Mercurial > hg > xemacs-beta
annotate man/lispref/windows.texi @ 5044:e84a30b0e4a2
remove duplicative code in change_frame_size()
-------------------- ChangeLog entries follow: --------------------
src/ChangeLog addition:
2010-02-15 Ben Wing <ben@xemacs.org>
* frame.c (change_frame_size_1):
Simplify the logic in this function.
(1) Don't allow 0 as the value of height or width. The old code
that tried to allow this was totally broken, anyway, so obviously
this never happens any more.
(2) Don't duplicate the code in frame_conversion_internal() that
converts displayable pixel size to total pixel size -- just call
that function.
| author | Ben Wing <ben@xemacs.org> |
|---|---|
| date | Mon, 15 Feb 2010 22:58:10 -0600 |
| parents | 755ae5b97edb |
| children | 0b4d355771bd |
| rev | line source |
|---|---|
| 428 | 1 @c -*-texinfo-*- |
| 2 @c This is part of the XEmacs Lisp Reference Manual. | |
| 444 | 3 @c Copyright (C) 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc. |
| 428 | 4 @c See the file lispref.texi for copying conditions. |
| 5 @setfilename ../../info/windows.info | |
| 6 @node Windows, Frames, Buffers, Top | |
| 7 @chapter Windows | |
| 8 | |
| 9 This chapter describes most of the functions and variables related to | |
| 10 Emacs windows. See @ref{Display}, for information on how text is | |
| 11 displayed in windows. | |
| 12 | |
| 13 @menu | |
| 14 * Basic Windows:: Basic information on using windows. | |
| 15 * Splitting Windows:: Splitting one window into two windows. | |
| 16 * Deleting Windows:: Deleting a window gives its space to other windows. | |
| 17 * Selecting Windows:: The selected window is the one that you edit in. | |
| 18 * Cyclic Window Ordering:: Moving around the existing windows. | |
| 19 * Buffers and Windows:: Each window displays the contents of a buffer. | |
| 20 * Displaying Buffers:: Higher-lever functions for displaying a buffer | |
| 21 and choosing a window for it. | |
| 22 * Choosing Window:: How to choose a window for displaying a buffer. | |
| 23 * Window Point:: Each window has its own location of point. | |
| 24 * Window Start:: The display-start position controls which text | |
| 444 | 25 is on-screen in the window. |
| 428 | 26 * Vertical Scrolling:: Moving text up and down in the window. |
| 27 * Horizontal Scrolling:: Moving text sideways on the window. | |
| 28 * Size of Window:: Accessing the size of a window. | |
| 29 * Position of Window:: Accessing the position of a window. | |
| 30 * Resizing Windows:: Changing the size of a window. | |
| 31 * Window Configurations:: Saving and restoring the state of the screen. | |
| 32 @end menu | |
| 33 | |
| 34 @node Basic Windows | |
| 35 @section Basic Concepts of Emacs Windows | |
| 36 @cindex window | |
| 37 @cindex selected window | |
| 38 | |
| 39 A @dfn{window} in XEmacs is the physical area of the screen in which a | |
| 40 buffer is displayed. The term is also used to refer to a Lisp object that | |
| 41 represents that screen area in XEmacs Lisp. It should be | |
| 42 clear from the context which is meant. | |
| 43 | |
| 44 XEmacs groups windows into frames. A frame represents an area of | |
| 45 screen available for XEmacs to use. Each frame always contains at least | |
| 46 one window, but you can subdivide it vertically or horizontally into | |
| 47 multiple nonoverlapping Emacs windows. | |
| 48 | |
| 49 In each frame, at any time, one and only one window is designated as | |
| 50 @dfn{selected within the frame}. The frame's cursor appears in that | |
| 2355 | 51 window. At any time, one frame is the selected frame; and the window |
| 428 | 52 selected within that frame is @dfn{the selected window}. The selected |
| 53 window's buffer is usually the current buffer (except when | |
| 54 @code{set-buffer} has been used). @xref{Current Buffer}. | |
| 55 | |
| 56 For practical purposes, a window exists only while it is displayed in | |
| 57 a frame. Once removed from the frame, the window is effectively deleted | |
| 58 and should not be used, @emph{even though there may still be references | |
| 59 to it} from other Lisp objects. Restoring a saved window configuration | |
| 60 is the only way for a window no longer on the screen to come back to | |
| 61 life. (@xref{Deleting Windows}.) | |
| 62 | |
| 63 Each window has the following attributes: | |
| 64 | |
| 65 @itemize @bullet | |
| 66 @item | |
| 67 containing frame | |
| 68 | |
| 444 | 69 @item |
| 428 | 70 window height |
| 71 | |
| 444 | 72 @item |
| 428 | 73 window width |
| 74 | |
| 444 | 75 @item |
| 428 | 76 window edges with respect to the frame or screen |
| 77 | |
| 444 | 78 @item |
| 428 | 79 the buffer it displays |
| 80 | |
| 444 | 81 @item |
| 428 | 82 position within the buffer at the upper left of the window |
| 83 | |
| 444 | 84 @item |
| 428 | 85 amount of horizontal scrolling, in columns |
| 86 | |
| 444 | 87 @item |
| 428 | 88 point |
| 89 | |
| 444 | 90 @item |
| 428 | 91 the mark |
| 92 | |
| 444 | 93 @item |
| 428 | 94 how recently the window was selected |
| 95 @end itemize | |
| 96 | |
| 97 @cindex multiple windows | |
| 98 Users create multiple windows so they can look at several buffers at | |
| 99 once. Lisp libraries use multiple windows for a variety of reasons, but | |
| 100 most often to display related information. In Rmail, for example, you | |
| 101 can move through a summary buffer in one window while the other window | |
| 102 shows messages one at a time as they are reached. | |
| 103 | |
| 104 The meaning of ``window'' in XEmacs is similar to what it means in the | |
| 105 context of general-purpose window systems such as X, but not identical. | |
| 106 The X Window System places X windows on the screen; XEmacs uses one or | |
| 107 more X windows as frames, and subdivides them into | |
| 108 Emacs windows. When you use XEmacs on a character-only terminal, XEmacs | |
| 109 treats the whole terminal screen as one frame. | |
| 110 | |
| 111 @cindex terminal frame | |
| 112 @cindex frame of terminal | |
| 113 @cindex tiled windows | |
| 114 Most window systems support arbitrarily located overlapping windows. | |
| 115 In contrast, Emacs windows are @dfn{tiled}; they never overlap, and | |
| 116 together they fill the whole screen or frame. Because of the way | |
| 117 in which XEmacs creates new windows and resizes them, you can't create | |
| 118 every conceivable tiling of windows on an Emacs frame. @xref{Splitting | |
| 119 Windows}, and @ref{Size of Window}. | |
| 120 | |
| 121 @xref{Display}, for information on how the contents of the | |
| 122 window's buffer are displayed in the window. | |
| 123 | |
| 124 @defun windowp object | |
| 125 This function returns @code{t} if @var{object} is a window. | |
| 126 @end defun | |
| 127 | |
| 128 @node Splitting Windows | |
| 129 @section Splitting Windows | |
| 130 @cindex splitting windows | |
| 131 @cindex window splitting | |
| 132 | |
| 133 The functions described here are the primitives used to split a window | |
| 134 into two windows. Two higher level functions sometimes split a window, | |
| 135 but not always: @code{pop-to-buffer} and @code{display-buffer} | |
| 136 (@pxref{Displaying Buffers}). | |
| 137 | |
| 138 The functions described here do not accept a buffer as an argument. | |
| 139 The two ``halves'' of the split window initially display the same buffer | |
| 140 previously visible in the window that was split. | |
| 141 | |
| 444 | 142 @defun one-window-p &optional nomini which-frames which-devices |
| 428 | 143 This function returns non-@code{nil} if there is only one window. The |
| 444 | 144 argument @var{nomini}, if non-@code{nil}, means don't count the |
| 428 | 145 minibuffer even if it is active; otherwise, the minibuffer window is |
| 146 included, if active, in the total number of windows which is compared | |
| 147 against one. | |
| 148 | |
| 444 | 149 The remaining arguments controls which set of windows are counted, as |
| 150 with @code{next-window}. | |
| 428 | 151 @end defun |
| 152 | |
| 153 @deffn Command split-window &optional window size horizontal | |
| 154 This function splits @var{window} into two windows. The original | |
| 155 window @var{window} remains the selected window, but occupies only | |
| 156 part of its former screen area. The rest is occupied by a newly created | |
| 157 window which is returned as the value of this function. | |
| 158 | |
| 159 If @var{horizontal} is non-@code{nil}, then @var{window} splits into | |
| 160 two side by side windows. The original window @var{window} keeps the | |
| 161 leftmost @var{size} columns, and gives the rest of the columns to the | |
| 162 new window. Otherwise, it splits into windows one above the other, and | |
| 163 @var{window} keeps the upper @var{size} lines and gives the rest of the | |
| 164 lines to the new window. The original window is therefore the | |
| 165 left-hand or upper of the two, and the new window is the right-hand or | |
| 166 lower. | |
| 167 | |
| 168 If @var{window} is omitted or @code{nil}, then the selected window is | |
| 169 split. If @var{size} is omitted or @code{nil}, then @var{window} is | |
| 170 divided evenly into two parts. (If there is an odd line, it is | |
| 171 allocated to the new window.) When @code{split-window} is called | |
| 172 interactively, all its arguments are @code{nil}. | |
| 173 | |
| 174 The following example starts with one window on a frame that is 50 | |
| 175 lines high by 80 columns wide; then the window is split. | |
| 176 | |
| 177 @smallexample | |
| 178 @group | |
| 179 (setq w (selected-window)) | |
| 180 @result{} #<window 8 on windows.texi> | |
| 181 (window-edges) ; @r{Edges in order:} | |
| 182 @result{} (0 0 80 50) ; @r{left--top--right--bottom} | |
| 183 @end group | |
| 184 | |
| 185 @group | |
| 186 ;; @r{Returns window created} | |
| 444 | 187 (setq w2 (split-window w 15)) |
| 428 | 188 @result{} #<window 28 on windows.texi> |
| 189 @end group | |
| 190 @group | |
| 191 (window-edges w2) | |
| 192 @result{} (0 15 80 50) ; @r{Bottom window;} | |
| 193 ; @r{top is line 15} | |
| 194 @end group | |
| 195 @group | |
