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| date | Mon, 13 Aug 2007 08:45:50 +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 Parameters,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 | |
| 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 The return value is @var{window}. | |
| 440 | |
| 441 @example | |
| 442 @group | |
| 443 (setq w (next-window)) | |
| 444 (select-window w) | |
| 445 @result{} #<window 65 on windows.texi> | |
| 446 @end group | |
| 447 @end example | |
| 448 @end defun | |
| 449 | |
| 450 @defmac save-selected-window forms@dots{} | |
| 451 This macro records the selected window, executes @var{forms} | |
| 452 in sequence, then restores the earlier selected window. | |
| 453 It does not save or restore anything about the sizes, arrangement | |
| 454 or contents of windows; therefore, if the @var{forms} change them, | |
| 455 the changes are permanent. | |
| 456 @end defmac | |
| 457 | |
| 458 @cindex finding windows | |
| 459 The following functions choose one of the windows on the screen, | |
| 460 offering various criteria for the choice. | |
| 461 | |
| 462 @defun get-lru-window &optional frame | |
| 463 This function returns the window least recently ``used'' (that is, | |
| 464 selected). The selected window is always the most recently used window. | |
| 465 | |
| 466 The selected window can be the least recently used window if it is the | |
| 467 only window. A newly created window becomes the least recently used | |
| 468 window until it is selected. A minibuffer window is never a candidate. | |
| 469 | |
| 470 The argument @var{frame} controls which windows are considered. | |
| 471 | |
| 472 @itemize @bullet | |
| 473 @item | |
| 474 If it is @code{nil}, consider windows on the selected frame. | |
| 475 @item | |
| 476 If it is @code{t}, consider windows on all frames. | |
| 477 @item | |
| 478 If it is @code{visible}, consider windows on all visible frames. | |
| 479 @item | |
| 480 If it is 0, consider windows on all visible or iconified frames. | |
| 481 @item | |
| 482 If it is a frame, consider windows on that frame. | |
| 483 @end itemize | |
| 484 @end defun | |
| 485 | |
| 486 @defun get-largest-window &optional frame | |
| 487 This function returns the window with the largest area (height times | |
| 488 width). If there are no side-by-side windows, then this is the window | |
| 489 with the most lines. A minibuffer window is never a candidate. | |
| 490 | |
| 491 If there are two windows of the same size, then the function returns | |
| 492 the window that is first in the cyclic ordering of windows (see | |
| 493 following section), starting from the selected window. | |
| 494 | |
| 495 The argument @var{frame} controls which set of windows are | |
| 496 considered. See @code{get-lru-window}, above. | |
| 497 @end defun | |
| 498 | |
| 499 @node Cyclic Window Ordering | |
| 500 @section Cyclic Ordering of Windows | |
| 501 @cindex cyclic ordering of windows | |
| 502 @cindex ordering of windows, cyclic | |
| 503 @cindex window ordering, cyclic | |
| 504 | |
| 505 When you use the command @kbd{C-x o} (@code{other-window}) to select | |
| 506 the next window, it moves through all the windows on the screen in a | |
| 507 specific cyclic order. For any given configuration of windows, this | |
| 508 order never varies. It is called the @dfn{cyclic ordering of windows}. | |
| 509 | |
| 510 This ordering generally goes from top to bottom, and from left to | |
| 511 right. But it may go down first or go right first, depending on the | |
| 512 order in which the windows were split. | |
| 513 | |
| 514 If the first split was vertical (into windows one above each other), | |
| 515 and then the subwindows were split horizontally, then the ordering is | |
| 516 left to right in the top of the frame, and then left to right in the | |
| 517 next lower part of the frame, and so on. If the first split was | |
| 518 horizontal, the ordering is top to bottom in the left part, and so on. | |
| 519 In general, within each set of siblings at any level in the window tree, | |
| 520 the order is left to right, or top to bottom. | |
| 521 | |
| 522 @defun next-window &optional window minibuf all-frames | |
| 523 @cindex minibuffer window | |
| 524 This function returns the window following @var{window} in the cyclic | |
| 525 ordering of windows. This is the window that @kbd{C-x o} would select | |
| 526 if typed when @var{window} is selected. If @var{window} is the only | |
| 527 window visible, then this function returns @var{window}. If omitted, | |
