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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
651f374c | 3 | @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2002, 2003, |
ceb4c4d3 | 4 | @c 2004, 2005, 2006 Free Software Foundation, Inc. |
b1b12a8e RS |
5 | @c See the file elisp.texi for copying conditions. |
6 | @setfilename ../info/windows | |
7 | @node Windows, Frames, Buffers, Top | |
8 | @chapter Windows | |
9 | ||
10 | This chapter describes most of the functions and variables related to | |
11 | Emacs windows. See @ref{Display}, for information on how text is | |
12 | displayed in windows. | |
13 | ||
14 | @menu | |
3c29caa8 DH |
15 | * Basic Windows:: Basic information on using windows. |
16 | * Splitting Windows:: Splitting one window into two windows. | |
17 | * Deleting Windows:: Deleting a window gives its space to other windows. | |
18 | * Selecting Windows:: The selected window is the one that you edit in. | |
19 | * Cyclic Window Ordering:: Moving around the existing windows. | |
20 | * Buffers and Windows:: Each window displays the contents of a buffer. | |
84e34002 | 21 | * Displaying Buffers:: Higher-level functions for displaying a buffer |
3c29caa8 DH |
22 | and choosing a window for it. |
23 | * Choosing Window:: How to choose a window for displaying a buffer. | |
24 | * Window Point:: Each window has its own location of point. | |
25 | * Window Start:: The display-start position controls which text | |
26 | is on-screen in the window. | |
8241495d RS |
27 | * Textual Scrolling:: Moving text up and down through the window. |
28 | * Vertical Scrolling:: Moving the contents up and down on the window. | |
29 | * Horizontal Scrolling:: Moving the contents sideways on the window. | |
3c29caa8 DH |
30 | * Size of Window:: Accessing the size of a window. |
31 | * Resizing Windows:: Changing the size of a window. | |
32 | * Coordinates and Windows:: Converting coordinates to windows. | |
8781c4d1 | 33 | * Window Tree:: The layout and sizes of all windows in a frame. |
3c29caa8 | 34 | * Window Configurations:: Saving and restoring the state of the screen. |
f9f59935 RS |
35 | * Window Hooks:: Hooks for scrolling, window size changes, |
36 | redisplay going past a certain point, | |
37 | or window configuration changes. | |
b1b12a8e RS |
38 | @end menu |
39 | ||
40 | @node Basic Windows | |
41 | @section Basic Concepts of Emacs Windows | |
42 | @cindex window | |
43 | @cindex selected window | |
44 | ||
bfe721d1 KH |
45 | A @dfn{window} in Emacs is the physical area of the screen in which a |
46 | buffer is displayed. The term is also used to refer to a Lisp object that | |
b1b12a8e RS |
47 | represents that screen area in Emacs Lisp. It should be |
48 | clear from the context which is meant. | |
49 | ||
bfe721d1 KH |
50 | Emacs groups windows into frames. A frame represents an area of |
51 | screen available for Emacs to use. Each frame always contains at least | |
52 | one window, but you can subdivide it vertically or horizontally into | |
53 | multiple nonoverlapping Emacs windows. | |
54 | ||
55 | In each frame, at any time, one and only one window is designated as | |
56 | @dfn{selected within the frame}. The frame's cursor appears in that | |
ae473bd3 RS |
57 | window, but the other windows have ``non-selected'' cursors, normally |
58 | less visible. At any time, one frame is the selected frame; and the | |
59 | window selected within that frame is @dfn{the selected window}. The | |
60 | selected window's buffer is usually the current buffer (except when | |
bfe721d1 KH |
61 | @code{set-buffer} has been used). @xref{Current Buffer}. |
62 | ||
ae473bd3 RS |
63 | @defvar cursor-in-non-selected-windows |
64 | If this variable is @code{nil}, Emacs displays only one cursor, | |
65 | in the selected window. Other windows have no cursor at all. | |
66 | @end defvar | |
67 | ||
bfe721d1 KH |
68 | For practical purposes, a window exists only while it is displayed in |
69 | a frame. Once removed from the frame, the window is effectively deleted | |
70 | and should not be used, @emph{even though there may still be references | |
71 | to it} from other Lisp objects. Restoring a saved window configuration | |
72 | is the only way for a window no longer on the screen to come back to | |
73 | life. (@xref{Deleting Windows}.) | |
b1b12a8e RS |
74 | |
75 | Each window has the following attributes: | |
76 | ||
77 | @itemize @bullet | |
78 | @item | |
79 | containing frame | |
80 | ||
3c29caa8 | 81 | @item |
b1b12a8e RS |
82 | window height |
83 | ||
3c29caa8 | 84 | @item |
b1b12a8e RS |
85 | window width |
86 | ||
3c29caa8 | 87 | @item |
b1b12a8e RS |
88 | window edges with respect to the screen or frame |
89 | ||
3c29caa8 | 90 | @item |
b1b12a8e RS |
91 | the buffer it displays |
92 | ||
3c29caa8 | 93 | @item |
b1b12a8e RS |
94 | position within the buffer at the upper left of the window |
95 | ||
3c29caa8 | 96 | @item |
c638661f | 97 | amount of horizontal scrolling, in columns |
b1b12a8e | 98 | |
3c29caa8 | 99 | @item |
b1b12a8e RS |
100 | point |
101 | ||
3c29caa8 | 102 | @item |
b1b12a8e RS |
103 | the mark |
104 | ||
3c29caa8 | 105 | @item |
b1b12a8e | 106 | how recently the window was selected |
27704b78 RS |
107 | |
108 | @item | |
109 | fringe settings | |
110 | ||
111 | @item | |
112 | display margins | |
113 | ||
114 | @item | |
115 | scroll-bar settings | |
b1b12a8e RS |
116 | @end itemize |
117 | ||
118 | @cindex multiple windows | |
119 | Users create multiple windows so they can look at several buffers at | |
120 | once. Lisp libraries use multiple windows for a variety of reasons, but | |
bfe721d1 KH |
121 | most often to display related information. In Rmail, for example, you |
122 | can move through a summary buffer in one window while the other window | |
123 | shows messages one at a time as they are reached. | |
b1b12a8e RS |
124 | |
125 | The meaning of ``window'' in Emacs is similar to what it means in the | |
c638661f | 126 | context of general-purpose window systems such as X, but not identical. |
bfe721d1 KH |
127 | The X Window System places X windows on the screen; Emacs uses one or |
128 | more X windows as frames, and subdivides them into | |
129 | Emacs windows. When you use Emacs on a character-only terminal, Emacs | |
130 | treats the whole terminal screen as one frame. | |
b1b12a8e RS |
131 | |
132 | @cindex terminal screen | |
133 | @cindex screen of terminal | |
134 | @cindex tiled windows | |
135 | Most window systems support arbitrarily located overlapping windows. | |
136 | In contrast, Emacs windows are @dfn{tiled}; they never overlap, and | |
f9f59935 RS |
137 | together they fill the whole screen or frame. Because of the way in |
138 | which Emacs creates new windows and resizes them, not all conceivable | |
139 | tilings of windows on an Emacs frame are actually possible. | |
140 | @xref{Splitting Windows}, and @ref{Size of Window}. | |
b1b12a8e RS |
141 | |
142 | @xref{Display}, for information on how the contents of the | |
143 | window's buffer are displayed in the window. | |
144 | ||
145 | @defun windowp object | |
f9f59935 | 146 | This function returns @code{t} if @var{object} is a window. |
b1b12a8e RS |
147 | @end defun |
148 | ||
149 | @node Splitting Windows | |
150 | @section Splitting Windows | |
151 | @cindex splitting windows | |
152 | @cindex window splitting | |
153 | ||
154 | The functions described here are the primitives used to split a window | |
155 | into two windows. Two higher level functions sometimes split a window, | |
156 | but not always: @code{pop-to-buffer} and @code{display-buffer} | |
157 | (@pxref{Displaying Buffers}). | |
158 | ||
159 | The functions described here do not accept a buffer as an argument. | |
160 | The two ``halves'' of the split window initially display the same buffer | |
161 | previously visible in the window that was split. | |
162 | ||
163 | @deffn Command split-window &optional window size horizontal | |
164 | This function splits @var{window} into two windows. The original | |
165 | window @var{window} remains the selected window, but occupies only | |
166 | part of its former screen area. The rest is occupied by a newly created | |
167 | window which is returned as the value of this function. | |
168 | ||
2726b68b | 169 | If @var{horizontal} is non-@code{nil}, then @var{window} splits into |
b1b12a8e RS |
170 | two side by side windows. The original window @var{window} keeps the |
171 | leftmost @var{size} columns, and gives the rest of the columns to the | |
172 | new window. Otherwise, it splits into windows one above the other, and | |
173 | @var{window} keeps the upper @var{size} lines and gives the rest of the | |
174 | lines to the new window. The original window is therefore the | |
c638661f | 175 | left-hand or upper of the two, and the new window is the right-hand or |
b1b12a8e RS |
176 | lower. |
177 | ||
2726b68b | 178 | If @var{window} is omitted or @code{nil}, then the selected window is |
b1b12a8e RS |
179 | split. If @var{size} is omitted or @code{nil}, then @var{window} is |
180 | divided evenly into two parts. (If there is an odd line, it is | |
181 | allocated to the new window.) When @code{split-window} is called | |
182 | interactively, all its arguments are @code{nil}. | |
183 | ||
2726b68b RS |
184 | If splitting would result in making a window that is smaller than |
185 | @code{window-min-height} or @code{window-min-width}, the function | |
186 | signals an error and does not split the window at all. | |
187 | ||
188 | The following example starts with one window on a screen that is 50 | |
926a5166 | 189 | lines high by 80 columns wide; then it splits the window. |
b1b12a8e RS |
190 | |
191 | @smallexample | |
192 | @group | |
193 | (setq w (selected-window)) | |
194 | @result{} #<window 8 on windows.texi> | |
195 | (window-edges) ; @r{Edges in order:} | |
196 | @result{} (0 0 80 50) ; @r{left--top--right--bottom} | |
197 | @end group | |
198 | ||
199 | @group | |
200 | ;; @r{Returns window created} | |
3c29caa8 | 201 | (setq w2 (split-window w 15)) |
b1b12a8e RS |
202 | @result{} #<window 28 on windows.texi> |
203 | @end group | |
204 | @group | |
205 | (window-edges w2) | |
206 | @result{} (0 15 80 50) ; @r{Bottom window;} | |
207 | ; @r{top is line 15} | |
208 | @end group | |
209 | @group | |
210 | (window-edges w) | |
211 | @result{} (0 0 80 15) ; @r{Top window} | |
212 | @end group | |
213 | @end smallexample | |
214 | ||
215 | The screen looks like this: | |
216 | ||
217 | @smallexample | |
218 | @group | |
3c29caa8 DH |
219 | __________ |
220 | | | line 0 | |
b1b12a8e RS |
221 | | w | |
222 | |__________| | |
223 | | | line 15 | |
224 | | w2 | | |
225 | |__________| | |
226 | line 50 | |
227 | column 0 column 80 | |
228 | @end group | |
229 | @end smallexample | |
230 | ||
926a5166 | 231 | Next, split the top window horizontally: |
b1b12a8e RS |
232 | |
233 | @smallexample | |
234 | @group | |
235 | (setq w3 (split-window w 35 t)) | |
236 | @result{} #<window 32 on windows.texi> | |
237 | @end group | |
238 | @group | |
239 | (window-edges w3) | |
240 | @result{} (35 0 80 15) ; @r{Left edge at column 35} | |
241 | @end group | |
242 | @group | |
243 | (window-edges w) | |
244 | @result{} (0 0 35 15) ; @r{Right edge at column 35} | |
245 | @end group | |
246 | @group | |
247 | (window-edges w2) | |
248 | @result{} (0 15 80 50) ; @r{Bottom window unchanged} | |
249 | @end group | |
250 | @end smallexample | |
251 | ||
bda144f4 | 252 | @need 3000 |
926a5166 | 253 | Now the screen looks like this: |
b1b12a8e RS |
254 | |
255 | @smallexample | |
256 | @group | |
257 | column 35 | |
3c29caa8 DH |
258 | __________ |
259 | | | | line 0 | |
b1b12a8e RS |
260 | | w | w3 | |
261 | |___|______| | |
262 | | | line 15 | |
263 | | w2 | | |
264 | |__________| | |
265 | line 50 | |
266 | column 0 column 80 | |
267 | @end group | |
268 | @end smallexample | |
aeb2c306 JB |
269 | |
270 | Normally, Emacs indicates the border between two side-by-side windows | |
b8da16c6 | 271 | with a scroll bar (@pxref{Layout Parameters,Scroll Bars}) or @samp{|} |
aeb2c306 JB |
272 | characters. The display table can specify alternative border |
273 | characters; see @ref{Display Tables}. | |
b1b12a8e RS |
274 | @end deffn |
275 | ||
8241495d | 276 | @deffn Command split-window-vertically &optional size |
1911e6e5 | 277 | This function splits the selected window into two windows, one above the |
ebc6903b | 278 | other, leaving the upper of the two windows selected, with @var{size} |
1911e6e5 RS |
279 | lines. (If @var{size} is negative, then the lower of the two windows |
280 | gets @minus{} @var{size} lines and the upper window gets the rest, but | |
3a052bd3 LT |
281 | the upper window is still the one selected.) However, if |
282 | @code{split-window-keep-point} (see below) is @code{nil}, then either | |
283 | window can be selected. | |
284 | ||
285 | In other respects, this function is similar to @code{split-window}. | |
286 | In particular, the upper window is the original one and the return | |
287 | value is the new, lower window. | |
b1b12a8e RS |
288 | @end deffn |
289 | ||
3a052bd3 LT |
290 | @defopt split-window-keep-point |
291 | If this variable is non-@code{nil} (the default), then | |
292 | @code{split-window-vertically} behaves as described above. | |
293 | ||
294 | If it is @code{nil}, then @code{split-window-vertically} adjusts point | |
295 | in each of the two windows to avoid scrolling. (This is useful on | |
296 | slow terminals.) It selects whichever window contains the screen line | |
297 | that point was previously on. | |
298 | ||
299 | This variable only affects the behavior of @code{split-window-vertically}. | |
300 | It has no effect on the other functions described here. | |
301 | @end defopt | |
302 | ||
2468d0c0 | 303 | @deffn Command split-window-horizontally &optional size |
b1b12a8e | 304 | This function splits the selected window into two windows |
3a052bd3 LT |
305 | side-by-side, leaving the selected window on the left with @var{size} |
306 | columns. If @var{size} is negative, the rightmost window gets | |
307 | @minus{} @var{size} columns, but the leftmost window still remains | |
308 | selected. | |
b1b12a8e | 309 | |
8241495d RS |
310 | This function is basically an interface to @code{split-window}. |
311 | You could define a simplified version of the function like this: | |
b1b12a8e RS |
312 | |
313 | @smallexample | |
314 | @group | |
315 | (defun split-window-horizontally (&optional arg) | |
316 | "Split selected window into two windows, side by side..." | |
317 | (interactive "P") | |
513331d3 | 318 | @end group |
8241495d RS |
319 | @group |
320 | (let ((size (and arg (prefix-numeric-value arg)))) | |
321 | (and size (< size 0) | |
322 | (setq size (+ (window-width) size))) | |
323 | (split-window nil size t))) | |
b1b12a8e RS |
324 | @end group |
325 | @end smallexample | |
326 | @end deffn | |
327 | ||
328 | @defun one-window-p &optional no-mini all-frames | |
329 | This function returns non-@code{nil} if there is only one window. The | |
330 | argument @var{no-mini}, if non-@code{nil}, means don't count the | |
331 | minibuffer even if it is active; otherwise, the minibuffer window is | |
27704b78 | 332 | counted when it is active. |
b1b12a8e RS |
333 | |
334 | The argument @var{all-frames} specifies which frames to consider. Here | |