| 196 (window-edges w) | |
| 197 @result{} (0 0 80 15) ; @r{Top window} | |
| 198 @end group | |
| 199 @end smallexample | |
| 200 | |
| 201 The frame looks like this: | |
| 202 | |
| 203 @smallexample | |
| 204 @group | |
| 444 | 205 __________ |
| 206 | | line 0 | |
| 428 | 207 | w | |
| 208 |__________| | |
| 209 | | line 15 | |
| 210 | w2 | | |
| 211 |__________| | |
| 212 line 50 | |
| 213 column 0 column 80 | |
| 214 @end group | |
| 215 @end smallexample | |
| 216 | |
| 217 Next, the top window is split horizontally: | |
| 218 | |
| 219 @smallexample | |
| 220 @group | |
| 221 (setq w3 (split-window w 35 t)) | |
| 222 @result{} #<window 32 on windows.texi> | |
| 223 @end group | |
| 224 @group | |
| 225 (window-edges w3) | |
| 226 @result{} (35 0 80 15) ; @r{Left edge at column 35} | |
| 227 @end group | |
| 228 @group | |
| 229 (window-edges w) | |
| 230 @result{} (0 0 35 15) ; @r{Right edge at column 35} | |
| 231 @end group | |
| 232 @group | |
| 233 (window-edges w2) | |
| 234 @result{} (0 15 80 50) ; @r{Bottom window unchanged} | |
| 235 @end group | |
| 236 @end smallexample | |
| 237 | |
| 238 @need 3000 | |
| 239 Now, the screen looks like this: | |
| 240 | |
| 241 @smallexample | |
| 242 @group | |
| 243 column 35 | |
| 444 | 244 __________ |
| 245 | | | line 0 | |
| 428 | 246 | w | w3 | |
| 247 |___|______| | |
| 248 | | line 15 | |
| 249 | w2 | | |
| 250 |__________| | |
| 251 line 50 | |
| 252 column 0 column 80 | |
| 253 @end group | |
| 254 @end smallexample | |
| 255 | |
| 256 Normally, Emacs indicates the border between two side-by-side windows | |
| 257 with a scroll bar (@pxref{X Frame Properties,Scroll Bars}) or @samp{|} | |
| 258 characters. The display table can specify alternative border | |
| 259 characters; see @ref{Display Tables}. | |
| 260 @end deffn | |
| 261 | |
| 262 @deffn Command split-window-vertically &optional size | |
| 263 This function splits the selected window into two windows, one above | |
| 264 the other, leaving the selected window with @var{size} lines. | |
| 265 | |
| 444 | 266 This function is simply an interface to @code{split-window}. |
| 428 | 267 Here is the complete function definition for it: |
| 268 | |
| 269 @smallexample | |
| 270 @group | |
| 271 (defun split-window-vertically (&optional arg) | |
| 272 "Split current window into two windows, one above the other." | |
| 273 (interactive "P") | |
| 274 (split-window nil (and arg (prefix-numeric-value arg)))) | |
| 275 @end group | |
| 276 @end smallexample | |
| 277 @end deffn | |
| 278 | |
| 279 @deffn Command split-window-horizontally &optional size | |
| 280 This function splits the selected window into two windows | |
| 281 side-by-side, leaving the selected window with @var{size} columns. | |
| 282 | |
| 444 | 283 This function is simply an interface to @code{split-window}. Here is |
| 428 | 284 the complete definition for @code{split-window-horizontally} (except for |
| 285 part of the documentation string): | |
| 286 | |
| 287 @smallexample | |
| 288 @group | |
| 289 (defun split-window-horizontally (&optional arg) | |
| 290 "Split selected window into two windows, side by side..." | |
| 291 (interactive "P") | |
| 292 (split-window nil (and arg (prefix-numeric-value arg)) t)) | |
| 293 @end group | |
| 294 @end smallexample | |
| 295 @end deffn | |
| 296 | |
| 297 @node Deleting Windows | |
| 298 @section Deleting Windows | |
| 299 @cindex deleting windows | |
| 300 | |
| 301 A window remains visible on its frame unless you @dfn{delete} it by | |
| 302 calling certain functions that delete windows. A deleted window cannot | |
| 303 appear on the screen, but continues to exist as a Lisp object until | |
| 304 there are no references to it. There is no way to cancel the deletion | |
| 305 of a window aside from restoring a saved window configuration | |
| 306 (@pxref{Window Configurations}). Restoring a window configuration also | |
| 307 deletes any windows that aren't part of that configuration. | |
| 308 | |
| 309 When you delete a window, the space it took up is given to one | |
| 310 adjacent sibling. (In Emacs version 18, the space was divided evenly | |
| 311 among all the siblings.) | |
| 312 | |
| 313 @c Emacs 19 feature | |
| 314 @defun window-live-p window | |
| 315 This function returns @code{nil} if @var{window} is deleted, and | |
| 316 @code{t} otherwise. | |
| 317 | |
| 318 @strong{Warning:} Erroneous information or fatal errors may result from | |
| 319 using a deleted window as if it were live. | |
| 320 @end defun | |
| 321 | |
| 444 | 322 @deffn Command delete-window &optional window force |
| 323 This function removes @var{window} from the display. If @var{window} is | |
| 324 omitted, then the selected window is deleted. If window is the only one | |
| 325 on its frame, the frame is deleted as well. | |
| 326 | |
| 327 Normally, you cannot delete the last non-minibuffer-only frame (you must | |
| 328 use @code{save-buffers-kill-emacs} or @code{kill-emacs}); an error is | |
| 329 signaled instead. However, if optional second argument @var{force} is | |
| 330 non-@code{nil}, you can delete the last frame. (This will automatically | |
| 331 call @code{save-buffers-kill-emacs}.) | |
| 428 | 332 |
| 333 This function returns @code{nil}. | |
| 334 | |
| 444 | 335 When @code{delete-window} is called interactively, the selected window |
| 336 is deleted. | |
| 428 | 337 @end deffn |
| 338 | |
| 339 @deffn Command delete-other-windows &optional window | |
| 340 This function makes @var{window} the only window on its frame, by | |
| 341 deleting the other windows in that frame. If @var{window} is omitted or | |
| 342 @code{nil}, then the selected window is used by default. | |
| 343 | |
| 344 The result is @code{nil}. | |
| 345 @end deffn | |
| 346 | |
| 444 | 347 @deffn Command delete-windows-on buffer &optional which-frames which-devices |
| 428 | 348 This function deletes all windows showing @var{buffer}. If there are |
| 349 no windows showing @var{buffer}, it does nothing. | |
| 350 | |
| 351 @code{delete-windows-on} operates frame by frame. If a frame has | |
| 352 several windows showing different buffers, then those showing | |
| 353 @var{buffer} are removed, and the others expand to fill the space. If | |
| 354 all windows in some frame are showing @var{buffer} (including the case | |
| 355 where there is only one window), then the frame reverts to having a | |
| 356 single window showing another buffer chosen with @code{other-buffer}. | |
| 357 @xref{The Buffer List}. | |
| 358 | |
| 444 | 359 The argument @var{which-frames} controls which frames to operate on: |
| 360 | |
| 361 @table @asis | |
| 362 @item @code{nil} | |
| 363 Delete all windows showing @var{buffer} in any frame. | |
| 364 | |
| 365 @item @code{t} | |
| 366 Delete only windows showing @var{buffer} in the selected frame. | |
| 367 | |
| 368 @item @code{visible} | |
| 369 Delete all windows showing @var{buffer} in any visible frame. | |
| 370 | |
| 371 @item @code{0} | |
| 372 Delete all windows showing @var{buffer} in any visible frame. | |
| 373 | |
| 374 @item @var{frame} | |
| 375 If it is a frame, delete all windows showing @var{buffer} in that frame. | |
| 376 @end table | |
| 377 | |
| 378 @strong{Warning:} This is similar to, but not identical to, the meaning | |
| 379 of the @var{which-frames} argument to @code{next-window}; the meanings | |
| 380 of @code{nil} and @code{t} are reversed. | |
| 428 | 381 |
| 444 | 382 The optional argument @var{which-devices} further clarifies on which |
| 383 devices to search for frames as specified by @var{which-frames}. | |
| 384 This value is only meaningful if @var{which-frames} is not @code{t}. | |
| 385 | |
| 386 @table @asis | |
| 387 @item @code{nil} | |
| 388 Consider all devices on the selected console. | |
| 389 | |
| 390 @item @var{device} | |
| 391 Consider only the one device @var{device}. | |
| 392 | |
| 393 @item @var{console} | |
| 394 Consider all devices on @var{console}. | |
| 395 | |
| 396 @item @var{device-type} | |
| 397 Consider all devices with device type @var{device-type}. | |
| 398 | |
| 399 @item @code{window-system} | |
| 400 Consider all devices on window system consoles. | |
| 401 | |
| 402 @item anything else | |
| 403 Consider all devices without restriction. | |
| 404 @end table | |
| 428 | 405 |
| 406 This function always returns @code{nil}. | |
| 407 @end deffn | |
| 408 | |
| 409 @node Selecting Windows | |
| 410 @section Selecting Windows | |
| 411 @cindex selecting windows | |
| 412 | |
| 413 When a window is selected, the buffer in the window becomes the current | |
| 414 buffer, and the cursor will appear in it. | |
| 415 | |
| 416 @defun selected-window &optional device | |
| 417 This function returns the selected window. This is the window in | |
| 418 which the cursor appears and to which many commands apply. Each | |
| 419 separate device can have its own selected window, which is remembered | |
| 420 as focus changes from device to device. Optional argument @var{device} | |
| 421 specifies which device to return the selected window for, and defaults | |
| 422 to the selected device. | |
| 423 @end defun | |
| 424 | |
| 425 @defun select-window window &optional norecord | |
| 426 This function makes @var{window} the selected window. The cursor then | |
| 427 appears in @var{window} (on redisplay). The buffer being displayed in | |
| 428 @var{window} is immediately designated the current buffer. | |
| 429 | |
| 430 If optional argument @var{norecord} is non-@code{nil} then the global | |
| 431 and per-frame buffer orderings are not modified, as by the function | |
| 444 | 432 @code{record-buffer}. |
| 428 | 433 |
| 434 The return value is @var{window}. | |
| 435 | |
| 436 @example | |
| 437 @group | |
| 438 (setq w (next-window)) | |
| 439 (select-window w) | |
| 440 @result{} #<window 65 on windows.texi> | |
| 441 @end group | |
| 442 @end example | |
| 443 @end defun | |
| 444 | |
| 444 | 445 @defspec save-selected-window forms@dots{} |
|
4905
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Change "special form" to "special operator" in our sources.