| 528 @var{window} defaults to the selected window. | |
| 529 | |
| 530 The value of the argument @var{minibuf} determines whether the | |
| 531 minibuffer is included in the window order. Normally, when | |
| 532 @var{minibuf} is @code{nil}, the minibuffer is included if it is | |
| 533 currently active; this is the behavior of @kbd{C-x o}. (The minibuffer | |
| 534 window is active while the minibuffer is in use. @xref{Minibuffers}.) | |
| 535 | |
| 536 If @var{minibuf} is @code{t}, then the cyclic ordering includes the | |
| 537 minibuffer window even if it is not active. | |
| 538 | |
| 539 If @var{minibuf} is neither @code{t} nor @code{nil}, then the minibuffer | |
| 540 window is not included even if it is active. | |
| 541 | |
| 542 The argument @var{all-frames} specifies which frames to consider. Here | |
| 543 are the possible values and their meanings: | |
| 544 | |
| 545 @table @asis | |
| 546 @item @code{nil} | |
| 547 Consider all the windows in @var{window}'s frame, plus the minibuffer | |
| 548 used by that frame even if it lies in some other frame. | |
| 549 | |
| 550 @item @code{t} | |
| 551 Consider all windows in all existing frames. | |
| 552 | |
| 553 @item @code{visible} | |
| 554 Consider all windows in all visible frames. (To get useful results, you | |
| 555 must ensure @var{window} is in a visible frame.) | |
| 556 | |
| 557 @item 0 | |
| 558 Consider all windows in all visible or iconified frames. | |
| 559 | |
| 560 @item anything else | |
| 561 Consider precisely the windows in @var{window}'s frame, and no others. | |
| 562 @end table | |
| 563 | |
| 564 This example assumes there are two windows, both displaying the | |
| 565 buffer @samp{windows.texi}: | |
| 566 | |
| 567 @example | |
| 568 @group | |
| 569 (selected-window) | |
| 570 @result{} #<window 56 on windows.texi> | |
| 571 @end group | |
| 572 @group | |
| 573 (next-window (selected-window)) | |
| 574 @result{} #<window 52 on windows.texi> | |
| 575 @end group | |
| 576 @group | |
| 577 (next-window (next-window (selected-window))) | |
| 578 @result{} #<window 56 on windows.texi> | |
| 579 @end group | |
| 580 @end example | |
| 581 @end defun | |
| 582 | |
| 583 @defun previous-window &optional window minibuf all-frames | |
| 584 This function returns the window preceding @var{window} in the cyclic | |
| 585 ordering of windows. The other arguments specify which windows to | |
| 586 include in the cycle, as in @code{next-window}. | |
| 587 @end defun | |
| 588 | |
| 589 @deffn Command other-window count &optional frame | |
| 590 This function selects the @var{count}th following window in the cyclic | |
| 591 order. If count is negative, then it selects the @minus{}@var{count}th | |
| 592 preceding window. It returns @code{nil}. | |
| 593 | |
| 594 In an interactive call, @var{count} is the numeric prefix argument. | |
| 595 | |
| 596 The argument @var{frame} controls which set of windows are considered. | |
| 597 @itemize @bullet | |
| 598 @item | |
| 599 If it is @code{nil} or omitted, then windows on the selected frame are | |
| 600 considered. | |
| 601 @item | |
| 602 If it is a frame, then windows on that frame are considered. | |
| 603 @item | |
| 604 If it is @code{t}, then windows on all frames that currently exist | |
| 605 (including invisible and iconified frames) are considered. | |
| 606 @item | |
| 607 If it is the symbol @code{visible}, then windows on all visible frames | |
| 608 are considered. | |
| 609 @item | |
| 610 If it is the number 0, then windows on all visible and iconified frames | |
| 611 are considered. | |
| 612 @item | |
| 613 If it is any other value, then the behavior is undefined. | |
| 614 @end itemize | |
| 615 @end deffn | |
| 616 | |
| 617 @c Emacs 19 feature | |
| 618 @defun walk-windows proc &optional minibuf all-frames | |
| 619 This function cycles through all windows, calling @code{proc} | |
| 620 once for each window with the window as its sole argument. | |
| 621 | |
| 622 The optional arguments @var{minibuf} and @var{all-frames} specify the | |
| 623 set of windows to include in the scan. See @code{next-window}, above, | |
| 624 for details. | |
| 625 @end defun | |
| 626 | |
| 627 @node Buffers and Windows | |
| 628 @section Buffers and Windows | |
| 629 @cindex examining windows | |
| 630 @cindex windows, controlling precisely | |
| 631 @cindex buffers, controlled in windows | |
| 632 | |
| 633 This section describes low-level functions to examine windows or to | |
| 634 display buffers in windows in a precisely controlled fashion. | |
| 635 @iftex | |
| 636 See the following section for | |
| 637 @end iftex | |