335 | are the possible values and their meanings: | |
336 | ||
337 | @table @asis | |
338 | @item @code{nil} | |
339 | Count the windows in the selected frame, plus the minibuffer used | |
340 | by that frame even if it lies in some other frame. | |
341 | ||
342 | @item @code{t} | |
343 | Count all windows in all existing frames. | |
344 | ||
345 | @item @code{visible} | |
346 | Count all windows in all visible frames. | |
347 | ||
bfe721d1 KH |
348 | @item 0 |
349 | Count all windows in all visible or iconified frames. | |
350 | ||
b1b12a8e RS |
351 | @item anything else |
352 | Count precisely the windows in the selected frame, and no others. | |
353 | @end table | |
354 | @end defun | |
355 | ||
356 | @node Deleting Windows | |
357 | @section Deleting Windows | |
358 | @cindex deleting windows | |
359 | ||
360 | A window remains visible on its frame unless you @dfn{delete} it by | |
361 | calling certain functions that delete windows. A deleted window cannot | |
362 | appear on the screen, but continues to exist as a Lisp object until | |
363 | there are no references to it. There is no way to cancel the deletion | |
364 | of a window aside from restoring a saved window configuration | |
365 | (@pxref{Window Configurations}). Restoring a window configuration also | |
366 | deletes any windows that aren't part of that configuration. | |
367 | ||
368 | When you delete a window, the space it took up is given to one | |
969fe9b5 | 369 | adjacent sibling. |
b1b12a8e RS |
370 | |
371 | @c Emacs 19 feature | |
372 | @defun window-live-p window | |
373 | This function returns @code{nil} if @var{window} is deleted, and | |
374 | @code{t} otherwise. | |
375 | ||
b22f3a19 | 376 | @strong{Warning:} Erroneous information or fatal errors may result from |
b1b12a8e RS |
377 | using a deleted window as if it were live. |
378 | @end defun | |
379 | ||
380 | @deffn Command delete-window &optional window | |
969fe9b5 RS |
381 | This function removes @var{window} from display, and returns @code{nil}. |
382 | If @var{window} is omitted, then the selected window is deleted. An | |
383 | error is signaled if there is only one window when @code{delete-window} | |
384 | is called. | |
b1b12a8e RS |
385 | @end deffn |
386 | ||
387 | @deffn Command delete-other-windows &optional window | |
388 | This function makes @var{window} the only window on its frame, by | |
389 | deleting the other windows in that frame. If @var{window} is omitted or | |
390 | @code{nil}, then the selected window is used by default. | |
391 | ||
969fe9b5 | 392 | The return value is @code{nil}. |
b1b12a8e RS |
393 | @end deffn |
394 | ||
3a052bd3 LT |
395 | @deffn Command delete-windows-on buffer-or-name &optional frame |
396 | This function deletes all windows showing @var{buffer-or-name}. If | |
397 | there are no windows showing @var{buffer-or-name}, it does nothing. | |
398 | @var{buffer-or-name} must be a buffer or the name of an existing | |
399 | buffer. | |
b1b12a8e RS |
400 | |
401 | @code{delete-windows-on} operates frame by frame. If a frame has | |
402 | several windows showing different buffers, then those showing | |
3a052bd3 LT |
403 | @var{buffer-or-name} are removed, and the others expand to fill the |
404 | space. If all windows in some frame are showing @var{buffer-or-name} | |
405 | (including the case where there is only one window), then the frame | |
406 | winds up with a single window showing another buffer chosen with | |
407 | @code{other-buffer}. @xref{The Buffer List}. | |
b1b12a8e | 408 | |
1911e6e5 RS |
409 | The argument @var{frame} controls which frames to operate on. This |
410 | function does not use it in quite the same way as the other functions | |
411 | which scan all windows; specifically, the values @code{t} and @code{nil} | |
412 | have the opposite of their meanings in other functions. Here are the | |
413 | full details: | |
b1b12a8e RS |
414 | |
415 | @itemize @bullet | |
416 | @item | |
1911e6e5 | 417 | If it is @code{nil}, operate on all frames. |
b1b12a8e | 418 | @item |
1911e6e5 | 419 | If it is @code{t}, operate on the selected frame. |
b1b12a8e RS |
420 | @item |
421 | If it is @code{visible}, operate on all visible frames. | |
1911e6e5 | 422 | @item |
bfe721d1 | 423 | If it is 0, operate on all visible or iconified frames. |
b1b12a8e RS |
424 | @item |
425 | If it is a frame, operate on that frame. | |
426 | @end itemize | |
427 | ||
428 | This function always returns @code{nil}. | |
429 | @end deffn | |
430 | ||
431 | @node Selecting Windows | |
432 | @section Selecting Windows | |
433 | @cindex selecting windows | |
434 | ||
435 | When a window is selected, the buffer in the window becomes the current | |
436 | buffer, and the cursor will appear in it. | |
437 | ||
438 | @defun selected-window | |
439 | This function returns the selected window. This is the window in | |
440 | which the cursor appears and to which many commands apply. | |
441 | @end defun | |
442 | ||
5a8a6af8 | 443 | @defun select-window window &optional norecord |
b1b12a8e | 444 | This function makes @var{window} the selected window. The cursor then |
3a052bd3 LT |
445 | appears in @var{window} (on redisplay). Unless @var{window} was |
446 | already selected, @code{select-window} makes @var{window}'s buffer the | |
447 | current buffer. | |
b1b12a8e | 448 | |
5a8a6af8 RS |
449 | Normally @var{window}'s selected buffer is moved to the front of the |
450 | buffer list, but if @var{norecord} is non-@code{nil}, the buffer list | |
451 | order is unchanged. | |
452 | ||
b1b12a8e RS |
453 | The return value is @var{window}. |
454 | ||
455 | @example | |
456 | @group | |
457 | (setq w (next-window)) | |
458 | (select-window w) | |
459 | @result{} #<window 65 on windows.texi> | |
460 | @end group | |
461 | @end example | |
462 | @end defun | |
463 | ||
bfe721d1 | 464 | @defmac save-selected-window forms@dots{} |
ae473bd3 | 465 | This macro records the selected frame, as well as the selected window |
3a052bd3 | 466 | of each frame, executes @var{forms} in sequence, then restores the |
0adde683 RS |
467 | earlier selected frame and windows. It also saves and restores the |
468 | current buffer. It returns the value of the last form in @var{forms}. | |
9258d604 RS |
469 | |
470 | This macro does not save or restore anything about the sizes, | |
471 | arrangement or contents of windows; therefore, if the @var{forms} | |
472 | change them, the change persists. If the previously selected window | |
3a052bd3 LT |
473 | of some frame is no longer live at the time of exit from @var{forms}, |
474 | that frame's selected window is left alone. If the previously | |
475 | selected window is no longer live, then whatever window is selected at | |
476 | the end of @var{forms} remains selected. | |
bfe721d1 KH |
477 | @end defmac |
478 | ||
5a8a6af8 RS |
479 | @defmac with-selected-window window forms@dots{} |
480 | This macro selects @var{window} (without changing the buffer list), | |
481 | executes @var{forms} in sequence, then restores the previously | |
0adde683 RS |
482 | selected window and current buffer. It is just like |
483 | @code{save-selected-window}, except that it explicitly selects | |
484 | @var{window}, also without altering the buffer list sequence. | |
5a8a6af8 RS |
485 | @end defmac |
486 | ||
b1b12a8e RS |
487 | @cindex finding windows |
488 | The following functions choose one of the windows on the screen, | |
489 | offering various criteria for the choice. | |
490 | ||
b3910238 | 491 | @defun get-lru-window &optional frame dedicated |
b1b12a8e | 492 | This function returns the window least recently ``used'' (that is, |
f8295bfb NR |
493 | selected). If any full-width windows are present, it only considers |
494 | these. The selected window is always the most recently used window. | |
b1b12a8e RS |
495 | |
496 | The selected window can be the least recently used window if it is the | |
497 | only window. A newly created window becomes the least recently used | |
43954849 | 498 | window until it is selected. A minibuffer window is never a |
b3910238 SM |
499 | candidate. Dedicated windows are never candidates unless the |
500 | @var{dedicated} argument is non-@code{nil}, so if all | |
43954849 | 501 | existing windows are dedicated, the value is @code{nil}. |
b1b12a8e | 502 | |
c638661f | 503 | The argument @var{frame} controls which windows are considered. |
b1b12a8e RS |
504 | |
505 | @itemize @bullet | |
506 | @item | |
507 | If it is @code{nil}, consider windows on the selected frame. | |
508 | @item | |
509 | If it is @code{t}, consider windows on all frames. | |
510 | @item | |
511 | If it is @code{visible}, consider windows on all visible frames. | |
512 | @item | |
bfe721d1 KH |
513 | If it is 0, consider windows on all visible or iconified frames. |
514 | @item | |
b1b12a8e RS |
515 | If it is a frame, consider windows on that frame. |
516 | @end itemize | |
517 | @end defun | |
518 | ||
b3910238 | 519 | @defun get-largest-window &optional frame dedicated |
b1b12a8e RS |
520 | This function returns the window with the largest area (height times |
521 | width). If there are no side-by-side windows, then this is the window | |
522 | with the most lines. A minibuffer window is never a candidate. | |
b3910238 SM |
523 | Dedicated windows are never candidates unless the |
524 | @var{dedicated} argument is non-@code{nil}, so if all existing windows | |
43954849 | 525 | are dedicated, the value is @code{nil}. |
b1b12a8e | 526 | |
43954849 RS |
527 | If there are two candidate windows of the same size, this function |
528 | prefers the one that comes first in the cyclic ordering of windows | |
529 | (see following section), starting from the selected window. | |
b1b12a8e | 530 | |
1911e6e5 RS |
531 | The argument @var{frame} controls which set of windows to |
532 | consider. See @code{get-lru-window}, above. | |
b1b12a8e RS |
533 | @end defun |
534 | ||
1e8ca3a9 EZ |
535 | @cindex window that satisfies a predicate |
536 | @cindex conditional selection of windows | |
537 | @defun get-window-with-predicate predicate &optional minibuf all-frames default | |
538 | This function returns a window satisfying @var{predicate}. It cycles | |
539 | through all visible windows using @code{walk-windows} (@pxref{Cyclic | |
b0d4743a | 540 | Window Ordering}), calling @var{predicate} on each one of them |
1e8ca3a9 EZ |
541 | with that window as its argument. The function returns the first |
542 | window for which @var{predicate} returns a non-@code{nil} value; if | |
543 | that never happens, it returns @var{default}. | |
544 | ||
545 | The optional arguments @var{minibuf} and @var{all-frames} specify the | |
546 | set of windows to include in the scan. See the description of | |
547 | @code{next-window} in @ref{Cyclic Window Ordering}, for details. | |
548 | @end defun | |
549 | ||
b1b12a8e RS |
550 | @node Cyclic Window Ordering |
551 | @comment node-name, next, previous, up | |
552 | @section Cyclic Ordering of Windows | |
553 | @cindex cyclic ordering of windows | |
554 | @cindex ordering of windows, cyclic | |
3c29caa8 | 555 | @cindex window ordering, cyclic |
b1b12a8e RS |
556 | |
557 | When you use the command @kbd{C-x o} (@code{other-window}) to select | |
558 | the next window, it moves through all the windows on the screen in a | |
559 | specific cyclic order. For any given configuration of windows, this | |
560 | order never varies. It is called the @dfn{cyclic ordering of windows}. | |
561 | ||
562 | This ordering generally goes from top to bottom, and from left to | |
563 | right. But it may go down first or go right first, depending on the | |
564 | order in which the windows were split. | |
565 | ||
566 | If the first split was vertical (into windows one above each other), | |
567 | and then the subwindows were split horizontally, then the ordering is | |
568 | left to right in the top of the frame, and then left to right in the | |
569 | next lower part of the frame, and so on. If the first split was | |
570 | horizontal, the ordering is top to bottom in the left part, and so on. | |
571 | In general, within each set of siblings at any level in the window tree, | |
572 | the order is left to right, or top to bottom. | |
573 | ||
574 | @defun next-window &optional window minibuf all-frames | |
575 | @cindex minibuffer window | |
576 | This function returns the window following @var{window} in the cyclic | |
c638661f RS |
577 | ordering of windows. This is the window that @kbd{C-x o} would select |
578 | if typed when @var{window} is selected. If @var{window} is the only | |
b1b12a8e RS |
579 | window visible, then this function returns @var{window}. If omitted, |
580 | @var{window} defaults to the selected window. | |
581 | ||
582 | The value of the argument @var{minibuf} determines whether the | |
583 | minibuffer is included in the window order. Normally, when | |
584 | @var{minibuf} is @code{nil}, the minibuffer is included if it is | |
585 | currently active; this is the behavior of @kbd{C-x o}. (The minibuffer | |
586 | window is active while the minibuffer is in use. @xref{Minibuffers}.) | |
587 | ||
588 | If @var{minibuf} is @code{t}, then the cyclic ordering includes the | |
589 | minibuffer window even if it is not active. | |
590 | ||
591 | If @var{minibuf} is neither @code{t} nor @code{nil}, then the minibuffer | |
592 | window is not included even if it is active. | |
593 | ||
594 | The argument @var{all-frames} specifies which frames to consider. Here | |
595 | are the possible values and their meanings: | |
596 | ||
597 | @table @asis | |
598 | @item @code{nil} | |
599 | Consider all the windows in @var{window}'s frame, plus the minibuffer | |
3a052bd3 LT |
600 | used by that frame even if it lies in some other frame. If the |
601 | minibuffer counts (as determined by @var{minibuf}), then all windows on | |
602 | all frames that share that minibuffer count too. | |
b1b12a8e RS |
603 | |
604 | @item @code{t} | |
605 | Consider all windows in all existing frames. | |
606 | ||
607 | @item @code{visible} | |
608 | Consider all windows in all visible frames. (To get useful results, you | |
609 | must ensure @var{window} is in a visible frame.) | |
610 | ||
83abd543 | 611 | @item 0 |
bfe721d1 KH |
612 | Consider all windows in all visible or iconified frames. |
613 | ||
27704b78 RS |
614 | @item a frame |
615 | Consider all windows on that frame. | |
616 | ||
b1b12a8e RS |
617 | @item anything else |
618 | Consider precisely the windows in @var{window}'s frame, and no others. | |
619 | @end table | |
620 | ||
3c29caa8 | 621 | This example assumes there are two windows, both displaying the |
b1b12a8e RS |
622 | buffer @samp{windows.texi}: |
623 | ||
624 | @example | |
625 | @group | |
626 | (selected-window) | |
627 | @result{} #<window 56 on windows.texi> | |
628 | @end group | |
629 | @group | |
630 | (next-window (selected-window)) | |
631 | @result{} #<window 52 on windows.texi> | |
632 | @end group | |
633 | @group | |
634 | (next-window (next-window (selected-window))) | |
635 | @result{} #<window 56 on windows.texi> | |
636 | @end group | |
637 | @end example | |
638 | @end defun | |
639 | ||
640 | @defun previous-window &optional window minibuf all-frames | |
641 | This function returns the window preceding @var{window} in the cyclic | |
