searches just the selected frame; however, if either the | |
1734 | variable @code{display-buffer-reuse-frames} or the variable | |
1735 | @code{pop-up-frames} is non-@code{nil}, it searches all frames on the | |
1736 | current terminal. @xref{Choosing Window Options}. | |
a9b9b7f5 CY |
1737 | |
1738 | If this function chooses a window on another frame, it makes that | |
1739 | frame visible and raises it if necessary. | |
9ec20d36 CY |
1740 | @end defun |
1741 | ||
1742 | @defun display-buffer-pop-up-frame buffer alist | |
1743 | This function creates a new frame, and displays the buffer in that | |
a9b9b7f5 CY |
1744 | frame's window. It actually performs the frame creation by calling |
1745 | the function specified in @code{pop-up-frame-function} | |
1746 | (@pxref{Choosing Window Options}). | |
9ec20d36 CY |
1747 | @end defun |
1748 | ||
1749 | @defun display-buffer-pop-up-window buffer alist | |
717a1362 | 1750 | This function tries to display @var{buffer} by splitting the largest |
a9b9b7f5 CY |
1751 | or least recently-used window (typically one on the selected frame). |
1752 | It actually performs the split by calling the function specified in | |
1753 | @code{split-window-preferred-function} (@pxref{Choosing Window | |
1754 | Options}). | |
1755 | ||
1756 | It can fail if no window splitting can be performed for some reason | |
1757 | (e.g. if there is just one frame and it has an @code{unsplittable} | |
1758 | frame parameter; @pxref{Buffer Parameters}). | |
9ec20d36 CY |
1759 | @end defun |
1760 | ||
1761 | @defun display-buffer-use-some-window buffer alist | |
1762 | This function tries to display @var{buffer} by choosing an existing | |
590c056d | 1763 | window and displaying the buffer in that window. It can fail if all |
9ec20d36 CY |
1764 | windows are dedicated to another buffer (@pxref{Dedicated Windows}). |
1765 | @end defun | |
1766 | ||
1767 | @node Choosing Window Options | |
1768 | @section Additional Options for Displaying Buffers | |
1769 | ||
1770 | The behavior of the standard display actions of @code{display-buffer} | |
1771 | (@pxref{Choosing Window}) can be modified by a variety of user | |
1772 | options. | |
b8d4c8d0 | 1773 | |
52a94b85 | 1774 | @defopt display-buffer-reuse-frames |
a9b9b7f5 CY |
1775 | If the value of this variable is non-@code{nil}, @code{display-buffer} |
1776 | may search all frames on the current terminal when looking for a | |
1777 | window already displaying the specified buffer. The default is | |
1778 | @code{nil}. This variable is consulted by the action function | |
1779 | @code{display-buffer-reuse-window} (@pxref{Display Action Functions}). | |
52a94b85 MR |
1780 | @end defopt |
1781 | ||
1782 | @defopt pop-up-windows | |
a9b9b7f5 CY |
1783 | If the value of this variable is non-@code{nil}, @code{display-buffer} |
1784 | is allowed to split an existing window to make a new window for | |
1785 | displaying in. This is the default. | |
1786 | ||
1787 | This variable is provided mainly for backward compatibility. It is | |
1788 | obeyed by @code{display-buffer} via a special mechanism in | |
1789 | @code{display-buffer-fallback-action}, which only calls the action | |
1790 | function @code{display-buffer-pop-up-window} (@pxref{Display Action | |
1791 | Functions}) when the value is @code{nil}. It is not consulted by | |
1792 | @code{display-buffer-pop-up-window} itself, which the user may specify | |
1793 | directly in @code{display-buffer-alist} etc. | |
52a94b85 MR |
1794 | @end defopt |
1795 | ||
01f17ae2 | 1796 | @defopt split-window-preferred-function |
a9b9b7f5 CY |
1797 | This variable specifies a function for splitting a window, in order to |
1798 | make a new window for displaying a buffer. It is used by the | |
1799 | @code{display-buffer-pop-up-window} action function to actually split | |
1800 | the window (@pxref{Display Action Functions}). | |
1801 | ||
1802 | The default value is @code{split-window-sensibly}, which is documented | |
1803 | below. The value must be a function that takes one argument, a | |
1804 | window, and return either a new window (which is used to display the | |
1805 | desired buffer) or @code{nil} (which means the splitting failed). | |
01f17ae2 | 1806 | @end defopt |
43c59a3d | 1807 | |
714c3541 | 1808 | @defun split-window-sensibly window |
a9b9b7f5 CY |
1809 | This function tries to split @code{window}, and return the newly |
1810 | created window. If @code{window} cannot be split, it returns | |
1811 | @code{nil}. | |
1812 | ||
1813 | This function obeys the usual rules that determine when a window may | |
1814 | be split (@pxref{Splitting Windows}). It first tries to split by | |
1815 | placing the new window below, subject to the restriction imposed by | |
1816 | @code{split-height-threshold} (see below) in addition to any other | |
1817 | restrictions. If that fails, it tries to split by placing the new | |
1818 | window to the right, subject to @code{split-width-threshold} (see | |
1819 | below). If that fails, and the window is the only window on its | |
1820 | frame, this function again tries to split and place the new window | |
1821 | below, disregarding @code{split-height-threshold}. If this fails as | |
1822 | well, this function gives up and returns @code{nil}. | |
d3c0c321 MR |
1823 | @end defun |
1824 | ||
b8d4c8d0 | 1825 | @defopt split-height-threshold |
a9b9b7f5 CY |
1826 | This variable, used by @code{split-window-sensibly}, specifies whether |
1827 | to split the window placing the new window below. If it is an | |
1828 | integer, that means to split only if the original window has at least | |
1829 | that many lines. If it is @code{nil}, that means not to split this | |
1830 | way. | |
43c59a3d EZ |
1831 | @end defopt |
1832 | ||
1833 | @defopt split-width-threshold | |
a9b9b7f5 CY |
1834 | This variable, used by @code{split-window-sensibly}, specifies whether |
1835 | to split the window placing the new window to the right. If the value | |
1836 | is an integer, that means to split only if the original window has at | |
1837 | least that many columns. If the value is @code{nil}, that means not | |
1838 | to split this way. | |
b8d4c8d0 GM |
1839 | @end defopt |
1840 | ||
b8d4c8d0 | 1841 | @defopt pop-up-frames |
a9b9b7f5 CY |
1842 | If the value of this variable is non-@code{nil}, that means |
1843 | @code{display-buffer} may display buffers by making new frames. The | |
1844 | default is @code{nil}. | |
1845 | ||
1846 | A non-@code{nil} value also means that when @code{display-buffer} is | |
1847 | looking for a window already displaying @var{buffer-or-name}, it can | |
1848 | search any visible or iconified frame, not just the selected frame. | |
1849 | ||
1850 | This variable is provided mainly for backward compatibility. It is | |
1851 | obeyed by @code{display-buffer} via a special mechanism in | |
1852 | @code{display-buffer-fallback-action}, which calls the action function | |
1853 | @code{display-buffer-pop-up-frame} (@pxref{Display Action Functions}) | |
1854 | if the value is non-@code{nil}. (This is done before attempting to | |
1855 | split a window.) This variable is not consulted by | |
1856 | @code{display-buffer-pop-up-frame} itself, which the user may specify | |
1857 | directly in @code{display-buffer-alist} etc. | |
b8d4c8d0 GM |
1858 | @end defopt |
1859 | ||
b8d4c8d0 | 1860 | @defopt pop-up-frame-function |
a9b9b7f5 CY |
1861 | This variable specifies a function for creating a new frame, in order |
1862 | to make a new window for displaying a buffer. It is used by the | |
1863 | @code{display-buffer-pop-up-frame} action function (@pxref{Display | |
1864 | Action Functions}). | |
1865 | ||
1866 | The value should be a function that takes no arguments and returns a | |
1867 | frame, or @code{nil} if no frame could be created. The default value | |
1868 | is a function that creates a frame using the parameters specified by | |
1869 | @code{pop-up-frame-alist} (see below). | |
b8d4c8d0 GM |
1870 | @end defopt |
1871 | ||
1872 | @defopt pop-up-frame-alist | |
a9b9b7f5 CY |
1873 | This variable holds an alist of frame parameters (@pxref{Frame |
1874 | Parameters}), which is used by the default function in | |
1875 | @code{pop-up-frame-function} to make a new frame. The default is | |
1876 | @code{nil}. | |
b8d4c8d0 GM |
1877 | @end defopt |
1878 | ||
1879 | @defopt special-display-buffer-names | |
0273ca3a MR |
1880 | A list of buffer names identifying buffers that should be displayed |
1881 | specially. If the name of @var{buffer-or-name} is in this list, | |
1882 | @code{display-buffer} handles the buffer specially. By default, special | |
1883 | display means to give the buffer a dedicated frame. | |
b8d4c8d0 | 1884 | |
52a94b85 MR |
1885 | If an element is a list, instead of a string, then the @sc{car} of that |
1886 | list is the buffer name, and the rest of that list says how to create | |
1887 | the frame. There are two possibilities for the rest of that list (its | |
1888 | @sc{cdr}): It can be an alist, specifying frame parameters, or it can | |
b8d4c8d0 GM |
1889 | contain a function and arguments to give to it. (The function's first |
1890 | argument is always the buffer to be displayed; the arguments from the | |
1891 | list come after that.) | |
1892 | ||
1893 | For example: | |
1894 | ||
1895 | @example | |
1896 | (("myfile" (minibuffer) (menu-bar-lines . 0))) | |
1897 | @end example | |
1898 | ||
1899 | @noindent | |
1900 | specifies to display a buffer named @samp{myfile} in a dedicated frame | |
1901 | with specified @code{minibuffer} and @code{menu-bar-lines} parameters. | |
1902 | ||
1903 | The list of frame parameters can also use the phony frame parameters | |
1904 | @code{same-frame} and @code{same-window}. If the specified frame | |
1905 | parameters include @code{(same-window . @var{value})} and @var{value} | |
1906 | is non-@code{nil}, that means to display the buffer in the current | |
1907 | selected window. Otherwise, if they include @code{(same-frame . | |
1908 | @var{value})} and @var{value} is non-@code{nil}, that means to display | |
1909 | the buffer in a new window in the currently selected frame. | |
1910 | @end defopt | |
1911 | ||
1912 | @defopt special-display-regexps | |
0273ca3a | 1913 | A list of regular expressions specifying buffers that should be |
b8d4c8d0 GM |
1914 | displayed specially. If the buffer's name matches any of the regular |
1915 | expressions in this list, @code{display-buffer} handles the buffer | |
0273ca3a MR |
1916 | specially. By default, special display means to give the buffer a |
1917 | dedicated frame. | |
b8d4c8d0 GM |
1918 | |
1919 | If an element is a list, instead of a string, then the @sc{car} of the | |
1920 | list is the regular expression, and the rest of the list says how to | |
0273ca3a | 1921 | create the frame. See @code{special-display-buffer-names} above. |
b8d4c8d0 GM |
1922 | @end defopt |
1923 | ||
1924 | @defun special-display-p buffer-name | |
1925 | This function returns non-@code{nil} if displaying a buffer | |
1926 | named @var{buffer-name} with @code{display-buffer} would | |
1927 | create a special frame. The value is @code{t} if it would | |
1928 | use the default frame parameters, or else the specified list | |
1929 | of frame parameters. | |
1930 | @end defun | |
1931 | ||
01f17ae2 | 1932 | @defopt special-display-function |
b8d4c8d0 GM |
1933 | This variable holds the function to call to display a buffer specially. |
1934 | It receives the buffer as an argument, and should return the window in | |
0273ca3a MR |
1935 | which it is displayed. The default value of this variable is |
1936 | @code{special-display-popup-frame}, see below. | |
