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comparison man/lispref/windows.texi @ 428:3ecd8885ac67 r21-2-22
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| author | cvs |
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| date | Mon, 13 Aug 2007 11:28:15 +0200 |
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| 1 @c -*-texinfo-*- | |
| 2 @c This is part of the XEmacs Lisp Reference Manual. | |
| 3 @c Copyright (C) 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc. | |
| 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 | |
| 25 is on-screen in the window. | |
| 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 | |
| 51 window. At ant time, one frame is the selected frame; and the window | |
| 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 | |
| 69 @item | |
| 70 window height | |
| 71 | |
| 72 @item | |
| 73 window width | |
| 74 | |
| 75 @item | |
| 76 window edges with respect to the frame or screen | |
| 77 | |
| 78 @item | |
| 79 the buffer it displays | |
| 80 | |
| 81 @item | |
| 82 position within the buffer at the upper left of the window | |
| 83 | |
| 84 @item | |
| 85 amount of horizontal scrolling, in columns | |
| 86 | |
| 87 @item | |
| 88 point | |
| 89 | |
| 90 @item | |
| 91 the mark | |
| 92 | |
| 93 @item | |
| 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 | |
| 142 @defun one-window-p &optional no-mini all-frames | |
| 143 This function returns non-@code{nil} if there is only one window. The | |
| 144 argument @var{no-mini}, if non-@code{nil}, means don't count the | |
| 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 | |
| 149 The argument @var{all-frame} controls which set of windows are | |
| 150 counted. | |
| 151 @itemize @bullet | |
| 152 @item | |
| 153 If it is @code{nil} or omitted, then count only the selected frame, plus | |
| 154 the minibuffer it uses (which may be on another frame). | |
| 155 @item | |
| 156 If it is @code{t}, then windows on all frames that currently exist | |
| 157 (including invisible and iconified frames) are counted. | |
| 158 @item | |
| 159 If it is the symbol @code{visible}, then windows on all visible frames | |
| 160 are counted. | |
| 161 @item | |
| 162 If it is the number 0, then windows on all visible and iconified frames | |
| 163 are counted. | |
| 164 @item | |
| 165 If it is any other value, then precisely the windows in @var{window}'s | |
| 166 frame are counted, excluding the minibuffer in use if it lies in | |
| 167 some other frame. | |
| 168 @end itemize | |
| 169 @end defun | |
| 170 | |
| 171 @deffn Command split-window &optional window size horizontal | |
| 172 This function splits @var{window} into two windows. The original | |
| 173 window @var{window} remains the selected window, but occupies only | |
| 174 part of its former screen area. The rest is occupied by a newly created | |
| 175 window which is returned as the value of this function. | |
| 176 | |
| 177 If @var{horizontal} is non-@code{nil}, then @var{window} splits into | |
| 178 two side by side windows. The original window @var{window} keeps the | |
| 179 leftmost @var{size} columns, and gives the rest of the columns to the | |
| 180 new window. Otherwise, it splits into windows one above the other, and | |
| 181 @var{window} keeps the upper @var{size} lines and gives the rest of the | |
| 182 lines to the new window. The original window is therefore the | |
| 183 left-hand or upper of the two, and the new window is the right-hand or | |
| 184 lower. | |
| 185 | |
| 186 If @var{window} is omitted or @code{nil}, then the selected window is | |
| 187 split. If @var{size} is omitted or @code{nil}, then @var{window} is | |
| 188 divided evenly into two parts. (If there is an odd line, it is | |
| 189 allocated to the new window.) When @code{split-window} is called | |
| 190 interactively, all its arguments are @code{nil}. | |
| 191 | |
| 192 The following example starts with one window on a frame that is 50 | |
| 193 lines high by 80 columns wide; then the window is split. | |
| 194 | |
| 195 @smallexample | |
| 196 @group | |
| 197 (setq w (selected-window)) | |
| 198 @result{} #<window 8 on windows.texi> | |
| 199 (window-edges) ; @r{Edges in order:} | |
| 200 @result{} (0 0 80 50) ; @r{left--top--right--bottom} | |
| 201 @end group | |
| 202 | |
| 203 @group | |
| 204 ;; @r{Returns window created} | |
| 205 (setq w2 (split-window w 15)) | |
| 206 @result{} #<window 28 on windows.texi> | |
| 207 @end group | |
| 208 @group | |
| 209 (window-edges w2) | |
| 210 @result{} (0 15 80 50) ; @r{Bottom window;} | |
| 211 ; @r{top is line 15} | |
| 212 @end group | |
| 213 @group | |
| 214 (window-edges w) | |
| 215 @result{} (0 0 80 15) ; @r{Top window} | |
| 216 @end group | |
| 217 @end smallexample | |
| 218 | |
| 219 The frame looks like this: | |
| 220 | |
| 221 @smallexample | |
| 222 @group | |
| 223 __________ | |
| 224 | | line 0 | |
| 225 | w | | |
| 226 |__________| | |
| 227 | | line 15 | |
| 228 | w2 | | |
| 229 |__________| | |
| 230 line 50 | |
| 231 column 0 column 80 | |
| 232 @end group | |
| 233 @end smallexample | |
| 234 | |
| 235 Next, the top window is split horizontally: | |
| 236 | |
| 237 @smallexample | |
| 238 @group | |
| 239 (setq w3 (split-window w 35 t)) | |
| 240 @result{} #<window 32 on windows.texi> | |
| 241 @end group | |
| 242 @group | |
| 243 (window-edges w3) | |
| 244 @result{} (35 0 80 15) ; @r{Left edge at column 35} | |
| 245 @end group | |
| 246 @group | |
| 247 (window-edges w) | |
| 248 @result{} (0 0 35 15) ; @r{Right edge at column 35} | |
| 249 @end group | |
| 250 @group | |
| 251 (window-edges w2) | |
| 252 @result{} (0 15 80 50) ; @r{Bottom window unchanged} | |
| 253 @end group | |
| 254 @end smallexample | |
| 255 | |
| 256 @need 3000 | |
| 257 Now, the screen looks like this: | |
| 258 | |
| 259 @smallexample | |
| 260 @group | |
| 261 column 35 | |
| 262 __________ | |
| 263 | | | line 0 | |
| 264 | w | w3 | | |
| 265 |___|______| | |
| 266 | | line 15 | |
| 267 | w2 | | |
| 268 |__________| | |
| 269 line 50 | |
| 270 column 0 column 80 | |
| 271 @end group | |
| 272 @end smallexample | |
| 273 | |
| 274 Normally, Emacs indicates the border between two side-by-side windows | |
| 275 with a scroll bar (@pxref{X Frame Properties,Scroll Bars}) or @samp{|} | |
| 276 characters. The display table can specify alternative border | |
| 277 characters; see @ref{Display Tables}. | |
| 278 @end deffn | |
| 279 | |
| 280 @deffn Command split-window-vertically &optional size | |
| 281 This function splits the selected window into two windows, one above | |
| 282 the other, leaving the selected window with @var{size} lines. | |
| 283 | |
| 284 This function is simply an interface to @code{split-windows}. | |
| 285 Here is the complete function definition for it: | |
| 286 | |
| 287 @smallexample | |
| 288 @group | |
| 289 (defun split-window-vertically (&optional arg) | |
| 290 "Split current window into two windows, one above the other." | |
| 291 (interactive "P") | |
| 292 (split-window nil (and arg (prefix-numeric-value arg)))) | |
| 293 @end group | |
| 294 @end smallexample | |
| 295 @end deffn | |
| 296 | |
| 297 @deffn Command split-window-horizontally &optional size | |
| 298 This function splits the selected window into two windows | |
| 299 side-by-side, leaving the selected window with @var{size} columns. | |
| 300 | |
| 301 This function is simply an interface to @code{split-windows}. Here is | |
| 302 the complete definition for @code{split-window-horizontally} (except for | |
| 303 part of the documentation string): | |
| 304 | |
| 305 @smallexample | |
| 306 @group | |
| 307 (defun split-window-horizontally (&optional arg) | |
| 308 "Split selected window into two windows, side by side..." | |
| 309 (interactive "P") | |
| 310 (split-window nil (and arg (prefix-numeric-value arg)) t)) | |
| 311 @end group | |
| 312 @end smallexample | |
| 313 @end deffn | |
| 314 | |
| 315 @defun one-window-p &optional no-mini all-frames | |
| 316 This function returns non-@code{nil} if there is only one window. The | |
| 317 argument @var{no-mini}, if non-@code{nil}, means don't count the | |
| 318 minibuffer even if it is active; otherwise, the minibuffer window is | |
| 319 included, if active, in the total number of windows, which is compared | |
| 320 against one. | |
| 321 | |
| 322 The argument @var{all-frames} specifies which frames to consider. Here | |
| 323 are the possible values and their meanings: | |
| 324 | |
| 325 @table @asis | |
| 326 @item @code{nil} | |
| 327 Count the windows in the selected frame, plus the minibuffer used | |
| 328 by that frame even if it lies in some other frame. | |
| 329 | |
| 330 @item @code{t} | |
| 331 Count all windows in all existing frames. | |
| 332 | |
| 333 @item @code{visible} | |
| 334 Count all windows in all visible frames. | |
| 335 | |
| 336 @item 0 | |
| 337 Count all windows in all visible or iconified frames. | |
| 338 | |
| 339 @item anything else | |
| 340 Count precisely the windows in the selected frame, and no others. | |
| 341 @end table | |
| 342 @end defun | |
| 343 | |
| 344 @node Deleting Windows | |
| 345 @section Deleting Windows | |
| 346 @cindex deleting windows | |
| 347 | |
| 348 A window remains visible on its frame unless you @dfn{delete} it by | |
| 349 calling certain functions that delete windows. A deleted window cannot | |
| 350 appear on the screen, but continues to exist as a Lisp object until | |
| 351 there are no references to it. There is no way to cancel the deletion | |
| 352 of a window aside from restoring a saved window configuration | |
| 353 (@pxref{Window Configurations}). Restoring a window configuration also | |
| 354 deletes any windows that aren't part of that configuration. | |
| 355 | |
| 356 When you delete a window, the space it took up is given to one | |
| 357 adjacent sibling. (In Emacs version 18, the space was divided evenly | |
| 358 among all the siblings.) | |
| 359 | |
| 360 @c Emacs 19 feature | |
| 361 @defun window-live-p window | |
| 362 This function returns @code{nil} if @var{window} is deleted, and | |
| 363 @code{t} otherwise. | |
| 364 | |
| 365 @strong{Warning:} Erroneous information or fatal errors may result from | |