642 | ordering of windows. The other arguments specify which windows to | |
643 | include in the cycle, as in @code{next-window}. | |
644 | @end defun | |
645 | ||
8241495d | 646 | @deffn Command other-window count &optional all-frames |
b1b12a8e | 647 | This function selects the @var{count}th following window in the cyclic |
969fe9b5 RS |
648 | order. If count is negative, then it moves back @minus{}@var{count} |
649 | windows in the cycle, rather than forward. It returns @code{nil}. | |
b1b12a8e | 650 | |
75708135 | 651 | The argument @var{all-frames} has the same meaning as in |
8241495d RS |
652 | @code{next-window}, but the @var{minibuf} argument of @code{next-window} |
653 | is always effectively @code{nil}. | |
654 | ||
b1b12a8e RS |
655 | In an interactive call, @var{count} is the numeric prefix argument. |
656 | @end deffn | |
657 | ||
658 | @c Emacs 19 feature | |
659 | @defun walk-windows proc &optional minibuf all-frames | |
ae473bd3 RS |
660 | This function cycles through all windows. It calls the function |
661 | @code{proc} once for each window, with the window as its sole | |
662 | argument. | |
b1b12a8e RS |
663 | |
664 | The optional arguments @var{minibuf} and @var{all-frames} specify the | |
665 | set of windows to include in the scan. See @code{next-window}, above, | |
666 | for details. | |
667 | @end defun | |
668 | ||
e258eedc GM |
669 | @defun window-list &optional frame minibuf window |
670 | This function returns a list of the windows on @var{frame}, starting | |
658819b6 RS |
671 | with @var{window}. If @var{frame} is @code{nil} or omitted, |
672 | @code{window-list} uses the selected frame instead; if @var{window} is | |
673 | @code{nil} or omitted, it uses the selected window. | |
674 | ||
675 | The value of @var{minibuf} determines if the minibuffer window is | |
676 | included in the result list. If @var{minibuf} is @code{t}, the result | |
677 | always includes the minibuffer window. If @var{minibuf} is @code{nil} | |
678 | or omitted, that includes the minibuffer window if it is active. If | |
679 | @var{minibuf} is neither @code{nil} nor @code{t}, the result never | |
680 | includes the minibuffer window. | |
429994d8 | 681 | @end defun |
e258eedc | 682 | |
b1b12a8e RS |
683 | @node Buffers and Windows |
684 | @section Buffers and Windows | |
685 | @cindex examining windows | |
686 | @cindex windows, controlling precisely | |
687 | @cindex buffers, controlled in windows | |
688 | ||
689 | This section describes low-level functions to examine windows or to | |
690 | display buffers in windows in a precisely controlled fashion. | |
691 | @iftex | |
692 | See the following section for | |
693 | @end iftex | |
37680279 | 694 | @ifnottex |
b1b12a8e | 695 | @xref{Displaying Buffers}, for |
37680279 | 696 | @end ifnottex |
b1b12a8e RS |
697 | related functions that find a window to use and specify a buffer for it. |
698 | The functions described there are easier to use than these, but they | |
699 | employ heuristics in choosing or creating a window; use these functions | |
700 | when you need complete control. | |
701 | ||
6ab4745b | 702 | @defun set-window-buffer window buffer-or-name &optional keep-margins |
b1b12a8e | 703 | This function makes @var{window} display @var{buffer-or-name} as its |
3a052bd3 LT |
704 | contents. It returns @code{nil}. @var{buffer-or-name} must be a |
705 | buffer, or the name of an existing buffer. This is the fundamental | |
706 | primitive for changing which buffer is displayed in a window, and all | |
707 | ways of doing that call this function. | |
b1b12a8e RS |
708 | |
709 | @example | |
710 | @group | |
711 | (set-window-buffer (selected-window) "foo") | |
712 | @result{} nil | |
713 | @end group | |
714 | @end example | |
6ab4745b RS |
715 | |
716 | Normally, displaying @var{buffer} in @var{window} resets the window's | |
27704b78 RS |
717 | display margins, fringe widths, scroll bar settings, and position |
718 | based on the local variables of @var{buffer}. However, if | |
719 | @var{keep-margins} is non-@code{nil}, the display margins and fringe | |
720 | widths of @var{window} remain unchanged. @xref{Fringes}. | |
b1b12a8e RS |
721 | @end defun |
722 | ||
475aab0d CY |
723 | @defvar buffer-display-count |
724 | This buffer-local variable records the number of times a buffer is | |
725 | displayed in a window. It is incremented each time | |
726 | @code{set-window-buffer} is called for the buffer. | |
727 | @end defvar | |
728 | ||
b1b12a8e RS |
729 | @defun window-buffer &optional window |
730 | This function returns the buffer that @var{window} is displaying. If | |
731 | @var{window} is omitted, this function returns the buffer for the | |
732 | selected window. | |
733 | ||
734 | @example | |
735 | @group | |
736 | (window-buffer) | |
737 | @result{} #<buffer windows.texi> | |
738 | @end group | |
739 | @end example | |
740 | @end defun | |
741 | ||
742 | @defun get-buffer-window buffer-or-name &optional all-frames | |
743 | This function returns a window currently displaying | |
744 | @var{buffer-or-name}, or @code{nil} if there is none. If there are | |
745 | several such windows, then the function returns the first one in the | |
746 | cyclic ordering of windows, starting from the selected window. | |
747 | @xref{Cyclic Window Ordering}. | |
748 | ||
749 | The argument @var{all-frames} controls which windows to consider. | |
750 | ||
751 | @itemize @bullet | |
752 | @item | |
753 | If it is @code{nil}, consider windows on the selected frame. | |
754 | @item | |
755 | If it is @code{t}, consider windows on all frames. | |
756 | @item | |
757 | If it is @code{visible}, consider windows on all visible frames. | |
758 | @item | |
bfe721d1 KH |
759 | If it is 0, consider windows on all visible or iconified frames. |
760 | @item | |
b1b12a8e RS |
761 | If it is a frame, consider windows on that frame. |
762 | @end itemize | |
763 | @end defun | |
764 | ||
3c29caa8 DH |
765 | @defun get-buffer-window-list buffer-or-name &optional minibuf all-frames |
766 | This function returns a list of all the windows currently displaying | |
767 | @var{buffer-or-name}. | |
768 | ||
769 | The two optional arguments work like the optional arguments of | |
770 | @code{next-window} (@pxref{Cyclic Window Ordering}); they are @emph{not} | |
771 | like the single optional argument of @code{get-buffer-window}. Perhaps | |
772 | we should change @code{get-buffer-window} in the future to make it | |
773 | compatible with the other functions. | |
3c29caa8 DH |
774 | @end defun |
775 | ||
a9f0a989 | 776 | @defvar buffer-display-time |
a9f0a989 RS |
777 | This variable records the time at which a buffer was last made visible |
778 | in a window. It is always local in each buffer; each time | |
779 | @code{set-window-buffer} is called, it sets this variable to | |
780 | @code{(current-time)} in the specified buffer (@pxref{Time of Day}). | |
1911e6e5 | 781 | When a buffer is first created, @code{buffer-display-time} starts out |
a9f0a989 RS |
782 | with the value @code{nil}. |
783 | @end defvar | |
784 | ||
b1b12a8e RS |
785 | @node Displaying Buffers |
786 | @section Displaying Buffers in Windows | |
787 | @cindex switching to a buffer | |
788 | @cindex displaying a buffer | |
789 | ||
790 | In this section we describe convenient functions that choose a window | |
791 | automatically and use it to display a specified buffer. These functions | |
792 | can also split an existing window in certain circumstances. We also | |
793 | describe variables that parameterize the heuristics used for choosing a | |
794 | window. | |
795 | @iftex | |
796 | See the preceding section for | |
797 | @end iftex | |
37680279 | 798 | @ifnottex |
b1b12a8e | 799 | @xref{Buffers and Windows}, for |
37680279 | 800 | @end ifnottex |
a9f0a989 RS |
801 | low-level functions that give you more precise control. All of these |
802 | functions work by calling @code{set-window-buffer}. | |
b1b12a8e RS |
803 | |
804 | Do not use the functions in this section in order to make a buffer | |
805 | current so that a Lisp program can access or modify it; they are too | |
806 | drastic for that purpose, since they change the display of buffers in | |
969fe9b5 | 807 | windows, which would be gratuitous and surprise the user. Instead, use |
1911e6e5 RS |
808 | @code{set-buffer} and @code{save-current-buffer} (@pxref{Current |
809 | Buffer}), which designate buffers as current for programmed access | |
810 | without affecting the display of buffers in windows. | |
b1b12a8e RS |
811 | |
812 | @deffn Command switch-to-buffer buffer-or-name &optional norecord | |
813 | This function makes @var{buffer-or-name} the current buffer, and also | |
814 | displays the buffer in the selected window. This means that a human can | |
815 | see the buffer and subsequent keyboard commands will apply to it. | |
816 | Contrast this with @code{set-buffer}, which makes @var{buffer-or-name} | |
817 | the current buffer but does not display it in the selected window. | |
818 | @xref{Current Buffer}. | |
819 | ||
22697dac KH |
820 | If @var{buffer-or-name} does not identify an existing buffer, then a new |
821 | buffer by that name is created. The major mode for the new buffer is | |
822 | set according to the variable @code{default-major-mode}. @xref{Auto | |
3a052bd3 LT |
823 | Major Mode}. If @var{buffer-or-name} is @code{nil}, |
824 | @code{switch-to-buffer} chooses a buffer using @code{other-buffer}. | |
b1b12a8e | 825 | |
969fe9b5 RS |
826 | Normally the specified buffer is put at the front of the buffer list |
827 | (both the selected frame's buffer list and the frame-independent buffer | |
828 | list). This affects the operation of @code{other-buffer}. However, if | |
b1b12a8e RS |
829 | @var{norecord} is non-@code{nil}, this is not done. @xref{The Buffer |
830 | List}. | |
831 | ||
832 | The @code{switch-to-buffer} function is often used interactively, as | |
833 | the binding of @kbd{C-x b}. It is also used frequently in programs. It | |
996d82f8 | 834 | returns the buffer that it switched to. |
b1b12a8e RS |
835 | @end deffn |
836 | ||
3a052bd3 LT |
837 | The next two functions are similar to @code{switch-to-buffer}, except |
838 | for the described features. | |
839 | ||
f9f59935 | 840 | @deffn Command switch-to-buffer-other-window buffer-or-name &optional norecord |
b1b12a8e RS |
841 | This function makes @var{buffer-or-name} the current buffer and |
842 | displays it in a window not currently selected. It then selects that | |
843 | window. The handling of the buffer is the same as in | |
844 | @code{switch-to-buffer}. | |
845 | ||
c638661f RS |
846 | The currently selected window is absolutely never used to do the job. |
847 | If it is the only window, then it is split to make a distinct window for | |
848 | this purpose. If the selected window is already displaying the buffer, | |
849 | then it continues to do so, but another window is nonetheless found to | |
850 | display it in as well. | |
f9f59935 RS |
851 | |
852 | This function updates the buffer list just like @code{switch-to-buffer} | |
853 | unless @var{norecord} is non-@code{nil}. | |
b1b12a8e RS |
854 | @end deffn |
855 | ||
f9f59935 | 856 | @defun pop-to-buffer buffer-or-name &optional other-window norecord |
b1b12a8e RS |
857 | This function makes @var{buffer-or-name} the current buffer and |
858 | switches to it in some window, preferably not the window previously | |
859 | selected. The ``popped-to'' window becomes the selected window within | |
996d82f8 | 860 | its frame. The return value is the buffer that was switched to. |
27704b78 RS |
861 | If @var{buffer-or-name} is @code{nil}, that means to choose some |
862 | other buffer, but you don't specify which. | |
b1b12a8e RS |
863 | |
864 | If the variable @code{pop-up-frames} is non-@code{nil}, | |
865 | @code{pop-to-buffer} looks for a window in any visible frame already | |
866 | displaying the buffer; if there is one, it returns that window and makes | |
867 | it be selected within its frame. If there is none, it creates a new | |
868 | frame and displays the buffer in it. | |
869 | ||
870 | If @code{pop-up-frames} is @code{nil}, then @code{pop-to-buffer} | |
871 | operates entirely within the selected frame. (If the selected frame has | |
872 | just a minibuffer, @code{pop-to-buffer} operates within the most | |
873 | recently selected frame that was not just a minibuffer.) | |
874 | ||
875 | If the variable @code{pop-up-windows} is non-@code{nil}, windows may | |
876 | be split to create a new window that is different from the original | |
877 | window. For details, see @ref{Choosing Window}. | |
878 | ||
879 | If @var{other-window} is non-@code{nil}, @code{pop-to-buffer} finds or | |
880 | creates another window even if @var{buffer-or-name} is already visible | |
881 | in the selected window. Thus @var{buffer-or-name} could end up | |
882 | displayed in two windows. On the other hand, if @var{buffer-or-name} is | |
883 | already displayed in the selected window and @var{other-window} is | |
884 | @code{nil}, then the selected window is considered sufficient display | |
885 | for @var{buffer-or-name}, so that nothing needs to be done. | |
886 | ||
bfe721d1 KH |
887 | All the variables that affect @code{display-buffer} affect |
888 | @code{pop-to-buffer} as well. @xref{Choosing Window}. | |
889 | ||
b1b12a8e | 890 | If @var{buffer-or-name} is a string that does not name an existing |
22697dac KH |
891 | buffer, a buffer by that name is created. The major mode for the new |
892 | buffer is set according to the variable @code{default-major-mode}. | |
893 | @xref{Auto Major Mode}. | |
f9f59935 RS |
894 | |
895 | This function updates the buffer list just like @code{switch-to-buffer} | |
896 | unless @var{norecord} is non-@code{nil}. | |
b1b12a8e RS |
897 | @end defun |
898 | ||
3a052bd3 LT |
899 | @deffn Command replace-buffer-in-windows buffer-or-name |
900 | This function replaces @var{buffer-or-name} with some other buffer in all | |
901 | windows displaying it. It chooses the other buffer with | |
bfe721d1 KH |
902 | @code{other-buffer}. In the usual applications of this function, you |
903 | don't care which other buffer is used; you just want to make sure that | |
3a052bd3 | 904 | @var{buffer-or-name} is no longer displayed. |
bfe721d1 KH |
905 | |
906 | This function returns @code{nil}. | |
907 | @end deffn | |
908 | ||
b1b12a8e RS |
909 | @node Choosing Window |
910 | @section Choosing a Window for Display | |
911 | ||
c638661f | 912 | This section describes the basic facility that chooses a window to |
b1b12a8e RS |
913 | display a buffer in---@code{display-buffer}. All the higher-level |
914 | functions and commands use this subroutine. Here we describe how to use | |
915 | @code{display-buffer} and how to customize it. | |
916 | ||
f9f59935 | 917 | @deffn Command display-buffer buffer-or-name &optional not-this-window frame |
b1b12a8e RS |
918 | This command makes @var{buffer-or-name} appear in some window, like |
919 | @code{pop-to-buffer}, but it does not select that window and does not | |
920 | make the buffer current. The identity of the selected window is | |
3a052bd3 LT |
921 | unaltered by this function. @var{buffer-or-name} must be a buffer, or |
922 | the name of an existing buffer. | |
b1b12a8e RS |
923 | |