Aidan Kehoe <kehoea@parhasard.net>
parents:
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changeset
|
446 This macro records the selected window, executes @var{forms} in |
| 444 | 447 sequence, then restores the earlier selected window. It does not save |
| 448 or restore anything about the sizes, arrangement or contents of windows; | |
| 449 therefore, if the @var{forms} change them, the changes are permanent. | |
| 450 @end defspec | |
| 428 | 451 |
| 452 @cindex finding windows | |
| 453 The following functions choose one of the windows on the screen, | |
| 454 offering various criteria for the choice. | |
| 455 | |
| 444 | 456 @defun get-lru-window &optional which-frames which-devices |
| 428 | 457 This function returns the window least recently ``used'' (that is, |
| 458 selected). The selected window is always the most recently used window. | |
| 459 | |
| 460 The selected window can be the least recently used window if it is the | |
| 461 only window. A newly created window becomes the least recently used | |
| 462 window until it is selected. A minibuffer window is never a candidate. | |
| 463 | |
| 444 | 464 By default, only the windows in the selected frame are considered. |
| 465 The optional argument @var{which-frames} changes this behavior. | |
| 466 Here are the possible values and their meanings: | |
| 467 | |
| 468 @table @asis | |
| 469 @item @code{nil} | |
| 470 Consider all the windows in the selected windows's frame, plus the | |
| 471 minibuffer used by that frame even if it lies in some other frame. | |
| 472 | |
| 473 @item @code{t} | |
| 474 Consider all windows in all existing frames. | |
| 475 | |
| 476 @item @code{visible} | |
| 477 Consider all windows in all visible frames. (To get useful results, you | |
| 478 must ensure @var{window} is in a visible frame.) | |
| 479 | |
| 480 @item @code{0} | |
| 481 Consider all windows in all visible or iconified frames. | |
| 482 | |
| 483 @item @var{frame} | |
| 484 Consider all windows on frame @var{frame}. | |
| 428 | 485 |
| 444 | 486 @item anything else |
| 487 Consider precisely the windows in the selected window's frame, and no others. | |
| 488 @end table | |
| 489 | |
| 490 The optional argument @var{which-devices} further clarifies on which | |
| 491 devices to search for frames as specified by @var{which-frames}. | |
| 492 This value is only meaningful if @var{which-frames} is non-@code{nil}. | |
| 493 | |
| 494 @table @asis | |
| 495 @item @code{nil} | |
| 496 Consider all devices on the selected console. | |
| 497 | |
| 498 @item @var{device} | |
| 499 Consider only the one device @var{device}. | |
| 500 | |
| 501 @item @var{console} | |
| 502 Consider all devices on @var{console}. | |
| 503 | |
| 504 @item @var{device-type} | |
| 505 Consider all devices with device type @var{device-type}. | |
| 506 | |
| 507 @item @code{window-system} | |
| 508 Consider all devices on window system consoles. | |
| 509 | |
| 510 @item anything else | |
| 511 Consider all devices without restriction. | |
| 512 @end table | |
| 513 | |
| 428 | 514 @end defun |
| 515 | |
| 444 | 516 @defun get-largest-window &optional which-frames which-devices |
| 428 | 517 This function returns the window with the largest area (height times |
| 518 width). If there are no side-by-side windows, then this is the window | |
| 519 with the most lines. A minibuffer window is never a candidate. | |
| 520 | |
| 521 If there are two windows of the same size, then the function returns | |
| 522 the window that is first in the cyclic ordering of windows (see | |
| 523 following section), starting from the selected window. | |
| 524 | |
| 444 | 525 The remaining arguments control which set of windows are considered. |
| 526 See @code{next-window}, above. | |
| 428 | 527 @end defun |
| 528 | |
| 529 @node Cyclic Window Ordering | |
| 530 @section Cyclic Ordering of Windows | |
| 531 @cindex cyclic ordering of windows | |
| 532 @cindex ordering of windows, cyclic | |
| 444 | 533 @cindex window ordering, cyclic |
| 428 | 534 |
| 535 When you use the command @kbd{C-x o} (@code{other-window}) to select | |
| 536 the next window, it moves through all the windows on the screen in a | |
| 537 specific cyclic order. For any given configuration of windows, this | |
| 538 order never varies. It is called the @dfn{cyclic ordering of windows}. | |
| 539 | |
| 540 This ordering generally goes from top to bottom, and from left to | |
| 541 right. But it may go down first or go right first, depending on the | |
| 542 order in which the windows were split. | |
| 543 | |
| 544 If the first split was vertical (into windows one above each other), | |
| 545 and then the subwindows were split horizontally, then the ordering is | |
| 546 left to right in the top of the frame, and then left to right in the | |
| 547 next lower part of the frame, and so on. If the first split was | |
| 548 horizontal, the ordering is top to bottom in the left part, and so on. | |
| 549 In general, within each set of siblings at any level in the window tree, | |
| 550 the order is left to right, or top to bottom. | |
| 551 | |
| 444 | 552 @defun next-window &optional window minibuf which-frames which-devices |
| 428 | 553 @cindex minibuffer window |
| 554 This function returns the window following @var{window} in the cyclic | |
| 555 ordering of windows. This is the window that @kbd{C-x o} would select | |
| 556 if typed when @var{window} is selected. If @var{window} is the only | |
| 557 window visible, then this function returns @var{window}. If omitted, | |
| 558 @var{window} defaults to the selected window. | |
| 559 | |
| 560 The value of the argument @var{minibuf} determines whether the | |
| 561 minibuffer is included in the window order. Normally, when | |
| 562 @var{minibuf} is @code{nil}, the minibuffer is included if it is | |
| 563 currently active; this is the behavior of @kbd{C-x o}. (The minibuffer | |
| 564 window is active while the minibuffer is in use. @xref{Minibuffers}.) | |
| 565 | |
| 566 If @var{minibuf} is @code{t}, then the cyclic ordering includes the | |
| 567 minibuffer window even if it is not active. | |
| 568 | |
| 569 If @var{minibuf} is neither @code{t} nor @code{nil}, then the minibuffer | |
| 570 window is not included even if it is active. | |
| 571 | |
| 444 | 572 By default, only the windows in the selected frame are considered. |
| 573 The optional argument @var{which-frames} changes this behavior. | |
| 574 Here are the possible values and their meanings: | |
| 428 | 575 |
| 576 @table @asis | |
| 577 @item @code{nil} | |
| 578 Consider all the windows in @var{window}'s frame, plus the minibuffer | |
| 579 used by that frame even if it lies in some other frame. | |
| 580 | |
| 581 @item @code{t} | |
| 582 Consider all windows in all existing frames. | |
| 583 | |
| 584 @item @code{visible} | |
| 585 Consider all windows in all visible frames. (To get useful results, you | |
| 586 must ensure @var{window} is in a visible frame.) | |
| 587 | |
| 444 | 588 @item @code{0} |
| 428 | 589 Consider all windows in all visible or iconified frames. |
| 590 | |
| 444 | 591 @item @var{frame} |
| 592 Consider all windows on frame @var{frame}. | |
| 593 | |
| 428 | 594 @item anything else |
| 595 Consider precisely the windows in @var{window}'s frame, and no others. | |
| 596 @end table | |
| 597 | |
| 444 | 598 The optional argument @var{which-devices} further clarifies on which |
| 599 devices to search for frames as specified by @var{which-frames}. | |
| 600 This value is only meaningful if @var{which-frames} is non-@code{nil}. | |
| 601 | |
| 602 @table @asis | |
| 603 @item @code{nil} | |
| 604 Consider all devices on the selected console. | |
| 605 | |
| 606 @item @var{device} | |
| 607 Consider only the one device @var{device}. | |
| 608 | |
| 609 @item @var{console} | |
| 610 Consider all devices on @var{console}. | |
| 611 | |
| 612 @item @var{device-type} | |
| 613 Consider all devices with device type @var{device-type}. | |
| 614 | |
| 615 @item @code{window-system} | |
| 616 Consider all devices on window system consoles. | |
| 617 | |
| 618 @item anything else | |
| 619 Consider all devices without restriction. | |
| 620 @end table | |
| 621 | |
| 622 If you use consistent values for @var{minibuf}, @var{which-frames}, and | |
| 623 @var{which-devices}, you can use @code{next-window} to iterate through the | |
| 624 entire cycle of acceptable windows, eventually ending up back at the | |
| 625 window you started with. @code{previous-window} traverses the same | |
| 626 cycle, in the reverse order. | |
| 627 | |
| 628 This example assumes there are two windows, both displaying the | |
| 428 | 629 buffer @samp{windows.texi}: |
| 630 | |
| 631 @example | |
| 632 @group | |
| 633 (selected-window) | |
| 634 @result{} #<window 56 on windows.texi> | |
| 635 @end group | |
| 636 @group | |
| 637 (next-window (selected-window)) | |
| 638 @result{} #<window 52 on windows.texi> | |
| 639 @end group | |
| 640 @group | |
| 641 (next-window (next-window (selected-window))) | |
| 642 @result{} #<window 56 on windows.texi> | |
| 643 @end group | |
| 644 @end example | |
| 645 @end defun | |
| 646 | |
| 444 | 647 @defun previous-window &optional window minibuf which-frames which-devices |
| 428 | 648 This function returns the window preceding @var{window} in the cyclic |
| 649 ordering of windows. The other arguments specify which windows to | |
| 650 include in the cycle, as in @code{next-window}. | |
| 651 @end defun | |
| 652 | |
| 444 | 653 @deffn Command other-window count &optional which-frames which-devices |
| 654 This function selects the @var{count}th following window in the cyclic order. | |
| 655 If @var{count} is negative, then it selects the @minus{}@var{count}th | |
| 428 | 656 preceding window. It returns @code{nil}. |
| 657 | |
| 658 In an interactive call, @var{count} is the numeric prefix argument. | |
| 659 | |
| 444 | 660 The other arguments specify which windows to include in the cycle, as in |
| 661 @code{next-window}. | |
| 428 | 662 @end deffn |
| 663 | |
| 444 | 664 @defun walk-windows function &optional minibuf which-frames which-devices |
| 665 This function cycles through all windows, calling @code{function} | |
| 428 | 666 once for each window with the window as its sole argument. |
| 667 | |
| 444 | 668 The other arguments specify which windows to cycle through, as in |
| 669 @code{next-window}. | |
| 428 | 670 @end defun |
| 671 | |
| 672 @node Buffers and Windows | |
| 673 @section Buffers and Windows | |
| 674 @cindex examining windows | |
| 675 @cindex windows, controlling precisely | |
| 676 @cindex buffers, controlled in windows | |
| 677 | |
| 678 This section describes low-level functions to examine windows or to | |
| 679 display buffers in windows in a precisely controlled fashion. | |
| 680 @iftex | |
| 681 See the following section for | |
| 682 @end iftex | |
| 683 @ifinfo | |
| 684 @xref{Displaying Buffers}, for | |
| 685 @end ifinfo | |
| 686 related functions that find a window to use and specify a buffer for it. | |
| 687 The functions described there are easier to use than these, but they | |
| 688 employ heuristics in choosing or creating a window; use these functions | |
| 689 when you need complete control. | |
| 690 | |
| 444 | 691 @defun set-window-buffer window buffer-or-name &optional norecord |
| 428 | 692 This function makes @var{window} display @var{buffer-or-name} as its |
| 444 | 693 contents. @var{buffer-or-name} can be a buffer or a buffer name. |
| 694 | |
| 695 With non-@code{nil} optional argument @var{norecord}, do not modify the | |
| 696 global or per-frame buffer ordering. | |
| 697 | |
| 698 This function returns @code{nil}. | |
| 428 | 699 |
| 700 @example | |
| 701 @group | |
| 702 (set-window-buffer (selected-window) "foo") | |
| 703 @result{} nil | |
| 704 @end group | |
| 705 @end example | |
| 706 @end defun | |
| 707 | |
| 708 @defun window-buffer &optional window | |
| 709 This function returns the buffer that @var{window} is displaying. If | |
| 710 @var{window} is omitted, this function returns the buffer for the | |
| 711 selected window. | |
| 712 | |
| 713 @example | |
| 714 @group | |
| 715 (window-buffer) | |
| 716 @result{} #<buffer windows.texi> | |
| 717 @end group | |
| 718 @end example | |
| 719 @end defun | |
| 720 | |
| 444 | 721 @defun get-buffer-window buffer-or-name &optional which-frames which-devices |