| 366 using a deleted window as if it were live. | |
| 367 @end defun | |
| 368 | |
| 369 @deffn Command delete-window &optional window | |
| 370 This function removes @var{window} from the display. If @var{window} | |
| 371 is omitted, then the selected window is deleted. An error is signaled | |
| 372 if there is only one window when @code{delete-window} is called. | |
| 373 | |
| 374 This function returns @code{nil}. | |
| 375 | |
| 376 When @code{delete-window} is called interactively, @var{window} | |
| 377 defaults to the selected window. | |
| 378 @end deffn | |
| 379 | |
| 380 @deffn Command delete-other-windows &optional window | |
| 381 This function makes @var{window} the only window on its frame, by | |
| 382 deleting the other windows in that frame. If @var{window} is omitted or | |
| 383 @code{nil}, then the selected window is used by default. | |
| 384 | |
| 385 The result is @code{nil}. | |
| 386 @end deffn | |
| 387 | |
| 388 @deffn Command delete-windows-on buffer &optional frame | |
| 389 This function deletes all windows showing @var{buffer}. If there are | |
| 390 no windows showing @var{buffer}, it does nothing. | |
| 391 | |
| 392 @code{delete-windows-on} operates frame by frame. If a frame has | |
| 393 several windows showing different buffers, then those showing | |
| 394 @var{buffer} are removed, and the others expand to fill the space. If | |
| 395 all windows in some frame are showing @var{buffer} (including the case | |
| 396 where there is only one window), then the frame reverts to having a | |
| 397 single window showing another buffer chosen with @code{other-buffer}. | |
| 398 @xref{The Buffer List}. | |
| 399 | |
| 400 The argument @var{frame} controls which frames to operate on: | |
| 401 | |
| 402 @itemize @bullet | |
| 403 @item | |
| 404 If it is @code{nil}, operate on the selected frame. | |
| 405 @item | |
| 406 If it is @code{t}, operate on all frames. | |
| 407 @item | |
| 408 If it is @code{visible}, operate on all visible frames. | |
| 409 @item 0 | |
| 410 If it is 0, operate on all visible or iconified frames. | |
| 411 @item | |
| 412 If it is a frame, operate on that frame. | |
| 413 @end itemize | |
| 414 | |
| 415 This function always returns @code{nil}. | |
| 416 @end deffn | |
| 417 | |
| 418 @node Selecting Windows | |
| 419 @section Selecting Windows | |
| 420 @cindex selecting windows | |
| 421 | |
| 422 When a window is selected, the buffer in the window becomes the current | |
| 423 buffer, and the cursor will appear in it. | |
| 424 | |
| 425 @defun selected-window &optional device | |
| 426 This function returns the selected window. This is the window in | |
| 427 which the cursor appears and to which many commands apply. Each | |
| 428 separate device can have its own selected window, which is remembered | |
| 429 as focus changes from device to device. Optional argument @var{device} | |
| 430 specifies which device to return the selected window for, and defaults | |
| 431 to the selected device. | |
| 432 @end defun | |
| 433 | |
| 434 @defun select-window window &optional norecord | |
| 435 This function makes @var{window} the selected window. The cursor then | |
| 436 appears in @var{window} (on redisplay). The buffer being displayed in | |
| 437 @var{window} is immediately designated the current buffer. | |
| 438 | |
| 439 If optional argument @var{norecord} is non-@code{nil} then the global | |
| 440 and per-frame buffer orderings are not modified, as by the function | |
| 441 @code{record-buffer}. | |
| 442 | |
| 443 The return value is @var{window}. | |
| 444 | |
| 445 @example | |
| 446 @group | |
| 447 (setq w (next-window)) | |
| 448 (select-window w) | |
| 449 @result{} #<window 65 on windows.texi> | |
| 450 @end group | |
| 451 @end example | |
| 452 @end defun | |
| 453 | |
| 454 @defmac save-selected-window forms@dots{} | |
| 455 This macro records the selected window, executes @var{forms} | |
| 456 in sequence, then restores the earlier selected window. | |
| 457 It does not save or restore anything about the sizes, arrangement | |
| 458 or contents of windows; therefore, if the @var{forms} change them, | |
| 459 the changes are permanent. | |
| 460 @end defmac | |
| 461 | |
| 462 @cindex finding windows | |
| 463 The following functions choose one of the windows on the screen, | |
| 464 offering various criteria for the choice. | |
| 465 | |
| 466 @defun get-lru-window &optional frame | |
| 467 This function returns the window least recently ``used'' (that is, | |
| 468 selected). The selected window is always the most recently used window. | |
| 469 | |
| 470 The selected window can be the least recently used window if it is the | |
| 471 only window. A newly created window becomes the least recently used | |
| 472 window until it is selected. A minibuffer window is never a candidate. | |
| 473 | |
| 474 The argument @var{frame} controls which windows are considered. | |
| 475 | |
| 476 @itemize @bullet | |
| 477 @item | |
| 478 If it is @code{nil}, consider windows on the selected frame. | |
| 479 @item | |
| 480 If it is @code{t}, consider windows on all frames. | |
| 481 @item | |
| 482 If it is @code{visible}, consider windows on all visible frames. | |
| 483 @item | |
| 484 If it is 0, consider windows on all visible or iconified frames. | |
| 485 @item | |
| 486 If it is a frame, consider windows on that frame. | |
| 487 @end itemize | |
| 488 @end defun | |
| 489 | |
| 490 @defun get-largest-window &optional frame | |
| 491 This function returns the window with the largest area (height times | |
| 492 width). If there are no side-by-side windows, then this is the window | |
| 493 with the most lines. A minibuffer window is never a candidate. | |
| 494 | |
| 495 If there are two windows of the same size, then the function returns | |
| 496 the window that is first in the cyclic ordering of windows (see | |
| 497 following section), starting from the selected window. | |
| 498 | |
| 499 The argument @var{frame} controls which set of windows are | |
| 500 considered. See @code{get-lru-window}, above. | |
| 501 @end defun | |
| 502 | |
| 503 @node Cyclic Window Ordering | |
| 504 @section Cyclic Ordering of Windows | |
| 505 @cindex cyclic ordering of windows | |
| 506 @cindex ordering of windows, cyclic | |
| 507 @cindex window ordering, cyclic | |
| 508 | |
| 509 When you use the command @kbd{C-x o} (@code{other-window}) to select | |
| 510 the next window, it moves through all the windows on the screen in a | |
| 511 specific cyclic order. For any given configuration of windows, this | |
| 512 order never varies. It is called the @dfn{cyclic ordering of windows}. | |
| 513 | |
| 514 This ordering generally goes from top to bottom, and from left to | |
| 515 right. But it may go down first or go right first, depending on the | |
| 516 order in which the windows were split. | |
| 517 | |
| 518 If the first split was vertical (into windows one above each other), | |
| 519 and then the subwindows were split horizontally, then the ordering is | |
| 520 left to right in the top of the frame, and then left to right in the | |
| 521 next lower part of the frame, and so on. If the first split was | |
| 522 horizontal, the ordering is top to bottom in the left part, and so on. | |
| 523 In general, within each set of siblings at any level in the window tree, | |
| 524 the order is left to right, or top to bottom. | |
| 525 | |
| 526 @defun next-window &optional window minibuf all-frames | |
| 527 @cindex minibuffer window | |
| 528 This function returns the window following @var{window} in the cyclic | |
| 529 ordering of windows. This is the window that @kbd{C-x o} would select | |
| 530 if typed when @var{window} is selected. If @var{window} is the only | |
| 531 window visible, then this function returns @var{window}. If omitted, | |
| 532 @var{window} defaults to the selected window. | |
| 533 | |
| 534 The value of the argument @var{minibuf} determines whether the | |
| 535 minibuffer is included in the window order. Normally, when | |
| 536 @var{minibuf} is @code{nil}, the minibuffer is included if it is | |
| 537 currently active; this is the behavior of @kbd{C-x o}. (The minibuffer | |
| 538 window is active while the minibuffer is in use. @xref{Minibuffers}.) | |
| 539 | |
| 540 If @var{minibuf} is @code{t}, then the cyclic ordering includes the | |
| 541 minibuffer window even if it is not active. | |
| 542 | |
| 543 If @var{minibuf} is neither @code{t} nor @code{nil}, then the minibuffer | |
| 544 window is not included even if it is active. | |
| 545 | |
| 546 The argument @var{all-frames} specifies which frames to consider. Here | |
| 547 are the possible values and their meanings: | |
| 548 | |
| 549 @table @asis | |
| 550 @item @code{nil} | |
| 551 Consider all the windows in @var{window}'s frame, plus the minibuffer | |
| 552 used by that frame even if it lies in some other frame. | |
| 553 | |
| 554 @item @code{t} | |
| 555 Consider all windows in all existing frames. | |
| 556 | |
| 557 @item @code{visible} | |
| 558 Consider all windows in all visible frames. (To get useful results, you | |
| 559 must ensure @var{window} is in a visible frame.) | |
| 560 | |
| 561 @item 0 | |
| 562 Consider all windows in all visible or iconified frames. | |
| 563 | |
| 564 @item anything else | |
| 565 Consider precisely the windows in @var{window}'s frame, and no others. | |
| 566 @end table | |
| 567 | |
| 568 This example assumes there are two windows, both displaying the | |
| 569 buffer @samp{windows.texi}: | |
| 570 | |
| 571 @example | |
| 572 @group | |
| 573 (selected-window) | |
| 574 @result{} #<window 56 on windows.texi> | |
| 575 @end group | |
| 576 @group | |
| 577 (next-window (selected-window)) | |
| 578 @result{} #<window 52 on windows.texi> | |
| 579 @end group | |
| 580 @group | |
| 581 (next-window (next-window (selected-window))) | |
| 582 @result{} #<window 56 on windows.texi> | |
| 583 @end group | |
| 584 @end example | |
| 585 @end defun | |
| 586 | |
| 587 @defun previous-window &optional window minibuf all-frames | |
| 588 This function returns the window preceding @var{window} in the cyclic | |
| 589 ordering of windows. The other arguments specify which windows to | |