924 | If @var{not-this-window} is non-@code{nil}, it means to display the | |
925 | specified buffer in a window other than the selected one, even if it is | |
926 | already on display in the selected window. This can cause the buffer to | |
927 | appear in two windows at once. Otherwise, if @var{buffer-or-name} is | |
928 | already being displayed in any window, that is good enough, so this | |
929 | function does nothing. | |
930 | ||
931 | @code{display-buffer} returns the window chosen to display | |
932 | @var{buffer-or-name}. | |
933 | ||
f9f59935 | 934 | If the argument @var{frame} is non-@code{nil}, it specifies which frames |
1911e6e5 RS |
935 | to check when deciding whether the buffer is already displayed. If the |
936 | buffer is already displayed in some window on one of these frames, | |
937 | @code{display-buffer} simply returns that window. Here are the possible | |
938 | values of @var{frame}: | |
939 | ||
940 | @itemize @bullet | |
941 | @item | |
942 | If it is @code{nil}, consider windows on the selected frame. | |
3a052bd3 | 943 | (Actually, the last non-minibuffer frame.) |
1911e6e5 RS |
944 | @item |
945 | If it is @code{t}, consider windows on all frames. | |
946 | @item | |
947 | If it is @code{visible}, consider windows on all visible frames. | |
948 | @item | |
949 | If it is 0, consider windows on all visible or iconified frames. | |
950 | @item | |
951 | If it is a frame, consider windows on that frame. | |
952 | @end itemize | |
f9f59935 | 953 | |
b1b12a8e RS |
954 | Precisely how @code{display-buffer} finds or creates a window depends on |
955 | the variables described below. | |
956 | @end deffn | |
957 | ||
704bdba1 GM |
958 | @defopt display-buffer-reuse-frames |
959 | If this variable is non-@code{nil}, @code{display-buffer} searches | |
960 | existing frames for a window displaying the buffer. If the buffer is | |
961 | already displayed in a window in some frame, @code{display-buffer} makes | |
962 | the frame visible and raises it, to use that window. If the buffer is | |
963 | not already displayed, or if @code{display-buffer-reuse-frames} is | |
964 | @code{nil}, @code{display-buffer}'s behavior is determined by other | |
965 | variables, described below. | |
966 | @end defopt | |
967 | ||
b1b12a8e RS |
968 | @defopt pop-up-windows |
969 | This variable controls whether @code{display-buffer} makes new windows. | |
970 | If it is non-@code{nil} and there is only one window, then that window | |
971 | is split. If it is @code{nil}, then @code{display-buffer} does not | |
972 | split the single window, but uses it whole. | |
973 | @end defopt | |
974 | ||
975 | @defopt split-height-threshold | |
976 | This variable determines when @code{display-buffer} may split a window, | |
977 | if there are multiple windows. @code{display-buffer} always splits the | |
978 | largest window if it has at least this many lines. If the largest | |
979 | window is not this tall, it is split only if it is the sole window and | |
980 | @code{pop-up-windows} is non-@code{nil}. | |
981 | @end defopt | |
982 | ||
4f0308e1 GM |
983 | @defopt even-window-heights |
984 | This variable determines if @code{display-buffer} should even out window | |
985 | heights if the buffer gets displayed in an existing window, above or | |
986 | beneath another existing window. If @code{even-window-heights} is | |
987 | @code{t}, the default, window heights will be evened out. If | |
5fe3b9bc | 988 | @code{even-window-heights} is @code{nil}, the original window heights |
4f0308e1 | 989 | will be left alone. |
fbd9f276 | 990 | @end defopt |
4f0308e1 | 991 | |
b1b12a8e RS |
992 | @c Emacs 19 feature |
993 | @defopt pop-up-frames | |
994 | This variable controls whether @code{display-buffer} makes new frames. | |
995 | If it is non-@code{nil}, @code{display-buffer} looks for an existing | |
996 | window already displaying the desired buffer, on any visible frame. If | |
997 | it finds one, it returns that window. Otherwise it makes a new frame. | |
998 | The variables @code{pop-up-windows} and @code{split-height-threshold} do | |
999 | not matter if @code{pop-up-frames} is non-@code{nil}. | |
1000 | ||
1001 | If @code{pop-up-frames} is @code{nil}, then @code{display-buffer} either | |
1002 | splits a window or reuses one. | |
1003 | ||
1004 | @xref{Frames}, for more information. | |
1005 | @end defopt | |
1006 | ||
1007 | @c Emacs 19 feature | |
27704b78 | 1008 | @defopt pop-up-frame-function |
b1b12a8e RS |
1009 | This variable specifies how to make a new frame if @code{pop-up-frames} |
1010 | is non-@code{nil}. | |
1011 | ||
1012 | Its value should be a function of no arguments. When | |
1013 | @code{display-buffer} makes a new frame, it does so by calling that | |
1014 | function, which should return a frame. The default value of the | |
c638661f | 1015 | variable is a function that creates a frame using parameters from |
b1b12a8e | 1016 | @code{pop-up-frame-alist}. |
b52a26fb | 1017 | @end defopt |
b1b12a8e | 1018 | |
8241495d | 1019 | @defopt pop-up-frame-alist |
b1b12a8e RS |
1020 | This variable holds an alist specifying frame parameters used when |
1021 | @code{display-buffer} makes a new frame. @xref{Frame Parameters}, for | |
1022 | more information about frame parameters. | |
8241495d | 1023 | @end defopt |
b1b12a8e | 1024 | |
1911e6e5 | 1025 | @defopt special-display-buffer-names |
c2264295 RS |
1026 | A list of buffer names for buffers that should be displayed specially. |
1027 | If the buffer's name is in this list, @code{display-buffer} handles the | |
1028 | buffer specially. | |
1029 | ||
1030 | By default, special display means to give the buffer a dedicated frame. | |
bfe721d1 KH |
1031 | |
1032 | If an element is a list, instead of a string, then the @sc{car} of the | |
c1f21754 RS |
1033 | list is the buffer name, and the rest of the list says how to create |
1034 | the frame. There are two possibilities for the rest of the list (its | |
1035 | @sc{cdr}). It can be an alist, specifying frame parameters, or it can | |
1036 | contain a function and arguments to give to it. (The function's first | |
1037 | argument is always the buffer to be displayed; the arguments from the | |
1038 | list come after that.) | |
1039 | ||
1040 | For example: | |
1041 | ||
1042 | @example | |
1043 | (("myfile" (minibuffer) (menu-bar-lines . 0))) | |
1044 | @end example | |
1045 | ||
1046 | @noindent | |
1047 | specifies to display a buffer named @samp{myfile} in a dedicated frame | |
1048 | with specified @code{minibuffer} and @code{menu-bar-lines} parameters. | |
27704b78 RS |
1049 | |
1050 | The list of frame parameters can also use the phony frame parameters | |
1051 | @code{same-frame} and @code{same-window}. If the specified frame | |
1052 | parameters include @code{(same-window . @var{value})} and @var{value} | |
1053 | is non-@code{nil}, that means to display the buffer in the current | |
1054 | selected window. Otherwise, if they include @code{(same-frame . | |
1055 | @var{value})} and @var{value} is non-@code{nil}, that means to display | |
1056 | the buffer in a new window in the currently selected frame. | |
1911e6e5 | 1057 | @end defopt |
c2264295 | 1058 | |
1911e6e5 | 1059 | @defopt special-display-regexps |
c2264295 RS |
1060 | A list of regular expressions that specify buffers that should be |
1061 | displayed specially. If the buffer's name matches any of the regular | |
1062 | expressions in this list, @code{display-buffer} handles the buffer | |
1063 | specially. | |
1064 | ||
1065 | By default, special display means to give the buffer a dedicated frame. | |
bfe721d1 KH |
1066 | |
1067 | If an element is a list, instead of a string, then the @sc{car} of the | |
1068 | list is the regular expression, and the rest of the list says how to | |
1069 | create the frame. See above, under @code{special-display-buffer-names}. | |
1911e6e5 | 1070 | @end defopt |
c2264295 | 1071 | |
4d25144d RS |
1072 | @defun special-display-p buffer-name |
1073 | This function returns non-@code{nil} if displaying a buffer | |
1074 | named @var{buffer-name} with @code{display-buffer} would | |
1075 | create a special frame. The value is @code{t} if it would | |
3a052bd3 | 1076 | use the default frame parameters, or else the specified list |
4d25144d RS |
1077 | of frame parameters. |
1078 | @end defun | |
1079 | ||
c2264295 RS |
1080 | @defvar special-display-function |
1081 | This variable holds the function to call to display a buffer specially. | |
1082 | It receives the buffer as an argument, and should return the window in | |
1083 | which it is displayed. | |
1084 | ||
1085 | The default value of this variable is | |
1086 | @code{special-display-popup-frame}. | |
1087 | @end defvar | |
1088 | ||
3a052bd3 | 1089 | @defun special-display-popup-frame buffer &optional args |
c2264295 RS |
1090 | This function makes @var{buffer} visible in a frame of its own. If |
1091 | @var{buffer} is already displayed in a window in some frame, it makes | |
1092 | the frame visible and raises it, to use that window. Otherwise, it | |
3a052bd3 LT |
1093 | creates a frame that will be dedicated to @var{buffer}. This |
1094 | function returns the window it used. | |
c638661f | 1095 | |
8241495d RS |
1096 | If @var{args} is an alist, it specifies frame parameters for the new |
1097 | frame. | |
1098 | ||
1099 | If @var{args} is a list whose @sc{car} is a symbol, then @code{(car | |
1100 | @var{args})} is called as a function to actually create and set up the | |
1101 | frame; it is called with @var{buffer} as first argument, and @code{(cdr | |
1102 | @var{args})} as additional arguments. | |
1103 | ||
1104 | This function always uses an existing window displaying @var{buffer}, | |
1105 | whether or not it is in a frame of its own; but if you set up the above | |
1106 | variables in your init file, before @var{buffer} was created, then | |
1107 | presumably the window was previously made by this function. | |
c2264295 RS |
1108 | @end defun |
1109 | ||
1110 | @defopt special-display-frame-alist | |
9a4ff31b | 1111 | @anchor{Definition of special-display-frame-alist} |
c2264295 RS |
1112 | This variable holds frame parameters for |
1113 | @code{special-display-popup-frame} to use when it creates a frame. | |
1114 | @end defopt | |
1115 | ||
864bd34b | 1116 | @defopt same-window-buffer-names |
bfe721d1 KH |
1117 | A list of buffer names for buffers that should be displayed in the |
1118 | selected window. If the buffer's name is in this list, | |
1119 | @code{display-buffer} handles the buffer by switching to it in the | |
1120 | selected window. | |
864bd34b | 1121 | @end defopt |
bfe721d1 | 1122 | |
864bd34b | 1123 | @defopt same-window-regexps |
bfe721d1 KH |
1124 | A list of regular expressions that specify buffers that should be |
1125 | displayed in the selected window. If the buffer's name matches any of | |
1126 | the regular expressions in this list, @code{display-buffer} handles the | |
1127 | buffer by switching to it in the selected window. | |
864bd34b | 1128 | @end defopt |
bfe721d1 | 1129 | |
4d25144d RS |
1130 | @defun same-window-p buffer-name |
1131 | This function returns @code{t} if displaying a buffer | |
1132 | named @var{buffer-name} with @code{display-buffer} would | |
1133 | put it in the selected window. | |
1134 | @end defun | |
1135 | ||
b1b12a8e RS |
1136 | @c Emacs 19 feature |
1137 | @defvar display-buffer-function | |
1138 | This variable is the most flexible way to customize the behavior of | |
1139 | @code{display-buffer}. If it is non-@code{nil}, it should be a function | |
1140 | that @code{display-buffer} calls to do the work. The function should | |
3a052bd3 | 1141 | accept two arguments, the first two arguments that @code{display-buffer} |
b1b12a8e | 1142 | received. It should choose or create a window, display the specified |
3a052bd3 | 1143 | buffer in it, and then return the window. |
b1b12a8e RS |
1144 | |
1145 | This hook takes precedence over all the other options and hooks | |
1146 | described above. | |
1147 | @end defvar | |
1148 | ||
1149 | @c Emacs 19 feature | |
1150 | @cindex dedicated window | |
1151 | A window can be marked as ``dedicated'' to its buffer. Then | |
969fe9b5 RS |
1152 | @code{display-buffer} will not try to use that window to display any |
1153 | other buffer. | |
b1b12a8e RS |
1154 | |
1155 | @defun window-dedicated-p window | |
27704b78 RS |
1156 | This function returns non-@code{nil} if @var{window} is marked as |
1157 | dedicated; otherwise @code{nil}. | |
b1b12a8e RS |
1158 | @end defun |
1159 | ||
1160 | @defun set-window-dedicated-p window flag | |
1161 | This function marks @var{window} as dedicated if @var{flag} is | |
1162 | non-@code{nil}, and nondedicated otherwise. | |
1163 | @end defun | |
1164 | ||
1165 | @node Window Point | |
1166 | @section Windows and Point | |
1167 | @cindex window position | |
1168 | @cindex window point | |
1169 | @cindex position in window | |
1170 | @cindex point in window | |
1171 | ||
1172 | Each window has its own value of point, independent of the value of | |
1173 | point in other windows displaying the same buffer. This makes it useful | |
1174 | to have multiple windows showing one buffer. | |
1175 | ||
1176 | @itemize @bullet | |
1177 | @item | |
1178 | The window point is established when a window is first created; it is | |
1179 | initialized from the buffer's point, or from the window point of another | |
1180 | window opened on the buffer if such a window exists. | |
1181 | ||
1182 | @item | |
f9f59935 RS |
1183 | Selecting a window sets the value of point in its buffer from the |
1184 | window's value of point. Conversely, deselecting a window sets the | |
1185 | window's value of point from that of the buffer. Thus, when you switch | |
1186 | between windows that display a given buffer, the point value for the | |
1187 | selected window is in effect in the buffer, while the point values for | |
1188 | the other windows are stored in those windows. | |
b1b12a8e RS |
1189 | |
1190 | @item | |
1191 | As long as the selected window displays the current buffer, the window's | |
1192 | point and the buffer's point always move together; they remain equal. | |
ae473bd3 | 1193 | @end itemize |
b1b12a8e | 1194 | |
ae473bd3 | 1195 | @noindent |
b1b12a8e | 1196 | @xref{Positions}, for more details on buffer positions. |
b1b12a8e RS |
1197 | |
1198 | As far as the user is concerned, point is where the cursor is, and | |
1199 | when the user switches to another buffer, the cursor jumps to the | |
1200 | position of point in that buffer. | |
1201 | ||
8241495d | 1202 | @defun window-point &optional window |
b1b12a8e RS |
1203 | This function returns the current position of point in @var{window}. |
1204 | For a nonselected window, this is the value point would have (in that | |
8241495d RS |
1205 | window's buffer) if that window were selected. If @var{window} is |
1206 | @code{nil}, the selected window is used. | |
b1b12a8e RS |
1207 | |
1208 | When @var{window} is the selected window and its buffer is also the | |
1209 | current buffer, the value returned is the same as point in that buffer. | |
1210 | ||
1211 | Strictly speaking, it would be more correct to return the | |
1212 | ``top-level'' value of point, outside of any @code{save-excursion} | |
1213 | forms. But that value is hard to find. | |
1214 | @end defun | |
1215 | ||