01f17ae2 | 1937 | @end defopt |
b8d4c8d0 GM |
1938 | |
1939 | @defun special-display-popup-frame buffer &optional args | |
0273ca3a MR |
1940 | This function tries to make @var{buffer} visible in a frame of its own. |
1941 | If @var{buffer} is already displayed in some window, it makes that | |
1942 | window's frame visible and raises it. Otherwise, it creates a frame | |
1943 | that is dedicated to @var{buffer}. The return value is the window used | |
1944 | to display @var{buffer}. | |
b8d4c8d0 GM |
1945 | |
1946 | If @var{args} is an alist, it specifies frame parameters for the new | |
0273ca3a MR |
1947 | frame. If @var{args} is a list whose @sc{car} is a symbol, then |
1948 | @code{(car @var{args})} is called as a function to actually create and | |
1949 | set up the frame; it is called with @var{buffer} as first argument, and | |
1950 | @code{(cdr @var{args})} as additional arguments. | |
b8d4c8d0 GM |
1951 | |
1952 | This function always uses an existing window displaying @var{buffer}, | |
1953 | whether or not it is in a frame of its own; but if you set up the above | |
1954 | variables in your init file, before @var{buffer} was created, then | |
1955 | presumably the window was previously made by this function. | |
1956 | @end defun | |
1957 | ||
1958 | @defopt special-display-frame-alist | |
1959 | @anchor{Definition of special-display-frame-alist} | |
1960 | This variable holds frame parameters for | |
1961 | @code{special-display-popup-frame} to use when it creates a frame. | |
1962 | @end defopt | |
1963 | ||
1964 | @defopt same-window-buffer-names | |
1965 | A list of buffer names for buffers that should be displayed in the | |
1966 | selected window. If the buffer's name is in this list, | |
1967 | @code{display-buffer} handles the buffer by switching to it in the | |
1968 | selected window. | |
1969 | @end defopt | |
1970 | ||
1971 | @defopt same-window-regexps | |
1972 | A list of regular expressions that specify buffers that should be | |
1973 | displayed in the selected window. If the buffer's name matches any of | |
1974 | the regular expressions in this list, @code{display-buffer} handles the | |
1975 | buffer by switching to it in the selected window. | |
1976 | @end defopt | |
1977 | ||
1978 | @defun same-window-p buffer-name | |
1979 | This function returns @code{t} if displaying a buffer | |
1980 | named @var{buffer-name} with @code{display-buffer} would | |
1981 | put it in the selected window. | |
1982 | @end defun | |
1983 | ||
1984 | @c Emacs 19 feature | |
01f17ae2 | 1985 | @defopt display-buffer-function |
b8d4c8d0 GM |
1986 | This variable is the most flexible way to customize the behavior of |
1987 | @code{display-buffer}. If it is non-@code{nil}, it should be a function | |
1988 | that @code{display-buffer} calls to do the work. The function should | |
1989 | accept two arguments, the first two arguments that @code{display-buffer} | |
1990 | received. It should choose or create a window, display the specified | |
1991 | buffer in it, and then return the window. | |
1992 | ||
52a94b85 MR |
1993 | This variable takes precedence over all the other options described |
1994 | above. | |
01f17ae2 | 1995 | @end defopt |
b8d4c8d0 | 1996 | |
0e406a72 CY |
1997 | @node Window History |
1998 | @section Window History | |
1999 | @cindex window history | |
2000 | ||
590c056d MR |
2001 | Each window remembers the buffers it has displayed earlier and the order |
2002 | in which these buffers have been removed from it. This history is used, | |
2003 | for example, by @code{replace-buffer-in-windows} (@pxref{Buffers and | |
2004 | Windows}). This list is automatically maintained by Emacs, but you can | |
2005 | use the following functions to explicitly inspect or alter it: | |
0e406a72 CY |
2006 | |
2007 | @defun window-prev-buffers &optional window | |
2008 | This function returns a list specifying the previous contents of | |
2009 | @var{window}, which should be a live window and defaults to the | |
2010 | selected window. | |
2011 | ||
2012 | Each list element has the form @code{(@var{buffer} @var{window-start} | |
2013 | @var{window-pos})}, where @var{buffer} is a buffer previously shown in | |
2014 | the window, @var{window-start} is the window start position when that | |
2015 | buffer was last shown, and @var{window-pos} is the point position when | |
2016 | that buffer was last shown. | |
2017 | ||
2018 | The list is ordered so that earlier elements correspond to more | |
590c056d | 2019 | recently-shown buffers, and the first element usually corresponds to the |
0e406a72 CY |
2020 | buffer most recently removed from the window. |
2021 | @end defun | |
2022 | ||
2023 | @defun set-window-prev-buffers window prev-buffers | |
2024 | This function sets @var{window}'s previous buffers to the value of | |
2025 | @var{prev-buffers}. The argument @var{window} must be a live window | |
2026 | and defaults to the selected one. The argument @var{prev-buffers} | |
2027 | should be a list of the same form as that returned by | |
2028 | @code{window-prev-buffers}. | |
2029 | @end defun | |
2030 | ||
2031 | In addition, each buffer maintains a list of @dfn{next buffers}, which | |
2032 | is a list of buffers re-shown by @code{switch-to-prev-buffer} (see | |
2033 | below). This list is mainly used by @code{switch-to-prev-buffer} and | |
2034 | @code{switch-to-next-buffer} for choosing buffers to switch to. | |
2035 | ||
2036 | @defun window-next-buffers &optional window | |
2037 | This function returns the list of buffers recently re-shown in | |
590c056d MR |
2038 | @var{window} via @code{switch-to-prev-buffer}. The @var{window} |
2039 | argument must denote a live window or @code{nil} (meaning the selected | |
2040 | window). | |
0e406a72 CY |
2041 | @end defun |
2042 | ||
2043 | @defun set-window-next-buffers window next-buffers | |
2044 | This function sets the next buffer list of @var{window} to | |
2045 | @var{next-buffers}. The @var{window} argument should be a live window | |
2046 | or @code{nil} (meaning the selected window). The argument | |
2047 | @var{next-buffers} should be a list of buffers. | |
2048 | @end defun | |
2049 | ||
2050 | The following commands can be used to cycle through the global buffer | |
2051 | list, much like @code{bury-buffer} and @code{unbury-buffer}. However, | |
2052 | they cycle according to the specified window's history list, rather | |
2053 | than the global buffer list. In addition, they restore | |
2054 | window-specific window start and point positions, and may show a | |
2055 | buffer even if it is already shown in another window. The | |
2056 | @code{switch-to-prev-buffer} command, in particular, is used by | |
2057 | @code{replace-buffer-in-windows}, @code{bury-buffer} and | |
2058 | @code{quit-window} to find a replacement buffer for a window. | |
2059 | ||
2060 | @deffn Command switch-to-prev-buffer &optional window bury-or-kill | |
2061 | This command displays the previous buffer in @var{window}. The | |
2062 | argument @var{window} should be a live window or @code{nil} (meaning | |
2063 | the selected window). If the optional argument @var{bury-or-kill} is | |
2064 | non-@code{nil}, this means that the buffer currently shown in | |
2065 | @var{window} is about to be buried or killed and consequently shall | |
2066 | not be switched to in future invocations of this command. | |
2067 | ||
2068 | The previous buffer is usually the buffer shown before the buffer | |
2069 | currently shown in @var{window}. However, a buffer that has been buried | |
2070 | or killed or has been already shown by a recent invocation of | |
2071 | @code{switch-to-prev-buffer} does not qualify as previous buffer. | |
2072 | ||
2073 | If repeated invocations of this command have already shown all buffers | |
2074 | previously shown in @var{window}, further invocations will show buffers | |
590c056d MR |
2075 | from the buffer list of the frame @var{window} appears on (@pxref{The |
2076 | Buffer List}). | |
0e406a72 CY |
2077 | @end deffn |
2078 | ||
2079 | @deffn Command switch-to-next-buffer &optional window | |
2080 | This command switches to the next buffer in @var{window} thus undoing | |
2081 | the effect of the last @code{switch-to-prev-buffer} command in | |
2082 | @var{window}. The argument @var{window} must be a live window and | |
2083 | defaults to the selected one. | |
2084 | ||
590c056d MR |
2085 | If there is no recent invocation of a @code{switch-to-prev-buffer} that |
2086 | can be undone, this function tries to show a buffer from the buffer list | |
2087 | of the frame @var{window} appears on (@pxref{The Buffer List}). | |
0e406a72 CY |
2088 | @end deffn |
2089 | ||
590c056d | 2090 | |
0273ca3a MR |
2091 | @node Dedicated Windows |
2092 | @section Dedicated Windows | |
2093 | @cindex dedicated window | |
2094 | ||
2095 | Functions for displaying a buffer can be told to not use specific | |
df006536 | 2096 | windows by marking these windows as @dfn{dedicated} to their buffers. |
0273ca3a MR |
2097 | @code{display-buffer} (@pxref{Choosing Window}) never uses a dedicated |
2098 | window for displaying another buffer in it. @code{get-lru-window} and | |
2099 | @code{get-largest-window} (@pxref{Selecting Windows}) do not consider | |
2100 | dedicated windows as candidates when their @var{dedicated} argument is | |
2101 | non-@code{nil}. The behavior of @code{set-window-buffer} | |
2102 | (@pxref{Buffers and Windows}) with respect to dedicated windows is | |
2103 | slightly different, see below. | |
2104 | ||
0e406a72 CY |
2105 | When @code{delete-windows-on} (@pxref{Deleting Windows}) wants to |
2106 | delete a dedicated window and that window is the only window on its | |
2107 | frame, it deletes the window's frame too, provided there are other | |
2108 | frames left. @code{replace-buffer-in-windows} (@pxref{Switching | |
2109 | Buffers}) tries to delete all dedicated windows showing its buffer | |
2110 | argument. When such a window is the only window on its frame, that | |
2111 | frame is deleted, provided there are other frames left. If there are | |
2112 | no more frames left, some other buffer is displayed in the window, and | |
2113 | the window is marked as non-dedicated. | |
0273ca3a MR |
2114 | |
2115 | When you kill a buffer (@pxref{Killing Buffers}) displayed in a | |
2116 | dedicated window, any such window usually gets deleted too, since | |
2117 | @code{kill-buffer} calls @code{replace-buffer-in-windows} for cleaning | |
2118 | up windows. Burying a buffer (@pxref{The Buffer List}) deletes the | |
b8766179 MR |
2119 | selected window if it is dedicated to that buffer. If, however, that |
2120 | window is the only window on its frame, @code{bury-buffer} displays | |
2121 | another buffer in it and iconifies the frame. | |
250959e0 MR |
2122 | |
2123 | @defun window-dedicated-p &optional window | |
52a94b85 MR |
2124 | This function returns non-@code{nil} if @var{window} is dedicated to its |
2125 | buffer and @code{nil} otherwise. More precisely, the return value is | |
2126 | the value assigned by the last call of @code{set-window-dedicated-p} for | |
2127 | @var{window} or @code{nil} if that function was never called with | |
aeeedf76 MR |
2128 | @var{window} as its argument. The default for @var{window} is the |
2129 | selected window. | |
b8d4c8d0 GM |
2130 | @end defun |
2131 | ||
2132 | @defun set-window-dedicated-p window flag | |
52a94b85 MR |
2133 | This function marks @var{window} as dedicated to its buffer if |
2134 | @var{flag} is non-@code{nil}, and non-dedicated otherwise. | |
52a94b85 | 2135 | |
0273ca3a MR |
2136 | As a special case, if @var{flag} is @code{t}, @var{window} becomes |