| 638 @ifinfo | |
| 639 @xref{Displaying Buffers}, for | |
| 640 @end ifinfo | |
| 641 related functions that find a window to use and specify a buffer for it. | |
| 642 The functions described there are easier to use than these, but they | |
| 643 employ heuristics in choosing or creating a window; use these functions | |
| 644 when you need complete control. | |
| 645 | |
| 646 @defun set-window-buffer window buffer-or-name | |
| 647 This function makes @var{window} display @var{buffer-or-name} as its | |
| 648 contents. It returns @code{nil}. | |
| 649 | |
| 650 @example | |
| 651 @group | |
| 652 (set-window-buffer (selected-window) "foo") | |
| 653 @result{} nil | |
| 654 @end group | |
| 655 @end example | |
| 656 @end defun | |
| 657 | |
| 658 @defun window-buffer &optional window | |
| 659 This function returns the buffer that @var{window} is displaying. If | |
| 660 @var{window} is omitted, this function returns the buffer for the | |
| 661 selected window. | |
| 662 | |
| 663 @example | |
| 664 @group | |
| 665 (window-buffer) | |
| 666 @result{} #<buffer windows.texi> | |
| 667 @end group | |
| 668 @end example | |
| 669 @end defun | |
| 670 | |
| 671 @defun get-buffer-window buffer-or-name &optional frame | |
| 672 This function returns a window currently displaying | |
| 673 @var{buffer-or-name}, or @code{nil} if there is none. If there are | |
| 674 several such windows, then the function returns the first one in the | |
| 675 cyclic ordering of windows, starting from the selected window. | |
| 676 @xref{Cyclic Window Ordering}. | |
| 677 | |
| 678 The argument @var{all-frames} controls which windows to consider. | |
| 679 | |
| 680 @itemize @bullet | |
| 681 @item | |
| 682 If it is @code{nil}, consider windows on the selected frame. | |
| 683 @item | |
| 684 If it is @code{t}, consider windows on all frames. | |
| 685 @item | |
| 686 If it is @code{visible}, consider windows on all visible frames. | |
| 687 @item | |
| 688 If it is 0, consider windows on all visible or iconified frames. | |
| 689 @item | |
| 690 If it is a frame, consider windows on that frame. | |
| 691 @end itemize | |
| 692 @end defun | |
| 693 | |
| 694 @node Displaying Buffers | |
| 695 @section Displaying Buffers in Windows | |
| 696 @cindex switching to a buffer | |
| 697 @cindex displaying a buffer | |
| 698 | |
| 699 In this section we describe convenient functions that choose a window | |
| 700 automatically and use it to display a specified buffer. These functions | |
| 701 can also split an existing window in certain circumstances. We also | |
| 702 describe variables that parameterize the heuristics used for choosing a | |
| 703 window. | |
| 704 @iftex | |
| 705 See the preceding section for | |
| 706 @end iftex | |
| 707 @ifinfo | |
| 708 @xref{Buffers and Windows}, for | |
| 709 @end ifinfo | |
| 710 low-level functions that give you more precise control. | |
| 711 | |
| 712 Do not use the functions in this section in order to make a buffer | |
| 713 current so that a Lisp program can access or modify it; they are too | |
| 714 drastic for that purpose, since they change the display of buffers in | |
| 715 windows, which is gratuitous and will surprise the user. Instead, use | |
| 716 @code{set-buffer} (@pxref{Current Buffer}) and @code{save-excursion} | |
| 717 (@pxref{Excursions}), which designate buffers as current for programmed | |
| 718 access without affecting the display of buffers in windows. | |
| 719 | |
| 720 @deffn Command switch-to-buffer buffer-or-name &optional norecord | |
| 721 This function makes @var{buffer-or-name} the current buffer, and also | |
| 722 displays the buffer in the selected window. This means that a human can | |
| 723 see the buffer and subsequent keyboard commands will apply to it. | |
| 724 Contrast this with @code{set-buffer}, which makes @var{buffer-or-name} | |
| 725 the current buffer but does not display it in the selected window. | |
| 726 @xref{Current Buffer}. | |
| 727 | |
| 728 If @var{buffer-or-name} does not identify an existing buffer, then a new | |
| 729 buffer by that name is created. The major mode for the new buffer is | |
| 730 set according to the variable @code{default-major-mode}. @xref{Auto | |
| 731 Major Mode}. | |
| 732 | |
| 733 Normally the specified buffer is put at the front of the buffer list. | |
| 734 This affects the operation of @code{other-buffer}. However, if | |
| 735 @var{norecord} is non-@code{nil}, this is not done. @xref{The Buffer | |
| 736 List}. | |
| 737 | |
| 738 The @code{switch-to-buffer} function is often used interactively, as | |