1216 | @defun set-window-point window position | |
1217 | This function positions point in @var{window} at position | |
eab4e895 | 1218 | @var{position} in @var{window}'s buffer. It returns @var{position}. |
7279aaf6 RS |
1219 | |
1220 | If @var{window} is selected, and its buffer is current, | |
1221 | this simply does @code{goto-char}. | |
b1b12a8e RS |
1222 | @end defun |
1223 | ||
1224 | @node Window Start | |
1225 | @section The Window Start Position | |
1226 | ||
1227 | Each window contains a marker used to keep track of a buffer position | |
c638661f | 1228 | that specifies where in the buffer display should start. This position |
b1b12a8e RS |
1229 | is called the @dfn{display-start} position of the window (or just the |
1230 | @dfn{start}). The character after this position is the one that appears | |
1231 | at the upper left corner of the window. It is usually, but not | |
1232 | inevitably, at the beginning of a text line. | |
1233 | ||
1234 | @defun window-start &optional window | |
1235 | @cindex window top line | |
1236 | This function returns the display-start position of window | |
1237 | @var{window}. If @var{window} is @code{nil}, the selected window is | |
3c29caa8 | 1238 | used. For example, |
b1b12a8e RS |
1239 | |
1240 | @example | |
1241 | @group | |
1242 | (window-start) | |
1243 | @result{} 7058 | |
1244 | @end group | |
1245 | @end example | |
1246 | ||
c638661f | 1247 | When you create a window, or display a different buffer in it, the |
b1b12a8e RS |
1248 | display-start position is set to a display-start position recently used |
1249 | for the same buffer, or 1 if the buffer doesn't have any. | |
1250 | ||
ea951766 | 1251 | Redisplay updates the window-start position (if you have not specified |
8241495d RS |
1252 | it explicitly since the previous redisplay)---for example, to make sure |
1253 | point appears on the screen. Nothing except redisplay automatically | |
1254 | changes the window-start position; if you move point, do not expect the | |
1255 | window-start position to change in response until after the next | |
1256 | redisplay. | |
ea951766 RS |
1257 | |
1258 | For a realistic example of using @code{window-start}, see the | |
eab4e895 | 1259 | description of @code{count-lines}. @xref{Definition of count-lines}. |
b1b12a8e RS |
1260 | @end defun |
1261 | ||
969fe9b5 | 1262 | @defun window-end &optional window update |
b1b12a8e RS |
1263 | This function returns the position of the end of the display in window |
1264 | @var{window}. If @var{window} is @code{nil}, the selected window is | |
1265 | used. | |
c638661f | 1266 | |
6c7418db RS |
1267 | Simply changing the buffer text or moving point does not update the |
1268 | value that @code{window-end} returns. The value is updated only when | |
969fe9b5 | 1269 | Emacs redisplays and redisplay completes without being preempted. |
6c7418db | 1270 | |
c638661f | 1271 | If the last redisplay of @var{window} was preempted, and did not finish, |
a283f4a3 | 1272 | Emacs does not know the position of the end of display in that window. |
969fe9b5 | 1273 | In that case, this function returns @code{nil}. |
c638661f | 1274 | |
41448f63 RS |
1275 | If @var{update} is non-@code{nil}, @code{window-end} always returns an |
1276 | up-to-date value for where the window ends, based on the current | |
1277 | @code{window-start} value. If the saved value is valid, | |
1278 | @code{window-end} returns that; otherwise it computes the correct | |
969fe9b5 | 1279 | value by scanning the buffer text. |
41448f63 RS |
1280 | |
1281 | Even if @var{update} is non-@code{nil}, @code{window-end} does not | |
1282 | attempt to scroll the display if point has moved off the screen, the | |
1283 | way real redisplay would do. It does not alter the | |
1284 | @code{window-start} value. In effect, it reports where the displayed | |
1285 | text will end if scrolling is not required. | |
b1b12a8e RS |
1286 | @end defun |
1287 | ||
1288 | @defun set-window-start window position &optional noforce | |
1289 | This function sets the display-start position of @var{window} to | |
c638661f | 1290 | @var{position} in @var{window}'s buffer. It returns @var{position}. |
b1b12a8e RS |
1291 | |
1292 | The display routines insist that the position of point be visible when a | |
1293 | buffer is displayed. Normally, they change the display-start position | |
1294 | (that is, scroll the window) whenever necessary to make point visible. | |
1295 | However, if you specify the start position with this function using | |
1296 | @code{nil} for @var{noforce}, it means you want display to start at | |
1297 | @var{position} even if that would put the location of point off the | |
1298 | screen. If this does place point off screen, the display routines move | |
1299 | point to the left margin on the middle line in the window. | |
1300 | ||
1301 | For example, if point @w{is 1} and you set the start of the window @w{to | |
1302 | 2}, then point would be ``above'' the top of the window. The display | |
1303 | routines will automatically move point if it is still 1 when redisplay | |
1304 | occurs. Here is an example: | |
1305 | ||
1306 | @example | |
1307 | @group | |
1308 | ;; @r{Here is what @samp{foo} looks like before executing} | |
1309 | ;; @r{the @code{set-window-start} expression.} | |
1310 | @end group | |
1311 | ||
1312 | @group | |
1313 | ---------- Buffer: foo ---------- | |
1314 | @point{}This is the contents of buffer foo. | |
1315 | 2 | |
1316 | 3 | |
1317 | 4 | |
1318 | 5 | |
1319 | 6 | |
1320 | ---------- Buffer: foo ---------- | |
1321 | @end group | |
1322 | ||
1323 | @group | |
1324 | (set-window-start | |
1325 | (selected-window) | |
1326 | (1+ (window-start))) | |
1327 | @result{} 2 | |
1328 | @end group | |
1329 | ||
1330 | @group | |
1331 | ;; @r{Here is what @samp{foo} looks like after executing} | |
1332 | ;; @r{the @code{set-window-start} expression.} | |
1333 | ---------- Buffer: foo ---------- | |
1334 | his is the contents of buffer foo. | |
1335 | 2 | |
1336 | 3 | |
1337 | @point{}4 | |
1338 | 5 | |
1339 | 6 | |
1340 | ---------- Buffer: foo ---------- | |
1341 | @end group | |
1342 | @end example | |
1343 | ||
1344 | If @var{noforce} is non-@code{nil}, and @var{position} would place point | |
1345 | off screen at the next redisplay, then redisplay computes a new window-start | |
1346 | position that works well with point, and thus @var{position} is not used. | |
b1b12a8e RS |
1347 | @end defun |
1348 | ||
00480554 | 1349 | @defun pos-visible-in-window-p &optional position window partially |
eab4e895 LT |
1350 | This function returns non-@code{nil} if @var{position} is within the |
1351 | range of text currently visible on the screen in @var{window}. It | |
1352 | returns @code{nil} if @var{position} is scrolled vertically out of | |
1353 | view. Locations that are partially obscured are not considered | |
00480554 MB |
1354 | visible unless @var{partially} is non-@code{nil}. The argument |
1355 | @var{position} defaults to the current position of point in | |
1356 | @var{window}; @var{window}, to the selected window. | |
1357 | ||
eab4e895 LT |
1358 | The @code{pos-visible-in-window-p} function considers only vertical |
1359 | scrolling. If @var{position} is out of view only because @var{window} | |
1360 | has been scrolled horizontally, @code{pos-visible-in-window-p} returns | |
1361 | non-@code{nil} anyway. @xref{Horizontal Scrolling}. | |
1362 | ||
1363 | If @var{position} is visible, @code{pos-visible-in-window-p} returns | |
1364 | @code{t} if @var{partially} is @code{nil}; if @var{partially} is | |
1365 | non-@code{nil}, it returns a list of the form @code{(@var{x} @var{y} | |
41ad5140 KS |
1366 | @var{partial})}, where @var{x} and @var{y} are the pixel coordinates |
1367 | relative to the top left corner of the window, and @var{partial} is | |
1368 | @code{nil} if the character after @var{position} is fully visible; | |
1369 | otherwise it is a cons @code{(@var{rtop} . @var{rbot})} where the | |
1370 | @var{rtop} and @var{rbot} specify the number of invisible pixels at | |
1371 | the top and bottom of the row at @var{position}. | |
eab4e895 | 1372 | |
00480554 | 1373 | Here is an example: |
b1b12a8e RS |
1374 | |
1375 | @example | |
1376 | @group | |
ae473bd3 | 1377 | ;; @r{If point is off the screen now, recenter it now.} |
b1b12a8e RS |
1378 | (or (pos-visible-in-window-p |
1379 | (point) (selected-window)) | |
1380 | (recenter 0)) | |
1381 | @end group | |
1382 | @end example | |
b1b12a8e RS |
1383 | @end defun |
1384 | ||
8241495d RS |
1385 | @node Textual Scrolling |
1386 | @section Textual Scrolling | |
1387 | @cindex textual scrolling | |
1388 | @cindex scrolling textually | |
1389 | ||
eab4e895 | 1390 | @dfn{Textual scrolling} means moving the text up or down through a |
8241495d RS |
1391 | window. It works by changing the value of the window's display-start |
1392 | location. It may also change the value of @code{window-point} to keep | |
1393 | point on the screen. | |
b1b12a8e | 1394 | |
8241495d RS |
1395 | Textual scrolling was formerly called ``vertical scrolling,'' but we |
1396 | changed its name to distinguish it from the new vertical fractional | |
1397 | scrolling feature (@pxref{Vertical Scrolling}). | |
b1b12a8e RS |
1398 | |
1399 | In the commands @code{scroll-up} and @code{scroll-down}, the directions | |
1400 | ``up'' and ``down'' refer to the motion of the text in the buffer at which | |
1401 | you are looking through the window. Imagine that the text is | |
1402 | written on a long roll of paper and that the scrolling commands move the | |
1403 | paper up and down. Thus, if you are looking at text in the middle of a | |
1404 | buffer and repeatedly call @code{scroll-down}, you will eventually see | |
1405 | the beginning of the buffer. | |
1406 | ||
1407 | Some people have urged that the opposite convention be used: they | |
1408 | imagine that the window moves over text that remains in place. Then | |
1409 | ``down'' commands would take you to the end of the buffer. This view is | |
1410 | more consistent with the actual relationship between windows and the | |
1411 | text in the buffer, but it is less like what the user sees. The | |
1412 | position of a window on the terminal does not move, and short scrolling | |
1413 | commands clearly move the text up or down on the screen. We have chosen | |
1414 | names that fit the user's point of view. | |
1415 | ||
8241495d RS |
1416 | The textual scrolling functions (aside from |
1417 | @code{scroll-other-window}) have unpredictable results if the current | |
1418 | buffer is different from the buffer that is displayed in the selected | |
1419 | window. @xref{Current Buffer}. | |
b1b12a8e | 1420 | |
41ad5140 | 1421 | If the window contains a row which is taller than the height of the |
5a36d834 | 1422 | window (for example in the presence of a large image), the scroll |
41ad5140 KS |
1423 | functions will adjust the window vscroll to scroll the partially |
1424 | visible row. To disable this feature, Lisp code may bind the variable | |
1425 | `auto-window-vscroll' to @code{nil} (@pxref{Vertical Scrolling}). | |
1426 | ||
b1b12a8e RS |
1427 | @deffn Command scroll-up &optional count |
1428 | This function scrolls the text in the selected window upward | |
1429 | @var{count} lines. If @var{count} is negative, scrolling is actually | |
1430 | downward. | |
1431 | ||
1432 | If @var{count} is @code{nil} (or omitted), then the length of scroll | |
1433 | is @code{next-screen-context-lines} lines less than the usable height of | |
1434 | the window (not counting its mode line). | |
1435 | ||
27704b78 RS |
1436 | @code{scroll-up} returns @code{nil}, unless it gets an error |
1437 | because it can't scroll any further. | |
b1b12a8e RS |
1438 | @end deffn |
1439 | ||
1440 | @deffn Command scroll-down &optional count | |
1441 | This function scrolls the text in the selected window downward | |
1442 | @var{count} lines. If @var{count} is negative, scrolling is actually | |
1443 | upward. | |
1444 | ||
1445 | If @var{count} is omitted or @code{nil}, then the length of the scroll | |
1446 | is @code{next-screen-context-lines} lines less than the usable height of | |
c638661f | 1447 | the window (not counting its mode line). |
b1b12a8e | 1448 | |
27704b78 RS |
1449 | @code{scroll-down} returns @code{nil}, unless it gets an error because |
1450 | it can't scroll any further. | |
b1b12a8e RS |
1451 | @end deffn |
1452 | ||
1453 | @deffn Command scroll-other-window &optional count | |
1454 | This function scrolls the text in another window upward @var{count} | |
1455 | lines. Negative values of @var{count}, or @code{nil}, are handled | |
1456 | as in @code{scroll-up}. | |
1457 | ||
8241495d RS |
1458 | You can specify which buffer to scroll by setting the variable |
1459 | @code{other-window-scroll-buffer} to a buffer. If that buffer isn't | |
1460 | already displayed, @code{scroll-other-window} displays it in some | |
1461 | window. | |
1462 | ||
1463 | When the selected window is the minibuffer, the next window is normally | |
1464 | the one at the top left corner. You can specify a different window to | |
1465 | scroll, when the minibuffer is selected, by setting the variable | |
b1b12a8e | 1466 | @code{minibuffer-scroll-window}. This variable has no effect when any |
eab4e895 LT |
1467 | other window is selected. When it is non-@code{nil} and the |
1468 | minibuffer is selected, it takes precedence over | |
1469 | @code{other-window-scroll-buffer}. @xref{Definition of | |
1470 | minibuffer-scroll-window}. | |
b1b12a8e RS |
1471 | |
1472 | When the minibuffer is active, it is the next window if the selected | |
1473 | window is the one at the bottom right corner. In this case, | |
1474 | @code{scroll-other-window} attempts to scroll the minibuffer. If the | |
1475 | minibuffer contains just one line, it has nowhere to scroll to, so the | |
1476 | line reappears after the echo area momentarily displays the message | |
1477 | ``Beginning of buffer''. | |
1478 | @end deffn | |
1479 | ||
1480 | @c Emacs 19 feature | |
1481 | @defvar other-window-scroll-buffer | |
1482 | If this variable is non-@code{nil}, it tells @code{scroll-other-window} | |
1483 | which buffer to scroll. | |
1484 | @end defvar | |
1485 | ||
1911e6e5 RS |
1486 | @defopt scroll-margin |
1487 | This option specifies the size of the scroll margin---a minimum number | |
1488 | of lines between point and the top or bottom of a window. Whenever | |
1489 | point gets within this many lines of the top or bottom of the window, | |
ac7845fd RS |
1490 | redisplay scrolls the text automatically (if possible) to move point |
1491 | out of the margin, closer to the center of the window. | |
1911e6e5 RS |
1492 | @end defopt |
1493 | ||
1911e6e5 | 1494 | @defopt scroll-conservatively |
b1b12a8e | 1495 | This variable controls how scrolling is done automatically when point |
ac7845fd RS |
1496 | moves off the screen (or into the scroll margin). If the value is a |
1497 | positive integer @var{n}, then redisplay scrolls the text up to | |
1498 | @var{n} lines in either direction, if that will bring point back into | |
1499 | proper view. This action is called @dfn{conservative scrolling}. | |
1500 | Otherwise, scrolling happens in the usual way, under the control of | |