2137 | @dfn{strongly} dedicated to its buffer. @code{set-window-buffer} | |
2138 | signals an error when the window it acts upon is strongly dedicated to | |
2139 | its buffer and does not already display the buffer it is asked to | |
b8766179 MR |
2140 | display. Other functions do not treat @code{t} differently from any |
2141 | non-@code{nil} value. | |
0273ca3a | 2142 | @end defun |
52a94b85 | 2143 | |
c419f5cb MR |
2144 | |
2145 | @node Quitting Windows | |
2146 | @section Quitting Windows | |
2147 | ||
2148 | When you want to get rid of a window used for displaying a buffer you | |
d83dc65b MR |
2149 | can call @code{delete-window} or @code{delete-windows-on} |
2150 | (@pxref{Deleting Windows}) to remove that window from its frame. If the | |
2151 | buffer is shown on a separate frame, you might want to call | |
2152 | @code{delete-frame} (@pxref{Deleting Frames}) instead. If, on the other | |
2153 | hand, a window has been reused for displaying the buffer, you might | |
2154 | prefer showing the buffer previously shown in that window by calling the | |
2155 | function @code{switch-to-prev-buffer} (@pxref{Window History}). | |
2156 | Finally, you might want to either bury (@pxref{The Buffer List}) or kill | |
c419f5cb MR |
2157 | (@pxref{Killing Buffers}) the window's buffer. |
2158 | ||
2159 | The following function uses information on how the window for | |
2160 | displaying the buffer was obtained in the first place thus attempting to | |
2161 | automatize the above decisions for you. | |
2162 | ||
2163 | @deffn Command quit-window &optional kill window | |
2164 | This command quits @var{window} and buries its buffer. The argument | |
2165 | @var{window} must be a live window and defaults to the selected one. | |
2166 | With prefix argument @var{kill} non-@code{nil}, it kills the buffer | |
2167 | instead of burying it. | |
2168 | ||
2169 | Quitting @var{window} means to proceed as follows: If @var{window} was | |
2170 | created specially for displaying its current buffer, delete @var{window} | |
2171 | provided its frame contains at least one other live window. If | |
d83dc65b MR |
2172 | @var{window} is the only window on its frame and there are other frames |
2173 | on the frame's terminal, the value of @var{kill} determines how to | |
2174 | proceed with the window. If @var{kill} is @code{nil}, the fate of the | |
2175 | frame is determined by calling @code{frame-auto-hide-function} (see | |
2176 | below) with that frame as sole argument. If @var{kill} is | |
2177 | non-@code{nil}, the frame is deleted unconditionally. | |
c419f5cb MR |
2178 | |
2179 | If @var{window} was reused for displaying its buffer, this command tries | |
2180 | to display the buffer previously shown in it. It also tries to restore | |
2181 | the window start (@pxref{Window Start and End}) and point (@pxref{Window | |
2182 | Point}) positions of the previously shown buffer. If, in addition, the | |
2183 | current buffer was temporarily resized, this command will also try to | |
2184 | restore the original height of @var{window}. | |
2185 | ||
2186 | The three cases described so far require that the buffer shown in | |
2187 | @var{window} is still the buffer displayed by the last buffer display | |
2188 | function for this window. If another buffer has been shown in the | |
2189 | meantime or the buffer previously shown no longer exists, this command | |
2190 | calls @code{switch-to-prev-buffer} (@pxref{Window History}) to show some | |
2191 | other buffer instead. | |
2192 | @end deffn | |
2193 | ||
2194 | The function @code{quit-window} bases its decisions on information | |
2195 | stored in @var{window}'s @code{quit-restore} window parameter | |
2196 | (@pxref{Window Parameters}) and resets that parameter to @code{nil} | |
2197 | after it's done. | |
2198 | ||
d83dc65b MR |
2199 | The following option specifies how to deal with a frame containing just |
2200 | one window that shall be either quit or whose buffer shall be buried. | |
2201 | ||
2202 | @defopt frame-auto-hide-function | |
2203 | The function specified by this option is called to automatically hide | |
2204 | frames. This function is called with one argument - a frame. | |
2205 | ||
2206 | The function specified here is called by @code{bury-buffer} (@pxref{The | |
2207 | Buffer List}) when the selected window is dedicated and shows the buffer | |
2208 | that shall be buried. It is also called by @code{quit-window} (see | |
2209 | above) when the frame of the window that shall be quit has been | |
2210 | specially created for displaying that window's buffer and the buffer | |
2211 | shall be buried. | |
2212 | ||
2213 | The default is to call @code{iconify-frame} (@pxref{Visibility of | |
2214 | Frames}). Alternatively, you may either specify @code{delete-frame} | |
2215 | (@pxref{Deleting Frames}) to remove the frame from its display, | |
2216 | @code{ignore} to leave the frame unchanged, or any other function that | |
2217 | can take a frame as its sole argument. | |
2218 | ||
2219 | Note that the function specified by this option is called if and only if | |
2220 | there's at least one other frame on the terminal of the frame it's | |
2221 | supposed to handle and that frame contains only one live window. | |
2222 | @end defopt | |
2223 | ||
c419f5cb | 2224 | |
b8d4c8d0 GM |
2225 | @node Window Point |
2226 | @section Windows and Point | |
2227 | @cindex window position | |
2228 | @cindex window point | |
2229 | @cindex position in window | |
2230 | @cindex point in window | |
2231 | ||
0273ca3a MR |
2232 | Each window has its own value of point (@pxref{Point}), independent of |
2233 | the value of point in other windows displaying the same buffer. This | |
2234 | makes it useful to have multiple windows showing one buffer. | |
b8d4c8d0 GM |
2235 | |
2236 | @itemize @bullet | |
2237 | @item | |
2238 | The window point is established when a window is first created; it is | |
2239 | initialized from the buffer's point, or from the window point of another | |
2240 | window opened on the buffer if such a window exists. | |
2241 | ||
2242 | @item | |
2243 | Selecting a window sets the value of point in its buffer from the | |
2244 | window's value of point. Conversely, deselecting a window sets the | |
2245 | window's value of point from that of the buffer. Thus, when you switch | |
2246 | between windows that display a given buffer, the point value for the | |
2247 | selected window is in effect in the buffer, while the point values for | |
2248 | the other windows are stored in those windows. | |
2249 | ||
2250 | @item | |
2251 | As long as the selected window displays the current buffer, the window's | |
2252 | point and the buffer's point always move together; they remain equal. | |
2253 | @end itemize | |
2254 | ||
b8d4c8d0 | 2255 | @cindex cursor |
af1a5cd5 | 2256 | As far as the user is concerned, point is where the cursor is, and |
b8d4c8d0 GM |
2257 | when the user switches to another buffer, the cursor jumps to the |
2258 | position of point in that buffer. | |
2259 | ||
2260 | @defun window-point &optional window | |
2261 | This function returns the current position of point in @var{window}. | |
2262 | For a nonselected window, this is the value point would have (in that | |
aeeedf76 MR |
2263 | window's buffer) if that window were selected. The default for |
2264 | @var{window} is the selected window. | |
b8d4c8d0 GM |
2265 | |
2266 | When @var{window} is the selected window and its buffer is also the | |
2267 | current buffer, the value returned is the same as point in that buffer. | |
0273ca3a MR |
2268 | Strictly speaking, it would be more correct to return the ``top-level'' |
2269 | value of point, outside of any @code{save-excursion} forms. But that | |
2270 | value is hard to find. | |
b8d4c8d0 GM |
2271 | @end defun |
2272 | ||
2273 | @defun set-window-point window position | |
2274 | This function positions point in @var{window} at position | |
2275 | @var{position} in @var{window}'s buffer. It returns @var{position}. | |
2276 | ||
2277 | If @var{window} is selected, and its buffer is current, | |
2278 | this simply does @code{goto-char}. | |
2279 | @end defun | |
2280 | ||
86ab855a MR |
2281 | @defvar window-point-insertion-type |
2282 | This variable specifies the marker insertion type (@pxref{Marker | |
2283 | Insertion Types}) of @code{window-point}. The default is @code{nil}, | |
2284 | so @code{window-point} will stay behind text inserted there. | |
2285 | @end defvar | |
2286 | ||
0273ca3a MR |
2287 | @node Window Start and End |
2288 | @section The Window Start and End Positions | |
b8d4c8d0 GM |
2289 | @cindex window start position |
2290 | ||
0273ca3a | 2291 | Each window maintains a marker used to keep track of a buffer position |
b8d4c8d0 GM |
2292 | that specifies where in the buffer display should start. This position |
2293 | is called the @dfn{display-start} position of the window (or just the | |
2294 | @dfn{start}). The character after this position is the one that appears | |
2295 | at the upper left corner of the window. It is usually, but not | |
2296 | inevitably, at the beginning of a text line. | |
2297 | ||
431b78c9 RS |
2298 | After switching windows or buffers, and in some other cases, if the |
2299 | window start is in the middle of a line, Emacs adjusts the window | |
2300 | start to the start of a line. This prevents certain operations from | |
2301 | leaving the window start at a meaningless point within a line. This | |
2302 | feature may interfere with testing some Lisp code by executing it | |
2303 | using the commands of Lisp mode, because they trigger this | |
2304 | readjustment. To test such code, put it into a command and bind the | |
2305 | command to a key. | |
2306 | ||
b8d4c8d0 GM |
2307 | @defun window-start &optional window |
2308 | @cindex window top line | |
2309 | This function returns the display-start position of window | |
2310 | @var{window}. If @var{window} is @code{nil}, the selected window is | |
2311 | used. For example, | |
2312 | ||
2313 | @example | |
2314 | @group | |
2315 | (window-start) | |
2316 | @result{} 7058 | |
2317 | @end group | |
2318 | @end example | |
2319 | ||
2320 | When you create a window, or display a different buffer in it, the | |
2321 | display-start position is set to a display-start position recently used | |
0273ca3a MR |
2322 | for the same buffer, or to @code{point-min} if the buffer doesn't have |
2323 | any. | |
b8d4c8d0 GM |
2324 | |
2325 | Redisplay updates the window-start position (if you have not specified | |
0273ca3a MR |
2326 | it explicitly since the previous redisplay)---to make sure point appears |
2327 | on the screen. Nothing except redisplay automatically changes the | |
2328 | window-start position; if you move point, do not expect the window-start | |
2329 | position to change in response until after the next redisplay. | |
b8d4c8d0 GM |
2330 | |
2331 | For a realistic example of using @code{window-start}, see the | |
2332 | description of @code{count-lines}. @xref{Definition of count-lines}. | |
2333 | @end defun | |
2334 | ||
0273ca3a | 2335 | @cindex window end position |
b8d4c8d0 | 2336 | @defun window-end &optional window update |
0273ca3a | 2337 | This function returns the position where display of its buffer ends in |
aeeedf76 | 2338 | @var{window}. The default for @var{window} is the selected window. |
b8d4c8d0 GM |
2339 | |
2340 | Simply changing the buffer text or moving point does not update the | |
2341 | value that @code{window-end} returns. The value is updated only when | |
2342 | Emacs redisplays and redisplay completes without being preempted. | |