| 590 include in the cycle, as in @code{next-window}. | |
| 591 @end defun | |
| 592 | |
| 593 @deffn Command other-window count &optional frame | |
| 594 This function selects the @var{count}th following window in the cyclic | |
| 595 order. If count is negative, then it selects the @minus{}@var{count}th | |
| 596 preceding window. It returns @code{nil}. | |
| 597 | |
| 598 In an interactive call, @var{count} is the numeric prefix argument. | |
| 599 | |
| 600 The argument @var{frame} controls which set of windows are considered. | |
| 601 @itemize @bullet | |
| 602 @item | |
| 603 If it is @code{nil} or omitted, then windows on the selected frame are | |
| 604 considered. | |
| 605 @item | |
| 606 If it is a frame, then windows on that frame are considered. | |
| 607 @item | |
| 608 If it is @code{t}, then windows on all frames that currently exist | |
| 609 (including invisible and iconified frames) are considered. | |
| 610 @item | |
| 611 If it is the symbol @code{visible}, then windows on all visible frames | |
| 612 are considered. | |
| 613 @item | |
| 614 If it is the number 0, then windows on all visible and iconified frames | |
| 615 are considered. | |
| 616 @item | |
| 617 If it is any other value, then the behavior is undefined. | |
| 618 @end itemize | |
| 619 @end deffn | |
| 620 | |
| 621 @c Emacs 19 feature | |
| 622 @defun walk-windows proc &optional minibuf all-frames | |
| 623 This function cycles through all windows, calling @code{proc} | |
| 624 once for each window with the window as its sole argument. | |
| 625 | |
| 626 The optional arguments @var{minibuf} and @var{all-frames} specify the | |
| 627 set of windows to include in the scan. See @code{next-window}, above, | |
| 628 for details. | |
| 629 @end defun | |
| 630 | |
| 631 @node Buffers and Windows | |
| 632 @section Buffers and Windows | |
| 633 @cindex examining windows | |
| 634 @cindex windows, controlling precisely | |
| 635 @cindex buffers, controlled in windows | |
| 636 | |
| 637 This section describes low-level functions to examine windows or to | |
| 638 display buffers in windows in a precisely controlled fashion. | |
| 639 @iftex | |
| 640 See the following section for | |
| 641 @end iftex | |
| 642 @ifinfo | |
| 643 @xref{Displaying Buffers}, for | |
| 644 @end ifinfo | |
| 645 related functions that find a window to use and specify a buffer for it. | |
| 646 The functions described there are easier to use than these, but they | |
| 647 employ heuristics in choosing or creating a window; use these functions | |
| 648 when you need complete control. | |
| 649 | |
| 650 @defun set-window-buffer window buffer-or-name | |
| 651 This function makes @var{window} display @var{buffer-or-name} as its | |
| 652 contents. It returns @code{nil}. | |
| 653 | |
| 654 @example | |
| 655 @group | |
| 656 (set-window-buffer (selected-window) "foo") | |
| 657 @result{} nil | |
| 658 @end group | |
| 659 @end example | |
| 660 @end defun | |
| 661 | |
| 662 @defun window-buffer &optional window | |
| 663 This function returns the buffer that @var{window} is displaying. If | |
| 664 @var{window} is omitted, this function returns the buffer for the | |
| 665 selected window. | |
| 666 | |
| 667 @example | |
| 668 @group | |
| 669 (window-buffer) | |
| 670 @result{} #<buffer windows.texi> | |
| 671 @end group | |
| 672 @end example | |
| 673 @end defun | |
| 674 | |
| 675 @defun get-buffer-window buffer-or-name &optional frame | |
| 676 This function returns a window currently displaying | |
| 677 @var{buffer-or-name}, or @code{nil} if there is none. If there are | |
| 678 several such windows, then the function returns the first one in the | |
| 679 cyclic ordering of windows, starting from the selected window. | |
| 680 @xref{Cyclic Window Ordering}. | |
| 681 | |
| 682 The argument @var{all-frames} controls which windows to consider. | |
| 683 | |
| 684 @itemize @bullet | |
| 685 @item | |
| 686 If it is @code{nil}, consider windows on the selected frame. | |
| 687 @item | |
| 688 If it is @code{t}, consider windows on all frames. | |
| 689 @item | |
| 690 If it is @code{visible}, consider windows on all visible frames. | |
| 691 @item | |
| 692 If it is 0, consider windows on all visible or iconified frames. | |
| 693 @item | |
| 694 If it is a frame, consider windows on that frame. | |
| 695 @end itemize | |
| 696 @end defun | |
| 697 | |
| 698 @node Displaying Buffers | |
| 699 @section Displaying Buffers in Windows | |
| 700 @cindex switching to a buffer | |
| 701 @cindex displaying a buffer | |
| 702 | |
| 703 In this section we describe convenient functions that choose a window | |
| 704 automatically and use it to display a specified buffer. These functions | |
| 705 can also split an existing window in certain circumstances. We also | |
| 706 describe variables that parameterize the heuristics used for choosing a | |
| 707 window. | |
| 708 @iftex | |
| 709 See the preceding section for | |
| 710 @end iftex | |
| 711 @ifinfo | |
| 712 @xref{Buffers and Windows}, for | |
| 713 @end ifinfo | |
| 714 low-level functions that give you more precise control. | |
| 715 | |
| 716 Do not use the functions in this section in order to make a buffer | |
| 717 current so that a Lisp program can access or modify it; they are too | |
| 718 drastic for that purpose, since they change the display of buffers in | |
| 719 windows, which is gratuitous and will surprise the user. Instead, use | |
| 720 @code{set-buffer} (@pxref{Current Buffer}) and @code{save-excursion} | |
| 721 (@pxref{Excursions}), which designate buffers as current for programmed | |
| 722 access without affecting the display of buffers in windows. | |
| 723 | |
| 724 @deffn Command switch-to-buffer buffer-or-name &optional norecord | |
| 725 This function makes @var{buffer-or-name} the current buffer, and also | |
| 726 displays the buffer in the selected window. This means that a human can | |
| 727 see the buffer and subsequent keyboard commands will apply to it. | |
| 728 Contrast this with @code{set-buffer}, which makes @var{buffer-or-name} | |
| 729 the current buffer but does not display it in the selected window. | |
| 730 @xref{Current Buffer}. | |
| 731 | |
| 732 If @var{buffer-or-name} does not identify an existing buffer, then a new | |
| 733 buffer by that name is created. The major mode for the new buffer is | |
| 734 set according to the variable @code{default-major-mode}. @xref{Auto | |
| 735 Major Mode}. | |
| 736 | |
| 737 Normally the specified buffer is put at the front of the buffer list. | |
| 738 This affects the operation of @code{other-buffer}. However, if | |
| 739 @var{norecord} is non-@code{nil}, this is not done. @xref{The Buffer | |
| 740 List}. | |
| 741 | |
| 742 The @code{switch-to-buffer} function is often used interactively, as | |
| 743 the binding of @kbd{C-x b}. It is also used frequently in programs. It | |
| 744 always returns @code{nil}. | |
| 745 @end deffn | |
| 746 | |
| 747 @deffn Command switch-to-buffer-other-window buffer-or-name | |
| 748 This function makes @var{buffer-or-name} the current buffer and | |
| 749 displays it in a window not currently selected. It then selects that | |
| 750 window. The handling of the buffer is the same as in | |
| 751 @code{switch-to-buffer}. | |
| 752 | |
| 753 The currently selected window is absolutely never used to do the job. | |
| 754 If it is the only window, then it is split to make a distinct window for | |
| 755 this purpose. If the selected window is already displaying the buffer, | |
| 756 then it continues to do so, but another window is nonetheless found to | |
| 757 display it in as well. | |
| 758 @end deffn | |
| 759 | |
| 760 @defun pop-to-buffer buffer-or-name &optional other-window on-frame | |
| 761 This function makes @var{buffer-or-name} the current buffer and | |
| 762 switches to it in some window, preferably not the window previously | |
| 763 selected. The ``popped-to'' window becomes the selected window within | |
| 764 its frame. | |
| 765 | |
| 766 If the variable @code{pop-up-frames} is non-@code{nil}, | |
| 767 @code{pop-to-buffer} looks for a window in any visible frame already | |
| 768 displaying the buffer; if there is one, it returns that window and makes | |
| 769 it be selected within its frame. If there is none, it creates a new | |
| 770 frame and displays the buffer in it. | |
| 771 | |
| 772 If @code{pop-up-frames} is @code{nil}, then @code{pop-to-buffer} | |
| 773 operates entirely within the selected frame. (If the selected frame has | |
| 774 just a minibuffer, @code{pop-to-buffer} operates within the most | |
| 775 recently selected frame that was not just a minibuffer.) | |
| 776 | |
| 777 If the variable @code{pop-up-windows} is non-@code{nil}, windows may | |
| 778 be split to create a new window that is different from the original | |
| 779 window. For details, see @ref{Choosing Window}. | |
| 780 | |
| 781 If @var{other-window} is non-@code{nil}, @code{pop-to-buffer} finds or | |
| 782 creates another window even if @var{buffer-or-name} is already visible | |
| 783 in the selected window. Thus @var{buffer-or-name} could end up | |
| 784 displayed in two windows. On the other hand, if @var{buffer-or-name} is | |
| 785 already displayed in the selected window and @var{other-window} is | |
| 786 @code{nil}, then the selected window is considered sufficient display | |
| 787 for @var{buffer-or-name}, so that nothing needs to be done. | |
| 788 | |
| 789 All the variables that affect @code{display-buffer} affect | |
| 790 @code{pop-to-buffer} as well. @xref{Choosing Window}. | |
| 791 | |
| 792 If @var{buffer-or-name} is a string that does not name an existing | |
| 793 buffer, a buffer by that name is created. The major mode for the new | |
| 794 buffer is set according to the variable @code{default-major-mode}. | |
| 795 @xref{Auto Major Mode}. | |
| 796 | |
| 797 If @var{on-frame} is non-@code{nil}, it is the frame to pop to this | |
| 798 buffer on. | |
| 799 | |
| 800 An example use of this function is found at the end of @ref{Filter | |
| 801 Functions}. | |
| 802 @end defun | |
| 803 | |
| 804 @deffn Command replace-buffer-in-windows buffer | |
| 805 This function replaces @var{buffer} with some other buffer in all | |