| 428 | 722 This function returns a window currently displaying |
| 723 @var{buffer-or-name}, or @code{nil} if there is none. If there are | |
| 724 several such windows, then the function returns the first one in the | |
| 725 cyclic ordering of windows, starting from the selected window. | |
| 726 @xref{Cyclic Window Ordering}. | |
| 727 | |
| 444 | 728 The remaining arguments control which windows to consider. They have |
| 729 the same meaning as for @code{next-window}. | |
| 428 | 730 @end defun |
| 731 | |
| 732 @node Displaying Buffers | |
| 733 @section Displaying Buffers in Windows | |
| 734 @cindex switching to a buffer | |
| 735 @cindex displaying a buffer | |
| 736 | |
| 737 In this section we describe convenient functions that choose a window | |
| 738 automatically and use it to display a specified buffer. These functions | |
| 739 can also split an existing window in certain circumstances. We also | |
| 740 describe variables that parameterize the heuristics used for choosing a | |
| 741 window. | |
| 742 @iftex | |
| 743 See the preceding section for | |
| 744 @end iftex | |
| 745 @ifinfo | |
| 746 @xref{Buffers and Windows}, for | |
| 747 @end ifinfo | |
| 748 low-level functions that give you more precise control. | |
| 749 | |
| 750 Do not use the functions in this section in order to make a buffer | |
| 751 current so that a Lisp program can access or modify it; they are too | |
| 752 drastic for that purpose, since they change the display of buffers in | |
| 753 windows, which is gratuitous and will surprise the user. Instead, use | |
| 754 @code{set-buffer} (@pxref{Current Buffer}) and @code{save-excursion} | |
| 755 (@pxref{Excursions}), which designate buffers as current for programmed | |
| 756 access without affecting the display of buffers in windows. | |
| 757 | |
| 758 @deffn Command switch-to-buffer buffer-or-name &optional norecord | |
| 759 This function makes @var{buffer-or-name} the current buffer, and also | |
| 760 displays the buffer in the selected window. This means that a human can | |
| 761 see the buffer and subsequent keyboard commands will apply to it. | |
| 762 Contrast this with @code{set-buffer}, which makes @var{buffer-or-name} | |
| 763 the current buffer but does not display it in the selected window. | |
| 764 @xref{Current Buffer}. | |
| 765 | |
| 766 If @var{buffer-or-name} does not identify an existing buffer, then a new | |
| 767 buffer by that name is created. The major mode for the new buffer is | |
| 768 set according to the variable @code{default-major-mode}. @xref{Auto | |
| 769 Major Mode}. | |
| 770 | |
| 771 Normally the specified buffer is put at the front of the buffer list. | |
| 772 This affects the operation of @code{other-buffer}. However, if | |
| 773 @var{norecord} is non-@code{nil}, this is not done. @xref{The Buffer | |
| 774 List}. | |
| 775 | |
| 776 The @code{switch-to-buffer} function is often used interactively, as | |
| 777 the binding of @kbd{C-x b}. It is also used frequently in programs. It | |
| 778 always returns @code{nil}. | |
| 779 @end deffn | |
| 780 | |
| 781 @deffn Command switch-to-buffer-other-window buffer-or-name | |
| 782 This function makes @var{buffer-or-name} the current buffer and | |
| 783 displays it in a window not currently selected. It then selects that | |
| 784 window. The handling of the buffer is the same as in | |
| 785 @code{switch-to-buffer}. | |
| 786 | |
| 787 The currently selected window is absolutely never used to do the job. | |
| 788 If it is the only window, then it is split to make a distinct window for | |
| 789 this purpose. If the selected window is already displaying the buffer, | |
| 790 then it continues to do so, but another window is nonetheless found to | |
| 791 display it in as well. | |
| 792 @end deffn | |
| 793 | |
| 794 @defun pop-to-buffer buffer-or-name &optional other-window on-frame | |
| 795 This function makes @var{buffer-or-name} the current buffer and | |
| 796 switches to it in some window, preferably not the window previously | |
| 797 selected. The ``popped-to'' window becomes the selected window within | |
| 798 its frame. | |
| 799 | |
| 800 If the variable @code{pop-up-frames} is non-@code{nil}, | |
| 801 @code{pop-to-buffer} looks for a window in any visible frame already | |
| 802 displaying the buffer; if there is one, it returns that window and makes | |
| 803 it be selected within its frame. If there is none, it creates a new | |
| 804 frame and displays the buffer in it. | |
| 805 | |
| 806 If @code{pop-up-frames} is @code{nil}, then @code{pop-to-buffer} | |
| 807 operates entirely within the selected frame. (If the selected frame has | |
| 808 just a minibuffer, @code{pop-to-buffer} operates within the most | |
| 809 recently selected frame that was not just a minibuffer.) | |
| 810 | |
| 811 If the variable @code{pop-up-windows} is non-@code{nil}, windows may | |
| 812 be split to create a new window that is different from the original | |
| 813 window. For details, see @ref{Choosing Window}. | |
| 814 | |
| 815 If @var{other-window} is non-@code{nil}, @code{pop-to-buffer} finds or | |
| 816 creates another window even if @var{buffer-or-name} is already visible | |
| 817 in the selected window. Thus @var{buffer-or-name} could end up | |
| 818 displayed in two windows. On the other hand, if @var{buffer-or-name} is | |
| 819 already displayed in the selected window and @var{other-window} is | |
| 820 @code{nil}, then the selected window is considered sufficient display | |
| 821 for @var{buffer-or-name}, so that nothing needs to be done. | |
| 822 | |
| 823 All the variables that affect @code{display-buffer} affect | |
| 824 @code{pop-to-buffer} as well. @xref{Choosing Window}. | |
| 825 | |
| 826 If @var{buffer-or-name} is a string that does not name an existing | |
| 827 buffer, a buffer by that name is created. The major mode for the new | |
| 828 buffer is set according to the variable @code{default-major-mode}. | |
| 829 @xref{Auto Major Mode}. | |
| 830 | |
| 831 If @var{on-frame} is non-@code{nil}, it is the frame to pop to this | |
| 832 buffer on. | |
| 833 | |
| 834 An example use of this function is found at the end of @ref{Filter | |
| 835 Functions}. | |
| 836 @end defun | |
| 837 | |
| 444 | 838 @deffn Command replace-buffer-in-windows buffer &optional which-frames which-devices |
| 428 | 839 This function replaces @var{buffer} with some other buffer in all |
| 840 windows displaying it. The other buffer used is chosen with | |
| 841 @code{other-buffer}. In the usual applications of this function, you | |
| 842 don't care which other buffer is used; you just want to make sure that | |
| 843 @var{buffer} is no longer displayed. | |
| 844 | |
| 444 | 845 The optional arguments @var{which-frames} and @var{which-devices} have |
| 846 the same meaning as with @code{delete-windows-on}. | |
| 847 | |
| 428 | 848 This function returns @code{nil}. |
| 849 @end deffn | |
| 850 | |
| 851 @node Choosing Window | |
| 852 @section Choosing a Window for Display | |
| 853 | |
| 854 This section describes the basic facility that chooses a window to | |
| 855 display a buffer in---@code{display-buffer}. All the higher-level | |
| 856 functions and commands use this subroutine. Here we describe how to use | |
| 857 @code{display-buffer} and how to customize it. | |
| 858 | |
| 444 | 859 @deffn Command display-buffer buffer-or-name &optional not-this-window override-frame |
| 428 | 860 This command makes @var{buffer-or-name} appear in some window, like |
| 861 @code{pop-to-buffer}, but it does not select that window and does not | |
| 862 make the buffer current. The identity of the selected window is | |
| 863 unaltered by this function. | |
| 864 | |
| 444 | 865 @var{buffer-or-name} can be a buffer or the name of one. |
| 866 | |
| 428 | 867 If @var{not-this-window} is non-@code{nil}, it means to display the |
| 868 specified buffer in a window other than the selected one, even if it is | |
| 869 already on display in the selected window. This can cause the buffer to | |
| 870 appear in two windows at once. Otherwise, if @var{buffer-or-name} is | |
| 871 already being displayed in any window, that is good enough, so this | |
| 872 function does nothing. | |
| 873 | |
| 444 | 874 If @var{override-frame} is non-@code{nil}, display on that frame instead |
| 875 of the current frame (or the dedicated frame). | |
| 876 | |
| 877 @code{display-buffer} returns the window chosen to display @var{buffer-or-name}. | |
| 428 | 878 |
| 879 Precisely how @code{display-buffer} finds or creates a window depends on | |
| 880 the variables described below. | |
| 881 @end deffn | |
| 882 | |
| 883 @c Emacs 19 feature | |
| 884 @cindex dedicated window | |
| 885 A window can be marked as ``dedicated'' to a particular buffer. | |
| 886 Then XEmacs will not automatically change which buffer appears in the | |
| 887 window, such as @code{display-buffer} might normally do. | |
| 888 | |
| 889 @defun window-dedicated-p window | |
| 890 This function returns @var{window}'s dedicated object, usually @code{t} | |
| 891 or @code{nil}. | |
| 892 @end defun | |
| 893 | |
| 894 @defun set-window-buffer-dedicated window buffer | |
| 895 This function makes @var{window} display @var{buffer} and be dedicated | |
| 896 to that buffer. Then XEmacs will not automatically change which buffer | |
| 897 appears in @var{window}. If @var{buffer} is @code{nil}, this function makes | |
| 898 @var{window} not be dedicated (but doesn't change which buffer appears | |
| 899 in it currently). | |
| 900 @end defun | |
| 901 | |
| 902 @defopt pop-up-windows | |
| 903 This variable controls whether @code{display-buffer} makes new windows. | |
| 904 If it is non-@code{nil} and there is only one window, then that window | |
| 905 is split. If it is @code{nil}, then @code{display-buffer} does not | |
| 906 split the single window, but uses it whole. | |
| 907 @end defopt | |
| 908 | |
| 909 @defopt split-height-threshold | |
| 910 This variable determines when @code{display-buffer} may split a window, | |
| 911 if there are multiple windows. @code{display-buffer} always splits the | |
| 912 largest window if it has at least this many lines. If the largest | |
| 913 window is not this tall, it is split only if it is the sole window and | |
| 914 @code{pop-up-windows} is non-@code{nil}. | |
| 915 @end defopt | |
| 916 | |
| 917 @c Emacs 19 feature | |
| 918 @defopt pop-up-frames | |
| 919 This variable controls whether @code{display-buffer} makes new frames. | |
| 920 If it is non-@code{nil}, @code{display-buffer} looks for an existing | |
| 921 window already displaying the desired buffer, on any visible frame. If | |
| 922 it finds one, it returns that window. Otherwise it makes a new frame. | |
| 923 The variables @code{pop-up-windows} and @code{split-height-threshold} do | |
| 924 not matter if @code{pop-up-frames} is non-@code{nil}. | |
| 925 | |
| 926 If @code{pop-up-frames} is @code{nil}, then @code{display-buffer} either | |
| 927 splits a window or reuses one. | |
| 928 | |
| 929 @xref{Frames}, for more information. | |
| 930 @end defopt | |
| 931 | |
| 932 @c Emacs 19 feature | |
| 933 @defvar pop-up-frame-function | |
| 934 This variable specifies how to make a new frame if @code{pop-up-frames} | |
| 935 is non-@code{nil}. | |
| 936 | |
| 937 Its value should be a function of no arguments. When | |
| 938 @code{display-buffer} makes a new frame, it does so by calling that | |
| 939 function, which should return a frame. The default value of the | |
| 940 variable is a function that creates a frame using properties from | |
| 941 @code{pop-up-frame-plist}. | |
| 942 @end defvar | |
| 943 | |
| 944 @defvar pop-up-frame-plist | |
| 945 This variable holds a plist specifying frame properties used when | |
| 946 @code{display-buffer} makes a new frame. @xref{Frame Properties}, for | |
| 947 more information about frame properties. | |
| 948 @end defvar | |
| 949 | |
| 950 @defvar special-display-buffer-names | |
| 951 A list of buffer names for buffers that should be displayed specially. | |
| 952 If the buffer's name is in this list, @code{display-buffer} handles the | |
| 953 buffer specially. | |
| 954 | |
| 955 By default, special display means to give the buffer a dedicated frame. | |
| 956 | |
| 957 If an element is a list, instead of a string, then the @sc{car} of the | |
| 958 list is the buffer name, and the rest of the list says how to create the | |