1501 | other variables such as @code{scroll-up-aggressively} and | |
1502 | @code{scroll-down-aggressively}. | |
1503 | ||
1504 | The default value is zero, which means that conservative scrolling | |
1505 | never happens. | |
1911e6e5 RS |
1506 | @end defopt |
1507 | ||
9db0af9e RS |
1508 | @defopt scroll-down-aggressively |
1509 | @tindex scroll-down-aggressively | |
04c1025b GM |
1510 | The value of this variable should be either @code{nil} or a fraction |
1511 | @var{f} between 0 and 1. If it is a fraction, that specifies where on | |
9db0af9e RS |
1512 | the screen to put point when scrolling down. More precisely, when a |
1513 | window scrolls down because point is above the window start, the new | |
1514 | start position is chosen to put point @var{f} part of the window | |
1515 | height from the top. The larger @var{f}, the more aggressive the | |
1516 | scrolling. | |
04c1025b | 1517 | |
2468d0c0 DL |
1518 | A value of @code{nil} is equivalent to .5, since its effect is to center |
1519 | point. This variable automatically becomes buffer-local when set in any | |
1520 | fashion. | |
04c1025b GM |
1521 | @end defopt |
1522 | ||
9db0af9e RS |
1523 | @defopt scroll-up-aggressively |
1524 | @tindex scroll-up-aggressively | |
1525 | Likewise, for scrolling up. The value, @var{f}, specifies how far | |
04c1025b GM |
1526 | point should be placed from the bottom of the window; thus, as with |
1527 | @code{scroll-up-aggressively}, a larger value scrolls more aggressively. | |
1528 | @end defopt | |
1529 | ||
1911e6e5 RS |
1530 | @defopt scroll-step |
1531 | This variable is an older variant of @code{scroll-conservatively}. The | |
1532 | difference is that it if its value is @var{n}, that permits scrolling | |
1533 | only by precisely @var{n} lines, not a smaller number. This feature | |
1534 | does not work with @code{scroll-margin}. The default value is zero. | |
1535 | @end defopt | |
1536 | ||
1911e6e5 | 1537 | @defopt scroll-preserve-screen-position |
dd25d022 RS |
1538 | If this option is @code{t}, scrolling which would move the current |
1539 | point position out of the window chooses the new position of point | |
1540 | so that the vertical position of the cursor is unchanged, if possible. | |
1541 | ||
1542 | If it is non-@code{nil} and not @code{t}, then the scrolling functions | |
1543 | always preserve the vertical position of point, if possible. | |
b1b12a8e RS |
1544 | @end defopt |
1545 | ||
1546 | @defopt next-screen-context-lines | |
1547 | The value of this variable is the number of lines of continuity to | |
1548 | retain when scrolling by full screens. For example, @code{scroll-up} | |
1549 | with an argument of @code{nil} scrolls so that this many lines at the | |
1550 | bottom of the window appear instead at the top. The default value is | |
1551 | @code{2}. | |
1552 | @end defopt | |
1553 | ||
1554 | @deffn Command recenter &optional count | |
1555 | @cindex centering point | |
ac7845fd RS |
1556 | This function scrolls the text in the selected window so that point is |
1557 | displayed at a specified vertical position within the window. It does | |
1558 | not ``move point'' with respect to the text. | |
1559 | ||
1560 | If @var{count} is a nonnegative number, that puts the line containing | |
1561 | point @var{count} lines down from the top of the window. If | |
1562 | @var{count} is a negative number, then it counts upward from the | |
1563 | bottom of the window, so that @minus{}1 stands for the last usable | |
1564 | line in the window. If @var{count} is a non-@code{nil} list, then it | |
1565 | stands for the line in the middle of the window. | |
b1b12a8e RS |
1566 | |
1567 | If @var{count} is @code{nil}, @code{recenter} puts the line containing | |
1568 | point in the middle of the window, then clears and redisplays the entire | |
1569 | selected frame. | |
1570 | ||
1571 | When @code{recenter} is called interactively, @var{count} is the raw | |
1572 | prefix argument. Thus, typing @kbd{C-u} as the prefix sets the | |
1573 | @var{count} to a non-@code{nil} list, while typing @kbd{C-u 4} sets | |
1574 | @var{count} to 4, which positions the current line four lines from the | |
1575 | top. | |
1576 | ||
c638661f RS |
1577 | With an argument of zero, @code{recenter} positions the current line at |
1578 | the top of the window. This action is so handy that some people make a | |
1579 | separate key binding to do this. For example, | |
b1b12a8e RS |
1580 | |
1581 | @example | |
1582 | @group | |
1583 | (defun line-to-top-of-window () | |
1584 | "Scroll current line to top of window. | |
1585 | Replaces three keystroke sequence C-u 0 C-l." | |
3c29caa8 | 1586 | (interactive) |
b1b12a8e RS |
1587 | (recenter 0)) |
1588 | ||
3c29caa8 | 1589 | (global-set-key [kp-multiply] 'line-to-top-of-window) |
b1b12a8e RS |
1590 | @end group |
1591 | @end example | |
1592 | @end deffn | |
1593 | ||
8241495d RS |
1594 | @node Vertical Scrolling |
1595 | @section Vertical Fractional Scrolling | |
1596 | @cindex Vertical Fractional Scrolling | |
1597 | ||
1598 | @dfn{Vertical fractional scrolling} means shifting the image in the | |
1599 | window up or down by a specified multiple or fraction of a line. | |
4e534552 | 1600 | Each window has a @dfn{vertical scroll position}, |
8241495d RS |
1601 | which is a number, never less than zero. It specifies how far to raise |
1602 | the contents of the window. Raising the window contents generally makes | |
1603 | all or part of some lines disappear off the top, and all or part of some | |
1604 | other lines appear at the bottom. The usual value is zero. | |
1605 | ||
1606 | The vertical scroll position is measured in units of the normal line | |
1607 | height, which is the height of the default font. Thus, if the value is | |
1608 | .5, that means the window contents are scrolled up half the normal line | |
1609 | height. If it is 3.3, that means the window contents are scrolled up | |
1610 | somewhat over three times the normal line height. | |
1611 | ||
1612 | What fraction of a line the vertical scrolling covers, or how many | |
1613 | lines, depends on what the lines contain. A value of .5 could scroll a | |
1614 | line whose height is very short off the screen, while a value of 3.3 | |
1615 | could scroll just part of the way through a tall line or an image. | |
1616 | ||
eab4e895 | 1617 | @defun window-vscroll &optional window pixels-p |
8241495d | 1618 | This function returns the current vertical scroll position of |
eab4e895 LT |
1619 | @var{window}. If @var{window} is @code{nil}, the selected window is |
1620 | used. If @var{pixels-p} is non-@code{nil}, the return value is | |
1621 | measured in pixels, rather than in units of the normal line height. | |
8241495d RS |
1622 | |
1623 | @example | |
1624 | @group | |
1625 | (window-vscroll) | |
1626 | @result{} 0 | |
1627 | @end group | |
1628 | @end example | |
1629 | @end defun | |
1630 | ||
eab4e895 | 1631 | @defun set-window-vscroll window lines &optional pixels-p |
8241495d RS |
1632 | This function sets @var{window}'s vertical scroll position to |
1633 | @var{lines}. The argument @var{lines} should be zero or positive; if | |
1634 | not, it is taken as zero. | |
1635 | ||
eb687116 EZ |
1636 | If @var{window} is @code{nil}, the selected window is used. |
1637 | ||
8241495d RS |
1638 | The actual vertical scroll position must always correspond |
1639 | to an integral number of pixels, so the value you specify | |
1640 | is rounded accordingly. | |
1641 | ||
1642 | The return value is the result of this rounding. | |
1643 | ||
1644 | @example | |
1645 | @group | |
1646 | (set-window-vscroll (selected-window) 1.2) | |
1647 | @result{} 1.13 | |
1648 | @end group | |
1649 | @end example | |
eab4e895 LT |
1650 | |
1651 | If @var{pixels-p} is non-@code{nil}, @var{lines} specifies a number of | |
1652 | pixels. In this case, the return value is @var{lines}. | |
8241495d RS |
1653 | @end defun |
1654 | ||
41ad5140 KS |
1655 | @defvar auto-window-vscroll |
1656 | If this variable is non-@code{nil}, the line-move, scroll-up, and | |
1657 | scroll-down functions will automatically modify the window vscroll to | |
1658 | scroll through display rows that are taller that the height of the | |
5a36d834 | 1659 | window, for example in the presence of large images. |
41ad5140 KS |
1660 | @end defvar |
1661 | ||
b1b12a8e RS |
1662 | @node Horizontal Scrolling |
1663 | @section Horizontal Scrolling | |
1664 | @cindex horizontal scrolling | |
1665 | ||
8241495d RS |
1666 | @dfn{Horizontal scrolling} means shifting the image in the window left |
1667 | or right by a specified multiple of the normal character width. Each | |
061967de | 1668 | window has a @dfn{horizontal scroll position}, which is a number, never |
8241495d RS |
1669 | less than zero. It specifies how far to shift the contents left. |
1670 | Shifting the window contents left generally makes all or part of some | |
1671 | characters disappear off the left, and all or part of some other | |
1672 | characters appear at the right. The usual value is zero. | |
1673 | ||
1674 | The horizontal scroll position is measured in units of the normal | |
1675 | character width, which is the width of space in the default font. Thus, | |
1676 | if the value is 5, that means the window contents are scrolled left by 5 | |
c400241b | 1677 | times the normal character width. How many characters actually |
8241495d RS |
1678 | disappear off to the left depends on their width, and could vary from |
1679 | line to line. | |
1680 | ||
1681 | Because we read from side to side in the ``inner loop'', and from top | |
1682 | to bottom in the ``outer loop'', the effect of horizontal scrolling is | |
1683 | not like that of textual or vertical scrolling. Textual scrolling | |
1684 | involves selection of a portion of text to display, and vertical | |
1685 | scrolling moves the window contents contiguously; but horizontal | |
1686 | scrolling causes part of @emph{each line} to go off screen. | |
b1b12a8e RS |
1687 | |
1688 | Usually, no horizontal scrolling is in effect; then the leftmost | |
1689 | column is at the left edge of the window. In this state, scrolling to | |
8241495d RS |
1690 | the right is meaningless, since there is no data to the left of the edge |
1691 | to be revealed by it; so this is not allowed. Scrolling to the left is | |
1692 | allowed; it scrolls the first columns of text off the edge of the window | |
1693 | and can reveal additional columns on the right that were truncated | |
1694 | before. Once a window has a nonzero amount of leftward horizontal | |
1695 | scrolling, you can scroll it back to the right, but only so far as to | |
1696 | reduce the net horizontal scroll to zero. There is no limit to how far | |
1697 | left you can scroll, but eventually all the text will disappear off the | |
1698 | left edge. | |
1699 | ||
0594fc7f | 1700 | @vindex auto-hscroll-mode |
27704b78 RS |
1701 | If @code{auto-hscroll-mode} is set, redisplay automatically alters |
1702 | the horizontal scrolling of a window as necessary to ensure that point | |
1703 | is always visible. However, you can still set the horizontal | |
1704 | scrolling value explicitly. The value you specify serves as a lower | |
1705 | bound for automatic scrolling, i.e. automatic scrolling will not | |
1706 | scroll a window to a column less than the specified one. | |
8241495d | 1707 | |
7279aaf6 | 1708 | @deffn Command scroll-left &optional count set-minimum |
b1b12a8e | 1709 | This function scrolls the selected window @var{count} columns to the |
8241495d RS |
1710 | left (or to the right if @var{count} is negative). The default |
1711 | for @var{count} is the window width, minus 2. | |
1712 | ||
8241495d RS |
1713 | The return value is the total amount of leftward horizontal scrolling in |
1714 | effect after the change---just like the value returned by | |
1715 | @code{window-hscroll} (below). | |
b1b12a8e RS |
1716 | |
1717 | Once you scroll a window as far right as it can go, back to its normal | |
1718 | position where the total leftward scrolling is zero, attempts to scroll | |
1719 | any farther right have no effect. | |
7279aaf6 RS |
1720 | |
1721 | If @var{set-minimum} is non-@code{nil}, the new scroll amount becomes | |
1722 | the lower bound for automatic scrolling; that is, automatic scrolling | |
1723 | will not scroll a window to a column less than the value returned by | |
1724 | this function. Interactive calls pass non-@code{nil} for | |
1725 | @var{set-minimum}. | |
1726 | @end deffn | |
1727 | ||
1728 | @deffn Command scroll-right &optional count set-minimum | |
1729 | This function scrolls the selected window @var{count} columns to the | |
1730 | right (or to the left if @var{count} is negative). The default | |
1731 | for @var{count} is the window width, minus 2. Aside from the direction | |
1732 | of scrolling, this works just like @code{scroll-left}. | |
b1b12a8e RS |
1733 | @end deffn |
1734 | ||
1735 | @defun window-hscroll &optional window | |
1736 | This function returns the total leftward horizontal scrolling of | |
1737 | @var{window}---the number of columns by which the text in @var{window} | |
1738 | is scrolled left past the left margin. | |
1739 | ||
1740 | The value is never negative. It is zero when no horizontal scrolling | |
1741 | has been done in @var{window} (which is usually the case). | |
1742 | ||
1743 | If @var{window} is @code{nil}, the selected window is used. | |
1744 | ||
1745 | @example | |
1746 | @group | |
1747 | (window-hscroll) | |
1748 | @result{} 0 | |
1749 | @end group | |
1750 | @group | |
1751 | (scroll-left 5) | |
1752 | @result{} 5 | |
1753 | @end group | |
1754 | @group | |
1755 | (window-hscroll) | |
1756 | @result{} 5 | |
1757 | @end group | |
1758 | @end example | |
1759 | @end defun | |
1760 | ||
1761 | @defun set-window-hscroll window columns | |
27704b78 RS |
1762 | This function sets horizontal scrolling of @var{window}. The value of |
1763 | @var{columns} specifies the amount of scrolling, in terms of columns | |
1764 | from the left margin. The argument @var{columns} should be zero or | |
1765 | positive; if not, it is taken as zero. Fractional values of | |
1766 | @var{columns} are not supported at present. | |
b1b12a8e | 1767 | |
515a9a0f RS |
1768 | Note that @code{set-window-hscroll} may appear not to work if you test |
1769 | it by evaluating a call with @kbd{M-:} in a simple way. What happens | |
1770 | is that the function sets the horizontal scroll value and returns, but | |
1771 | then redisplay adjusts the horizontal scrolling to make point visible, | |
1772 | and this overrides what the function did. You can observe the | |
1773 | function's effect if you call it while point is sufficiently far from | |
1774 | the left margin that it will remain visible. | |
1775 | ||
b1b12a8e RS |
1776 | The value returned is @var{columns}. |
1777 | ||
1778 | @example | |
1779 | @group | |
1780 | (set-window-hscroll (selected-window) 10) | |
1781 | @result{} 10 | |
1782 | @end group | |
1783 | @end example | |
1784 | @end defun | |
1785 | ||
1786 | Here is how you can determine whether a given position @var{position} | |
1787 | is off the screen due to horizontal scrolling: | |
1788 | ||
1789 | @example | |
1790 | @group | |
c638661f | 1791 | (defun hscroll-on-screen (window position) |
3c29caa8 | 1792 | (save-excursion |