| 739 the binding of @kbd{C-x b}. It is also used frequently in programs. It | |
| 740 always returns @code{nil}. | |
| 741 @end deffn | |
| 742 | |
| 743 @deffn Command switch-to-buffer-other-window buffer-or-name | |
| 744 This function makes @var{buffer-or-name} the current buffer and | |
| 745 displays it in a window not currently selected. It then selects that | |
| 746 window. The handling of the buffer is the same as in | |
| 747 @code{switch-to-buffer}. | |
| 748 | |
| 749 The currently selected window is absolutely never used to do the job. | |
| 750 If it is the only window, then it is split to make a distinct window for | |
| 751 this purpose. If the selected window is already displaying the buffer, | |
| 752 then it continues to do so, but another window is nonetheless found to | |
| 753 display it in as well. | |
| 754 @end deffn | |
| 755 | |
| 756 @defun pop-to-buffer buffer-or-name &optional other-window on-frame | |
| 757 This function makes @var{buffer-or-name} the current buffer and | |
| 758 switches to it in some window, preferably not the window previously | |
| 759 selected. The ``popped-to'' window becomes the selected window within | |
| 760 its frame. | |
| 761 | |
| 762 If the variable @code{pop-up-frames} is non-@code{nil}, | |
| 763 @code{pop-to-buffer} looks for a window in any visible frame already | |
| 764 displaying the buffer; if there is one, it returns that window and makes | |
| 765 it be selected within its frame. If there is none, it creates a new | |
| 766 frame and displays the buffer in it. | |
| 767 | |
| 768 If @code{pop-up-frames} is @code{nil}, then @code{pop-to-buffer} | |
| 769 operates entirely within the selected frame. (If the selected frame has | |
| 770 just a minibuffer, @code{pop-to-buffer} operates within the most | |
| 771 recently selected frame that was not just a minibuffer.) | |
| 772 | |
| 773 If the variable @code{pop-up-windows} is non-@code{nil}, windows may | |
| 774 be split to create a new window that is different from the original | |
| 775 window. For details, see @ref{Choosing Window}. | |
| 776 | |
| 777 If @var{other-window} is non-@code{nil}, @code{pop-to-buffer} finds or | |
| 778 creates another window even if @var{buffer-or-name} is already visible | |
| 779 in the selected window. Thus @var{buffer-or-name} could end up | |
| 780 displayed in two windows. On the other hand, if @var{buffer-or-name} is | |
| 781 already displayed in the selected window and @var{other-window} is | |
| 782 @code{nil}, then the selected window is considered sufficient display | |
| 783 for @var{buffer-or-name}, so that nothing needs to be done. | |
| 784 | |
| 785 All the variables that affect @code{display-buffer} affect | |
| 786 @code{pop-to-buffer} as well. @xref{Choosing Window}. | |
| 787 | |
| 788 If @var{buffer-or-name} is a string that does not name an existing | |
| 789 buffer, a buffer by that name is created. The major mode for the new | |
| 790 buffer is set according to the variable @code{default-major-mode}. | |
| 791 @xref{Auto Major Mode}. | |
| 792 | |
| 793 If @var{on-frame} is non-@code{nil}, it is the frame to pop to this | |
| 794 buffer on. | |
| 795 | |
| 796 An example use of this function is found at the end of @ref{Filter | |
| 797 Functions}. | |
| 798 @end defun | |
| 799 | |
| 800 @deffn Command replace-buffer-in-windows buffer | |
| 801 This function replaces @var{buffer} with some other buffer in all | |
| 802 windows displaying it. The other buffer used is chosen with | |
| 803 @code{other-buffer}. In the usual applications of this function, you | |
| 804 don't care which other buffer is used; you just want to make sure that | |
| 805 @var{buffer} is no longer displayed. | |
| 806 | |
| 807 This function returns @code{nil}. | |
| 808 @end deffn | |
| 809 | |
| 810 @node Choosing Window | |
| 811 @section Choosing a Window for Display | |
| 812 | |
| 813 This section describes the basic facility that chooses a window to | |
| 814 display a buffer in---@code{display-buffer}. All the higher-level | |
| 815 functions and commands use this subroutine. Here we describe how to use | |
| 816 @code{display-buffer} and how to customize it. | |
| 817 | |
| 818 @deffn Command display-buffer buffer-or-name &optional not-this-window | |
| 819 This command makes @var{buffer-or-name} appear in some window, like | |
| 820 @code{pop-to-buffer}, but it does not select that window and does not | |
| 821 make the buffer current. The identity of the selected window is | |
| 822 unaltered by this function. | |
| 823 | |