| 959 frame. There are two possibilities for the rest of the list. It can be | |
| 960 a plist, specifying frame properties, or it can contain a function and | |
| 961 arguments to give to it. (The function's first argument is always the | |
| 962 buffer to be displayed; the arguments from the list come after that.) | |
| 963 @end defvar | |
| 964 | |
| 965 @defvar special-display-regexps | |
| 966 A list of regular expressions that specify buffers that should be | |
| 967 displayed specially. If the buffer's name matches any of the regular | |
| 968 expressions in this list, @code{display-buffer} handles the buffer | |
| 969 specially. | |
| 970 | |
| 971 By default, special display means to give the buffer a dedicated frame. | |
| 972 | |
| 973 If an element is a list, instead of a string, then the @sc{car} of the | |
| 974 list is the regular expression, and the rest of the list says how to | |
| 975 create the frame. See above, under @code{special-display-buffer-names}. | |
| 976 @end defvar | |
| 977 | |
| 978 @defvar special-display-function | |
| 979 This variable holds the function to call to display a buffer specially. | |
| 980 It receives the buffer as an argument, and should return the window in | |
| 981 which it is displayed. | |
| 982 | |
| 983 The default value of this variable is | |
| 984 @code{special-display-popup-frame}. | |
| 985 @end defvar | |
| 986 | |
| 987 @defun special-display-popup-frame buffer | |
| 988 This function makes @var{buffer} visible in a frame of its own. If | |
| 989 @var{buffer} is already displayed in a window in some frame, it makes | |
| 990 the frame visible and raises it, to use that window. Otherwise, it | |
| 991 creates a frame that will be dedicated to @var{buffer}. | |
| 992 | |
| 993 This function uses an existing window displaying @var{buffer} whether or | |
| 994 not it is in a frame of its own; but if you set up the above variables | |
| 995 in your init file, before @var{buffer} was created, then presumably the | |
| 996 window was previously made by this function. | |
| 997 @end defun | |
| 998 | |
| 999 @defopt special-display-frame-plist | |
| 1000 This variable holds frame properties for | |
| 1001 @code{special-display-popup-frame} to use when it creates a frame. | |
| 1002 @end defopt | |
| 1003 | |
| 1004 @defvar same-window-buffer-names | |
| 1005 A list of buffer names for buffers that should be displayed in the | |
| 1006 selected window. If the buffer's name is in this list, | |
| 1007 @code{display-buffer} handles the buffer by switching to it in the | |
| 1008 selected window. | |
| 1009 @end defvar | |
| 1010 | |
| 1011 @defvar same-window-regexps | |
| 1012 A list of regular expressions that specify buffers that should be | |
| 1013 displayed in the selected window. If the buffer's name matches any of | |
| 1014 the regular expressions in this list, @code{display-buffer} handles the | |
| 1015 buffer by switching to it in the selected window. | |
| 1016 @end defvar | |
| 1017 | |
| 1018 @c Emacs 19 feature | |
| 1019 @defvar display-buffer-function | |
| 1020 This variable is the most flexible way to customize the behavior of | |
| 1021 @code{display-buffer}. If it is non-@code{nil}, it should be a function | |
| 1022 that @code{display-buffer} calls to do the work. The function should | |
| 1023 accept two arguments, the same two arguments that @code{display-buffer} | |
| 1024 received. It should choose or create a window, display the specified | |
| 1025 buffer, and then return the window. | |
| 1026 | |
| 1027 This hook takes precedence over all the other options and hooks | |
| 1028 described above. | |
| 1029 @end defvar | |
| 1030 | |
| 1031 @c Emacs 19 feature | |
| 1032 @cindex dedicated window | |
| 1033 A window can be marked as ``dedicated'' to its buffer. Then | |
| 1034 @code{display-buffer} does not try to use that window. | |
| 1035 | |
| 1036 @defun window-dedicated-p window | |
| 1037 This function returns @code{t} if @var{window} is marked as dedicated; | |
| 1038 otherwise @code{nil}. | |
| 1039 @end defun | |
| 1040 | |
| 1041 @defun set-window-dedicated-p window flag | |
| 1042 This function marks @var{window} as dedicated if @var{flag} is | |
| 1043 non-@code{nil}, and nondedicated otherwise. | |
| 1044 @end defun | |
| 1045 | |
| 1046 @node Window Point | |
| 1047 @section Windows and Point | |
| 1048 @cindex window position | |
| 1049 @cindex window point | |
| 1050 @cindex position in window | |
| 1051 @cindex point in window | |
| 2289 | 1052 @cindex cursor in window |
| 428 | 1053 |
| 1054 Each window has its own value of point, independent of the value of | |
| 1055 point in other windows displaying the same buffer. This makes it useful | |
| 1056 to have multiple windows showing one buffer. | |
| 1057 | |
| 1058 @itemize @bullet | |
| 1059 @item | |
| 1060 The window point is established when a window is first created; it is | |
| 1061 initialized from the buffer's point, or from the window point of another | |
| 1062 window opened on the buffer if such a window exists. | |
| 1063 | |
| 1064 @item | |
| 1065 Selecting a window sets the value of point in its buffer to the window's | |
| 1066 value of point. Conversely, deselecting a window sets the window's | |
| 1067 value of point from that of the buffer. Thus, when you switch between | |
| 1068 windows that display a given buffer, the point value for the selected | |
| 1069 window is in effect in the buffer, while the point values for the other | |
| 1070 windows are stored in those windows. | |
| 1071 | |
| 1072 @item | |
| 1073 As long as the selected window displays the current buffer, the window's | |
| 1074 point and the buffer's point always move together; they remain equal. | |
| 1075 | |
| 1076 @item | |
| 1077 @xref{Positions}, for more details on buffer positions. | |
| 1078 @end itemize | |
| 1079 | |
| 1080 As far as the user is concerned, point is where the cursor is, and | |
| 1081 when the user switches to another buffer, the cursor jumps to the | |
| 1082 position of point in that buffer. | |
| 1083 | |
| 444 | 1084 @defun window-point &optional window |
| 428 | 1085 This function returns the current position of point in @var{window}. |
| 442 | 1086 For a non-selected window, this is the value point would have (in that |
| 428 | 1087 window's buffer) if that window were selected. |
| 1088 | |
| 1089 When @var{window} is the selected window and its buffer is also the | |
| 444 | 1090 current buffer, the value returned is the same as the value of point in |
| 1091 that buffer. | |
| 428 | 1092 |
| 1093 Strictly speaking, it would be more correct to return the | |
| 1094 ``top-level'' value of point, outside of any @code{save-excursion} | |
| 1095 forms. But that value is hard to find. | |
| 1096 @end defun | |
| 1097 | |
| 1098 @defun set-window-point window position | |
| 1099 This function positions point in @var{window} at position | |
| 1100 @var{position} in @var{window}'s buffer. | |
| 1101 @end defun | |
| 1102 | |
| 2289 | 1103 @defun current-pixel-row &optional window pos |
| 1104 @defunx current-pixel-column &optional window pos | |
| 1105 @cindex cursor pixel row | |
| 1106 @cindex window point pixel row | |
| 1107 @cindex cursor pixel column | |
| 1108 @cindex window point pixel column | |
| 1109 The function, @code{current-pixel-row}, returns the vertical location, | |
| 1110 in pixels, of the point @var{pos} within the specified @var{window}; | |
| 1111 similarly, @code{current-pixel-column} returns the corresponding | |
| 1112 horizontal location. The position returned is that of the upper-left | |
| 1113 corner of the cursor, and is relative to the upper-left location of the | |
| 1114 window. If @var{window} is @code{nil}, the function uses the selected | |
| 1115 window. If @var{pos} is @code{nil}, the value of @code{window-point} is | |
| 1116 used. | |
| 1117 | |
| 1118 Note that the coordinates are relative to the current XEmacs window, and | |
| 1119 are not relative to the XEmacs X11 window. To obtain the coordinates | |
| 1120 relative to the X11 window, you must also take into account the spacings | |
| 1121 of any menubars, gutters, toolbars, margins, etc., as well as any window | |
| 1122 offsets. The function, @code{window-pixel-edges} (@pxref{Position of | |
| 1123 Window}), can be used to help calculate the location relative to the | |
| 1124 frame. | |
| 1125 | |
| 1126 @emph{Important note}: in order for these functions to return a correct, | |
| 1127 non-nil value, two criteria @emph{must} be satisfied: | |
| 1128 | |
| 1129 @itemize @bullet | |
| 1130 | |
| 1131 @item | |
| 1132 The location of @code{pos} must be visible within the specified window. | |
| 1133 If @var{pos} is outside the visible area, @code{nil} is returned. | |
| 1134 | |
| 1135 @item | |
| 1136 As the pixel location is determined from the redisplay tables, the | |
| 1137 redisplay tables must be up-to-date. In other words, the XEmacs | |
| 1138 window(s), as seen by the user, must be correct (to improve performance, | |
| 1139 XEmacs generally defers display updates until control returns back to | |
| 1140 the idle loop). To insure that the redisplay tables are up-to-date, one | |
| 1141 of the following must generally be done @emph{before} calling | |
| 1142 @code{current-pixel-row} or @code{current-pixel-column}: | |
| 1143 | |
| 1144 @itemize @bullet | |
| 1145 | |
| 1146 @item | |
| 1147 If the window in question is not in a new frame, you can force a | |
| 1148 redisplay using @code{(sit-for 0)}. See @code{sit-for} in | |
| 1149 @ref{Waiting}. | |
| 1150 | |
| 1151 @item | |
| 1152 If the window in question is in a new frame, you must call code like the | |
| 1153 following: | |
| 1154 | |
| 1155 @example | |
| 1156 @group | |
| 1157 (while (not (frame-visible-p frame)) | |
| 1158 (sleep-for .5)) | |
| 1159 @end group | |
| 1160 @end example | |
| 1161 | |
| 1162 @end itemize | |
| 1163 | |
| 1164 @end itemize | |
| 1165 | |
| 1166 If one of these is not done, the return value may be incorrect, even if | |
| 1167 it is non-nil. | |
| 1168 | |
| 1169 @end defun | |
| 1170 | |
| 428 | 1171 @node Window Start |
| 1172 @section The Window Start Position | |
| 1173 | |
| 1174 Each window contains a marker used to keep track of a buffer position | |
| 1175 that specifies where in the buffer display should start. This position | |
| 1176 is called the @dfn{display-start} position of the window (or just the | |
| 1177 @dfn{start}). The character after this position is the one that appears | |
| 1178 at the upper left corner of the window. It is usually, but not | |
| 1179 inevitably, at the beginning of a text line. | |
| 1180 | |
| 1181 @defun window-start &optional window | |
| 1182 @cindex window top line | |
| 1183 This function returns the display-start position of window | |
| 1184 @var{window}. If @var{window} is @code{nil}, the selected window is | |
| 444 | 1185 used. For example, |
| 428 | 1186 |
| 1187 @example | |
| 1188 @group | |
| 1189 (window-start) | |
| 1190 @result{} 7058 | |
| 1191 @end group | |
| 1192 @end example | |
| 1193 | |
| 1194 When you create a window, or display a different buffer in it, the | |
| 1195 display-start position is set to a display-start position recently used | |
| 1196 for the same buffer, or 1 if the buffer doesn't have any. | |
| 1197 | |
| 1198 For a realistic example, see the description of @code{count-lines} in | |
| 1199 @ref{Text Lines}. | |
| 1200 @end defun | |
| 1201 | |
| 444 | 1202 @defun window-end &optional window guarantee |
| 428 | 1203 This function returns the position of the end of the display in window |
| 1204 @var{window}. If @var{window} is @code{nil}, the selected window is | |
| 1205 used. | |
| 1206 | |
| 444 | 1207 Simply changing the buffer text or setting @code{window-start} does not |
| 1208 update the value that @code{window-end} returns. The value is updated | |
| 1209 only when Emacs redisplays and redisplay actually finishes. | |
| 428 | 1210 |
| 1211 If the last redisplay of @var{window} was preempted, and did not finish, | |
| 1212 Emacs does not know the position of the end of display in that window. | |
| 1213 In that case, this function returns a value that is not correct. In a | |
| 1214 future version, @code{window-end} will return @code{nil} in that case. | |
| 444 | 1215 |
| 1216 If optional arg @var{guarantee} is non-@code{nil}, the return value is | |