| 806 windows displaying it. The other buffer used is chosen with | |
| 807 @code{other-buffer}. In the usual applications of this function, you | |
| 808 don't care which other buffer is used; you just want to make sure that | |
| 809 @var{buffer} is no longer displayed. | |
| 810 | |
| 811 This function returns @code{nil}. | |
| 812 @end deffn | |
| 813 | |
| 814 @node Choosing Window | |
| 815 @section Choosing a Window for Display | |
| 816 | |
| 817 This section describes the basic facility that chooses a window to | |
| 818 display a buffer in---@code{display-buffer}. All the higher-level | |
| 819 functions and commands use this subroutine. Here we describe how to use | |
| 820 @code{display-buffer} and how to customize it. | |
| 821 | |
| 822 @deffn Command display-buffer buffer-or-name &optional not-this-window | |
| 823 This command makes @var{buffer-or-name} appear in some window, like | |
| 824 @code{pop-to-buffer}, but it does not select that window and does not | |
| 825 make the buffer current. The identity of the selected window is | |
| 826 unaltered by this function. | |
| 827 | |
| 828 If @var{not-this-window} is non-@code{nil}, it means to display the | |
| 829 specified buffer in a window other than the selected one, even if it is | |
| 830 already on display in the selected window. This can cause the buffer to | |
| 831 appear in two windows at once. Otherwise, if @var{buffer-or-name} is | |
| 832 already being displayed in any window, that is good enough, so this | |
| 833 function does nothing. | |
| 834 | |
| 835 @code{display-buffer} returns the window chosen to display | |
| 836 @var{buffer-or-name}. | |
| 837 | |
| 838 Precisely how @code{display-buffer} finds or creates a window depends on | |
| 839 the variables described below. | |
| 840 @end deffn | |
| 841 | |
| 842 @c Emacs 19 feature | |
| 843 @cindex dedicated window | |
| 844 A window can be marked as ``dedicated'' to a particular buffer. | |
| 845 Then XEmacs will not automatically change which buffer appears in the | |
| 846 window, such as @code{display-buffer} might normally do. | |
| 847 | |
| 848 @defun window-dedicated-p window | |
| 849 This function returns @var{window}'s dedicated object, usually @code{t} | |
| 850 or @code{nil}. | |
| 851 @end defun | |
| 852 | |
| 853 @defun set-window-buffer-dedicated window buffer | |
| 854 This function makes @var{window} display @var{buffer} and be dedicated | |
| 855 to that buffer. Then XEmacs will not automatically change which buffer | |
| 856 appears in @var{window}. If @var{buffer} is @code{nil}, this function makes | |
| 857 @var{window} not be dedicated (but doesn't change which buffer appears | |
| 858 in it currently). | |
| 859 @end defun | |
| 860 | |
| 861 @defopt pop-up-windows | |
| 862 This variable controls whether @code{display-buffer} makes new windows. | |
| 863 If it is non-@code{nil} and there is only one window, then that window | |
| 864 is split. If it is @code{nil}, then @code{display-buffer} does not | |
| 865 split the single window, but uses it whole. | |
| 866 @end defopt | |
| 867 | |
| 868 @defopt split-height-threshold | |
| 869 This variable determines when @code{display-buffer} may split a window, | |
| 870 if there are multiple windows. @code{display-buffer} always splits the | |
| 871 largest window if it has at least this many lines. If the largest | |
| 872 window is not this tall, it is split only if it is the sole window and | |
| 873 @code{pop-up-windows} is non-@code{nil}. | |
| 874 @end defopt | |
| 875 | |
| 876 @c Emacs 19 feature | |
| 877 @defopt pop-up-frames | |
| 878 This variable controls whether @code{display-buffer} makes new frames. | |
| 879 If it is non-@code{nil}, @code{display-buffer} looks for an existing | |
| 880 window already displaying the desired buffer, on any visible frame. If | |
| 881 it finds one, it returns that window. Otherwise it makes a new frame. | |
| 882 The variables @code{pop-up-windows} and @code{split-height-threshold} do | |
| 883 not matter if @code{pop-up-frames} is non-@code{nil}. | |
| 884 | |
| 885 If @code{pop-up-frames} is @code{nil}, then @code{display-buffer} either | |
| 886 splits a window or reuses one. | |
| 887 | |
| 888 @xref{Frames}, for more information. | |
| 889 @end defopt | |
| 890 | |
| 891 @c Emacs 19 feature | |
| 892 @defvar pop-up-frame-function | |
| 893 This variable specifies how to make a new frame if @code{pop-up-frames} | |
| 894 is non-@code{nil}. | |
| 895 | |
| 896 Its value should be a function of no arguments. When | |
| 897 @code{display-buffer} makes a new frame, it does so by calling that | |
| 898 function, which should return a frame. The default value of the | |
| 899 variable is a function that creates a frame using properties from | |
| 900 @code{pop-up-frame-plist}. | |
| 901 @end defvar | |
| 902 | |
| 903 @defvar pop-up-frame-plist | |
| 904 This variable holds a plist specifying frame properties used when | |
| 905 @code{display-buffer} makes a new frame. @xref{Frame Properties}, for | |
| 906 more information about frame properties. | |
| 907 @end defvar | |
| 908 | |
| 909 @defvar special-display-buffer-names | |
| 910 A list of buffer names for buffers that should be displayed specially. | |
| 911 If the buffer's name is in this list, @code{display-buffer} handles the | |
| 912 buffer specially. | |
| 913 | |
| 914 By default, special display means to give the buffer a dedicated frame. | |
| 915 | |
| 916 If an element is a list, instead of a string, then the @sc{car} of the | |
| 917 list is the buffer name, and the rest of the list says how to create the | |
| 918 frame. There are two possibilities for the rest of the list. It can be | |
| 919 a plist, specifying frame properties, or it can contain a function and | |
| 920 arguments to give to it. (The function's first argument is always the | |
| 921 buffer to be displayed; the arguments from the list come after that.) | |
| 922 @end defvar | |
| 923 | |
| 924 @defvar special-display-regexps | |
| 925 A list of regular expressions that specify buffers that should be | |
| 926 displayed specially. If the buffer's name matches any of the regular | |
| 927 expressions in this list, @code{display-buffer} handles the buffer | |
| 928 specially. | |
| 929 | |
| 930 By default, special display means to give the buffer a dedicated frame. | |
| 931 | |
| 932 If an element is a list, instead of a string, then the @sc{car} of the | |
| 933 list is the regular expression, and the rest of the list says how to | |
| 934 create the frame. See above, under @code{special-display-buffer-names}. | |
| 935 @end defvar | |
| 936 | |
| 937 @defvar special-display-function | |
| 938 This variable holds the function to call to display a buffer specially. | |
| 939 It receives the buffer as an argument, and should return the window in | |
| 940 which it is displayed. | |
| 941 | |
| 942 The default value of this variable is | |
| 943 @code{special-display-popup-frame}. | |
| 944 @end defvar | |
| 945 | |
| 946 @defun special-display-popup-frame buffer | |
| 947 This function makes @var{buffer} visible in a frame of its own. If | |
| 948 @var{buffer} is already displayed in a window in some frame, it makes | |
| 949 the frame visible and raises it, to use that window. Otherwise, it | |
| 950 creates a frame that will be dedicated to @var{buffer}. | |
| 951 | |
| 952 This function uses an existing window displaying @var{buffer} whether or | |
| 953 not it is in a frame of its own; but if you set up the above variables | |
| 954 in your init file, before @var{buffer} was created, then presumably the | |
| 955 window was previously made by this function. | |
| 956 @end defun | |
| 957 | |
| 958 @defopt special-display-frame-plist | |
| 959 This variable holds frame properties for | |
| 960 @code{special-display-popup-frame} to use when it creates a frame. | |
| 961 @end defopt | |
| 962 | |
| 963 @defvar same-window-buffer-names | |
| 964 A list of buffer names for buffers that should be displayed in the | |
| 965 selected window. If the buffer's name is in this list, | |
| 966 @code{display-buffer} handles the buffer by switching to it in the | |
| 967 selected window. | |
| 968 @end defvar | |
| 969 | |
| 970 @defvar same-window-regexps | |
| 971 A list of regular expressions that specify buffers that should be | |
| 972 displayed in the selected window. If the buffer's name matches any of | |
| 973 the regular expressions in this list, @code{display-buffer} handles the | |
| 974 buffer by switching to it in the selected window. | |
| 975 @end defvar | |
| 976 | |
| 977 @c Emacs 19 feature | |
| 978 @defvar display-buffer-function | |
| 979 This variable is the most flexible way to customize the behavior of | |
| 980 @code{display-buffer}. If it is non-@code{nil}, it should be a function | |
| 981 that @code{display-buffer} calls to do the work. The function should | |
| 982 accept two arguments, the same two arguments that @code{display-buffer} | |
| 983 received. It should choose or create a window, display the specified | |
| 984 buffer, and then return the window. | |
| 985 | |
| 986 This hook takes precedence over all the other options and hooks | |
| 987 described above. | |
| 988 @end defvar | |
| 989 | |
| 990 @c Emacs 19 feature | |
| 991 @cindex dedicated window | |
| 992 A window can be marked as ``dedicated'' to its buffer. Then | |
| 993 @code{display-buffer} does not try to use that window. | |
| 994 | |
| 995 @defun window-dedicated-p window | |
| 996 This function returns @code{t} if @var{window} is marked as dedicated; | |
| 997 otherwise @code{nil}. | |
| 998 @end defun | |
| 999 | |
| 1000 @defun set-window-dedicated-p window flag | |
| 1001 This function marks @var{window} as dedicated if @var{flag} is | |
| 1002 non-@code{nil}, and nondedicated otherwise. | |
| 1003 @end defun | |
| 1004 | |
| 1005 @node Window Point | |
| 1006 @section Windows and Point | |
| 1007 @cindex window position | |
| 1008 @cindex window point | |
| 1009 @cindex position in window | |
| 1010 @cindex point in window | |
| 1011 | |
| 1012 Each window has its own value of point, independent of the value of | |
| 1013 point in other windows displaying the same buffer. This makes it useful | |