| 824 If @var{not-this-window} is non-@code{nil}, it means to display the | |
| 825 specified buffer in a window other than the selected one, even if it is | |
| 826 already on display in the selected window. This can cause the buffer to | |
| 827 appear in two windows at once. Otherwise, if @var{buffer-or-name} is | |
| 828 already being displayed in any window, that is good enough, so this | |
| 829 function does nothing. | |
| 830 | |
| 831 @code{display-buffer} returns the window chosen to display | |
| 832 @var{buffer-or-name}. | |
| 833 | |
| 834 Precisely how @code{display-buffer} finds or creates a window depends on | |
| 835 the variables described below. | |
| 836 @end deffn | |
| 837 | |
| 838 @c Emacs 19 feature | |
| 839 @cindex dedicated window | |
| 840 A window can be marked as ``dedicated'' to a particular buffer. | |
| 841 Then XEmacs will not automatically change which buffer appears in the | |
| 842 window, such as @code{display-buffer} might normally do. | |
| 843 | |
| 844 @defun window-dedicated-p window | |
| 845 This function returns @var{window}'s dedicated object, usually @code{t} | |
| 846 or @code{nil}. | |
| 847 @end defun | |
| 848 | |
| 849 @defun set-window-buffer-dedicated window buffer | |
| 850 This function makes @var{window} display @var{buffer} and be dedicated | |
| 851 to that buffer. Then XEmacs will not automatically change which buffer | |
| 852 appears in @var{window}. If @var{buffer} is @code{nil}, this function makes | |
| 853 @var{window} not be dedicated (but doesn't change which buffer appears | |
| 854 in it currently). | |
| 855 @end defun | |
| 856 | |
| 857 @defopt pop-up-windows | |
| 858 This variable controls whether @code{display-buffer} makes new windows. | |
| 859 If it is non-@code{nil} and there is only one window, then that window | |
| 860 is split. If it is @code{nil}, then @code{display-buffer} does not | |
| 861 split the single window, but uses it whole. | |
| 862 @end defopt | |
| 863 | |
| 864 @defopt split-height-threshold | |
| 865 This variable determines when @code{display-buffer} may split a window, | |
| 866 if there are multiple windows. @code{display-buffer} always splits the | |
| 867 largest window if it has at least this many lines. If the largest | |
| 868 window is not this tall, it is split only if it is the sole window and | |
| 869 @code{pop-up-windows} is non-@code{nil}. | |
| 870 @end defopt | |
| 871 | |
| 872 @c Emacs 19 feature | |
| 873 @defopt pop-up-frames | |
| 874 This variable controls whether @code{display-buffer} makes new frames. | |
| 875 If it is non-@code{nil}, @code{display-buffer} looks for an existing | |
| 876 window already displaying the desired buffer, on any visible frame. If | |
| 877 it finds one, it returns that window. Otherwise it makes a new frame. | |
| 878 The variables @code{pop-up-windows} and @code{split-height-threshold} do | |
| 879 not matter if @code{pop-up-frames} is non-@code{nil}. | |
| 880 | |
| 881 If @code{pop-up-frames} is @code{nil}, then @code{display-buffer} either | |
| 882 splits a window or reuses one. | |
| 883 | |
| 884 @xref{Frames}, for more information. | |
| 885 @end defopt | |
| 886 | |
| 887 @c Emacs 19 feature | |
| 888 @defvar pop-up-frame-function | |
| 889 This variable specifies how to make a new frame if @code{pop-up-frames} | |
| 890 is non-@code{nil}. | |
| 891 | |
| 892 Its value should be a function of no arguments. When | |
| 893 @code{display-buffer} makes a new frame, it does so by calling that | |
| 894 function, which should return a frame. The default value of the | |
| 895 variable is a function that creates a frame using parameters from | |
| 896 @code{pop-up-frame-alist}. | |
| 897 @end defvar | |
| 898 | |
| 899 @defvar pop-up-frame-alist | |
| 900 This variable holds an alist specifying frame parameters used when | |
| 901 @code{display-buffer} makes a new frame. @xref{Frame Parameters}, for | |
| 902 more information about frame parameters. | |
| 903 @end defvar | |
| 904 | |
| 905 @defvar special-display-buffer-names | |
| 906 A list of buffer names for buffers that should be displayed specially. | |
| 907 If the buffer's name is in this list, @code{display-buffer} handles the | |
| 908 buffer specially. | |
| 909 | |
| 910 By default, special display means to give the buffer a dedicated frame. | |
| 911 | |
| 912 If an element is a list, instead of a string, then the @sc{car} of the | |
| 913 list is the buffer name, and the rest of the list says how to create the | |
| 914 frame. There are two possibilities for the rest of the list. It can be | |
| 915 an alist, specifying frame parameters, or it can contain a function and | |