| 1217 guaranteed to be the same as @code{window-end} would return at the end | |
| 1218 of the next full redisplay assuming nothing else changes in the | |
| 1219 meantime. This function is potentially much slower with this flag set. | |
| 1220 | |
| 428 | 1221 @ignore |
| 1222 in that case, this function returns @code{nil}. You can compute where | |
| 1223 the end of the window @emph{would} have been, if redisplay had finished, | |
| 1224 like this: | |
| 1225 | |
| 1226 @example | |
| 1227 (save-excursion | |
| 1228 (goto-char (window-start window)) | |
| 1229 (vertical-motion (1- (window-height window)) | |
| 1230 window) | |
| 1231 (point)) | |
| 1232 @end example | |
| 1233 @end ignore | |
| 1234 @end defun | |
| 1235 | |
| 1236 @defun set-window-start window position &optional noforce | |
| 1237 This function sets the display-start position of @var{window} to | |
| 1238 @var{position} in @var{window}'s buffer. It returns @var{position}. | |
| 1239 | |
| 1240 The display routines insist that the position of point be visible when a | |
| 1241 buffer is displayed. Normally, they change the display-start position | |
| 1242 (that is, scroll the window) whenever necessary to make point visible. | |
| 1243 However, if you specify the start position with this function using | |
| 1244 @code{nil} for @var{noforce}, it means you want display to start at | |
| 1245 @var{position} even if that would put the location of point off the | |
| 1246 screen. If this does place point off screen, the display routines move | |
| 1247 point to the left margin on the middle line in the window. | |
| 1248 | |
| 1249 For example, if point @w{is 1} and you set the start of the window @w{to | |
| 1250 2}, then point would be ``above'' the top of the window. The display | |
| 1251 routines will automatically move point if it is still 1 when redisplay | |
| 1252 occurs. Here is an example: | |
| 1253 | |
| 1254 @example | |
| 1255 @group | |
| 1256 ;; @r{Here is what @samp{foo} looks like before executing} | |
| 1257 ;; @r{the @code{set-window-start} expression.} | |
| 1258 @end group | |
| 1259 | |
| 1260 @group | |
| 1261 ---------- Buffer: foo ---------- | |
| 1262 @point{}This is the contents of buffer foo. | |
| 1263 2 | |
| 1264 3 | |
| 1265 4 | |
| 1266 5 | |
| 1267 6 | |
| 1268 ---------- Buffer: foo ---------- | |
| 1269 @end group | |
| 1270 | |
| 1271 @group | |
| 1272 (set-window-start | |
| 1273 (selected-window) | |
| 1274 (1+ (window-start))) | |
| 1275 @result{} 2 | |
| 1276 @end group | |
| 1277 | |
| 1278 @group | |
| 1279 ;; @r{Here is what @samp{foo} looks like after executing} | |
| 1280 ;; @r{the @code{set-window-start} expression.} | |
| 1281 ---------- Buffer: foo ---------- | |
| 1282 his is the contents of buffer foo. | |
| 1283 2 | |
| 1284 3 | |
| 1285 @point{}4 | |
| 1286 5 | |
| 1287 6 | |
| 1288 ---------- Buffer: foo ---------- | |
| 1289 @end group | |
| 1290 @end example | |
| 1291 | |
| 1292 If @var{noforce} is non-@code{nil}, and @var{position} would place point | |
| 1293 off screen at the next redisplay, then redisplay computes a new window-start | |
| 1294 position that works well with point, and thus @var{position} is not used. | |
| 1295 @end defun | |
| 1296 | |
| 1297 @defun pos-visible-in-window-p &optional position window | |
| 1298 This function returns @code{t} if @var{position} is within the range | |
| 1299 of text currently visible on the screen in @var{window}. It returns | |
| 1300 @code{nil} if @var{position} is scrolled vertically out of view. The | |
| 1301 argument @var{position} defaults to the current position of point; | |
| 1302 @var{window}, to the selected window. Here is an example: | |
| 1303 | |
| 1304 @example | |
| 1305 @group | |
| 1306 (or (pos-visible-in-window-p | |
| 1307 (point) (selected-window)) | |
| 1308 (recenter 0)) | |
| 1309 @end group | |
| 1310 @end example | |
| 1311 | |
| 1312 The @code{pos-visible-in-window-p} function considers only vertical | |
| 1313 scrolling. If @var{position} is out of view only because @var{window} | |
| 1314 has been scrolled horizontally, @code{pos-visible-in-window-p} returns | |
| 1315 @code{t}. @xref{Horizontal Scrolling}. | |
| 1316 @end defun | |
| 1317 | |
| 1318 @node Vertical Scrolling | |
| 1319 @section Vertical Scrolling | |
| 1320 @cindex vertical scrolling | |
| 1321 @cindex scrolling vertically | |
| 1322 | |
| 1323 Vertical scrolling means moving the text up or down in a window. It | |
| 1324 works by changing the value of the window's display-start location. It | |
| 1325 may also change the value of @code{window-point} to keep it on the | |
| 1326 screen. | |
| 1327 | |
| 1328 In the commands @code{scroll-up} and @code{scroll-down}, the directions | |
| 1329 ``up'' and ``down'' refer to the motion of the text in the buffer at which | |
| 1330 you are looking through the window. Imagine that the text is | |
| 1331 written on a long roll of paper and that the scrolling commands move the | |
| 1332 paper up and down. Thus, if you are looking at text in the middle of a | |
| 1333 buffer and repeatedly call @code{scroll-down}, you will eventually see | |
| 1334 the beginning of the buffer. | |
| 1335 | |
| 1336 Some people have urged that the opposite convention be used: they | |
| 1337 imagine that the window moves over text that remains in place. Then | |
| 1338 ``down'' commands would take you to the end of the buffer. This view is | |
| 1339 more consistent with the actual relationship between windows and the | |
| 1340 text in the buffer, but it is less like what the user sees. The | |
| 1341 position of a window on the terminal does not move, and short scrolling | |
| 1342 commands clearly move the text up or down on the screen. We have chosen | |
| 1343 names that fit the user's point of view. | |
| 1344 | |
| 1345 The scrolling functions (aside from @code{scroll-other-window}) have | |
| 1346 unpredictable results if the current buffer is different from the buffer | |
| 1347 that is displayed in the selected window. @xref{Current Buffer}. | |
| 1348 | |
| 444 | 1349 @deffn Command scroll-up &optional lines |
| 428 | 1350 This function scrolls the text in the selected window upward |
| 444 | 1351 @var{lines} lines. If @var{lines} is negative, scrolling is actually |
| 428 | 1352 downward. |
| 1353 | |
| 444 | 1354 If @var{lines} is @code{nil} (or omitted), then the length of scroll |
| 428 | 1355 is @code{next-screen-context-lines} lines less than the usable height of |
| 1356 the window (not counting its modeline). | |
| 1357 | |
| 1358 @code{scroll-up} returns @code{nil}. | |
| 1359 @end deffn | |
| 1360 | |
| 444 | 1361 @deffn Command scroll-down &optional lines |
| 428 | 1362 This function scrolls the text in the selected window downward |
| 444 | 1363 @var{lines} lines. If @var{lines} is negative, scrolling is actually |
| 428 | 1364 upward. |
| 1365 | |
| 444 | 1366 If @var{lines} is omitted or @code{nil}, then the length of the scroll |
| 428 | 1367 is @code{next-screen-context-lines} lines less than the usable height of |
| 1368 the window (not counting its mode line). | |
| 1369 | |
| 1370 @code{scroll-down} returns @code{nil}. | |
| 1371 @end deffn | |
| 1372 | |
| 444 | 1373 @deffn Command scroll-other-window &optional lines |
| 1374 This function scrolls the text in another window upward @var{lines} | |
| 1375 lines. Negative values of @var{lines}, or @code{nil}, are handled | |
| 428 | 1376 as in @code{scroll-up}. |
| 1377 | |
| 1378 You can specify a buffer to scroll with the variable | |
| 1379 @code{other-window-scroll-buffer}. When the selected window is the | |
| 1380 minibuffer, the next window is normally the one at the top left corner. | |
| 1381 You can specify a different window to scroll with the variable | |
| 1382 @code{minibuffer-scroll-window}. This variable has no effect when any | |
| 1383 other window is selected. @xref{Minibuffer Misc}. | |
| 1384 | |
| 1385 When the minibuffer is active, it is the next window if the selected | |
| 1386 window is the one at the bottom right corner. In this case, | |
| 1387 @code{scroll-other-window} attempts to scroll the minibuffer. If the | |
| 1388 minibuffer contains just one line, it has nowhere to scroll to, so the | |
| 1389 line reappears after the echo area momentarily displays the message | |
| 1390 ``Beginning of buffer''. | |
| 1391 @end deffn | |
| 1392 | |
| 1393 @c Emacs 19 feature | |
| 1394 @defvar other-window-scroll-buffer | |
| 1395 If this variable is non-@code{nil}, it tells @code{scroll-other-window} | |
| 1396 which buffer to scroll. | |
| 1397 @end defvar | |
| 1398 | |
| 1399 @defopt scroll-step | |
| 1400 This variable controls how scrolling is done automatically when point | |
| 1401 moves off the screen. If the value is zero, then redisplay scrolls the | |
| 1402 text to center point vertically in the window. If the value is a | |
| 1403 positive integer @var{n}, then redisplay brings point back on screen by | |
| 1404 scrolling @var{n} lines in either direction, if possible; otherwise, it | |
| 1405 centers point. The default value is zero. | |
| 1406 @end defopt | |
| 1407 | |
| 1408 @defopt scroll-conservatively | |
| 1409 This variable controls how many lines Emacs tries to scroll before | |
| 1410 recentering. If you set it to a small number, then when you move point | |
| 1411 a short distance off the screen, XEmacs will scroll the screen just far | |
| 1412 enough to bring point back on screen, provided that does not exceed | |
| 1413 @code{scroll-conservatively} lines. This variable overrides the | |
| 1414 redisplay preemption. | |
| 1415 @end defopt | |
| 1416 | |
| 1417 @defopt next-screen-context-lines | |
| 1418 The value of this variable is the number of lines of continuity to | |
| 1419 retain when scrolling by full screens. For example, @code{scroll-up} | |
| 1420 with an argument of @code{nil} scrolls so that this many lines at the | |
| 1421 bottom of the window appear instead at the top. The default value is | |
| 1422 @code{2}. | |
| 1423 @end defopt | |
| 1424 | |
| 444 | 1425 @deffn Command recenter &optional location window |
| 428 | 1426 @cindex centering point |
| 444 | 1427 This function scrolls @var{window} (which defaults to the selected |
| 1428 window) to put the text where point is located at a specified vertical | |
| 1429 position within the window. | |
| 428 | 1430 |
| 444 | 1431 If @var{location} is a nonnegative number, it puts the line containing |
| 1432 point @var{location} lines down from the top of the window. If @var{location} | |
| 428 | 1433 is a negative number, then it counts upward from the bottom of the |
| 1434 window, so that @minus{}1 stands for the last usable line in the window. | |
| 444 | 1435 If @var{location} is a non-@code{nil} list, then it stands for the line in |
| 428 | 1436 the middle of the window. |
| 1437 | |
| 444 | 1438 If @var{location} is @code{nil}, @code{recenter} puts the line containing |
| 428 | 1439 point in the middle of the window, then clears and redisplays the entire |
| 1440 selected frame. | |
| 1441 | |
| 444 | 1442 When @code{recenter} is called interactively, @var{location} is the raw |
| 428 | 1443 prefix argument. Thus, typing @kbd{C-u} as the prefix sets the |
| 444 | 1444 @var{location} to a non-@code{nil} list, while typing @kbd{C-u 4} sets |
| 1445 @var{location} to 4, which positions the current line four lines from the | |
| 428 | 1446 top. |
| 1447 | |
| 1448 With an argument of zero, @code{recenter} positions the current line at | |
| 1449 the top of the window. This action is so handy that some people make a | |
| 1450 separate key binding to do this. For example, | |
| 1451 | |
| 1452 @example | |
| 1453 @group | |
| 1454 (defun line-to-top-of-window () | |
| 1455 "Scroll current line to top of window. | |
| 1456 Replaces three keystroke sequence C-u 0 C-l." | |
| 444 | 1457 (interactive) |
| 428 | 1458 (recenter 0)) |
| 1459 | |
| 444 | 1460 (global-set-key [kp-multiply] 'line-to-top-of-window) |
| 428 | 1461 @end group |
| 1462 @end example | |
| 1463 @end deffn | |
| 1464 | |
| 1465 @node Horizontal Scrolling | |
| 1466 @section Horizontal Scrolling | |
| 1467 @cindex horizontal scrolling | |
| 1468 | |
| 1469 Because we read English first from top to bottom and second from left | |
| 1470 to right, horizontal scrolling is not like vertical scrolling. Vertical | |
| 1471 scrolling involves selection of a contiguous portion of text to display. | |