| 1014 to have multiple windows showing one buffer. | |
| 1015 | |
| 1016 @itemize @bullet | |
| 1017 @item | |
| 1018 The window point is established when a window is first created; it is | |
| 1019 initialized from the buffer's point, or from the window point of another | |
| 1020 window opened on the buffer if such a window exists. | |
| 1021 | |
| 1022 @item | |
| 1023 Selecting a window sets the value of point in its buffer to the window's | |
| 1024 value of point. Conversely, deselecting a window sets the window's | |
| 1025 value of point from that of the buffer. Thus, when you switch between | |
| 1026 windows that display a given buffer, the point value for the selected | |
| 1027 window is in effect in the buffer, while the point values for the other | |
| 1028 windows are stored in those windows. | |
| 1029 | |
| 1030 @item | |
| 1031 As long as the selected window displays the current buffer, the window's | |
| 1032 point and the buffer's point always move together; they remain equal. | |
| 1033 | |
| 1034 @item | |
| 1035 @xref{Positions}, for more details on buffer positions. | |
| 1036 @end itemize | |
| 1037 | |
| 1038 As far as the user is concerned, point is where the cursor is, and | |
| 1039 when the user switches to another buffer, the cursor jumps to the | |
| 1040 position of point in that buffer. | |
| 1041 | |
| 1042 @defun window-point window | |
| 1043 This function returns the current position of point in @var{window}. | |
| 1044 For a nonselected window, this is the value point would have (in that | |
| 1045 window's buffer) if that window were selected. | |
| 1046 | |
| 1047 When @var{window} is the selected window and its buffer is also the | |
| 1048 current buffer, the value returned is the same as point in that buffer. | |
| 1049 | |
| 1050 Strictly speaking, it would be more correct to return the | |
| 1051 ``top-level'' value of point, outside of any @code{save-excursion} | |
| 1052 forms. But that value is hard to find. | |
| 1053 @end defun | |
| 1054 | |
| 1055 @defun set-window-point window position | |
| 1056 This function positions point in @var{window} at position | |
| 1057 @var{position} in @var{window}'s buffer. | |
| 1058 @end defun | |
| 1059 | |
| 1060 @node Window Start | |
| 1061 @section The Window Start Position | |
| 1062 | |
| 1063 Each window contains a marker used to keep track of a buffer position | |
| 1064 that specifies where in the buffer display should start. This position | |
| 1065 is called the @dfn{display-start} position of the window (or just the | |
| 1066 @dfn{start}). The character after this position is the one that appears | |
| 1067 at the upper left corner of the window. It is usually, but not | |
| 1068 inevitably, at the beginning of a text line. | |
| 1069 | |
| 1070 @defun window-start &optional window | |
| 1071 @cindex window top line | |
| 1072 This function returns the display-start position of window | |
| 1073 @var{window}. If @var{window} is @code{nil}, the selected window is | |
| 1074 used. For example, | |
| 1075 | |
| 1076 @example | |
| 1077 @group | |
| 1078 (window-start) | |
| 1079 @result{} 7058 | |
| 1080 @end group | |
| 1081 @end example | |
| 1082 | |
| 1083 When you create a window, or display a different buffer in it, the | |
| 1084 display-start position is set to a display-start position recently used | |
| 1085 for the same buffer, or 1 if the buffer doesn't have any. | |
| 1086 | |
| 1087 For a realistic example, see the description of @code{count-lines} in | |
| 1088 @ref{Text Lines}. | |
| 1089 @end defun | |
| 1090 | |
| 1091 @defun window-end &optional window | |
| 1092 This function returns the position of the end of the display in window | |
| 1093 @var{window}. If @var{window} is @code{nil}, the selected window is | |
| 1094 used. | |
| 1095 | |
| 1096 Simply changing the buffer text or moving point does not update the | |
| 1097 value that @code{window-end} returns. The value is updated only when | |
| 1098 Emacs redisplays and redisplay actually finishes. | |
| 1099 | |
| 1100 If the last redisplay of @var{window} was preempted, and did not finish, | |
| 1101 Emacs does not know the position of the end of display in that window. | |
| 1102 In that case, this function returns a value that is not correct. In a | |
| 1103 future version, @code{window-end} will return @code{nil} in that case. | |
| 1104 @ignore | |
| 1105 in that case, this function returns @code{nil}. You can compute where | |
| 1106 the end of the window @emph{would} have been, if redisplay had finished, | |
| 1107 like this: | |
| 1108 | |
| 1109 @example | |
| 1110 (save-excursion | |
| 1111 (goto-char (window-start window)) | |
| 1112 (vertical-motion (1- (window-height window)) | |
| 1113 window) | |
| 1114 (point)) | |
| 1115 @end example | |
| 1116 @end ignore | |
| 1117 @end defun | |
| 1118 | |
| 1119 @defun set-window-start window position &optional noforce | |
| 1120 This function sets the display-start position of @var{window} to | |
| 1121 @var{position} in @var{window}'s buffer. It returns @var{position}. | |
| 1122 | |
| 1123 The display routines insist that the position of point be visible when a | |
| 1124 buffer is displayed. Normally, they change the display-start position | |
| 1125 (that is, scroll the window) whenever necessary to make point visible. | |
| 1126 However, if you specify the start position with this function using | |
| 1127 @code{nil} for @var{noforce}, it means you want display to start at | |
| 1128 @var{position} even if that would put the location of point off the | |
| 1129 screen. If this does place point off screen, the display routines move | |
| 1130 point to the left margin on the middle line in the window. | |
| 1131 | |
| 1132 For example, if point @w{is 1} and you set the start of the window @w{to | |
| 1133 2}, then point would be ``above'' the top of the window. The display | |
| 1134 routines will automatically move point if it is still 1 when redisplay | |
| 1135 occurs. Here is an example: | |
| 1136 | |
| 1137 @example | |
| 1138 @group | |
| 1139 ;; @r{Here is what @samp{foo} looks like before executing} | |
| 1140 ;; @r{the @code{set-window-start} expression.} | |
| 1141 @end group | |
| 1142 | |
| 1143 @group | |
| 1144 ---------- Buffer: foo ---------- | |
| 1145 @point{}This is the contents of buffer foo. | |
| 1146 2 | |
| 1147 3 | |
| 1148 4 | |
| 1149 5 | |
| 1150 6 | |
| 1151 ---------- Buffer: foo ---------- | |
| 1152 @end group | |
| 1153 | |
| 1154 @group | |
| 1155 (set-window-start | |
| 1156 (selected-window) | |
| 1157 (1+ (window-start))) | |
| 1158 @result{} 2 | |
| 1159 @end group | |
| 1160 | |
| 1161 @group | |
| 1162 ;; @r{Here is what @samp{foo} looks like after executing} | |
| 1163 ;; @r{the @code{set-window-start} expression.} | |
| 1164 ---------- Buffer: foo ---------- | |
| 1165 his is the contents of buffer foo. | |
| 1166 2 | |
| 1167 3 | |
| 1168 @point{}4 | |
| 1169 5 | |
| 1170 6 | |
| 1171 ---------- Buffer: foo ---------- | |
| 1172 @end group | |
| 1173 @end example | |
| 1174 | |
| 1175 If @var{noforce} is non-@code{nil}, and @var{position} would place point | |
| 1176 off screen at the next redisplay, then redisplay computes a new window-start | |
| 1177 position that works well with point, and thus @var{position} is not used. | |
| 1178 @end defun | |
| 1179 | |
| 1180 @defun pos-visible-in-window-p &optional position window | |
| 1181 This function returns @code{t} if @var{position} is within the range | |
| 1182 of text currently visible on the screen in @var{window}. It returns | |
| 1183 @code{nil} if @var{position} is scrolled vertically out of view. The | |
| 1184 argument @var{position} defaults to the current position of point; | |
| 1185 @var{window}, to the selected window. Here is an example: | |
| 1186 | |
| 1187 @example | |
| 1188 @group | |
| 1189 (or (pos-visible-in-window-p | |
| 1190 (point) (selected-window)) | |
| 1191 (recenter 0)) | |
| 1192 @end group | |
| 1193 @end example | |
| 1194 | |
| 1195 The @code{pos-visible-in-window-p} function considers only vertical | |
| 1196 scrolling. If @var{position} is out of view only because @var{window} | |
| 1197 has been scrolled horizontally, @code{pos-visible-in-window-p} returns | |
| 1198 @code{t}. @xref{Horizontal Scrolling}. | |
| 1199 @end defun | |
| 1200 | |
| 1201 @node Vertical Scrolling | |
| 1202 @section Vertical Scrolling | |
| 1203 @cindex vertical scrolling | |
| 1204 @cindex scrolling vertically | |
| 1205 | |
| 1206 Vertical scrolling means moving the text up or down in a window. It | |
| 1207 works by changing the value of the window's display-start location. It | |
| 1208 may also change the value of @code{window-point} to keep it on the | |
| 1209 screen. | |
| 1210 | |
| 1211 In the commands @code{scroll-up} and @code{scroll-down}, the directions | |
| 1212 ``up'' and ``down'' refer to the motion of the text in the buffer at which | |
| 1213 you are looking through the window. Imagine that the text is | |
| 1214 written on a long roll of paper and that the scrolling commands move the | |
| 1215 paper up and down. Thus, if you are looking at text in the middle of a | |
| 1216 buffer and repeatedly call @code{scroll-down}, you will eventually see | |
| 1217 the beginning of the buffer. | |
| 1218 | |
| 1219 Some people have urged that the opposite convention be used: they | |
| 1220 imagine that the window moves over text that remains in place. Then | |
| 1221 ``down'' commands would take you to the end of the buffer. This view is | |
| 1222 more consistent with the actual relationship between windows and the | |
| 1223 text in the buffer, but it is less like what the user sees. The | |
| 1224 position of a window on the terminal does not move, and short scrolling | |
| 1225 commands clearly move the text up or down on the screen. We have chosen | |
| 1226 names that fit the user's point of view. | |
| 1227 | |
| 1228 The scrolling functions (aside from @code{scroll-other-window}) have | |
| 1229 unpredictable results if the current buffer is different from the buffer | |
| 1230 that is displayed in the selected window. @xref{Current Buffer}. | |
| 1231 | |