| 916 arguments to give to it. (The function's first argument is always the | |
| 917 buffer to be displayed; the arguments from the list come after that.) | |
| 918 @end defvar | |
| 919 | |
| 920 @defvar special-display-regexps | |
| 921 A list of regular expressions that specify buffers that should be | |
| 922 displayed specially. If the buffer's name matches any of the regular | |
| 923 expressions in this list, @code{display-buffer} handles the buffer | |
| 924 specially. | |
| 925 | |
| 926 By default, special display means to give the buffer a dedicated frame. | |
| 927 | |
| 928 If an element is a list, instead of a string, then the @sc{car} of the | |
| 929 list is the regular expression, and the rest of the list says how to | |
| 930 create the frame. See above, under @code{special-display-buffer-names}. | |
| 931 @end defvar | |
| 932 | |
| 933 @defvar special-display-function | |
| 934 This variable holds the function to call to display a buffer specially. | |
| 935 It receives the buffer as an argument, and should return the window in | |
| 936 which it is displayed. | |
| 937 | |
| 938 The default value of this variable is | |
| 939 @code{special-display-popup-frame}. | |
| 940 @end defvar | |
| 941 | |
| 942 @defun special-display-popup-frame buffer | |
| 943 This function makes @var{buffer} visible in a frame of its own. If | |
| 944 @var{buffer} is already displayed in a window in some frame, it makes | |
| 945 the frame visible and raises it, to use that window. Otherwise, it | |
| 946 creates a frame that will be dedicated to @var{buffer}. | |
| 947 | |
| 948 This function uses an existing window displaying @var{buffer} whether or | |
| 949 not it is in a frame of its own; but if you set up the above variables | |
| 950 in your init file, before @var{buffer} was created, then presumably the | |
| 951 window was previously made by this function. | |
| 952 @end defun | |
| 953 | |
| 954 @defopt special-display-frame-alist | |
| 955 This variable holds frame parameters for | |
| 956 @code{special-display-popup-frame} to use when it creates a frame. | |
| 957 @end defopt | |
| 958 | |
| 959 @defvar same-window-buffer-names | |
| 960 A list of buffer names for buffers that should be displayed in the | |
| 961 selected window. If the buffer's name is in this list, | |
| 962 @code{display-buffer} handles the buffer by switching to it in the | |
| 963 selected window. | |
| 964 @end defvar | |
| 965 | |
| 966 @defvar same-window-regexps | |
| 967 A list of regular expressions that specify buffers that should be | |
| 968 displayed in the selected window. If the buffer's name matches any of | |
| 969 the regular expressions in this list, @code{display-buffer} handles the | |
| 970 buffer by switching to it in the selected window. | |
| 971 @end defvar | |
| 972 | |
| 973 @c Emacs 19 feature | |
| 974 @defvar display-buffer-function | |
| 975 This variable is the most flexible way to customize the behavior of | |
| 976 @code{display-buffer}. If it is non-@code{nil}, it should be a function | |
| 977 that @code{display-buffer} calls to do the work. The function should | |
| 978 accept two arguments, the same two arguments that @code{display-buffer} | |
| 979 received. It should choose or create a window, display the specified | |
| 980 buffer, and then return the window. | |
| 981 | |
| 982 This hook takes precedence over all the other options and hooks | |
| 983 described above. | |
| 984 @end defvar | |
| 985 | |
| 986 @c Emacs 19 feature | |
| 987 @cindex dedicated window | |
| 988 A window can be marked as ``dedicated'' to its buffer. Then | |
| 989 @code{display-buffer} does not try to use that window. | |
| 990 | |
| 991 @defun window-dedicated-p window | |
| 992 This function returns @code{t} if @var{window} is marked as dedicated; | |
| 993 otherwise @code{nil}. | |
| 994 @end defun | |
| 995 | |
| 996 @defun set-window-dedicated-p window flag | |
| 997 This function marks @var{window} as dedicated if @var{flag} is | |
| 998 non-@code{nil}, and nondedicated otherwise. | |
| 999 @end defun | |
| 1000 | |
| 1001 @node Window Point | |
| 1002 @section Windows and Point | |
| 1003 @cindex window position | |
| 1004 @cindex window point | |
| 1005 @cindex position in window | |
| 1006 @cindex point in window | |
| 1007 | |
| 1008 Each window has its own value of point, independent of the value of | |
| 1009 point in other windows displaying the same buffer. This makes it useful | |
| 1010 to have multiple windows showing one buffer. | |
| 1011 | |
| 1012 @itemize @bullet | |