2343 | ||
2344 | If the last redisplay of @var{window} was preempted, and did not finish, | |
2345 | Emacs does not know the position of the end of display in that window. | |
2346 | In that case, this function returns @code{nil}. | |
2347 | ||
2348 | If @var{update} is non-@code{nil}, @code{window-end} always returns an | |
0273ca3a MR |
2349 | up-to-date value for where display ends, based on the current |
2350 | @code{window-start} value. If a previously saved value of that position | |
2351 | is still valid, @code{window-end} returns that value; otherwise it | |
2352 | computes the correct value by scanning the buffer text. | |
b8d4c8d0 GM |
2353 | |
2354 | Even if @var{update} is non-@code{nil}, @code{window-end} does not | |
2355 | attempt to scroll the display if point has moved off the screen, the | |
2356 | way real redisplay would do. It does not alter the | |
2357 | @code{window-start} value. In effect, it reports where the displayed | |
2358 | text will end if scrolling is not required. | |
2359 | @end defun | |
2360 | ||
2361 | @defun set-window-start window position &optional noforce | |
2362 | This function sets the display-start position of @var{window} to | |
2363 | @var{position} in @var{window}'s buffer. It returns @var{position}. | |
2364 | ||
2365 | The display routines insist that the position of point be visible when a | |
2366 | buffer is displayed. Normally, they change the display-start position | |
2367 | (that is, scroll the window) whenever necessary to make point visible. | |
2368 | However, if you specify the start position with this function using | |
2369 | @code{nil} for @var{noforce}, it means you want display to start at | |
2370 | @var{position} even if that would put the location of point off the | |
2371 | screen. If this does place point off screen, the display routines move | |
2372 | point to the left margin on the middle line in the window. | |
2373 | ||
431b78c9 RS |
2374 | For example, if point @w{is 1} and you set the start of the window |
2375 | @w{to 37}, the start of the next line, point will be ``above'' the top | |
2376 | of the window. The display routines will automatically move point if | |
2377 | it is still 1 when redisplay occurs. Here is an example: | |
b8d4c8d0 GM |
2378 | |
2379 | @example | |
2380 | @group | |
2381 | ;; @r{Here is what @samp{foo} looks like before executing} | |
2382 | ;; @r{the @code{set-window-start} expression.} | |
2383 | @end group | |
2384 | ||
2385 | @group | |
2386 | ---------- Buffer: foo ---------- | |
2387 | @point{}This is the contents of buffer foo. | |
2388 | 2 | |
2389 | 3 | |
2390 | 4 | |
2391 | 5 | |
2392 | 6 | |
2393 | ---------- Buffer: foo ---------- | |
2394 | @end group | |
2395 | ||
2396 | @group | |
2397 | (set-window-start | |
2398 | (selected-window) | |
431b78c9 RS |
2399 | (save-excursion |
2400 | (goto-char 1) | |
2401 | (forward-line 1) | |
2402 | (point))) | |
2403 | @result{} 37 | |
b8d4c8d0 GM |
2404 | @end group |
2405 | ||
2406 | @group | |
2407 | ;; @r{Here is what @samp{foo} looks like after executing} | |
2408 | ;; @r{the @code{set-window-start} expression.} | |
2409 | ---------- Buffer: foo ---------- | |
b8d4c8d0 GM |
2410 | 2 |
2411 | 3 | |
2412 | @point{}4 | |
2413 | 5 | |
2414 | 6 | |
2415 | ---------- Buffer: foo ---------- | |
2416 | @end group | |
2417 | @end example | |
2418 | ||
2419 | If @var{noforce} is non-@code{nil}, and @var{position} would place point | |
2420 | off screen at the next redisplay, then redisplay computes a new window-start | |
2421 | position that works well with point, and thus @var{position} is not used. | |
2422 | @end defun | |
2423 | ||
2424 | @defun pos-visible-in-window-p &optional position window partially | |
2425 | This function returns non-@code{nil} if @var{position} is within the | |
2426 | range of text currently visible on the screen in @var{window}. It | |
0273ca3a MR |
2427 | returns @code{nil} if @var{position} is scrolled vertically out of view. |
2428 | Locations that are partially obscured are not considered visible unless | |
2429 | @var{partially} is non-@code{nil}. The argument @var{position} defaults | |
2430 | to the current position of point in @var{window}; @var{window}, to the | |
2431 | selected window. If @var{position} is @code{t}, that means to check the | |
2432 | last visible position in @var{window}. | |
b8d4c8d0 | 2433 | |
049bcbcb CY |
2434 | This function considers only vertical scrolling. If @var{position} is |
2435 | out of view only because @var{window} has been scrolled horizontally, | |
2436 | @code{pos-visible-in-window-p} returns non-@code{nil} anyway. | |
2437 | @xref{Horizontal Scrolling}. | |
b8d4c8d0 GM |
2438 | |
2439 | If @var{position} is visible, @code{pos-visible-in-window-p} returns | |
2440 | @code{t} if @var{partially} is @code{nil}; if @var{partially} is | |
0273ca3a | 2441 | non-@code{nil}, and the character following @var{position} is fully |
b8d4c8d0 GM |
2442 | visible, it returns a list of the form @code{(@var{x} @var{y})}, where |
2443 | @var{x} and @var{y} are the pixel coordinates relative to the top left | |
0273ca3a MR |
2444 | corner of the window; otherwise it returns an extended list of the form |
2445 | @code{(@var{x} @var{y} @var{rtop} @var{rbot} @var{rowh} @var{vpos})}, | |
2446 | where @var{rtop} and @var{rbot} specify the number of off-window pixels | |
2447 | at the top and bottom of the row at @var{position}, @var{rowh} specifies | |
2448 | the visible height of that row, and @var{vpos} specifies the vertical | |
2449 | position (zero-based row number) of that row. | |
b8d4c8d0 GM |
2450 | |
2451 | Here is an example: | |
2452 | ||
2453 | @example | |
2454 | @group | |
2455 | ;; @r{If point is off the screen now, recenter it now.} | |
2456 | (or (pos-visible-in-window-p | |
2457 | (point) (selected-window)) | |
2458 | (recenter 0)) | |
2459 | @end group | |
2460 | @end example | |
2461 | @end defun | |
2462 | ||
2463 | @defun window-line-height &optional line window | |
aeeedf76 MR |
2464 | This function returns the height of text line @var{line} in |
2465 | @var{window}. If @var{line} is one of @code{header-line} or | |
2466 | @code{mode-line}, @code{window-line-height} returns information about | |
2467 | the corresponding line of the window. Otherwise, @var{line} is a text | |
2468 | line number starting from 0. A negative number counts from the end of | |
2469 | the window. The default for @var{line} is the current line in | |
2470 | @var{window}; the default for @var{window} is the selected window. | |
b8d4c8d0 GM |
2471 | |
2472 | If the display is not up to date, @code{window-line-height} returns | |
2473 | @code{nil}. In that case, @code{pos-visible-in-window-p} may be used | |
2474 | to obtain related information. | |
2475 | ||
2476 | If there is no line corresponding to the specified @var{line}, | |
2477 | @code{window-line-height} returns @code{nil}. Otherwise, it returns | |
2478 | a list @code{(@var{height} @var{vpos} @var{ypos} @var{offbot})}, | |
2479 | where @var{height} is the height in pixels of the visible part of the | |
2480 | line, @var{vpos} and @var{ypos} are the vertical position in lines and | |
2481 | pixels of the line relative to the top of the first text line, and | |
2482 | @var{offbot} is the number of off-window pixels at the bottom of the | |
2483 | text line. If there are off-window pixels at the top of the (first) | |
2484 | text line, @var{ypos} is negative. | |
2485 | @end defun | |
2486 | ||
2487 | @node Textual Scrolling | |
2488 | @section Textual Scrolling | |
2489 | @cindex textual scrolling | |
2490 | @cindex scrolling textually | |
2491 | ||
2492 | @dfn{Textual scrolling} means moving the text up or down through a | |
550f41cd CY |
2493 | window. It works by changing the window's display-start location. It |
2494 | may also change the value of @code{window-point} to keep point on the | |
2495 | screen (@pxref{Window Point}). | |
2496 | ||
2497 | The basic textual scrolling functions are @code{scroll-up} (which | |
2498 | scrolls forward) and @code{scroll-down} (which scrolls backward). In | |
2499 | these function names, ``up'' and ``down'' refer to the direction of | |
2500 | motion of the buffer text relative to the window. Imagine that the | |
2501 | text is written on a long roll of paper and that the scrolling | |
2502 | commands move the paper up and down. Thus, if you are looking at the | |
2503 | middle of a buffer and repeatedly call @code{scroll-down}, you will | |
2504 | eventually see the beginning of the buffer. | |
b8d4c8d0 GM |
2505 | |
2506 | Some people have urged that the opposite convention be used: they | |
550f41cd CY |
2507 | imagine the window moving over text that remains in place, so that |
2508 | ``down'' commands take you to the end of the buffer. This convention | |
2509 | is consistent with fact that such a command is bound to a key named | |
2510 | @key{PageDown} on modern keyboards. We have not switched to this | |
2511 | convention as that is likely to break existing Emacs Lisp code. | |
2512 | ||
2513 | Textual scrolling functions (aside from @code{scroll-other-window}) | |
2514 | have unpredictable results if the current buffer is not the one | |
2515 | displayed in the selected window. @xref{Current Buffer}. | |
2516 | ||
2517 | If the window contains a row taller than the height of the window | |
2518 | (for example in the presence of a large image), the scroll functions | |
2519 | will adjust the window's vertical scroll position to scroll the | |
2520 | partially visible row. Lisp callers can disable this feature by | |
2521 | binding the variable @code{auto-window-vscroll} to @code{nil} | |
2522 | (@pxref{Vertical Scrolling}). | |
b8d4c8d0 GM |
2523 | |
2524 | @deffn Command scroll-up &optional count | |
550f41cd CY |
2525 | This function scrolls forward by @var{count} lines in the selected |
2526 | window. | |
b8d4c8d0 | 2527 | |
550f41cd CY |
2528 | If @var{count} is negative, it scrolls backward instead. If |
2529 | @var{count} is @code{nil} (or omitted), the distance scrolled is | |
2530 | @code{next-screen-context-lines} lines less than the height of the | |
2531 | window's text area. | |
b8d4c8d0 | 2532 | |
550f41cd CY |
2533 | If the selected window cannot be scrolled any further, this function |
2534 | signals an error. Otherwise, it returns @code{nil}. | |
b8d4c8d0 GM |
2535 | @end deffn |
2536 | ||
2537 | @deffn Command scroll-down &optional count | |
550f41cd CY |
2538 | This function scrolls backward by @var{count} lines in the selected |
2539 | window. | |
2540 | ||
2541 | If @var{count} is negative, it scrolls forward instead. If | |
2542 | @var{count} is omitted or @code{nil}, the distance scrolled is | |
2543 | @code{next-screen-context-lines} lines less than the height of the | |
2544 | window's text area. | |
b8d4c8d0 | 2545 | |
550f41cd CY |
2546 | If the selected window cannot be scrolled any further, this function |
2547 | signals an error. Otherwise, it returns @code{nil}. | |
2548 | @end deffn | |
2549 | ||
2550 | @deffn Command scroll-up-command &optional count | |
2551 | This behaves like @code{scroll-up}, except that if the selected window | |
2552 | cannot be scrolled any further and the value of the variable | |
2553 | @code{scroll-error-top-bottom} is @code{t}, it tries to move to the | |
2554 | end of the buffer instead. If point is already there, it signals an | |
2555 | error. | |
2556 | @end deffn | |
b8d4c8d0 | 2557 | |
550f41cd CY |
2558 | @deffn Command scroll-down-command &optional count |
2559 | This behaves like @code{scroll-down}, except that if the selected | |