| 1232 @deffn Command scroll-up &optional count | |
| 1233 This function scrolls the text in the selected window upward | |
| 1234 @var{count} lines. If @var{count} is negative, scrolling is actually | |
| 1235 downward. | |
| 1236 | |
| 1237 If @var{count} is @code{nil} (or omitted), then the length of scroll | |
| 1238 is @code{next-screen-context-lines} lines less than the usable height of | |
| 1239 the window (not counting its modeline). | |
| 1240 | |
| 1241 @code{scroll-up} returns @code{nil}. | |
| 1242 @end deffn | |
| 1243 | |
| 1244 @deffn Command scroll-down &optional count | |
| 1245 This function scrolls the text in the selected window downward | |
| 1246 @var{count} lines. If @var{count} is negative, scrolling is actually | |
| 1247 upward. | |
| 1248 | |
| 1249 If @var{count} is omitted or @code{nil}, then the length of the scroll | |
| 1250 is @code{next-screen-context-lines} lines less than the usable height of | |
| 1251 the window (not counting its mode line). | |
| 1252 | |
| 1253 @code{scroll-down} returns @code{nil}. | |
| 1254 @end deffn | |
| 1255 | |
| 1256 @deffn Command scroll-other-window &optional count | |
| 1257 This function scrolls the text in another window upward @var{count} | |
| 1258 lines. Negative values of @var{count}, or @code{nil}, are handled | |
| 1259 as in @code{scroll-up}. | |
| 1260 | |
| 1261 You can specify a buffer to scroll with the variable | |
| 1262 @code{other-window-scroll-buffer}. When the selected window is the | |
| 1263 minibuffer, the next window is normally the one at the top left corner. | |
| 1264 You can specify a different window to scroll with the variable | |
| 1265 @code{minibuffer-scroll-window}. This variable has no effect when any | |
| 1266 other window is selected. @xref{Minibuffer Misc}. | |
| 1267 | |
| 1268 When the minibuffer is active, it is the next window if the selected | |
| 1269 window is the one at the bottom right corner. In this case, | |
| 1270 @code{scroll-other-window} attempts to scroll the minibuffer. If the | |
| 1271 minibuffer contains just one line, it has nowhere to scroll to, so the | |
| 1272 line reappears after the echo area momentarily displays the message | |
| 1273 ``Beginning of buffer''. | |
| 1274 @end deffn | |
| 1275 | |
| 1276 @c Emacs 19 feature | |
| 1277 @defvar other-window-scroll-buffer | |
| 1278 If this variable is non-@code{nil}, it tells @code{scroll-other-window} | |
| 1279 which buffer to scroll. | |
| 1280 @end defvar | |
| 1281 | |
| 1282 @defopt scroll-step | |
| 1283 This variable controls how scrolling is done automatically when point | |
| 1284 moves off the screen. If the value is zero, then redisplay scrolls the | |
| 1285 text to center point vertically in the window. If the value is a | |
| 1286 positive integer @var{n}, then redisplay brings point back on screen by | |
| 1287 scrolling @var{n} lines in either direction, if possible; otherwise, it | |
| 1288 centers point. The default value is zero. | |
| 1289 @end defopt | |
| 1290 | |
| 1291 @defopt scroll-conservatively | |
| 1292 This variable controls how many lines Emacs tries to scroll before | |
| 1293 recentering. If you set it to a small number, then when you move point | |
| 1294 a short distance off the screen, XEmacs will scroll the screen just far | |
| 1295 enough to bring point back on screen, provided that does not exceed | |
| 1296 @code{scroll-conservatively} lines. This variable overrides the | |
| 1297 redisplay preemption. | |
| 1298 @end defopt | |
| 1299 | |
| 1300 @defopt next-screen-context-lines | |
| 1301 The value of this variable is the number of lines of continuity to | |
| 1302 retain when scrolling by full screens. For example, @code{scroll-up} | |
| 1303 with an argument of @code{nil} scrolls so that this many lines at the | |
| 1304 bottom of the window appear instead at the top. The default value is | |
| 1305 @code{2}. | |
| 1306 @end defopt | |
| 1307 | |
| 1308 @deffn Command recenter &optional count | |
| 1309 @cindex centering point | |
| 1310 This function scrolls the selected window to put the text where point | |
| 1311 is located at a specified vertical position within the window. | |
| 1312 | |
| 1313 If @var{count} is a nonnegative number, it puts the line containing | |
| 1314 point @var{count} lines down from the top of the window. If @var{count} | |
| 1315 is a negative number, then it counts upward from the bottom of the | |
| 1316 window, so that @minus{}1 stands for the last usable line in the window. | |
| 1317 If @var{count} is a non-@code{nil} list, then it stands for the line in | |
| 1318 the middle of the window. | |
| 1319 | |
| 1320 If @var{count} is @code{nil}, @code{recenter} puts the line containing | |
| 1321 point in the middle of the window, then clears and redisplays the entire | |
| 1322 selected frame. | |
| 1323 | |
| 1324 When @code{recenter} is called interactively, @var{count} is the raw | |
| 1325 prefix argument. Thus, typing @kbd{C-u} as the prefix sets the | |
| 1326 @var{count} to a non-@code{nil} list, while typing @kbd{C-u 4} sets | |
| 1327 @var{count} to 4, which positions the current line four lines from the | |
| 1328 top. | |
| 1329 | |
| 1330 With an argument of zero, @code{recenter} positions the current line at | |
| 1331 the top of the window. This action is so handy that some people make a | |
| 1332 separate key binding to do this. For example, | |
| 1333 | |
| 1334 @example | |
| 1335 @group | |
| 1336 (defun line-to-top-of-window () | |
| 1337 "Scroll current line to top of window. | |
| 1338 Replaces three keystroke sequence C-u 0 C-l." | |
| 1339 (interactive) | |
| 1340 (recenter 0)) | |
| 1341 | |
| 1342 (global-set-key [kp-multiply] 'line-to-top-of-window) | |
| 1343 @end group | |
| 1344 @end example | |
| 1345 @end deffn | |
| 1346 | |
| 1347 @node Horizontal Scrolling | |
| 1348 @section Horizontal Scrolling | |
| 1349 @cindex horizontal scrolling | |
| 1350 | |
| 1351 Because we read English first from top to bottom and second from left | |
| 1352 to right, horizontal scrolling is not like vertical scrolling. Vertical | |
| 1353 scrolling involves selection of a contiguous portion of text to display. | |
| 1354 Horizontal scrolling causes part of each line to go off screen. The | |
| 1355 amount of horizontal scrolling is therefore specified as a number of | |
| 1356 columns rather than as a position in the buffer. It has nothing to do | |
| 1357 with the display-start position returned by @code{window-start}. | |
| 1358 | |
| 1359 Usually, no horizontal scrolling is in effect; then the leftmost | |
| 1360 column is at the left edge of the window. In this state, scrolling to | |
| 1361 the right is meaningless, since there is no data to the left of the | |
| 1362 screen to be revealed by it; so this is not allowed. Scrolling to the | |
| 1363 left is allowed; it scrolls the first columns of text off the edge of | |
| 1364 the window and can reveal additional columns on the right that were | |
| 1365 truncated before. Once a window has a nonzero amount of leftward | |
| 1366 horizontal scrolling, you can scroll it back to the right, but only so | |
| 1367 far as to reduce the net horizontal scroll to zero. There is no limit | |
| 1368 to how far left you can scroll, but eventually all the text will | |
| 1369 disappear off the left edge. | |
| 1370 | |
| 1371 @deffn Command scroll-left count | |
| 1372 This function scrolls the selected window @var{count} columns to the | |
| 1373 left (or to the right if @var{count} is negative). The return value is | |
| 1374 the total amount of leftward horizontal scrolling in effect after the | |
| 1375 change---just like the value returned by @code{window-hscroll} (below). | |
| 1376 @end deffn | |
| 1377 | |
| 1378 @deffn Command scroll-right count | |
| 1379 This function scrolls the selected window @var{count} columns to the | |
| 1380 right (or to the left if @var{count} is negative). The return value is | |
| 1381 the total amount of leftward horizontal scrolling in effect after the | |
| 1382 change---just like the value returned by @code{window-hscroll} (below). | |
| 1383 | |
| 1384 Once you scroll a window as far right as it can go, back to its normal | |
| 1385 position where the total leftward scrolling is zero, attempts to scroll | |
| 1386 any farther right have no effect. | |
| 1387 @end deffn | |
| 1388 | |
| 1389 @defun window-hscroll &optional window | |
| 1390 This function returns the total leftward horizontal scrolling of | |
| 1391 @var{window}---the number of columns by which the text in @var{window} | |
| 1392 is scrolled left past the left margin. | |
| 1393 | |
| 1394 The value is never negative. It is zero when no horizontal scrolling | |
| 1395 has been done in @var{window} (which is usually the case). | |
| 1396 | |
| 1397 If @var{window} is @code{nil}, the selected window is used. | |
| 1398 | |
| 1399 @example | |
| 1400 @group | |
| 1401 (window-hscroll) | |
| 1402 @result{} 0 | |
| 1403 @end group | |
| 1404 @group | |
| 1405 (scroll-left 5) | |
| 1406 @result{} 5 | |
| 1407 @end group | |
| 1408 @group | |
| 1409 (window-hscroll) | |
| 1410 @result{} 5 | |
| 1411 @end group | |
| 1412 @end example | |
| 1413 @end defun | |
| 1414 | |
| 1415 @defun set-window-hscroll window columns | |
| 1416 This function sets the number of columns from the left margin that | |
| 1417 @var{window} is scrolled to the value of @var{columns}. The argument | |
| 1418 @var{columns} should be zero or positive; if not, it is taken as zero. | |
| 1419 | |
| 1420 The value returned is @var{columns}. | |
| 1421 | |
| 1422 @example | |
| 1423 @group | |
| 1424 (set-window-hscroll (selected-window) 10) | |
| 1425 @result{} 10 | |
| 1426 @end group | |
| 1427 @end example | |
| 1428 @end defun | |
| 1429 | |
| 1430 Here is how you can determine whether a given position @var{position} | |
| 1431 is off the screen due to horizontal scrolling: | |
| 1432 | |
| 1433 @example | |
| 1434 @group | |
| 1435 (defun hscroll-on-screen (window position) | |
| 1436 (save-excursion | |
| 1437 (goto-char position) | |
| 1438 (and | |
| 1439 (>= (- (current-column) (window-hscroll window)) 0) | |
| 1440 (< (- (current-column) (window-hscroll window)) | |
| 1441 (window-width window))))) | |