| 1013 @item | |
| 1014 The window point is established when a window is first created; it is | |
| 1015 initialized from the buffer's point, or from the window point of another | |
| 1016 window opened on the buffer if such a window exists. | |
| 1017 | |
| 1018 @item | |
| 1019 Selecting a window sets the value of point in its buffer to the window's | |
| 1020 value of point. Conversely, deselecting a window sets the window's | |
| 1021 value of point from that of the buffer. Thus, when you switch between | |
| 1022 windows that display a given buffer, the point value for the selected | |
| 1023 window is in effect in the buffer, while the point values for the other | |
| 1024 windows are stored in those windows. | |
| 1025 | |
| 1026 @item | |
| 1027 As long as the selected window displays the current buffer, the window's | |
| 1028 point and the buffer's point always move together; they remain equal. | |
| 1029 | |
| 1030 @item | |
| 1031 @xref{Positions}, for more details on buffer positions. | |
| 1032 @end itemize | |
| 1033 | |
| 1034 As far as the user is concerned, point is where the cursor is, and | |
| 1035 when the user switches to another buffer, the cursor jumps to the | |
| 1036 position of point in that buffer. | |
| 1037 | |
| 1038 @defun window-point window | |
| 1039 This function returns the current position of point in @var{window}. | |
| 1040 For a nonselected window, this is the value point would have (in that | |
| 1041 window's buffer) if that window were selected. | |
| 1042 | |
| 1043 When @var{window} is the selected window and its buffer is also the | |
| 1044 current buffer, the value returned is the same as point in that buffer. | |
| 1045 | |
| 1046 Strictly speaking, it would be more correct to return the | |
| 1047 ``top-level'' value of point, outside of any @code{save-excursion} | |
| 1048 forms. But that value is hard to find. | |
| 1049 @end defun | |
| 1050 | |
| 1051 @defun set-window-point window position | |
| 1052 This function positions point in @var{window} at position | |
| 1053 @var{position} in @var{window}'s buffer. | |
| 1054 @end defun | |
| 1055 | |
| 1056 @node Window Start | |
| 1057 @section The Window Start Position | |
| 1058 | |
| 1059 Each window contains a marker used to keep track of a buffer position | |
| 1060 that specifies where in the buffer display should start. This position | |
| 1061 is called the @dfn{display-start} position of the window (or just the | |
| 1062 @dfn{start}). The character after this position is the one that appears | |
| 1063 at the upper left corner of the window. It is usually, but not | |
| 1064 inevitably, at the beginning of a text line. | |
| 1065 | |
| 1066 @defun window-start &optional window | |
| 1067 @cindex window top line | |
| 1068 This function returns the display-start position of window | |
| 1069 @var{window}. If @var{window} is @code{nil}, the selected window is | |
| 1070 used. For example, | |
| 1071 | |
| 1072 @example | |
| 1073 @group | |
| 1074 (window-start) | |
| 1075 @result{} 7058 | |
| 1076 @end group | |
| 1077 @end example | |
| 1078 | |
| 1079 When you create a window, or display a different buffer in it, the | |
| 1080 display-start position is set to a display-start position recently used | |
| 1081 for the same buffer, or 1 if the buffer doesn't have any. | |
| 1082 | |
| 1083 For a realistic example, see the description of @code{count-lines} in | |
| 1084 @ref{Text Lines}. | |
| 1085 @end defun | |
| 1086 | |
| 1087 @defun window-end &optional window | |
| 1088 This function returns the position of the end of the display in window | |
| 1089 @var{window}. If @var{window} is @code{nil}, the selected window is | |
| 1090 used. | |
| 1091 | |
| 1092 Simply changing the buffer text or moving point does not update the | |
| 1093 value that @code{window-end} returns. The value is updated only when | |
| 1094 Emacs redisplays and redisplay actually finishes. | |
| 1095 | |
| 1096 If the last redisplay of @var{window} was preempted, and did not finish, | |
| 1097 Emacs does not know the position of the end of display in that window. | |
| 1098 In that case, this function returns a value that is not correct. In a | |
| 1099 future version, @code{window-end} will return @code{nil} in that case. | |
| 1100 @ignore | |
| 1101 in that case, this function returns @code{nil}. You can compute where | |
| 1102 the end of the window @emph{would} have been, if redisplay had finished, | |
| 1103 like this: | |
| 1104 | |
| 1105 @example | |
| 1106 (save-excursion | |
| 1107 (goto-char (window-start window)) | |