2560 | window cannot be scrolled any further and the value of the variable | |
2561 | @code{scroll-error-top-bottom} is @code{t}, it tries to move to the | |
2562 | beginning of the buffer instead. If point is already there, it | |
2563 | signals an error. | |
b8d4c8d0 GM |
2564 | @end deffn |
2565 | ||
2566 | @deffn Command scroll-other-window &optional count | |
2567 | This function scrolls the text in another window upward @var{count} | |
2568 | lines. Negative values of @var{count}, or @code{nil}, are handled | |
2569 | as in @code{scroll-up}. | |
2570 | ||
2571 | You can specify which buffer to scroll by setting the variable | |
2572 | @code{other-window-scroll-buffer} to a buffer. If that buffer isn't | |
2573 | already displayed, @code{scroll-other-window} displays it in some | |
2574 | window. | |
2575 | ||
2576 | When the selected window is the minibuffer, the next window is normally | |
2577 | the one at the top left corner. You can specify a different window to | |
2578 | scroll, when the minibuffer is selected, by setting the variable | |
2579 | @code{minibuffer-scroll-window}. This variable has no effect when any | |
2580 | other window is selected. When it is non-@code{nil} and the | |
2581 | minibuffer is selected, it takes precedence over | |
2582 | @code{other-window-scroll-buffer}. @xref{Definition of | |
2583 | minibuffer-scroll-window}. | |
2584 | ||
2585 | When the minibuffer is active, it is the next window if the selected | |
2586 | window is the one at the bottom right corner. In this case, | |
2587 | @code{scroll-other-window} attempts to scroll the minibuffer. If the | |
2588 | minibuffer contains just one line, it has nowhere to scroll to, so the | |
2589 | line reappears after the echo area momentarily displays the message | |
2590 | @samp{Beginning of buffer}. | |
2591 | @end deffn | |
2592 | ||
b8d4c8d0 GM |
2593 | @defvar other-window-scroll-buffer |
2594 | If this variable is non-@code{nil}, it tells @code{scroll-other-window} | |
0273ca3a | 2595 | which buffer's window to scroll. |
b8d4c8d0 GM |
2596 | @end defvar |
2597 | ||
2598 | @defopt scroll-margin | |
2599 | This option specifies the size of the scroll margin---a minimum number | |
2600 | of lines between point and the top or bottom of a window. Whenever | |
2601 | point gets within this many lines of the top or bottom of the window, | |
2602 | redisplay scrolls the text automatically (if possible) to move point | |
2603 | out of the margin, closer to the center of the window. | |
2604 | @end defopt | |
2605 | ||
2606 | @defopt scroll-conservatively | |
2607 | This variable controls how scrolling is done automatically when point | |
2608 | moves off the screen (or into the scroll margin). If the value is a | |
2609 | positive integer @var{n}, then redisplay scrolls the text up to | |
2610 | @var{n} lines in either direction, if that will bring point back into | |
0273ca3a | 2611 | proper view. This behavior is called @dfn{conservative scrolling}. |
b8d4c8d0 GM |
2612 | Otherwise, scrolling happens in the usual way, under the control of |
2613 | other variables such as @code{scroll-up-aggressively} and | |
2614 | @code{scroll-down-aggressively}. | |
2615 | ||
2616 | The default value is zero, which means that conservative scrolling | |
2617 | never happens. | |
2618 | @end defopt | |
2619 | ||
2620 | @defopt scroll-down-aggressively | |
2621 | The value of this variable should be either @code{nil} or a fraction | |
2622 | @var{f} between 0 and 1. If it is a fraction, that specifies where on | |
2623 | the screen to put point when scrolling down. More precisely, when a | |
2624 | window scrolls down because point is above the window start, the new | |
2625 | start position is chosen to put point @var{f} part of the window | |
2626 | height from the top. The larger @var{f}, the more aggressive the | |
2627 | scrolling. | |
2628 | ||
2629 | A value of @code{nil} is equivalent to .5, since its effect is to center | |
2630 | point. This variable automatically becomes buffer-local when set in any | |
2631 | fashion. | |
2632 | @end defopt | |
2633 | ||
2634 | @defopt scroll-up-aggressively | |
2635 | Likewise, for scrolling up. The value, @var{f}, specifies how far | |
2636 | point should be placed from the bottom of the window; thus, as with | |
2637 | @code{scroll-up-aggressively}, a larger value scrolls more aggressively. | |
2638 | @end defopt | |
2639 | ||
2640 | @defopt scroll-step | |
da0bbbc4 CY |
2641 | This variable is an older variant of @code{scroll-conservatively}. |
2642 | The difference is that if its value is @var{n}, that permits scrolling | |
b8d4c8d0 GM |
2643 | only by precisely @var{n} lines, not a smaller number. This feature |
2644 | does not work with @code{scroll-margin}. The default value is zero. | |
2645 | @end defopt | |
2646 | ||
550f41cd | 2647 | @cindex @code{scroll-command} property |
b8d4c8d0 | 2648 | @defopt scroll-preserve-screen-position |
550f41cd CY |
2649 | If this option is @code{t}, whenever a scrolling command moves point |
2650 | off-window, Emacs tries to adjust point to keep the cursor at its old | |
2651 | vertical position in the window, rather than the window edge. | |
2652 | ||
2653 | If the value is non-@code{nil} and not @code{t}, Emacs adjusts point | |
2654 | to keep the cursor at the same vertical position, even if the | |
2655 | scrolling command didn't move point off-window. | |
b8d4c8d0 | 2656 | |
550f41cd CY |
2657 | This option affects all scroll commands that have a non-@code{nil} |
2658 | @code{scroll-command} symbol property. | |
b8d4c8d0 GM |
2659 | @end defopt |
2660 | ||
2661 | @defopt next-screen-context-lines | |
2662 | The value of this variable is the number of lines of continuity to | |
2663 | retain when scrolling by full screens. For example, @code{scroll-up} | |
2664 | with an argument of @code{nil} scrolls so that this many lines at the | |
2665 | bottom of the window appear instead at the top. The default value is | |
2666 | @code{2}. | |
2667 | @end defopt | |
2668 | ||
550f41cd CY |
2669 | @defopt scroll-error-top-bottom |
2670 | If this option is @code{nil} (the default), @code{scroll-up-command} | |
2671 | and @code{scroll-down-command} simply signal an error when no more | |
2672 | scrolling is possible. | |
2673 | ||
2674 | If the value is @code{t}, these commands instead move point to the | |
2675 | beginning or end of the buffer (depending on scrolling direction); | |
2676 | only if point is already on that position do they signal an error. | |
2677 | @end defopt | |
2678 | ||
b8d4c8d0 GM |
2679 | @deffn Command recenter &optional count |
2680 | @cindex centering point | |
2681 | This function scrolls the text in the selected window so that point is | |
2682 | displayed at a specified vertical position within the window. It does | |
2683 | not ``move point'' with respect to the text. | |
2684 | ||
a79db6e0 | 2685 | If @var{count} is a non-negative number, that puts the line containing |
b8d4c8d0 GM |
2686 | point @var{count} lines down from the top of the window. If |
2687 | @var{count} is a negative number, then it counts upward from the | |
2688 | bottom of the window, so that @minus{}1 stands for the last usable | |
2689 | line in the window. If @var{count} is a non-@code{nil} list, then it | |
2690 | stands for the line in the middle of the window. | |
2691 | ||
2692 | If @var{count} is @code{nil}, @code{recenter} puts the line containing | |
2693 | point in the middle of the window, then clears and redisplays the entire | |
2694 | selected frame. | |
2695 | ||
2696 | When @code{recenter} is called interactively, @var{count} is the raw | |
2697 | prefix argument. Thus, typing @kbd{C-u} as the prefix sets the | |
2698 | @var{count} to a non-@code{nil} list, while typing @kbd{C-u 4} sets | |
2699 | @var{count} to 4, which positions the current line four lines from the | |
2700 | top. | |
2701 | ||
2702 | With an argument of zero, @code{recenter} positions the current line at | |
2703 | the top of the window. This action is so handy that some people make a | |
2704 | separate key binding to do this. For example, | |
2705 | ||
2706 | @example | |
2707 | @group | |
2708 | (defun line-to-top-of-window () | |
2709 | "Scroll current line to top of window. | |
2710 | Replaces three keystroke sequence C-u 0 C-l." | |
2711 | (interactive) | |
2712 | (recenter 0)) | |
2713 | ||
2714 | (global-set-key [kp-multiply] 'line-to-top-of-window) | |
2715 | @end group | |
2716 | @end example | |
2717 | @end deffn | |
2718 | ||
2719 | @node Vertical Scrolling | |
2720 | @section Vertical Fractional Scrolling | |
2721 | @cindex vertical fractional scrolling | |
0273ca3a | 2722 | @cindex vertical scroll position |
b8d4c8d0 | 2723 | |
af1a5cd5 MR |
2724 | @dfn{Vertical fractional scrolling} means shifting text in a window |
2725 | up or down by a specified multiple or fraction of a line. Each window | |
2726 | has a @dfn{vertical scroll position}, which is a number, never less than | |
0273ca3a MR |
2727 | zero. It specifies how far to raise the contents of the window. |
2728 | Raising the window contents generally makes all or part of some lines | |
2729 | disappear off the top, and all or part of some other lines appear at the | |
2730 | bottom. The usual value is zero. | |
b8d4c8d0 | 2731 | |
af1a5cd5 | 2732 | The vertical scroll position is measured in units of the normal line |
b8d4c8d0 GM |
2733 | height, which is the height of the default font. Thus, if the value is |
2734 | .5, that means the window contents are scrolled up half the normal line | |
2735 | height. If it is 3.3, that means the window contents are scrolled up | |
2736 | somewhat over three times the normal line height. | |
2737 | ||
af1a5cd5 | 2738 | What fraction of a line the vertical scrolling covers, or how many |
b8d4c8d0 GM |
2739 | lines, depends on what the lines contain. A value of .5 could scroll a |
2740 | line whose height is very short off the screen, while a value of 3.3 | |
2741 | could scroll just part of the way through a tall line or an image. | |
2742 | ||
2743 | @defun window-vscroll &optional window pixels-p | |
2744 | This function returns the current vertical scroll position of | |
aeeedf76 MR |
2745 | @var{window}. The default for @var{window} is the selected window. |
2746 | If @var{pixels-p} is non-@code{nil}, the return value is measured in | |
0273ca3a | 2747 | pixels, rather than in units of the normal line height. |
b8d4c8d0 GM |
2748 | |
2749 | @example | |
2750 | @group | |
2751 | (window-vscroll) | |
2752 | @result{} 0 | |
2753 | @end group | |
2754 | @end example | |
2755 | @end defun | |
2756 | ||
2757 | @defun set-window-vscroll window lines &optional pixels-p | |
2758 | This function sets @var{window}'s vertical scroll position to | |
0273ca3a MR |
2759 | @var{lines}. If @var{window} is @code{nil}, the selected window is |
2760 | used. The argument @var{lines} should be zero or positive; if not, it | |
2761 | is taken as zero. | |
b8d4c8d0 | 2762 | |
b8d4c8d0 GM |
2763 | |
2764 | The actual vertical scroll position must always correspond | |
2765 | to an integral number of pixels, so the value you specify | |
2766 | is rounded accordingly. | |
2767 | ||
2768 | The return value is the result of this rounding. | |
2769 | ||
2770 | @example | |
2771 | @group | |
2772 | (set-window-vscroll (selected-window) 1.2) | |
2773 | @result{} 1.13 | |
2774 | @end group | |
2775 | @end example | |
2776 | ||
2777 | If @var{pixels-p} is non-@code{nil}, @var{lines} specifies a number of | |
2778 | pixels. In this case, the return value is @var{lines}. | |
2779 | @end defun | |
2780 | ||
2781 | @defvar auto-window-vscroll | |