| 1442 @end group | |
| 1443 @end example | |
| 1444 @node Size of Window | |
| 1445 @section The Size of a Window | |
| 1446 @cindex window size | |
| 1447 @cindex size of window | |
| 1448 | |
| 1449 An Emacs window is rectangular, and its size information consists of | |
| 1450 the height (in lines or pixels) and the width (in character positions | |
| 1451 or pixels). The modeline is included in the height. The pixel | |
| 1452 width and height values include scrollbars and margins, while the | |
| 1453 line/character-position values do not. | |
| 1454 | |
| 1455 Note that the height in lines, and the width in characters, are | |
| 1456 determined by dividing the corresponding pixel value by the height or | |
| 1457 width of the default font in that window (if this is a variable-width | |
| 1458 font, the average width is used). The resulting values may or may not | |
| 1459 represent the actual number of lines in the window, or the actual number | |
| 1460 of character positions in any particular line, esp. if there are pixmaps | |
| 1461 or various different fonts in the window. | |
| 1462 | |
| 1463 The following functions return size information about a window: | |
| 1464 | |
| 1465 @defun window-height &optional window | |
| 1466 This function returns the number of lines in @var{window}, including | |
| 1467 its modeline but not including the horizontal scrollbar, if any (this | |
| 1468 is different from @code{window-pixel-height}). If @var{window} is | |
| 1469 @code{nil}, the function uses the selected window. | |
| 1470 | |
| 1471 @example | |
| 1472 @group | |
| 1473 (window-height) | |
| 1474 @result{} 40 | |
| 1475 @end group | |
| 1476 @group | |
| 1477 (split-window-vertically) | |
| 1478 @result{} #<window on "windows.texi" 0x679b> | |
| 1479 @end group | |
| 1480 @group | |
| 1481 (window-height) | |
| 1482 @result{} 20 | |
| 1483 @end group | |
| 1484 @end example | |
| 1485 @end defun | |
| 1486 | |
| 1487 @defun window-width &optional window | |
| 1488 This function returns the number of columns in @var{window}, not | |
| 1489 including any left margin, right margin, or vertical scrollbar (this is | |
| 1490 different from @code{window-pixel-width}). If @var{window} is | |
| 1491 @code{nil}, the function uses the selected window. | |
| 1492 | |
| 1493 @example | |
| 1494 @group | |
| 1495 (window-width) | |
| 1496 @result{} 80 | |
| 1497 @end group | |
| 1498 @group | |
| 1499 (window-height) | |
| 1500 @result{} 40 | |
| 1501 @end group | |
| 1502 @group | |
| 1503 (split-window-horizontally) | |
| 1504 @result{} #<window on "windows.texi" 0x7538> | |
| 1505 @end group | |
| 1506 @group | |
| 1507 (window-width) | |
| 1508 @result{} 39 | |
| 1509 @end group | |
| 1510 @end example | |
| 1511 @end defun | |
| 1512 | |
| 1513 Note that after splitting the window into two side-by-side windows, | |
| 1514 the width of each window is less the half the width of the original | |
| 1515 window because a vertical scrollbar appeared between the windows, | |
| 1516 occupying two columns worth of space. Also, the height shrunk by | |
| 1517 one because horizontal scrollbars appeared that weren't there | |
| 1518 before. (Horizontal scrollbars appear only when lines are | |
| 1519 truncated, not when they wrap. This is usually the case for | |
| 1520 horizontally split windows but not for full-frame windows. You | |
| 1521 can change this using the variables @code{truncate-lines} and | |
| 1522 @code{truncate-partial-width-windows}.) | |
| 1523 | |
| 1524 @defun window-pixel-height &optional window | |
| 1525 This function returns the height of @var{window} in pixels, including | |
| 1526 its modeline and horizontal scrollbar, if any. If @var{window} is | |
| 1527 @code{nil}, the function uses the selected window. | |
| 1528 | |
| 1529 @example | |
| 1530 @group | |
| 1531 (window-pixel-height) | |
| 1532 @result{} 600 | |
| 1533 @end group | |
| 1534 @group | |
| 1535 (split-window-vertically) | |
| 1536 @result{} #<window on "windows.texi" 0x68a6> | |
| 1537 @end group | |
| 1538 @group | |
| 1539 (window-pixel-height) | |
| 1540 @result{} 300 | |
| 1541 @end group | |
| 1542 @end example | |
| 1543 @end defun | |
| 1544 | |
| 1545 @defun window-pixel-width &optional window | |
| 1546 This function returns the width of @var{window} in pixels, including | |
| 1547 any left margin, right margin, or vertical scrollbar that may be | |
| 1548 displayed alongside it. If @var{window} is @code{nil}, the function | |
| 1549 uses the selected window. | |
| 1550 | |
| 1551 @example | |
| 1552 @group | |
| 1553 (window-pixel-width) | |
| 1554 @result{} 735 | |
| 1555 @end group | |
| 1556 @group | |
| 1557 (window-pixel-height) | |
| 1558 @result{} 600 | |
| 1559 @end group | |
| 1560 @group | |
| 1561 (split-window-horizontally) | |
| 1562 @result{} #<window on "windows.texi" 0x7538> | |
| 1563 @end group | |
| 1564 @group | |
| 1565 (window-pixel-width) | |
| 1566 @result{} 367 | |
| 1567 @end group | |
| 1568 @group | |
| 1569 (window-pixel-height) | |
| 1570 @result{} 600 | |
| 1571 @end group | |
| 1572 @end example | |
| 1573 @end defun | |
| 1574 | |
| 1575 @defun window-text-area-pixel-height &optional window | |
| 1576 This function returns the height in pixels of the text displaying | |
| 1577 portion of @var{window}, which defaults to the selected window. Unlike | |
| 1578 @code{window-pixel-height}, the space occupied by the modeline and | |
| 1579 horizontal scrollbar, if any, is not counted. | |
| 1580 @end defun | |
| 1581 | |
| 1582 @defun window-text-area-pixel-width &optional window | |
| 1583 This function returns the width in pixels of the text displaying | |
| 1584 portion of @var{window}, which defaults to the selected window. Unlike | |
| 1585 @code{window-pixel-width}, the space occupied by the vertical scrollbar | |
| 1586 and divider, if any, is not counted. | |
| 1587 @end defun | |
| 1588 | |
| 1589 @defun window-displayed-text-pixel-height &optional window noclipped | |
| 1590 This function returns the height in pixels of the text displayed in | |
| 1591 @var{window}, which defaults to the selected window. Unlike | |
| 1592 @code{window-text-area-pixel-height}, any blank space below the | |
| 1593 end of the buffer is not included. If optional argument @var{noclipped} | |
| 1594 is non-@code{nil}, any space occupied by clipped lines will not be | |
| 1595 included. | |
| 1596 @end defun | |
| 1597 | |
| 1598 @node Position of Window | |
| 1599 @section The Position of a Window | |
| 1600 @cindex window position | |
| 1601 @cindex position of window | |
| 1602 | |
| 1603 XEmacs provides functions to determine the absolute location of windows | |
| 1604 within a frame, and the relative location of a window in comparison to | |
| 1605 other windows in the same frame. | |
| 1606 | |
| 1607 @defun window-pixel-edges &optional window | |
| 1608 This function returns a list of the pixel edge coordinates of | |
| 1609 @var{window}. If @var{window} is @code{nil}, the selected window is | |
| 1610 used. | |
| 1611 | |
| 1612 The order of the list is @code{(@var{left} @var{top} @var{right} | |
| 1613 @var{bottom})}, all elements relative to 0, 0 at the top left corner of | |
| 1614 the frame. The element @var{right} of the value is one more than the | |
| 1615 rightmost pixel used by @var{window} (including any left margin, right | |
| 1616 margin, or vertical scrollbar displayed alongside it), and | |
| 1617 @var{bottom} is one more than the bottommost pixel used by @var{window} | |
| 1618 (including any modeline or horizontal scrollbar displayed above | |
| 1619 or below it). The frame area does not include any frame menubars or | |
| 1620 toolbars that may be displayed; thus, for example, if there is only | |
| 1621 one window on the frame, the values for @var{left} and @var{top} will | |
| 1622 always be 0. | |
| 1623 | |
| 1624 If @var{window} is at the upper left corner of its frame, @var{right} | |
| 1625 and @var{bottom} are the same as the values returned by | |
| 1626 @code{(window-pixel-width)} and @code{(window-pixel-height)} | |
| 1627 respectively, and @var{top} and @var{bottom} are zero. | |
| 1628 @end defun | |
| 1629 | |
| 1630 There is no longer a function @code{window-edges} because it does not | |
| 1631 make sense in a world with variable-width and variable-height lines, | |
| 1632 as are allowed in XEmacs. | |
| 1633 | |
| 1634 @defun window-highest-p window | |
| 1635 This function returns non-@code{nil} if @var{window} is along the | |
| 1636 top of its frame. | |
| 1637 @end defun | |
| 1638 | |
| 1639 @defun window-lowest-p window | |
| 1640 This function returns non-@code{nil} if @var{window} is along the | |
| 1641 bottom of its frame. | |
| 1642 @end defun | |
| 1643 | |
| 1644 @defun window-text-area-pixel-edges &optional window | |
| 1645 This function allows one to determine the location of the | |
| 1646 text-displaying portion of @var{window}, which defaults to the selected | |
| 1647 window, with respect to the top left corner of the window. It returns | |
| 1648 a list of integer pixel positions @code{(left top right bottom)}, all | |
| 1649 relative to @code{(0,0)} at the top left corner of the window. | |
| 1650 @end defun | |
| 1651 | |
| 1652 @node Resizing Windows | |
| 1653 @section Changing the Size of a Window | |
| 1654 @cindex window resizing | |
| 1655 @cindex changing window size | |
| 1656 @cindex window size, changing | |
| 1657 | |
| 1658 The window size functions fall into two classes: high-level commands | |
| 1659 that change the size of windows and low-level functions that access | |
| 1660 window size. XEmacs does not permit overlapping windows or gaps between | |
| 1661 windows, so resizing one window affects other windows. | |
| 1662 | |
| 1663 @deffn Command enlarge-window size &optional horizontal window | |
| 1664 This function makes the selected window @var{size} lines taller, | |
| 1665 stealing lines from neighboring windows. It takes the lines from one | |
| 1666 window at a time until that window is used up, then takes from another. | |
| 1667 If a window from which lines are stolen shrinks below | |
| 1668 @code{window-min-height} lines, that window disappears. | |
| 1669 | |