c638661f | 1793 | (goto-char position) |
3c29caa8 | 1794 | (and |
c638661f RS |
1795 | (>= (- (current-column) (window-hscroll window)) 0) |
1796 | (< (- (current-column) (window-hscroll window)) | |
1797 | (window-width window))))) | |
b1b12a8e RS |
1798 | @end group |
1799 | @end example | |
1800 | ||
1801 | @node Size of Window | |
1802 | @section The Size of a Window | |
1803 | @cindex window size | |
1804 | @cindex size of window | |
1805 | ||
1806 | An Emacs window is rectangular, and its size information consists of | |
1807 | the height (the number of lines) and the width (the number of character | |
1808 | positions in each line). The mode line is included in the height. But | |
1809 | the width does not count the scroll bar or the column of @samp{|} | |
c638661f | 1810 | characters that separates side-by-side windows. |
b1b12a8e RS |
1811 | |
1812 | The following three functions return size information about a window: | |
1813 | ||
1814 | @defun window-height &optional window | |
88f7b76a RS |
1815 | This function returns the number of lines in @var{window}, including |
1816 | its mode line and header line, if any. If @var{window} fills its | |
27704b78 RS |
1817 | entire frame except for the echo area, this is typically one less than |
1818 | the value of @code{frame-height} on that frame. | |
b1b12a8e RS |
1819 | |
1820 | If @var{window} is @code{nil}, the function uses the selected window. | |
1821 | ||
1822 | @example | |
1823 | @group | |
1824 | (window-height) | |
1825 | @result{} 23 | |
1826 | @end group | |
1827 | @group | |
1828 | (split-window-vertically) | |
1829 | @result{} #<window 4 on windows.texi> | |
1830 | @end group | |
1831 | @group | |
1832 | (window-height) | |
1833 | @result{} 11 | |
1834 | @end group | |
1835 | @end example | |
1836 | @end defun | |
1837 | ||
88f7b76a RS |
1838 | @tindex window-body-height |
1839 | @defun window-body-height &optional window | |
177c0ea7 | 1840 | Like @code{window-height} but the value does not include the |
88f7b76a RS |
1841 | mode line (if any) or the header line (if any). |
1842 | @end defun | |
1843 | ||
b1b12a8e RS |
1844 | @defun window-width &optional window |
1845 | This function returns the number of columns in @var{window}. If | |
1846 | @var{window} fills its entire frame, this is the same as the value of | |
1847 | @code{frame-width} on that frame. The width does not include the | |
1848 | window's scroll bar or the column of @samp{|} characters that separates | |
1849 | side-by-side windows. | |
1850 | ||
1851 | If @var{window} is @code{nil}, the function uses the selected window. | |
1852 | ||
1853 | @example | |
1854 | @group | |
1855 | (window-width) | |
1856 | @result{} 80 | |
1857 | @end group | |
1858 | @end example | |
1859 | @end defun | |
1860 | ||
1861 | @defun window-edges &optional window | |
1862 | This function returns a list of the edge coordinates of @var{window}. | |
1863 | If @var{window} is @code{nil}, the selected window is used. | |
1864 | ||
1865 | The order of the list is @code{(@var{left} @var{top} @var{right} | |
1866 | @var{bottom})}, all elements relative to 0, 0 at the top left corner of | |
1867 | the frame. The element @var{right} of the value is one more than the | |
1868 | rightmost column used by @var{window}, and @var{bottom} is one more than | |
1869 | the bottommost row used by @var{window} and its mode-line. | |
1870 | ||
eab4e895 LT |
1871 | The edges include the space used by the window's scroll bar, display |
1872 | margins, fringes, header line, and mode line, if it has them. Also, | |
1873 | if the window has a neighbor on the right, its right edge value | |
1874 | includes the width of the separator line between the window and that | |
1875 | neighbor. Since the width of the window does not include this | |
1876 | separator, the width does not usually equal the difference between the | |
1877 | right and left edges. | |
5a8a6af8 RS |
1878 | @end defun |
1879 | ||
eab4e895 | 1880 | @defun window-inside-edges &optional window |
5a8a6af8 RS |
1881 | This is similar to @code{window-edges}, but the edge values |
1882 | it returns include only the text area of the window. They | |
1883 | do not include the header line, mode line, scroll bar or | |
1884 | vertical separator, fringes, or display margins. | |
1885 | @end defun | |
b1b12a8e | 1886 | |
5a8a6af8 RS |
1887 | Here are the results obtained on a typical 24-line terminal with just |
1888 | one window, with menu bar enabled: | |
b1b12a8e RS |
1889 | |
1890 | @example | |
1891 | @group | |
1892 | (window-edges (selected-window)) | |
5a8a6af8 RS |
1893 | @result{} (0 1 80 23) |
1894 | @end group | |
1895 | @group | |
1896 | (window-inside-edges (selected-window)) | |
1897 | @result{} (0 1 80 22) | |
b1b12a8e RS |
1898 | @end group |
1899 | @end example | |
1900 | ||
c638661f RS |
1901 | @noindent |
1902 | The bottom edge is at line 23 because the last line is the echo area. | |
5a8a6af8 RS |
1903 | The bottom inside edge is at line 22, which is the window's mode line. |
1904 | ||
1905 | If @var{window} is at the upper left corner of its frame, and there is | |
1906 | no menu bar, then @var{bottom} returned by @code{window-edges} is the | |
1907 | same as the value of @code{(window-height)}, @var{right} is almost the | |
1908 | same as the value of @code{(window-width)}, and @var{top} and | |
1909 | @var{left} are zero. For example, the edges of the following window | |
1910 | are @w{@samp{0 0 8 5}}. Assuming that the frame has more than 8 | |
1911 | columns, the last column of the window (column 7) holds a border | |
1912 | rather than text. The last row (row 4) holds the mode line, shown | |
1913 | here with @samp{xxxxxxxxx}. | |
b1b12a8e RS |
1914 | |
1915 | @example | |
1916 | @group | |
3c29caa8 | 1917 | 0 |
b1b12a8e | 1918 | _______ |
3c29caa8 DH |
1919 | 0 | | |
1920 | | | | |
1921 | | | | |
1922 | | | | |
b1b12a8e RS |
1923 | xxxxxxxxx 4 |
1924 | ||
3c29caa8 | 1925 | 7 |
b1b12a8e RS |
1926 | @end group |
1927 | @end example | |
1928 | ||
b1b12a8e RS |
1929 | In the following example, let's suppose that the frame is 7 |
1930 | columns wide. Then the edges of the left window are @w{@samp{0 0 4 3}} | |
5a8a6af8 RS |
1931 | and the edges of the right window are @w{@samp{4 0 7 3}}. |
1932 | The inside edges of the left window are @w{@samp{0 0 3 2}}, | |
1933 | and the inside edges of the right window are @w{@samp{4 0 7 2}}, | |
b1b12a8e RS |
1934 | |
1935 | @example | |
1936 | @group | |
1937 | ___ ___ | |
3c29caa8 DH |
1938 | | | | |
1939 | | | | | |
1940 | xxxxxxxxx | |
b1b12a8e RS |
1941 | |
1942 | 0 34 7 | |
1943 | @end group | |
1944 | @end example | |
5a8a6af8 | 1945 | |
eab4e895 | 1946 | @defun window-pixel-edges &optional window |
5a8a6af8 RS |
1947 | This function is like @code{window-edges} except that, on a graphical |
1948 | display, the edge values are measured in pixels instead of in | |
1949 | character lines and columns. | |
1950 | @end defun | |
1951 | ||
eab4e895 | 1952 | @defun window-inside-pixel-edges &optional window |
5a8a6af8 RS |
1953 | This function is like @code{window-inside-edges} except that, on a |
1954 | graphical display, the edge values are measured in pixels instead of | |
1955 | in character lines and columns. | |
b1b12a8e RS |
1956 | @end defun |
1957 | ||
1958 | @node Resizing Windows | |
1959 | @section Changing the Size of a Window | |
1960 | @cindex window resizing | |
1961 | @cindex changing window size | |
1962 | @cindex window size, changing | |
1963 | ||
1964 | The window size functions fall into two classes: high-level commands | |
1965 | that change the size of windows and low-level functions that access | |
1966 | window size. Emacs does not permit overlapping windows or gaps between | |
1967 | windows, so resizing one window affects other windows. | |
1968 | ||
e44c5273 | 1969 | @deffn Command enlarge-window size &optional horizontal |
c638661f | 1970 | This function makes the selected window @var{size} lines taller, |
b1b12a8e RS |
1971 | stealing lines from neighboring windows. It takes the lines from one |
1972 | window at a time until that window is used up, then takes from another. | |
1973 | If a window from which lines are stolen shrinks below | |
1974 | @code{window-min-height} lines, that window disappears. | |
1975 | ||
1976 | If @var{horizontal} is non-@code{nil}, this function makes | |
1977 | @var{window} wider by @var{size} columns, stealing columns instead of | |
1978 | lines. If a window from which columns are stolen shrinks below | |
1979 | @code{window-min-width} columns, that window disappears. | |
1980 | ||
c638661f RS |
1981 | If the requested size would exceed that of the window's frame, then the |
1982 | function makes the window occupy the entire height (or width) of the | |
1983 | frame. | |
b1b12a8e | 1984 | |
8241495d RS |
1985 | If there are various other windows from which lines or columns can be |
1986 | stolen, and some of them specify fixed size (using | |
1987 | @code{window-size-fixed}, see below), they are left untouched while | |
1988 | other windows are ``robbed.'' If it would be necessary to alter the | |
1989 | size of a fixed-size window, @code{enlarge-window} gets an error | |
1990 | instead. | |
1991 | ||
b1b12a8e RS |
1992 | If @var{size} is negative, this function shrinks the window by |
1993 | @minus{}@var{size} lines or columns. If that makes the window smaller | |
1994 | than the minimum size (@code{window-min-height} and | |
1995 | @code{window-min-width}), @code{enlarge-window} deletes the window. | |
1996 | ||
3c29caa8 | 1997 | @code{enlarge-window} returns @code{nil}. |
b1b12a8e RS |
1998 | @end deffn |
1999 | ||
2000 | @deffn Command enlarge-window-horizontally columns | |
2001 | This function makes the selected window @var{columns} wider. | |
2002 | It could be defined as follows: | |
2003 | ||
2004 | @example | |
2005 | @group | |
2006 | (defun enlarge-window-horizontally (columns) | |
ae473bd3 | 2007 | (interactive "p") |
b1b12a8e RS |
2008 | (enlarge-window columns t)) |
2009 | @end group | |
2010 | @end example | |
2011 | @end deffn | |
2012 | ||
e44c5273 | 2013 | @deffn Command shrink-window size &optional horizontal |
b1b12a8e RS |
2014 | This function is like @code{enlarge-window} but negates the argument |
2015 | @var{size}, making the selected window smaller by giving lines (or | |
2016 | columns) to the other windows. If the window shrinks below | |
2017 | @code{window-min-height} or @code{window-min-width}, then it disappears. | |
2018 | ||
2019 | If @var{size} is negative, the window is enlarged by @minus{}@var{size} | |
2020 | lines or columns. | |
2021 | @end deffn | |
2022 | ||
2023 | @deffn Command shrink-window-horizontally columns | |
2024 | This function makes the selected window @var{columns} narrower. | |
2025 | It could be defined as follows: | |
2026 | ||
2027 | @example | |
2028 | @group | |
2029 | (defun shrink-window-horizontally (columns) | |
ae473bd3 | 2030 | (interactive "p") |
b1b12a8e RS |
2031 | (shrink-window columns t)) |
2032 | @end group | |
2033 | @end example | |
2034 | @end deffn | |
2035 | ||
7279aaf6 RS |
2036 | @defun adjust-window-trailing-edge window delta horizontal |
2037 | This function makes the selected window @var{delta} lines taller or | |
2038 | @var{delta} columns wider, by moving the bottom or right edge. This | |
2039 | function does not delete other windows; if it cannot make the | |
2040 | requested size adjustment, it signals an error. On success, this | |
2041 | function returns @code{nil}. | |
2042 | @end defun | |
2043 | ||
ae473bd3 RS |
2044 | @defun fit-window-to-buffer &optional window max-height min-height |
2045 | This function makes @var{window} the right height to display its | |
2046 | contents exactly. If @var{window} is omitted or @code{nil}, it uses | |
2047 | the selected window. | |
2048 | ||
2049 | The argument @var{max-height} specifies the maximum height the window | |
2050 | is allowed to be; @code{nil} means use the frame height. The argument | |
2051 | @var{min-height} specifies the minimum height for the window; | |
2052 | @code{nil} means use @code{window-min-height}. All these height | |
2053 | values include the mode-line and/or header-line. | |
2054 | @end defun | |
2055 | ||
8241495d | 2056 | @deffn Command shrink-window-if-larger-than-buffer &optional window |
ae473bd3 RS |
2057 | This command shrinks @var{window} vertically to be as small as |
2058 | possible while still showing the full contents of its buffer---but not | |
2059 | less than @code{window-min-height} lines. If @var{window} is not | |
2060 | given, it defaults to the selected window. | |
1911e6e5 RS |
2061 | |
2062 | However, the command does nothing if the window is already too small to | |
2063 | display the whole text of the buffer, or if part of the contents are | |
2064 | currently scrolled off screen, or if the window is not the full width of | |
2065 | its frame, or if the window is the only window in its frame. | |
eab4e895 LT |
2066 | |
2067 | This command returns non-@code{nil} if it actually shrank the window | |
2068 | and @code{nil} otherwise. | |
1911e6e5 RS |
2069 | @end deffn |
2070 | ||
8241495d RS |
2071 | @tindex window-size-fixed |
2072 | @defvar window-size-fixed | |
2073 | If this variable is non-@code{nil}, in any given buffer, | |
2074 | then the size of any window displaying the buffer remains fixed | |
2075 | unless you explicitly change it or Emacs has no other choice. | |
8241495d RS |
2076 | |
2077 | If the value is @code{height}, then only the window's height is fixed; | |
2078 | if the value is @code{width}, then only the window's width is fixed. | |
2079 | Any other non-@code{nil} value fixes both the width and the height. | |
2080 | ||
eab4e895 | 2081 | This variable automatically becomes buffer-local when set. |
8241495d RS |
2082 | |
2083 | Explicit size-change functions such as @code{enlarge-window} | |
2084 | get an error if they would have to change a window size which is fixed. | |
2085 | Therefore, when you want to change the size of such a window, | |
2086 | you should bind @code{window-size-fixed} to @code{nil}, like this: | |
2087 | ||
2088 | @example | |
2089 | (let ((window-size-fixed nil)) | |
2090 | (enlarge-window 10)) | |
2091 | @end example | |
2092 | ||
2093 | Note that changing the frame size will change the size of a | |
2094 | fixed-size window, if there is no other alternative. | |
2095 | @end defvar | |
2096 | ||
b1b12a8e | 2097 | @cindex minimum window size |
926a5166 | 2098 | The following two variables constrain the window-structure-changing |
b1b12a8e RS |
2099 | functions to a minimum height and width. |
2100 | ||
2101 | @defopt window-min-height | |
2102 | The value of this variable determines how short a window may become | |
2103 | before it is automatically deleted. Making a window smaller than | |
926a5166 RS |
2104 | @code{window-min-height} automatically deletes it, and no window may |
2105 | be created shorter than this. The default value is 4. | |
2106 | ||
2107 | The absolute minimum window height is one; actions that change window | |
2108 | sizes reset this variable to one if it is less than one. | |
b1b12a8e RS |
2109 | @end defopt |
2110 | ||
2111 | @defopt window-min-width | |
2112 | The value of this variable determines how narrow a window may become | |