2782 | If this variable is non-@code{nil}, the line-move, scroll-up, and | |
0273ca3a | 2783 | scroll-down functions will automatically modify the vertical scroll |
b8766179 | 2784 | position to scroll through display rows that are taller than the height |
0273ca3a | 2785 | of the window, for example in the presence of large images. |
b8d4c8d0 GM |
2786 | @end defvar |
2787 | ||
2788 | @node Horizontal Scrolling | |
2789 | @section Horizontal Scrolling | |
2790 | @cindex horizontal scrolling | |
2791 | ||
2792 | @dfn{Horizontal scrolling} means shifting the image in the window left | |
2793 | or right by a specified multiple of the normal character width. Each | |
2794 | window has a @dfn{horizontal scroll position}, which is a number, never | |
2795 | less than zero. It specifies how far to shift the contents left. | |
2796 | Shifting the window contents left generally makes all or part of some | |
2797 | characters disappear off the left, and all or part of some other | |
2798 | characters appear at the right. The usual value is zero. | |
2799 | ||
2800 | The horizontal scroll position is measured in units of the normal | |
2801 | character width, which is the width of space in the default font. Thus, | |
2802 | if the value is 5, that means the window contents are scrolled left by 5 | |
2803 | times the normal character width. How many characters actually | |
2804 | disappear off to the left depends on their width, and could vary from | |
2805 | line to line. | |
2806 | ||
2807 | Because we read from side to side in the ``inner loop,'' and from top | |
2808 | to bottom in the ``outer loop,'' the effect of horizontal scrolling is | |
2809 | not like that of textual or vertical scrolling. Textual scrolling | |
2810 | involves selection of a portion of text to display, and vertical | |
2811 | scrolling moves the window contents contiguously; but horizontal | |
2812 | scrolling causes part of @emph{each line} to go off screen. | |
2813 | ||
2814 | Usually, no horizontal scrolling is in effect; then the leftmost | |
2815 | column is at the left edge of the window. In this state, scrolling to | |
2816 | the right is meaningless, since there is no data to the left of the edge | |
2817 | to be revealed by it; so this is not allowed. Scrolling to the left is | |
2818 | allowed; it scrolls the first columns of text off the edge of the window | |
2819 | and can reveal additional columns on the right that were truncated | |
2820 | before. Once a window has a nonzero amount of leftward horizontal | |
2821 | scrolling, you can scroll it back to the right, but only so far as to | |
2822 | reduce the net horizontal scroll to zero. There is no limit to how far | |
2823 | left you can scroll, but eventually all the text will disappear off the | |
2824 | left edge. | |
2825 | ||
2826 | @vindex auto-hscroll-mode | |
2827 | If @code{auto-hscroll-mode} is set, redisplay automatically alters | |
2828 | the horizontal scrolling of a window as necessary to ensure that point | |
2829 | is always visible. However, you can still set the horizontal | |
2830 | scrolling value explicitly. The value you specify serves as a lower | |
2831 | bound for automatic scrolling, i.e. automatic scrolling will not | |
2832 | scroll a window to a column less than the specified one. | |
2833 | ||
2834 | @deffn Command scroll-left &optional count set-minimum | |
2835 | This function scrolls the selected window @var{count} columns to the | |
2836 | left (or to the right if @var{count} is negative). The default | |
2837 | for @var{count} is the window width, minus 2. | |
2838 | ||
2839 | The return value is the total amount of leftward horizontal scrolling in | |
2840 | effect after the change---just like the value returned by | |
2841 | @code{window-hscroll} (below). | |
2842 | ||
2843 | Once you scroll a window as far right as it can go, back to its normal | |
2844 | position where the total leftward scrolling is zero, attempts to scroll | |
2845 | any farther right have no effect. | |
2846 | ||
2847 | If @var{set-minimum} is non-@code{nil}, the new scroll amount becomes | |
2848 | the lower bound for automatic scrolling; that is, automatic scrolling | |
2849 | will not scroll a window to a column less than the value returned by | |
2850 | this function. Interactive calls pass non-@code{nil} for | |
2851 | @var{set-minimum}. | |
2852 | @end deffn | |
2853 | ||
2854 | @deffn Command scroll-right &optional count set-minimum | |
2855 | This function scrolls the selected window @var{count} columns to the | |
2856 | right (or to the left if @var{count} is negative). The default | |
2857 | for @var{count} is the window width, minus 2. Aside from the direction | |
2858 | of scrolling, this works just like @code{scroll-left}. | |
2859 | @end deffn | |
2860 | ||
2861 | @defun window-hscroll &optional window | |
2862 | This function returns the total leftward horizontal scrolling of | |
2863 | @var{window}---the number of columns by which the text in @var{window} | |
aeeedf76 MR |
2864 | is scrolled left past the left margin. The default for |
2865 | @var{window} is the selected window. | |
b8d4c8d0 | 2866 | |
0273ca3a MR |
2867 | The return value is never negative. It is zero when no horizontal |
2868 | scrolling has been done in @var{window} (which is usually the case). | |
b8d4c8d0 | 2869 | |
b8d4c8d0 GM |
2870 | |
2871 | @example | |
2872 | @group | |
2873 | (window-hscroll) | |
2874 | @result{} 0 | |
2875 | @end group | |
2876 | @group | |
2877 | (scroll-left 5) | |
2878 | @result{} 5 | |
2879 | @end group | |
2880 | @group | |
2881 | (window-hscroll) | |
2882 | @result{} 5 | |
2883 | @end group | |
2884 | @end example | |
2885 | @end defun | |
2886 | ||
2887 | @defun set-window-hscroll window columns | |
2888 | This function sets horizontal scrolling of @var{window}. The value of | |
2889 | @var{columns} specifies the amount of scrolling, in terms of columns | |
2890 | from the left margin. The argument @var{columns} should be zero or | |
2891 | positive; if not, it is taken as zero. Fractional values of | |
2892 | @var{columns} are not supported at present. | |
2893 | ||
2894 | Note that @code{set-window-hscroll} may appear not to work if you test | |
2895 | it by evaluating a call with @kbd{M-:} in a simple way. What happens | |
2896 | is that the function sets the horizontal scroll value and returns, but | |
2897 | then redisplay adjusts the horizontal scrolling to make point visible, | |
2898 | and this overrides what the function did. You can observe the | |
2899 | function's effect if you call it while point is sufficiently far from | |
2900 | the left margin that it will remain visible. | |
2901 | ||
2902 | The value returned is @var{columns}. | |
2903 | ||
2904 | @example | |
2905 | @group | |
2906 | (set-window-hscroll (selected-window) 10) | |
2907 | @result{} 10 | |
2908 | @end group | |
2909 | @end example | |
2910 | @end defun | |
2911 | ||
af1a5cd5 MR |
2912 | Here is how you can determine whether a given position @var{position} |
2913 | is off the screen due to horizontal scrolling: | |
b8d4c8d0 GM |
2914 | |
2915 | @example | |
2916 | @group | |
2917 | (defun hscroll-on-screen (window position) | |
2918 | (save-excursion | |
2919 | (goto-char position) | |
2920 | (and | |
2921 | (>= (- (current-column) (window-hscroll window)) 0) | |
2922 | (< (- (current-column) (window-hscroll window)) | |
2923 | (window-width window))))) | |
2924 | @end group | |
2925 | @end example | |
2926 | ||
b8d4c8d0 GM |
2927 | @node Coordinates and Windows |
2928 | @section Coordinates and Windows | |
1c3d7a13 CY |
2929 | @cindex frame-relative coordinate |
2930 | @cindex coordinate, relative to frame | |
2931 | @cindex window position | |
b8d4c8d0 | 2932 | |
1c3d7a13 CY |
2933 | This section describes functions that report the position of a |
2934 | window. Most of these functions report positions relative to the | |
2935 | window's frame. In this case, the coordinate origin @samp{(0,0)} lies | |
2936 | near the upper left corner of the frame. For technical reasons, on | |
2937 | graphical displays the origin is not located at the exact corner of | |
2938 | the graphical window as it appears on the screen. If Emacs is built | |
2939 | with the GTK+ toolkit, the origin is at the upper left corner of the | |
2940 | frame area used for displaying Emacs windows, below the title-bar, | |
2941 | GTK+ menu bar, and tool bar (since these are drawn by the window | |
2942 | manager and/or GTK+, not by Emacs). But if Emacs is not built with | |
2943 | GTK+, the origin is at the upper left corner of the tool bar (since in | |
2944 | this case Emacs itself draws the tool bar). In both cases, the X and | |
2945 | Y coordinates increase rightward and downward respectively. | |
2946 | ||
2947 | Except where noted, X and Y coordinates are reported in integer | |
2948 | character units, i.e. numbers of lines and columns respectively. On a | |
2949 | graphical display, each ``line'' and ``column'' corresponds to the | |
2950 | height and width of a default character specified by the frame's | |
2951 | default font. | |
2952 | ||
2953 | @defun window-edges &optional window | |
2954 | This function returns a list of the edge coordinates of @var{window}. | |
2955 | If @var{window} is omitted or @code{nil}, it defaults to the selected | |
2956 | window. | |
b8d4c8d0 | 2957 | |
1c3d7a13 CY |
2958 | The return value has the form @code{(@var{left} @var{top} @var{right} |
2959 | @var{bottom})}. These list elements are, respectively, the X | |
2960 | coordinate of the leftmost column occupied by the window, the Y | |
2961 | coordinate of the topmost row, the X coordinate one column to the | |
2962 | right of the rightmost column, and the Y coordinate one row down from | |
2963 | the bottommost row. | |
b8d4c8d0 | 2964 | |
1c3d7a13 CY |
2965 | Note that these are the actual outer edges of the window, including |
2966 | any header line, mode line, scroll bar, fringes, and display margins. | |
a08a07e3 CY |
2967 | On a text terminal, if the window has a neighbor on its right, its |
2968 | right edge includes the separator line between the window and its | |
1c3d7a13 | 2969 | neighbor. |
b8d4c8d0 GM |
2970 | @end defun |
2971 | ||
1c3d7a13 CY |
2972 | @defun window-inside-edges &optional window |
2973 | This function is similar to @code{window-edges}, but the returned edge | |
2974 | values are for the text area of the window. They exclude any header | |
2975 | line, mode line, scroll bar, fringes, display margins, and vertical | |
2976 | separator. | |
2977 | @end defun | |
2978 | ||
2979 | @defun window-top-line &optional window | |
2980 | This function returns the Y coordinate of the topmost row of | |
2981 | @var{window}, equivalent to the @var{top} entry in the list returned | |
2982 | by @code{window-edges}. | |
2983 | @end defun | |
2984 | ||
2985 | @defun window-left-column &optional window | |
2986 | This function returns the X coordinate of the leftmost column of | |
2987 | @var{window}, equivalent to the @var{left} entry in the list returned | |
2988 | by @code{window-edges}. | |
2989 | @end defun | |
b8d4c8d0 | 2990 | |
1c3d7a13 CY |
2991 | The following functions can be used to relate a set of |
2992 | frame-relative coordinates to a window: | |
b8d4c8d0 | 2993 | |
1c3d7a13 CY |
2994 | @defun window-at x y &optional frame |
2995 | This function returns the live window at the frame-relative | |
2996 | coordinates @var{x} and @var{y}, on frame @var{frame}. If there is no | |
2997 | window at that position, the return value is @code{nil}. If | |
2998 | @var{frame} is omitted or @code{nil}, it defaults to the selected | |
2999 | frame. | |
3000 | @end defun | |