| 1472 Horizontal scrolling causes part of each line to go off screen. The | |
| 1473 amount of horizontal scrolling is therefore specified as a number of | |
| 1474 columns rather than as a position in the buffer. It has nothing to do | |
| 1475 with the display-start position returned by @code{window-start}. | |
| 1476 | |
| 1477 Usually, no horizontal scrolling is in effect; then the leftmost | |
| 1478 column is at the left edge of the window. In this state, scrolling to | |
| 1479 the right is meaningless, since there is no data to the left of the | |
| 1480 screen to be revealed by it; so this is not allowed. Scrolling to the | |
| 1481 left is allowed; it scrolls the first columns of text off the edge of | |
| 1482 the window and can reveal additional columns on the right that were | |
| 1483 truncated before. Once a window has a nonzero amount of leftward | |
| 1484 horizontal scrolling, you can scroll it back to the right, but only so | |
| 1485 far as to reduce the net horizontal scroll to zero. There is no limit | |
| 1486 to how far left you can scroll, but eventually all the text will | |
| 1487 disappear off the left edge. | |
| 1488 | |
| 444 | 1489 @deffn Command scroll-left &optional count |
| 428 | 1490 This function scrolls the selected window @var{count} columns to the |
| 1491 left (or to the right if @var{count} is negative). The return value is | |
| 1492 the total amount of leftward horizontal scrolling in effect after the | |
| 1493 change---just like the value returned by @code{window-hscroll} (below). | |
| 1494 @end deffn | |
| 1495 | |
| 444 | 1496 @deffn Command scroll-right &optional count |
| 428 | 1497 This function scrolls the selected window @var{count} columns to the |
| 1498 right (or to the left if @var{count} is negative). The return value is | |
| 1499 the total amount of leftward horizontal scrolling in effect after the | |
| 1500 change---just like the value returned by @code{window-hscroll} (below). | |
| 1501 | |
| 1502 Once you scroll a window as far right as it can go, back to its normal | |
| 1503 position where the total leftward scrolling is zero, attempts to scroll | |
| 1504 any farther right have no effect. | |
| 1505 @end deffn | |
| 1506 | |
| 1507 @defun window-hscroll &optional window | |
| 1508 This function returns the total leftward horizontal scrolling of | |
| 1509 @var{window}---the number of columns by which the text in @var{window} | |
| 1510 is scrolled left past the left margin. | |
| 1511 | |
| 1512 The value is never negative. It is zero when no horizontal scrolling | |
| 1513 has been done in @var{window} (which is usually the case). | |
| 1514 | |
| 1515 If @var{window} is @code{nil}, the selected window is used. | |
| 1516 | |
| 1517 @example | |
| 1518 @group | |
| 1519 (window-hscroll) | |
| 1520 @result{} 0 | |
| 1521 @end group | |
| 1522 @group | |
| 1523 (scroll-left 5) | |
| 1524 @result{} 5 | |
| 1525 @end group | |
| 1526 @group | |
| 1527 (window-hscroll) | |
| 1528 @result{} 5 | |
| 1529 @end group | |
| 1530 @end example | |
| 1531 @end defun | |
| 1532 | |
| 1533 @defun set-window-hscroll window columns | |
| 1534 This function sets the number of columns from the left margin that | |
| 1535 @var{window} is scrolled to the value of @var{columns}. The argument | |
| 1536 @var{columns} should be zero or positive; if not, it is taken as zero. | |
| 1537 | |
| 1538 The value returned is @var{columns}. | |
| 1539 | |
| 1540 @example | |
| 1541 @group | |
| 1542 (set-window-hscroll (selected-window) 10) | |
| 1543 @result{} 10 | |
| 1544 @end group | |
| 1545 @end example | |
| 1546 @end defun | |
| 1547 | |
| 1548 Here is how you can determine whether a given position @var{position} | |
| 1549 is off the screen due to horizontal scrolling: | |
| 1550 | |
| 1551 @example | |
| 1552 @group | |
| 1553 (defun hscroll-on-screen (window position) | |
| 444 | 1554 (save-excursion |
| 428 | 1555 (goto-char position) |
| 444 | 1556 (and |
| 428 | 1557 (>= (- (current-column) (window-hscroll window)) 0) |
| 1558 (< (- (current-column) (window-hscroll window)) | |
| 1559 (window-width window))))) | |
| 1560 @end group | |
| 1561 @end example | |
| 1562 @node Size of Window | |
| 1563 @section The Size of a Window | |
| 1564 @cindex window size | |
| 1565 @cindex size of window | |
| 1566 | |
| 1567 An Emacs window is rectangular, and its size information consists of | |
| 1568 the height (in lines or pixels) and the width (in character positions | |
| 1569 or pixels). The modeline is included in the height. The pixel | |
| 1570 width and height values include scrollbars and margins, while the | |
| 1571 line/character-position values do not. | |
| 1572 | |
| 1573 Note that the height in lines, and the width in characters, are | |
| 1574 determined by dividing the corresponding pixel value by the height or | |
| 1575 width of the default font in that window (if this is a variable-width | |
| 1576 font, the average width is used). The resulting values may or may not | |
| 1577 represent the actual number of lines in the window, or the actual number | |
| 1578 of character positions in any particular line, esp. if there are pixmaps | |
| 1579 or various different fonts in the window. | |
| 1580 | |
| 1581 The following functions return size information about a window: | |
| 1582 | |
| 1583 @defun window-height &optional window | |
| 1584 This function returns the number of lines in @var{window}, including | |
| 1585 its modeline but not including the horizontal scrollbar, if any (this | |
| 1586 is different from @code{window-pixel-height}). If @var{window} is | |
| 1587 @code{nil}, the function uses the selected window. | |
| 1588 | |
| 1589 @example | |
| 1590 @group | |
| 1591 (window-height) | |
| 1592 @result{} 40 | |
| 1593 @end group | |
| 1594 @group | |
| 1595 (split-window-vertically) | |
| 1596 @result{} #<window on "windows.texi" 0x679b> | |
| 1597 @end group | |
| 1598 @group | |
| 1599 (window-height) | |
| 1600 @result{} 20 | |
| 1601 @end group | |
| 1602 @end example | |
| 1603 @end defun | |
| 1604 | |
| 1605 @defun window-width &optional window | |
| 1606 This function returns the number of columns in @var{window}, not | |
| 1607 including any left margin, right margin, or vertical scrollbar (this is | |
| 1608 different from @code{window-pixel-width}). If @var{window} is | |
| 1609 @code{nil}, the function uses the selected window. | |
| 1610 | |
| 1611 @example | |
| 1612 @group | |
| 1613 (window-width) | |
| 1614 @result{} 80 | |
| 1615 @end group | |
| 1616 @group | |
| 1617 (window-height) | |
| 1618 @result{} 40 | |
| 1619 @end group | |
| 1620 @group | |
| 1621 (split-window-horizontally) | |
| 1622 @result{} #<window on "windows.texi" 0x7538> | |
| 1623 @end group | |
| 1624 @group | |
| 1625 (window-width) | |
| 1626 @result{} 39 | |
| 1627 @end group | |
| 1628 @end example | |
| 1629 @end defun | |
| 1630 | |
| 1631 Note that after splitting the window into two side-by-side windows, | |
| 1632 the width of each window is less the half the width of the original | |
| 1633 window because a vertical scrollbar appeared between the windows, | |
| 1634 occupying two columns worth of space. Also, the height shrunk by | |
| 1635 one because horizontal scrollbars appeared that weren't there | |
| 1636 before. (Horizontal scrollbars appear only when lines are | |
| 1637 truncated, not when they wrap. This is usually the case for | |
| 1638 horizontally split windows but not for full-frame windows. You | |
| 1639 can change this using the variables @code{truncate-lines} and | |
| 1640 @code{truncate-partial-width-windows}.) | |
| 1641 | |
| 1642 @defun window-pixel-height &optional window | |
| 1643 This function returns the height of @var{window} in pixels, including | |
| 1644 its modeline and horizontal scrollbar, if any. If @var{window} is | |
| 1645 @code{nil}, the function uses the selected window. | |
| 1646 | |
| 1647 @example | |
| 1648 @group | |
| 1649 (window-pixel-height) | |
| 1650 @result{} 600 | |
| 1651 @end group | |
| 1652 @group | |
| 1653 (split-window-vertically) | |
| 1654 @result{} #<window on "windows.texi" 0x68a6> | |
| 1655 @end group | |
| 1656 @group | |
| 1657 (window-pixel-height) | |
| 1658 @result{} 300 | |
| 1659 @end group | |
| 1660 @end example | |
| 1661 @end defun | |
| 1662 | |
| 1663 @defun window-pixel-width &optional window | |
| 1664 This function returns the width of @var{window} in pixels, including | |
| 1665 any left margin, right margin, or vertical scrollbar that may be | |
| 1666 displayed alongside it. If @var{window} is @code{nil}, the function | |
| 1667 uses the selected window. | |
| 1668 | |
| 1669 @example | |
| 1670 @group | |
| 1671 (window-pixel-width) | |
| 1672 @result{} 735 | |
| 1673 @end group | |
| 1674 @group | |
| 1675 (window-pixel-height) | |
| 1676 @result{} 600 | |
| 1677 @end group | |
| 1678 @group | |
| 1679 (split-window-horizontally) | |
| 1680 @result{} #<window on "windows.texi" 0x7538> | |
| 1681 @end group | |
| 1682 @group | |
| 1683 (window-pixel-width) | |
| 1684 @result{} 367 | |
| 1685 @end group | |
| 1686 @group | |
| 1687 (window-pixel-height) | |
| 1688 @result{} 600 | |
| 1689 @end group | |
| 1690 @end example | |
| 1691 @end defun | |
| 1692 | |
| 1693 @defun window-text-area-pixel-height &optional window | |
| 1694 This function returns the height in pixels of the text displaying | |
| 1695 portion of @var{window}, which defaults to the selected window. Unlike | |
| 1696 @code{window-pixel-height}, the space occupied by the modeline and | |
| 1697 horizontal scrollbar, if any, is not counted. | |
| 1698 @end defun | |
| 1699 | |
| 1700 @defun window-text-area-pixel-width &optional window | |
| 1701 This function returns the width in pixels of the text displaying | |
| 1702 portion of @var{window}, which defaults to the selected window. Unlike | |
| 1703 @code{window-pixel-width}, the space occupied by the vertical scrollbar | |
| 1704 and divider, if any, is not counted. | |
| 1705 @end defun | |
| 1706 | |
| 1707 @defun window-displayed-text-pixel-height &optional window noclipped | |
| 1708 This function returns the height in pixels of the text displayed in | |
| 1709 @var{window}, which defaults to the selected window. Unlike | |
| 1710 @code{window-text-area-pixel-height}, any blank space below the | |
| 444 | 1711 end of the buffer is not included. If optional argument @var{noclipped} |
| 428 | 1712 is non-@code{nil}, any space occupied by clipped lines will not be |
| 1713 included. | |
| 1714 @end defun | |
| 1715 | |
| 1716 @node Position of Window | |
| 1717 @section The Position of a Window | |
| 1718 @cindex window position | |
| 1719 @cindex position of window | |
| 1720 | |
| 1721 XEmacs provides functions to determine the absolute location of windows | |
| 1722 within a frame, and the relative location of a window in comparison to | |
| 1723 other windows in the same frame. | |
| 1724 | |
| 1725 @defun window-pixel-edges &optional window | |
| 1726 This function returns a list of the pixel edge coordinates of | |
| 1727 @var{window}. If @var{window} is @code{nil}, the selected window is | |
| 1728 used. | |
| 1729 | |
| 1730 The order of the list is @code{(@var{left} @var{top} @var{right} | |
| 1731 @var{bottom})}, all elements relative to 0, 0 at the top left corner of | |
| 444 | 1732 @var{window}'s frame. The element @var{right} of the value is one more |
| 1733 than the rightmost pixel used by @var{window} (including any left | |
| 1734 margin, right margin, or vertical scrollbar displayed alongside it), and | |
| 428 | 1735 @var{bottom} is one more than the bottommost pixel used by @var{window} |
| 444 | 1736 (including any modeline or horizontal scrollbar displayed above or below |
| 1737 it). The frame area does not include any frame menubars, toolbars, or | |
| 1738 gutters that may be displayed; thus, for example, if there is only one | |
| 1739 window on the frame, the values for @var{left} and @var{top} will always | |
| 1740 be 0. | |
| 428 | 1741 |
| 1742 If @var{window} is at the upper left corner of its frame, @var{right} | |
| 1743 and @var{bottom} are the same as the values returned by | |
| 1744 @code{(window-pixel-width)} and @code{(window-pixel-height)} | |
| 444 | 1745 respectively, and @var{left} and @var{top} are zero. |
| 428 | 1746 @end defun |
| 1747 | |
| 1748 There is no longer a function @code{window-edges} because it does not | |