1911e6e5 | 2113 | before it is automatically deleted. Making a window smaller than |
b1b12a8e | 2114 | @code{window-min-width} automatically deletes it, and no window may be |
926a5166 RS |
2115 | created narrower than this. The default value is 10. |
2116 | ||
2117 | The absolute minimum window width is two; actions that change window | |
2118 | sizes reset this variable to two if it is less than two. | |
b1b12a8e RS |
2119 | @end defopt |
2120 | ||
2121 | @node Coordinates and Windows | |
2122 | @section Coordinates and Windows | |
2123 | ||
c638661f | 2124 | This section describes how to relate screen coordinates to windows. |
b1b12a8e RS |
2125 | |
2126 | @defun window-at x y &optional frame | |
2127 | This function returns the window containing the specified cursor | |
2128 | position in the frame @var{frame}. The coordinates @var{x} and @var{y} | |
2129 | are measured in characters and count from the top left corner of the | |
2130 | frame. If they are out of range, @code{window-at} returns @code{nil}. | |
2131 | ||
2132 | If you omit @var{frame}, the selected frame is used. | |
2133 | @end defun | |
2134 | ||
2135 | @defun coordinates-in-window-p coordinates window | |
2136 | This function checks whether a particular frame position falls within | |
2137 | the window @var{window}. | |
2138 | ||
969fe9b5 RS |
2139 | The argument @var{coordinates} is a cons cell of the form @code{(@var{x} |
2140 | . @var{y})}. The coordinates @var{x} and @var{y} are measured in | |
2141 | characters, and count from the top left corner of the screen or frame. | |
b1b12a8e | 2142 | |
f9f59935 RS |
2143 | The value returned by @code{coordinates-in-window-p} is non-@code{nil} |
2144 | if the coordinates are inside @var{window}. The value also indicates | |
2145 | what part of the window the position is in, as follows: | |
b1b12a8e RS |
2146 | |
2147 | @table @code | |
2148 | @item (@var{relx} . @var{rely}) | |
2149 | The coordinates are inside @var{window}. The numbers @var{relx} and | |
2150 | @var{rely} are the equivalent window-relative coordinates for the | |
2151 | specified position, counting from 0 at the top left corner of the | |
2152 | window. | |
2153 | ||
2154 | @item mode-line | |
2155 | The coordinates are in the mode line of @var{window}. | |
2156 | ||
8241495d RS |
2157 | @item header-line |
2158 | The coordinates are in the header line of @var{window}. | |
2159 | ||
2160 | @item vertical-line | |
b1b12a8e | 2161 | The coordinates are in the vertical line between @var{window} and its |
3c29caa8 | 2162 | neighbor to the right. This value occurs only if the window doesn't |
b1b12a8e | 2163 | have a scroll bar; positions in a scroll bar are considered outside the |
8241495d | 2164 | window for these purposes. |
b1b12a8e | 2165 | |
27704b78 RS |
2166 | @item left-fringe |
2167 | @itemx right-fringe | |
2168 | The coordinates are in the left or right fringe of the window. | |
2169 | ||
2170 | @item left-margin | |
2171 | @itemx right-margin | |
2172 | The coordinates are in the left or right margin of the window. | |
2173 | ||
b1b12a8e RS |
2174 | @item nil |
2175 | The coordinates are not in any part of @var{window}. | |
2176 | @end table | |
2177 | ||
2178 | The function @code{coordinates-in-window-p} does not require a frame as | |
2179 | argument because it always uses the frame that @var{window} is on. | |
2180 | @end defun | |
2181 | ||
8781c4d1 KS |
2182 | @node Window Tree |
2183 | @section The Window Tree | |
2184 | @cindex window tree | |
180ce0f4 | 2185 | |
8781c4d1 | 2186 | A @dfn{window tree} specifies the layout, size, and relationship |
180ce0f4 KS |
2187 | between all windows in one frame. |
2188 | ||
8781c4d1 KS |
2189 | @defun window-tree &optional frame |
2190 | This function returns the window tree for frame @var{frame}. | |
180ce0f4 KS |
2191 | If @var{frame} is omitted, the selected frame is used. |
2192 | ||
2193 | The return value is a list of the form @code{(@var{root} @var{mini})}, | |
8781c4d1 | 2194 | where @var{root} represents the window tree of the frame's |
180ce0f4 KS |
2195 | root window, and @var{mini} is the frame's minibuffer window. |
2196 | ||
2197 | If the root window is not split, @var{root} is the root window itself. | |
2198 | Otherwise, @var{root} is a list @code{(@var{dir} @var{edges} @var{w1} | |
d040665a | 2199 | @var{w2} ...)} where @var{dir} is @code{nil} for a horizontal split, |
180ce0f4 KS |
2200 | and @code{t} for a vertical split, @var{edges} gives the combined size and |
2201 | position of the subwindows in the split, and the rest of the elements | |
2202 | are the subwindows in the split. Each of the subwindows may again be | |
2203 | a window or a list representing a window split, and so on. The | |
2204 | @var{edges} element is a list @code{(@var{left}@var{ top}@var{ right}@var{ bottom})} | |
2205 | similar to the value returned by @code{window-edges}. | |
2206 | @end defun | |
2207 | ||
b1b12a8e RS |
2208 | @node Window Configurations |
2209 | @section Window Configurations | |
2210 | @cindex window configurations | |
2211 | @cindex saving window information | |
2212 | ||
f9f59935 | 2213 | A @dfn{window configuration} records the entire layout of one |
c02dd51a RS |
2214 | frame---all windows, their sizes, which buffers they contain, what |
2215 | part of each buffer is displayed, and the values of point and the | |
27704b78 RS |
2216 | mark; also their fringes, margins, and scroll bar settings. It also |
2217 | includes the values of @code{window-min-height}, | |
c02dd51a RS |
2218 | @code{window-min-width} and @code{minibuffer-scroll-window}. An |
2219 | exception is made for point in the selected window for the current | |
2220 | buffer; its value is not saved in the window configuration. | |
2221 | ||
2222 | You can bring back an entire previous layout by restoring a window | |
2223 | configuration previously saved. If you want to record all frames | |
2224 | instead of just one, use a frame configuration instead of a window | |
2225 | configuration. @xref{Frame Configurations}. | |
b1b12a8e | 2226 | |
8241495d | 2227 | @defun current-window-configuration &optional frame |
c02dd51a RS |
2228 | This function returns a new object representing @var{frame}'s current |
2229 | window configuration. If @var{frame} is omitted, the selected frame | |
2230 | is used. | |
b1b12a8e RS |
2231 | @end defun |
2232 | ||
2233 | @defun set-window-configuration configuration | |
f9f59935 | 2234 | This function restores the configuration of windows and buffers as |
8241495d RS |
2235 | specified by @var{configuration}, for the frame that @var{configuration} |
2236 | was created for. | |
2237 | ||
2238 | The argument @var{configuration} must be a value that was previously | |
2239 | returned by @code{current-window-configuration}. This configuration is | |
2240 | restored in the frame from which @var{configuration} was made, whether | |
2241 | that frame is selected or not. This always counts as a window size | |
2242 | change and triggers execution of the @code{window-size-change-functions} | |
969fe9b5 RS |
2243 | (@pxref{Window Hooks}), because @code{set-window-configuration} doesn't |
2244 | know how to tell whether the new configuration actually differs from the | |
2245 | old one. | |
2246 | ||
2247 | If the frame which @var{configuration} was saved from is dead, all this | |
2248 | function does is restore the three variables @code{window-min-height}, | |
eab4e895 LT |
2249 | @code{window-min-width} and @code{minibuffer-scroll-window}. In this |
2250 | case, the function returns @code{nil}. Otherwise, it returns @code{t}. | |
bfe721d1 | 2251 | |
b1b12a8e RS |
2252 | Here is a way of using this function to get the same effect |
2253 | as @code{save-window-excursion}: | |
2254 | ||
2255 | @example | |
2256 | @group | |
2257 | (let ((config (current-window-configuration))) | |
2258 | (unwind-protect | |
2259 | (progn (split-window-vertically nil) | |
2260 | @dots{}) | |
2261 | (set-window-configuration config))) | |
2262 | @end group | |
2263 | @end example | |
2264 | @end defun | |
2265 | ||
2266 | @defspec save-window-excursion forms@dots{} | |
2267 | This special form records the window configuration, executes @var{forms} | |
2268 | in sequence, then restores the earlier window configuration. The window | |
eab4e895 LT |
2269 | configuration includes, for each window, the value of point and the |
2270 | portion of the buffer that is visible. It also includes the choice of | |
2271 | selected window. However, it does not include the value of point in | |
2272 | the current buffer; use @code{save-excursion} also, if you wish to | |
2273 | preserve that. | |
b1b12a8e | 2274 | |
9258d604 | 2275 | Don't use this construct when @code{save-selected-window} is sufficient. |
bfe721d1 KH |
2276 | |
2277 | Exit from @code{save-window-excursion} always triggers execution of the | |
2278 | @code{window-size-change-functions}. (It doesn't know how to tell | |
2279 | whether the restored configuration actually differs from the one in | |
2280 | effect at the end of the @var{forms}.) | |
2281 | ||
b1b12a8e RS |
2282 | The return value is the value of the final form in @var{forms}. |
2283 | For example: | |
2284 | ||
2285 | @example | |
2286 | @group | |
2287 | (split-window) | |
2288 | @result{} #<window 25 on control.texi> | |
2289 | @end group | |
2290 | @group | |
2291 | (setq w (selected-window)) | |
2292 | @result{} #<window 19 on control.texi> | |
2293 | @end group | |
2294 | @group | |
2295 | (save-window-excursion | |
2296 | (delete-other-windows w) | |
2297 | (switch-to-buffer "foo") | |
2298 | 'do-something) | |
2299 | @result{} do-something | |
2300 | ;; @r{The screen is now split again.} | |
2301 | @end group | |
2302 | @end example | |
2303 | @end defspec | |
2304 | ||
2305 | @defun window-configuration-p object | |
2306 | This function returns @code{t} if @var{object} is a window configuration. | |
969fe9b5 RS |
2307 | @end defun |
2308 | ||
2309 | @defun compare-window-configurations config1 config2 | |
2310 | This function compares two window configurations as regards the | |
2311 | structure of windows, but ignores the values of point and mark and the | |
2312 | saved scrolling positions---it can return @code{t} even if those | |
2313 | aspects differ. | |
2314 | ||
2315 | The function @code{equal} can also compare two window configurations; it | |
2316 | regards configurations as unequal if they differ in any respect, even a | |
2317 | saved point or mark. | |
b1b12a8e RS |
2318 | @end defun |
2319 | ||
4d25144d RS |
2320 | @defun window-configuration-frame config |
2321 | This function returns the frame for which the window configuration | |
2322 | @var{config} was made. | |
2323 | @end defun | |
2324 | ||
2325 | Other primitives to look inside of window configurations would make | |
2326 | sense, but are not implemented because we did not need them. See the | |
2327 | file @file{winner.el} for some more operations on windows | |
2328 | configurations. | |
f9f59935 RS |
2329 | |
2330 | @node Window Hooks | |
2331 | @section Hooks for Window Scrolling and Changes | |
2332 | ||
2333 | This section describes how a Lisp program can take action whenever a | |
2334 | window displays a different part of its buffer or a different buffer. | |
2335 | There are three actions that can change this: scrolling the window, | |
2336 | switching buffers in the window, and changing the size of the window. | |
2337 | The first two actions run @code{window-scroll-functions}; the last runs | |
b98ba93a | 2338 | @code{window-size-change-functions}. |
f9f59935 RS |
2339 | |
2340 | @defvar window-scroll-functions | |
2341 | This variable holds a list of functions that Emacs should call before | |
2342 | redisplaying a window with scrolling. It is not a normal hook, because | |
2343 | each function is called with two arguments: the window, and its new | |
2344 | display-start position. | |
2345 | ||
2346 | Displaying a different buffer in the window also runs these functions. | |
2347 | ||
1911e6e5 RS |
2348 | These functions must be careful in using @code{window-end} |
2349 | (@pxref{Window Start}); if you need an up-to-date value, you must use | |
2350 | the @var{update} argument to ensure you get it. | |
f9f59935 RS |
2351 | @end defvar |
2352 | ||
2353 | @defvar window-size-change-functions | |
2354 | This variable holds a list of functions to be called if the size of any | |
2355 | window changes for any reason. The functions are called just once per | |
2356 | redisplay, and just once for each frame on which size changes have | |
2357 | occurred. | |
2358 | ||
2359 | Each function receives the frame as its sole argument. There is no | |
2360 | direct way to find out which windows on that frame have changed size, or | |
2361 | precisely how. However, if a size-change function records, at each | |
2362 | call, the existing windows and their sizes, it can also compare the | |
2363 | present sizes and the previous sizes. | |
2364 | ||
2365 | Creating or deleting windows counts as a size change, and therefore | |
2366 | causes these functions to be called. Changing the frame size also | |
2367 | counts, because it changes the sizes of the existing windows. | |
2368 | ||
2369 | It is not a good idea to use @code{save-window-excursion} (@pxref{Window | |
2370 | Configurations}) in these functions, because that always counts as a | |
2371 | size change, and it would cause these functions to be called over and | |
2372 | over. In most cases, @code{save-selected-window} (@pxref{Selecting | |
2373 | Windows}) is what you need here. | |
2374 | @end defvar | |
2375 | ||
f9f59935 | 2376 | @defvar redisplay-end-trigger-functions |
1911e6e5 | 2377 | This abnormal hook is run whenever redisplay in a window uses text that |
f9f59935 RS |
2378 | extends past a specified end trigger position. You set the end trigger |
2379 | position with the function @code{set-window-redisplay-end-trigger}. The | |
2380 | functions are called with two arguments: the window, and the end trigger | |
2381 | position. Storing @code{nil} for the end trigger position turns off the | |
2382 | feature, and the trigger value is automatically reset to @code{nil} just | |
2383 | after the hook is run. | |
2384 | @end defvar | |
2385 | ||
f9f59935 RS |
2386 | @defun set-window-redisplay-end-trigger window position |
2387 | This function sets @var{window}'s end trigger position at | |
2388 | @var{position}. | |
2389 | @end defun | |
2390 | ||
8241495d | 2391 | @defun window-redisplay-end-trigger &optional window |
f9f59935 | 2392 | This function returns @var{window}'s current end trigger position. |
eab4e895 | 2393 | If @var{window} is @code{nil} or omitted, it uses the selected window. |
f9f59935 RS |
2394 | @end defun |
2395 | ||
f9f59935 RS |
2396 | @defvar window-configuration-change-hook |
2397 | A normal hook that is run every time you change the window configuration | |
2398 | of an existing frame. This includes splitting or deleting windows, | |
2399 | changing the sizes of windows, or displaying a different buffer in a | |
2400 | window. The frame whose window configuration has changed is the | |
2401 | selected frame when this hook runs. | |
2402 | @end defvar | |
ab5796a9 MB |
2403 | |
2404 | @ignore | |
2405 | arch-tag: 3f6c36e8-df49-4986-b757-417feed88be3 | |
2406 | @end ignore |