3001 | ||
3002 | @defun coordinates-in-window-p coordinates window | |
3003 | This function checks whether a window @var{window} occupies the | |
3004 | frame-relative coordinates @var{coordinates}, and if so which part of | |
3005 | the window that is. @var{window} should be a live window. | |
3006 | @var{coordinates} should be a cons cell of the form @code{(@var{x} | |
3007 | . @var{y})}, where @var{x} and @var{y} are frame-relative coordinates. | |
3008 | ||
3009 | If there is no window at the specified position, the return value is | |
3010 | @code{nil} . Otherwise, the return value is one of the following: | |
b8d4c8d0 GM |
3011 | |
3012 | @table @code | |
3013 | @item (@var{relx} . @var{rely}) | |
3014 | The coordinates are inside @var{window}. The numbers @var{relx} and | |
3015 | @var{rely} are the equivalent window-relative coordinates for the | |
3016 | specified position, counting from 0 at the top left corner of the | |
3017 | window. | |
3018 | ||
3019 | @item mode-line | |
3020 | The coordinates are in the mode line of @var{window}. | |
3021 | ||
3022 | @item header-line | |
3023 | The coordinates are in the header line of @var{window}. | |
3024 | ||
3025 | @item vertical-line | |
3026 | The coordinates are in the vertical line between @var{window} and its | |
3027 | neighbor to the right. This value occurs only if the window doesn't | |
3028 | have a scroll bar; positions in a scroll bar are considered outside the | |
3029 | window for these purposes. | |
3030 | ||
3031 | @item left-fringe | |
3032 | @itemx right-fringe | |
3033 | The coordinates are in the left or right fringe of the window. | |
3034 | ||
3035 | @item left-margin | |
3036 | @itemx right-margin | |
3037 | The coordinates are in the left or right margin of the window. | |
3038 | ||
3039 | @item nil | |
3040 | The coordinates are not in any part of @var{window}. | |
3041 | @end table | |
3042 | ||
3043 | The function @code{coordinates-in-window-p} does not require a frame as | |
3044 | argument because it always uses the frame that @var{window} is on. | |
3045 | @end defun | |
3046 | ||
1c3d7a13 CY |
3047 | The following functions return window positions in pixels, rather |
3048 | than character units. Though mostly useful on graphical displays, | |
a08a07e3 CY |
3049 | they can also be called on text terminals, where the screen area of |
3050 | each text character is taken to be ``one pixel''. | |
1c3d7a13 CY |
3051 | |
3052 | @defun window-pixel-edges &optional window | |
3053 | This function returns a list of pixel coordinates for the edges of | |
3054 | @var{window}. If @var{window} is omitted or @code{nil}, it defaults | |
3055 | to the selected window. | |
3056 | ||
3057 | The return value has the form @code{(@var{left} @var{top} @var{right} | |
3058 | @var{bottom})}. The list elements are, respectively, the X pixel | |
3059 | coordinate of the left window edge, the Y pixel coordinate of the top | |
3060 | edge, one more than the X pixel coordinate of the right edge, and one | |
3061 | more than the Y pixel coordinate of the bottom edge. | |
3062 | @end defun | |
3063 | ||
3064 | @defun window-inside-pixel-edges &optional window | |
3065 | This function is like @code{window-pixel-edges}, except that it | |
3066 | returns the pixel coordinates for the edges of the window's text area, | |
3067 | rather than the pixel coordinates for the edges of the window itself. | |
3068 | @var{window} must specify a live window. | |
3069 | @end defun | |
3070 | ||
3071 | The following functions return window positions in pixels, relative | |
3072 | to the display screen rather than the frame: | |
3073 | ||
3074 | @defun window-absolute-pixel-edges &optional window | |
3075 | This function is like @code{window-pixel-edges}, except that it | |
3076 | returns the edge pixel coordinates relative to the top left corner of | |
3077 | the display screen. | |
3078 | @end defun | |
3079 | ||
3080 | @defun window-inside-absolute-pixel-edges &optional window | |
3081 | This function is like @code{window-inside-pixel-edges}, except that it | |
3082 | returns the edge pixel coordinates relative to the top left corner of | |
3083 | the display screen. @var{window} must specify a live window. | |
3084 | @end defun | |
b8d4c8d0 GM |
3085 | |
3086 | @node Window Configurations | |
3087 | @section Window Configurations | |
3088 | @cindex window configurations | |
3089 | @cindex saving window information | |
3090 | ||
c419f5cb | 3091 | A @dfn{window configuration} records the entire layout of one |
0273ca3a MR |
3092 | frame---all windows, their sizes, which buffers they contain, how those |
3093 | buffers are scrolled, and their values of point and the mark; also their | |
3094 | fringes, margins, and scroll bar settings. It also includes the value | |
3095 | of @code{minibuffer-scroll-window}. As a special exception, the window | |
3096 | configuration does not record the value of point in the selected window | |
c419f5cb | 3097 | for the current buffer. |
0273ca3a | 3098 | |
a1401ab1 EZ |
3099 | You can bring back an entire frame layout by restoring a previously |
3100 | saved window configuration. If you want to record the layout of all | |
0273ca3a | 3101 | frames instead of just one, use a frame configuration instead of a |
47264a97 | 3102 | window configuration; see @ref{Frame Configurations}. |
b8d4c8d0 GM |
3103 | |
3104 | @defun current-window-configuration &optional frame | |
3105 | This function returns a new object representing @var{frame}'s current | |
aeeedf76 | 3106 | window configuration. The default for @var{frame} is the selected |
34a02f46 MR |
3107 | frame. The variable @code{window-persistent-parameters} specifies |
3108 | whether and which window parameters are saved by this function, see | |
3109 | @ref{Window Parameters} for details. | |
b8d4c8d0 GM |
3110 | @end defun |
3111 | ||
3112 | @defun set-window-configuration configuration | |
3113 | This function restores the configuration of windows and buffers as | |
3114 | specified by @var{configuration}, for the frame that @var{configuration} | |
3115 | was created for. | |
3116 | ||
3117 | The argument @var{configuration} must be a value that was previously | |
0273ca3a | 3118 | returned by @code{current-window-configuration}. The configuration is |
b8d4c8d0 GM |
3119 | restored in the frame from which @var{configuration} was made, whether |
3120 | that frame is selected or not. This always counts as a window size | |
3121 | change and triggers execution of the @code{window-size-change-functions} | |
3122 | (@pxref{Window Hooks}), because @code{set-window-configuration} doesn't | |
3123 | know how to tell whether the new configuration actually differs from the | |
3124 | old one. | |
3125 | ||
3126 | If the frame which @var{configuration} was saved from is dead, all this | |
3127 | function does is restore the three variables @code{window-min-height}, | |
3128 | @code{window-min-width} and @code{minibuffer-scroll-window}. In this | |
3129 | case, the function returns @code{nil}. Otherwise, it returns @code{t}. | |
3130 | ||
3131 | Here is a way of using this function to get the same effect | |
3132 | as @code{save-window-excursion}: | |
3133 | ||
3134 | @example | |
3135 | @group | |
3136 | (let ((config (current-window-configuration))) | |
3137 | (unwind-protect | |
291d142b | 3138 | (progn (split-window-below nil) |
b8d4c8d0 GM |
3139 | @dots{}) |
3140 | (set-window-configuration config))) | |
3141 | @end group | |
3142 | @end example | |
3143 | @end defun | |
3144 | ||
2cc775f9 | 3145 | @defmac save-window-excursion forms@dots{} |
b8d4c8d0 GM |
3146 | This special form records the window configuration, executes @var{forms} |
3147 | in sequence, then restores the earlier window configuration. The window | |
3148 | configuration includes, for each window, the value of point and the | |
3149 | portion of the buffer that is visible. It also includes the choice of | |
3150 | selected window. However, it does not include the value of point in | |
3151 | the current buffer; use @code{save-excursion} also, if you wish to | |
3152 | preserve that. | |
3153 | ||
3154 | Don't use this construct when @code{save-selected-window} is sufficient. | |
3155 | ||
0273ca3a | 3156 | Exit from @code{save-window-excursion} always triggers execution of |
b8d4c8d0 GM |
3157 | @code{window-size-change-functions}. (It doesn't know how to tell |
3158 | whether the restored configuration actually differs from the one in | |
3159 | effect at the end of the @var{forms}.) | |
3160 | ||
3161 | The return value is the value of the final form in @var{forms}. | |
3162 | For example: | |
3163 | ||
3164 | @example | |
3165 | @group | |
3166 | (split-window) | |
3167 | @result{} #<window 25 on control.texi> | |
3168 | @end group | |
3169 | @group | |
3170 | (setq w (selected-window)) | |
3171 | @result{} #<window 19 on control.texi> | |
3172 | @end group | |
3173 | @group | |
3174 | (save-window-excursion | |
3175 | (delete-other-windows w) | |
3176 | (switch-to-buffer "foo") | |
3177 | 'do-something) | |
3178 | @result{} do-something | |
3179 | ;; @r{The screen is now split again.} | |
3180 | @end group | |
3181 | @end example | |
2cc775f9 | 3182 | @end defmac |
b8d4c8d0 GM |
3183 | |
3184 | @defun window-configuration-p object | |
3185 | This function returns @code{t} if @var{object} is a window configuration. | |
3186 | @end defun | |
3187 | ||
3188 | @defun compare-window-configurations config1 config2 | |
3189 | This function compares two window configurations as regards the | |
3190 | structure of windows, but ignores the values of point and mark and the | |
3191 | saved scrolling positions---it can return @code{t} even if those | |
3192 | aspects differ. | |
3193 | ||
3194 | The function @code{equal} can also compare two window configurations; it | |
3195 | regards configurations as unequal if they differ in any respect, even a | |
3196 | saved point or mark. | |
3197 | @end defun | |
3198 | ||
3199 | @defun window-configuration-frame config | |
3200 | This function returns the frame for which the window configuration | |
3201 | @var{config} was made. | |
3202 | @end defun | |
3203 | ||
3204 | Other primitives to look inside of window configurations would make | |
3205 | sense, but are not implemented because we did not need them. See the | |
3206 | file @file{winner.el} for some more operations on windows | |
3207 | configurations. | |
3208 | ||
c419f5cb MR |
3209 | The objects returned by @code{current-window-configuration} die |
3210 | together with the Emacs process. In order to store a window | |
6a6ee00d MR |
3211 | configuration on disk and read it back in another Emacs session, the |
3212 | functions described next can be used. These functions are also useful | |
3213 | to clone the state of a frame into an arbitrary live window | |
3214 | (@code{set-window-configuration} effectively clones the windows of a | |
3215 | frame into the root window of that very frame only). | |
c419f5cb | 3216 | |
34a02f46 | 3217 | @defun window-state-get &optional window writable |
c419f5cb MR |
3218 | This function returns the state of @var{window} as a Lisp object. The |
3219 | argument @var{window} can be any window and defaults to the root window | |
3220 | of the selected frame. | |
3221 | ||
34a02f46 | 3222 | If the optional argument @var{writable} is non-@code{nil}, this means to |
6a6ee00d MR |
3223 | not use markers for sampling positions like @code{window-point} or |
3224 | @code{window-start}. This argument should be non-@code{nil} when the | |
34a02f46 | 3225 | state shall be written to disk and read back in another session. |
6a6ee00d | 3226 | |