| 1670 If @var{horizontal} is non-@code{nil}, this function makes | |
| 1671 @var{window} wider by @var{size} columns, stealing columns instead of | |
| 1672 lines. If a window from which columns are stolen shrinks below | |
| 1673 @code{window-min-width} columns, that window disappears. | |
| 1674 | |
| 1675 If the requested size would exceed that of the window's frame, then the | |
| 1676 function makes the window occupy the entire height (or width) of the | |
| 1677 frame. | |
| 1678 | |
| 1679 If @var{size} is negative, this function shrinks the window by | |
| 1680 @minus{}@var{size} lines or columns. If that makes the window smaller | |
| 1681 than the minimum size (@code{window-min-height} and | |
| 1682 @code{window-min-width}), @code{enlarge-window} deletes the window. | |
| 1683 | |
| 1684 If @var{window} is non-@code{nil}, it specifies a window to change | |
| 1685 instead of the selected window. | |
| 1686 | |
| 1687 @code{enlarge-window} returns @code{nil}. | |
| 1688 @end deffn | |
| 1689 | |
| 1690 @deffn Command enlarge-window-horizontally columns | |
| 1691 This function makes the selected window @var{columns} wider. | |
| 1692 It could be defined as follows: | |
| 1693 | |
| 1694 @example | |
| 1695 @group | |
| 1696 (defun enlarge-window-horizontally (columns) | |
| 1697 (enlarge-window columns t)) | |
| 1698 @end group | |
| 1699 @end example | |
| 1700 @end deffn | |
| 1701 | |
| 1702 @deffn Command enlarge-window-pixels count &optional side window | |
| 1703 This function makes the selected window @var{count} pixels larger. When | |
| 1704 called from Lisp, optional second argument @var{side} non-@code{nil} | |
| 1705 means to grow sideways @var{count} pixels, and optional third argument | |
| 1706 @var{window} specifies the window to change instead of the selected | |
| 1707 window. | |
| 1708 @end deffn | |
| 1709 | |
| 1710 @deffn Command shrink-window size &optional horizontal window | |
| 1711 This function is like @code{enlarge-window} but negates the argument | |
| 1712 @var{size}, making the selected window smaller by giving lines (or | |
| 1713 columns) to the other windows. If the window shrinks below | |
| 1714 @code{window-min-height} or @code{window-min-width}, then it disappears. | |
| 1715 | |
| 1716 If @var{size} is negative, the window is enlarged by @minus{}@var{size} | |
| 1717 lines or columns. | |
| 1718 | |
| 1719 If @var{window} is non-@code{nil}, it specifies a window to change | |
| 1720 instead of the selected window. | |
| 1721 @end deffn | |
| 1722 | |
| 1723 @deffn Command shrink-window-horizontally columns | |
| 1724 This function makes the selected window @var{columns} narrower. | |
| 1725 It could be defined as follows: | |
| 1726 | |
| 1727 @example | |
| 1728 @group | |
| 1729 (defun shrink-window-horizontally (columns) | |
| 1730 (shrink-window columns t)) | |
| 1731 @end group | |
| 1732 @end example | |
| 1733 @end deffn | |
| 1734 | |
| 1735 @deffn Command shrink-window-pixels count &optional side window | |
| 1736 This function makes the selected window @var{count} pixels smaller. | |
| 1737 When called from Lisp, optional second argument @var{side} | |
| 1738 non-@code{nil} means to shrink sideways @var{count} pixels, and optional | |
| 1739 third argument @var{window} specifies the window to change instead of | |
| 1740 the selected window. | |
| 1741 @end deffn | |
| 1742 | |
| 1743 @cindex minimum window size | |
| 1744 The following two variables constrain the window-size-changing | |
| 1745 functions to a minimum height and width. | |
| 1746 | |
| 1747 @defopt window-min-height | |
| 1748 The value of this variable determines how short a window may become | |
| 1749 before it is automatically deleted. Making a window smaller than | |
| 1750 @code{window-min-height} automatically deletes it, and no window may be | |
| 1751 created shorter than this. The absolute minimum height is two (allowing | |
| 1752 one line for the mode line, and one line for the buffer display). | |
| 1753 Actions that change window sizes reset this variable to two if it is | |
| 1754 less than two. The default value is 4. | |
| 1755 @end defopt | |
| 1756 | |
| 1757 @defopt window-min-width | |
| 1758 The value of this variable determines how narrow a window may become | |
| 1759 before it automatically deleted. Making a window smaller than | |
| 1760 @code{window-min-width} automatically deletes it, and no window may be | |
| 1761 created narrower than this. The absolute minimum width is one; any | |
| 1762 value below that is ignored. The default value is 10. | |
| 1763 @end defopt | |
| 1764 | |
| 1765 @c This is not yet implemented. Why is it "documented"? | |
| 1766 @defvar window-size-change-functions | |
| 1767 This variable holds a list of functions to be called if the size of any | |
| 1768 window changes for any reason. The functions are called just once per | |
| 1769 redisplay, and just once for each frame on which size changes have | |
| 1770 occurred. | |
| 1771 | |
| 1772 Each function receives the frame as its sole argument. There is no | |
| 1773 direct way to find out which windows changed size, or precisely how; | |
| 1774 however, if your size-change function keeps track, after each change, of | |
| 1775 the windows that interest you, you can figure out what has changed by | |
| 1776 comparing the old size data with the new. | |
| 1777 | |
| 1778 Creating or deleting windows counts as a size change, and therefore | |
| 1779 causes these functions to be called. Changing the frame size also | |
| 1780 counts, because it changes the sizes of the existing windows. | |
| 1781 | |
| 1782 It is not a good idea to use @code{save-window-excursion} in these | |
| 1783 functions, because that always counts as a size change, and it would | |
| 1784 cause these functions to be called over and over. In most cases, | |
| 1785 @code{save-selected-window} is what you need here. | |
| 1786 @end defvar | |
| 1787 | |
| 1788 @node Window Configurations | |
| 1789 @section Window Configurations | |
| 1790 @cindex window configurations | |
| 1791 @cindex saving window information | |
| 1792 | |
| 1793 A @dfn{window configuration} records the entire layout of a | |
| 1794 frame---all windows, their sizes, which buffers they contain, what part | |
| 1795 of each buffer is displayed, and the values of point and the mark. You | |
| 1796 can bring back an entire previous layout by restoring a window | |
| 1797 configuration previously saved. | |
| 1798 | |
| 1799 If you want to record all frames instead of just one, use a frame | |
| 1800 configuration instead of a window configuration. @xref{Frame | |
| 1801 Configurations}. | |
| 1802 | |
| 1803 @defun current-window-configuration | |
| 1804 This function returns a new object representing XEmacs's current window | |
| 1805 configuration, namely the number of windows, their sizes and current | |
| 1806 buffers, which window is the selected window, and for each window the | |
| 1807 displayed buffer, the display-start position, and the positions of point | |
| 1808 and the mark. An exception is made for point in the current buffer, | |
| 1809 whose value is not saved. | |
| 1810 @end defun | |
| 1811 | |
| 1812 @defun set-window-configuration configuration | |
| 1813 This function restores the configuration of XEmacs's windows and | |
| 1814 buffers to the state specified by @var{configuration}. The argument | |
| 1815 @var{configuration} must be a value that was previously returned by | |
| 1816 @code{current-window-configuration}. | |
| 1817 | |
| 1818 This function always counts as a window size change and triggers | |
| 1819 execution of the @code{window-size-change-functions}. (It doesn't know | |
| 1820 how to tell whether the new configuration actually differs from the old | |
| 1821 one.) | |
| 1822 | |
| 1823 Here is a way of using this function to get the same effect | |
| 1824 as @code{save-window-excursion}: | |
| 1825 | |
| 1826 @example | |
| 1827 @group | |
| 1828 (let ((config (current-window-configuration))) | |
| 1829 (unwind-protect | |
| 1830 (progn (split-window-vertically nil) | |
| 1831 @dots{}) | |
| 1832 (set-window-configuration config))) | |
| 1833 @end group | |
| 1834 @end example | |
| 1835 @end defun | |
| 1836 | |
| 1837 @defspec save-window-excursion forms@dots{} | |
| 1838 This special form records the window configuration, executes @var{forms} | |
| 1839 in sequence, then restores the earlier window configuration. The window | |
| 1840 configuration includes the value of point and the portion of the buffer | |
| 1841 that is visible. It also includes the choice of selected window. | |
| 1842 However, it does not include the value of point in the current buffer; | |
| 1843 use @code{save-excursion} if you wish to preserve that. | |
| 1844 | |
| 1845 Don't use this construct when @code{save-selected-window} is all you need. | |
| 1846 | |
| 1847 Exit from @code{save-window-excursion} always triggers execution of the | |
| 1848 @code{window-size-change-functions}. (It doesn't know how to tell | |
| 1849 whether the restored configuration actually differs from the one in | |
| 1850 effect at the end of the @var{forms}.) | |
| 1851 | |
| 1852 The return value is the value of the final form in @var{forms}. | |
| 1853 For example: | |
| 1854 | |
| 1855 @example | |
| 1856 @group | |
| 1857 (split-window) | |
| 1858 @result{} #<window 25 on control.texi> | |
| 1859 @end group | |
| 1860 @group | |
| 1861 (setq w (selected-window)) | |
| 1862 @result{} #<window 19 on control.texi> | |
| 1863 @end group | |
| 1864 @group | |
| 1865 (save-window-excursion | |
| 1866 (delete-other-windows w) | |
| 1867 (switch-to-buffer "foo") | |
| 1868 'do-something) | |
| 1869 @result{} do-something | |
| 1870 ;; @r{The frame is now split again.} | |
| 1871 @end group | |
| 1872 @end example | |
| 1873 @end defspec | |
| 1874 | |
| 1875 @defun window-configuration-p object | |
| 1876 This function returns @code{t} if @var{object} is a window configuration. | |
| 1877 @end defun | |
| 1878 | |
| 1879 Primitives to look inside of window configurations would make sense, | |
| 1880 but none are implemented. It is not clear they are useful enough to be | |
| 1881 worth implementing. |