| 1749 make sense in a world with variable-width and variable-height lines, | |
| 1750 as are allowed in XEmacs. | |
| 1751 | |
| 1752 @defun window-highest-p window | |
| 1753 This function returns non-@code{nil} if @var{window} is along the | |
| 1754 top of its frame. | |
| 1755 @end defun | |
| 1756 | |
| 1757 @defun window-lowest-p window | |
| 1758 This function returns non-@code{nil} if @var{window} is along the | |
| 1759 bottom of its frame. | |
| 1760 @end defun | |
| 1761 | |
| 1762 @defun window-text-area-pixel-edges &optional window | |
| 1763 This function allows one to determine the location of the | |
| 1764 text-displaying portion of @var{window}, which defaults to the selected | |
| 1765 window, with respect to the top left corner of the window. It returns | |
| 1766 a list of integer pixel positions @code{(left top right bottom)}, all | |
| 1767 relative to @code{(0,0)} at the top left corner of the window. | |
| 1768 @end defun | |
| 1769 | |
| 1770 @node Resizing Windows | |
| 1771 @section Changing the Size of a Window | |
| 1772 @cindex window resizing | |
| 1773 @cindex changing window size | |
| 1774 @cindex window size, changing | |
| 1775 | |
| 1776 The window size functions fall into two classes: high-level commands | |
| 1777 that change the size of windows and low-level functions that access | |
| 1778 window size. XEmacs does not permit overlapping windows or gaps between | |
| 1779 windows, so resizing one window affects other windows. | |
| 1780 | |
| 444 | 1781 @deffn Command enlarge-window count &optional horizontal window |
| 1782 This function makes the selected window @var{count} lines taller, | |
| 428 | 1783 stealing lines from neighboring windows. It takes the lines from one |
| 1784 window at a time until that window is used up, then takes from another. | |
| 1785 If a window from which lines are stolen shrinks below | |
| 1786 @code{window-min-height} lines, that window disappears. | |
| 1787 | |
| 1788 If @var{horizontal} is non-@code{nil}, this function makes | |
| 444 | 1789 @var{window} wider by @var{count} columns, stealing columns instead of |
| 428 | 1790 lines. If a window from which columns are stolen shrinks below |
| 1791 @code{window-min-width} columns, that window disappears. | |
| 1792 | |
| 1793 If the requested size would exceed that of the window's frame, then the | |
| 1794 function makes the window occupy the entire height (or width) of the | |
| 1795 frame. | |
| 1796 | |
| 444 | 1797 If @var{count} is negative, this function shrinks the window by |
| 1798 @minus{}@var{count} lines or columns. If that makes the window smaller | |
| 428 | 1799 than the minimum size (@code{window-min-height} and |
| 1800 @code{window-min-width}), @code{enlarge-window} deletes the window. | |
| 1801 | |
| 1802 If @var{window} is non-@code{nil}, it specifies a window to change | |
| 1803 instead of the selected window. | |
| 1804 | |
| 444 | 1805 @code{enlarge-window} returns @code{nil}. |
| 428 | 1806 @end deffn |
| 1807 | |
| 1808 @deffn Command enlarge-window-horizontally columns | |
| 1809 This function makes the selected window @var{columns} wider. | |
| 1810 It could be defined as follows: | |
| 1811 | |
| 1812 @example | |
| 1813 @group | |
| 1814 (defun enlarge-window-horizontally (columns) | |
| 1815 (enlarge-window columns t)) | |
| 1816 @end group | |
| 1817 @end example | |
| 1818 @end deffn | |
| 1819 | |
| 1820 @deffn Command enlarge-window-pixels count &optional side window | |
| 444 | 1821 This function makes the selected window @var{count} pixels larger. |
| 1822 When called from Lisp, optional second argument @var{side} | |
| 1823 non-@code{nil} means to grow sideways @var{count} pixels, and optional | |
| 1824 third argument @var{window} specifies the window to change instead of | |
| 1825 the selected window. | |
| 428 | 1826 @end deffn |
| 1827 | |
| 444 | 1828 @deffn Command shrink-window count &optional horizontal window |
| 428 | 1829 This function is like @code{enlarge-window} but negates the argument |
| 444 | 1830 @var{count}, making the selected window smaller by giving lines (or |
| 428 | 1831 columns) to the other windows. If the window shrinks below |
| 1832 @code{window-min-height} or @code{window-min-width}, then it disappears. | |
| 1833 | |
| 444 | 1834 If @var{count} is negative, the window is enlarged by @minus{}@var{count} |
| 428 | 1835 lines or columns. |
| 1836 | |
| 1837 If @var{window} is non-@code{nil}, it specifies a window to change | |
| 1838 instead of the selected window. | |
| 1839 @end deffn | |
| 1840 | |
| 1841 @deffn Command shrink-window-horizontally columns | |
| 1842 This function makes the selected window @var{columns} narrower. | |
| 1843 It could be defined as follows: | |
| 1844 | |
| 1845 @example | |
| 1846 @group | |
| 1847 (defun shrink-window-horizontally (columns) | |
| 1848 (shrink-window columns t)) | |
| 1849 @end group | |
| 1850 @end example | |
| 1851 @end deffn | |
| 1852 | |
| 1853 @deffn Command shrink-window-pixels count &optional side window | |
| 1854 This function makes the selected window @var{count} pixels smaller. | |
| 1855 When called from Lisp, optional second argument @var{side} | |
| 1856 non-@code{nil} means to shrink sideways @var{count} pixels, and optional | |
| 1857 third argument @var{window} specifies the window to change instead of | |
| 1858 the selected window. | |
| 1859 @end deffn | |
| 1860 | |
| 1861 @cindex minimum window size | |
| 1862 The following two variables constrain the window-size-changing | |
| 1863 functions to a minimum height and width. | |
| 1864 | |
| 1865 @defopt window-min-height | |
| 1866 The value of this variable determines how short a window may become | |
| 1867 before it is automatically deleted. Making a window smaller than | |
| 1868 @code{window-min-height} automatically deletes it, and no window may be | |
| 1869 created shorter than this. The absolute minimum height is two (allowing | |
| 1870 one line for the mode line, and one line for the buffer display). | |
| 1871 Actions that change window sizes reset this variable to two if it is | |
| 1872 less than two. The default value is 4. | |
| 1873 @end defopt | |
| 1874 | |
| 1875 @defopt window-min-width | |
| 1876 The value of this variable determines how narrow a window may become | |
| 1877 before it automatically deleted. Making a window smaller than | |
| 1878 @code{window-min-width} automatically deletes it, and no window may be | |
| 1879 created narrower than this. The absolute minimum width is one; any | |
| 1880 value below that is ignored. The default value is 10. | |
| 1881 @end defopt | |
| 1882 | |
| 1883 @c This is not yet implemented. Why is it "documented"? | |
| 1884 @defvar window-size-change-functions | |
| 1885 This variable holds a list of functions to be called if the size of any | |
| 1886 window changes for any reason. The functions are called just once per | |
| 1887 redisplay, and just once for each frame on which size changes have | |
| 1888 occurred. | |
| 1889 | |
| 1890 Each function receives the frame as its sole argument. There is no | |
| 1891 direct way to find out which windows changed size, or precisely how; | |
| 1892 however, if your size-change function keeps track, after each change, of | |
| 1893 the windows that interest you, you can figure out what has changed by | |
| 1894 comparing the old size data with the new. | |
| 1895 | |
| 1896 Creating or deleting windows counts as a size change, and therefore | |
| 1897 causes these functions to be called. Changing the frame size also | |
| 1898 counts, because it changes the sizes of the existing windows. | |
| 1899 | |
| 1900 It is not a good idea to use @code{save-window-excursion} in these | |
| 1901 functions, because that always counts as a size change, and it would | |
| 1902 cause these functions to be called over and over. In most cases, | |
| 1903 @code{save-selected-window} is what you need here. | |
| 1904 @end defvar | |
| 1905 | |
| 1906 @node Window Configurations | |
| 1907 @section Window Configurations | |
| 1908 @cindex window configurations | |
| 1909 @cindex saving window information | |
| 1910 | |
| 1911 A @dfn{window configuration} records the entire layout of a | |
| 1912 frame---all windows, their sizes, which buffers they contain, what part | |
| 1913 of each buffer is displayed, and the values of point and the mark. You | |
| 1914 can bring back an entire previous layout by restoring a window | |
| 1915 configuration previously saved. | |
| 1916 | |
| 1917 If you want to record all frames instead of just one, use a frame | |
| 1918 configuration instead of a window configuration. @xref{Frame | |
| 1919 Configurations}. | |
| 1920 | |
| 444 | 1921 @defun current-window-configuration &optional frame |
| 625 | 1922 This function returns a new object representing the current window |
| 1923 configuration of @var{frame}, namely the number of windows, their sizes | |
| 1924 and current buffers, which window is the selected window, and for each | |
| 1925 window the displayed buffer, the display-start position, and the | |
| 444 | 1926 positions of point and the mark. An exception is made for point in the |
| 1927 current buffer, whose value is not saved. | |
| 1928 | |
| 1929 @var{frame} defaults to the selected frame. | |
| 428 | 1930 @end defun |
| 1931 | |
| 1932 @defun set-window-configuration configuration | |
| 1933 This function restores the configuration of XEmacs's windows and | |
| 1934 buffers to the state specified by @var{configuration}. The argument | |
| 1935 @var{configuration} must be a value that was previously returned by | |
| 1936 @code{current-window-configuration}. | |
| 1937 | |
| 1938 This function always counts as a window size change and triggers | |
| 1939 execution of the @code{window-size-change-functions}. (It doesn't know | |
| 1940 how to tell whether the new configuration actually differs from the old | |
| 1941 one.) | |
| 1942 | |
| 1943 Here is a way of using this function to get the same effect | |
| 1944 as @code{save-window-excursion}: | |
| 1945 | |
| 1946 @example | |
| 1947 @group | |
| 1948 (let ((config (current-window-configuration))) | |
| 1949 (unwind-protect | |
| 1950 (progn (split-window-vertically nil) | |
| 1951 @dots{}) | |
| 1952 (set-window-configuration config))) | |
| 1953 @end group | |
| 1954 @end example | |
| 1955 @end defun | |
| 1956 | |
| 1957 @defspec save-window-excursion forms@dots{} | |
|
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|
1958 This macro records the window configuration, executes @var{forms} |
| 428 | 1959 in sequence, then restores the earlier window configuration. The window |
| 1960 configuration includes the value of point and the portion of the buffer | |
| 1961 that is visible. It also includes the choice of selected window. | |
| 1962 However, it does not include the value of point in the current buffer; | |
| 1963 use @code{save-excursion} if you wish to preserve that. | |
| 1964 | |
| 1965 Don't use this construct when @code{save-selected-window} is all you need. | |
| 1966 | |
| 1967 Exit from @code{save-window-excursion} always triggers execution of the | |
| 1968 @code{window-size-change-functions}. (It doesn't know how to tell | |
| 1969 whether the restored configuration actually differs from the one in | |
| 1970 effect at the end of the @var{forms}.) | |
| 1971 | |
| 1972 The return value is the value of the final form in @var{forms}. | |
| 1973 For example: | |
| 1974 | |
| 1975 @example | |
| 1976 @group | |
| 1977 (split-window) | |
| 1978 @result{} #<window 25 on control.texi> | |
| 1979 @end group | |
| 1980 @group | |
| 1981 (setq w (selected-window)) | |
| 1982 @result{} #<window 19 on control.texi> | |
| 1983 @end group | |
| 1984 @group | |
| 1985 (save-window-excursion | |
| 1986 (delete-other-windows w) | |
| 1987 (switch-to-buffer "foo") | |
| 1988 'do-something) | |
| 1989 @result{} do-something | |
| 1990 ;; @r{The frame is now split again.} | |
| 1991 @end group | |
| 1992 @end example | |
| 1993 @end defspec | |
| 1994 | |
| 1995 @defun window-configuration-p object | |
| 1996 This function returns @code{t} if @var{object} is a window configuration. | |
| 1997 @end defun | |
| 1998 | |
| 1999 Primitives to look inside of window configurations would make sense, | |
| 2000 but none are implemented. It is not clear they are useful enough to be | |
| 2001 worth implementing. |