34a02f46 MR |
3227 | Together, the argument @var{writable} and the variable |
3228 | @code{window-persistent-parameters} specify which window parameters are | |
3229 | saved by this function, see @ref{Window Parameters} for details. | |
c419f5cb MR |
3230 | @end defun |
3231 | ||
34a02f46 MR |
3232 | The value returned by @code{window-state-get} can be used in the same |
3233 | session to make a clone of a window in another window. It can be also | |
3234 | written to disk and read back in another session. In either case, use | |
3235 | the function described next to restore the state of the window. | |
c419f5cb MR |
3236 | |
3237 | @defun window-state-put state &optional window ignore | |
3238 | This function puts the window state @var{state} into @var{window}. The | |
3239 | argument @var{state} should be the state of a window returned by an | |
3240 | earlier invocation of @code{window-state-get}, see above. The optional | |
3241 | argument @var{window} must specify a live window and defaults to the | |
3242 | selected one. | |
3243 | ||
3244 | The optional argument @var{ignore} non-@code{nil} means to ignore | |
3245 | minimum window sizes and fixed size restrictions. If @var{ignore} | |
be7f5545 | 3246 | equals @code{safe}, this means windows can get as small as one line |
c419f5cb MR |
3247 | and/or two columns. |
3248 | @end defun | |
3249 | ||
3250 | ||
0273ca3a MR |
3251 | @node Window Parameters |
3252 | @section Window Parameters | |
3253 | @cindex window parameters | |
3254 | ||
c419f5cb | 3255 | This section describes how window parameters can be used to associate |
0273ca3a MR |
3256 | additional information with windows. |
3257 | ||
3258 | @defun window-parameter window parameter | |
aeeedf76 | 3259 | This function returns @var{window}'s value for @var{parameter}. The |
c419f5cb MR |
3260 | default for @var{window} is the selected window. If @var{window} has no |
3261 | setting for @var{parameter}, this function returns @code{nil}. | |
0273ca3a MR |
3262 | @end defun |
3263 | ||
a1401ab1 | 3264 | @defun window-parameters &optional window |
0273ca3a | 3265 | This function returns all parameters of @var{window} and their values. |
c419f5cb MR |
3266 | The default for @var{window} is the selected window. The return value, |
3267 | if non-@code{nil} is an association list whose elements have the form | |
3268 | @code{(@var{parameter} . @var{value})}. | |
0273ca3a MR |
3269 | @end defun |
3270 | ||
3271 | @defun set-window-parameter window parameter value | |
3272 | This function sets @var{window}'s value of @var{parameter} to | |
aeeedf76 MR |
3273 | @var{value} and returns @var{value}. The default for @var{window} |
3274 | is the selected window. | |
0273ca3a MR |
3275 | @end defun |
3276 | ||
6a6ee00d | 3277 | By default, functions saving and restoring window configurations or the |
f5064cae | 3278 | states of windows (@pxref{Window Configurations}) do not care about |
6a6ee00d MR |
3279 | window parameters. This means, that when you change the value of a |
3280 | parameter within the body of a @code{save-window-excursion}, the | |
3281 | previous value is not restored upon exit of that macro. It also means | |
34a02f46 MR |
3282 | that when you restore via @code{window-state-put} a window state saved |
3283 | earlier by @code{window-state-get}, all cloned windows have their | |
3284 | parameters reset to @code{nil}. The following variable allows to | |
3285 | override the standard behavior. | |
6a6ee00d MR |
3286 | |
3287 | @defvar window-persistent-parameters | |
3288 | This variable is an alist specifying which parameters get saved by | |
3289 | @code{current-window-configuration} and @code{window-state-get} and | |
3290 | subsequently restored by @code{set-window-configuration} and | |
3291 | @code{window-state-put}, see @ref{Window Configurations}. | |
3292 | ||
3293 | The @sc{car} of each entry of this alist is the symbol specifying the | |
34a02f46 | 3294 | parameter. The @sc{cdr} should be one of the following: |
6a6ee00d MR |
3295 | |
3296 | @table @asis | |
6a6ee00d | 3297 | @item @code{nil} |
34a02f46 MR |
3298 | This value means the parameter is neither saved by |
3299 | @code{window-state-get} nor by @code{current-window-configuration}. | |
3300 | ||
3301 | @item @code{t} | |
6a6ee00d | 3302 | This value specifies that the parameter is saved by |
34a02f46 | 3303 | @code{current-window-configuration} and, provided its @var{writable} |
6a6ee00d MR |
3304 | argument is @code{nil}, by @code{window-state-get}. |
3305 | ||
34a02f46 | 3306 | @item @code{writable} |
6a6ee00d MR |
3307 | This means that the parameter is saved unconditionally by both |
3308 | @code{current-window-configuration} and @code{window-state-get}. This | |
3309 | value should not be used for parameters whose values do not have a read | |
3310 | syntax. Otherwise, invoking @code{window-state-put} in another session | |
3311 | may fail with an @code{invalid-read-syntax} error. | |
3312 | @end table | |
6a6ee00d MR |
3313 | @end defvar |
3314 | ||
c419f5cb MR |
3315 | Some functions, notably @code{delete-window}, |
3316 | @code{delete-other-windows} and @code{split-window} may behave specially | |
3317 | when their @var{window} argument has a parameter set. You can override | |
3318 | such special behavior by binding the following variable to a | |
3319 | non-@code{nil} value: | |
3320 | ||
3321 | @defvar ignore-window-parameters | |
3322 | If this variable is non-@code{nil}, some standard functions do not | |
3323 | process window parameters. The functions currently affected by this are | |
3324 | @code{split-window}, @code{delete-window}, @code{delete-other-windows} | |
3325 | and @code{other-window}. | |
3326 | ||
3327 | An application can bind this variable to a non-@code{nil} value around | |
3328 | calls to these functions. If it does so, the application is fully | |
3329 | responsible for correctly assigning the parameters of all involved | |
3330 | windows when exiting that function. | |
3331 | @end defvar | |
3332 | ||
3333 | The following parameters are currently used by the window management | |
6a6ee00d | 3334 | code: |
c419f5cb MR |
3335 | |
3336 | @table @asis | |
3337 | @item @code{delete-window} | |
3338 | This parameter affects the execution of @code{delete-window} | |
3339 | (@pxref{Deleting Windows}). | |
3340 | ||
3341 | @item @code{delete-other-windows} | |
3342 | This parameter affects the execution of @code{delete-other-windows} | |
3343 | (@pxref{Deleting Windows}). | |
3344 | ||
3345 | @item @code{split-window} | |
3346 | This parameter affects the execution of @code{split-window} | |
3347 | (@pxref{Splitting Windows}). | |
3348 | ||
3349 | @item @code{other-window} | |
3350 | This parameter affects the execution of @code{other-window} | |
3351 | (@pxref{Cyclic Window Ordering}). | |
3352 | ||
3353 | @item @code{no-other-window} | |
3354 | This parameter marks the window as not selectable by @code{other-window} | |
3355 | (@pxref{Cyclic Window Ordering}). | |
6a6ee00d MR |
3356 | |
3357 | @item @code{clone-of} | |
3358 | This parameter specifies the window this one has been cloned from and is | |
3359 | installed by @code{window-state-get}, see @ref{Window Configurations}. | |
3360 | ||
3361 | @item @code{quit-restore} | |
3362 | This parameter tells how to proceed with a window when the buffer it | |
3363 | shows is no more needed. It is installed by the buffer display | |
3364 | functions (@pxref{Choosing Window}) and consulted by the function | |
3365 | @code{quit-window} (@pxref{Quitting Windows}). | |
c419f5cb MR |
3366 | @end table |
3367 | ||
3368 | In addition, the parameters @code{window-atom} and @code{window-side} | |
6a6ee00d | 3369 | are reserved and should not be used by applications. |
c419f5cb | 3370 | |
0273ca3a | 3371 | |
b8d4c8d0 GM |
3372 | @node Window Hooks |
3373 | @section Hooks for Window Scrolling and Changes | |
3374 | @cindex hooks for window operations | |
3375 | ||
3376 | This section describes how a Lisp program can take action whenever a | |
3377 | window displays a different part of its buffer or a different buffer. | |
3378 | There are three actions that can change this: scrolling the window, | |
3379 | switching buffers in the window, and changing the size of the window. | |
3380 | The first two actions run @code{window-scroll-functions}; the last runs | |
3381 | @code{window-size-change-functions}. | |
3382 | ||
3383 | @defvar window-scroll-functions | |
3384 | This variable holds a list of functions that Emacs should call before | |
0273ca3a MR |
3385 | redisplaying a window with scrolling. Displaying a different buffer in |
3386 | the window also runs these functions. | |
b8d4c8d0 | 3387 | |
0273ca3a MR |
3388 | This variable is not a normal hook, because each function is called with |
3389 | two arguments: the window, and its new display-start position. | |
b8d4c8d0 GM |
3390 | |
3391 | These functions must be careful in using @code{window-end} | |
0273ca3a MR |
3392 | (@pxref{Window Start and End}); if you need an up-to-date value, you |
3393 | must use the @var{update} argument to ensure you get it. | |
b8d4c8d0 GM |
3394 | |
3395 | @strong{Warning:} don't use this feature to alter the way the window | |
3396 | is scrolled. It's not designed for that, and such use probably won't | |
3397 | work. | |
3398 | @end defvar | |
3399 | ||
3400 | @defvar window-size-change-functions | |
3401 | This variable holds a list of functions to be called if the size of any | |
3402 | window changes for any reason. The functions are called just once per | |
3403 | redisplay, and just once for each frame on which size changes have | |
3404 | occurred. | |
3405 | ||
3406 | Each function receives the frame as its sole argument. There is no | |
3407 | direct way to find out which windows on that frame have changed size, or | |
3408 | precisely how. However, if a size-change function records, at each | |
3409 | call, the existing windows and their sizes, it can also compare the | |
3410 | present sizes and the previous sizes. | |
3411 | ||
3412 | Creating or deleting windows counts as a size change, and therefore | |
3413 | causes these functions to be called. Changing the frame size also | |
3414 | counts, because it changes the sizes of the existing windows. | |
3415 | ||
3416 | It is not a good idea to use @code{save-window-excursion} (@pxref{Window | |
3417 | Configurations}) in these functions, because that always counts as a | |
3418 | size change, and it would cause these functions to be called over and | |
3419 | over. In most cases, @code{save-selected-window} (@pxref{Selecting | |
3420 | Windows}) is what you need here. | |
3421 | @end defvar | |
3422 | ||
b8d4c8d0 GM |
3423 | @defvar window-configuration-change-hook |
3424 | A normal hook that is run every time you change the window configuration | |
3425 | of an existing frame. This includes splitting or deleting windows, | |
3426 | changing the sizes of windows, or displaying a different buffer in a | |
0273ca3a MR |
3427 | window. |
3428 | ||
3429 | The buffer-local part of this hook is run once per each window on the | |
3430 | affected frame, with the relevant window selected and its buffer | |
3431 | current. The global part is run once for the modified frame, with that | |
3432 | frame selected. | |
b8d4c8d0 GM |
3433 | @end defvar |
3434 | ||
38b1d346 | 3435 | In addition, you can use @code{jit-lock-register} to register a Font |
b8766179 MR |
3436 | Lock fontification function, which will be called whenever parts of a |
3437 | buffer are (re)fontified because a window was scrolled or its size | |
3438 | changed. @xref{Other Font Lock Variables}. |