| 1108 (vertical-motion (1- (window-height window)) | |
| 1109 window) | |
| 1110 (point)) | |
| 1111 @end example | |
| 1112 @end ignore | |
| 1113 @end defun | |
| 1114 | |
| 1115 @defun set-window-start window position &optional noforce | |
| 1116 This function sets the display-start position of @var{window} to | |
| 1117 @var{position} in @var{window}'s buffer. It returns @var{position}. | |
| 1118 | |
| 1119 The display routines insist that the position of point be visible when a | |
| 1120 buffer is displayed. Normally, they change the display-start position | |
| 1121 (that is, scroll the window) whenever necessary to make point visible. | |
| 1122 However, if you specify the start position with this function using | |
| 1123 @code{nil} for @var{noforce}, it means you want display to start at | |
| 1124 @var{position} even if that would put the location of point off the | |
| 1125 screen. If this does place point off screen, the display routines move | |
| 1126 point to the left margin on the middle line in the window. | |
| 1127 | |
| 1128 For example, if point @w{is 1} and you set the start of the window @w{to | |
| 1129 2}, then point would be ``above'' the top of the window. The display | |
| 1130 routines will automatically move point if it is still 1 when redisplay | |
| 1131 occurs. Here is an example: | |
| 1132 | |
| 1133 @example | |
| 1134 @group | |
| 1135 ;; @r{Here is what @samp{foo} looks like before executing} | |
| 1136 ;; @r{the @code{set-window-start} expression.} | |
| 1137 @end group | |
| 1138 | |
| 1139 @group | |
| 1140 ---------- Buffer: foo ---------- | |
| 1141 @point{}This is the contents of buffer foo. | |
| 1142 2 | |
| 1143 3 | |
| 1144 4 | |
| 1145 5 | |
| 1146 6 | |
| 1147 ---------- Buffer: foo ---------- | |
| 1148 @end group | |
| 1149 | |
| 1150 @group | |
| 1151 (set-window-start | |
| 1152 (selected-window) | |
| 1153 (1+ (window-start))) | |
| 1154 @result{} 2 | |
| 1155 @end group | |
| 1156 | |
| 1157 @group | |
| 1158 ;; @r{Here is what @samp{foo} looks like after executing} | |
| 1159 ;; @r{the @code{set-window-start} expression.} | |
| 1160 ---------- Buffer: foo ---------- | |
| 1161 his is the contents of buffer foo. | |
| 1162 2 | |
| 1163 3 | |
| 1164 @point{}4 | |
| 1165 5 | |
| 1166 6 | |
| 1167 ---------- Buffer: foo ---------- | |
| 1168 @end group | |
| 1169 @end example | |
| 1170 | |
| 1171 If @var{noforce} is non-@code{nil}, and @var{position} would place point | |
| 1172 off screen at the next redisplay, then redisplay computes a new window-start | |
| 1173 position that works well with point, and thus @var{position} is not used. | |
| 1174 @end defun | |
| 1175 | |
| 1176 @defun pos-visible-in-window-p &optional position window | |
| 1177 This function returns @code{t} if @var{position} is within the range | |
| 1178 of text currently visible on the screen in @var{window}. It returns | |
| 1179 @code{nil} if @var{position} is scrolled vertically out of view. The | |
| 1180 argument @var{position} defaults to the current position of point; | |
| 1181 @var{window}, to the selected window. Here is an example: | |
| 1182 | |
| 1183 @example | |
| 1184 @group | |
| 1185 (or (pos-visible-in-window-p | |
| 1186 (point) (selected-window)) | |
| 1187 (recenter 0)) | |
| 1188 @end group | |
| 1189 @end example | |
| 1190 | |
| 1191 The @code{pos-visible-in-window-p} function considers only vertical | |
| 1192 scrolling. If @var{position} is out of view only because @var{window} | |
| 1193 has been scrolled horizontally, @code{pos-visible-in-window-p} returns | |
| 1194 @code{t}. @xref{Horizontal Scrolling}. | |
| 1195 @end defun | |
| 1196 | |
| 1197 @node Vertical Scrolling | |
| 1198 @section Vertical Scrolling | |
| 1199 @cindex vertical scrolling | |
| 1200 @cindex scrolling vertically | |
| 1201 | |
| 1202 Vertical scrolling means moving the text up or down in a window. It | |
| 1203 works by changing the value of the window's display-start location. It | |
| 1204 may also change the value of @code{window-point} to keep it on the | |
| 1205 screen. | |
| 1206 | |
| 1207 In the commands @code{scroll-up} and @code{scroll-down}, the directions | |
| 1208 ``up'' and ``down'' refer to the motion of the text in the buffer at which | |
| 1209 you are looking through the window. Imagine that the text is | |
| 1210 written on a long roll of paper and that the scrolling commands move the | |
| 1211 paper up and down. Thus, if you are looking at text in the middle of a | |
| 1212 buffer and repeatedly call @code{scroll-down}, you will eventually see | |
| 1213 the beginning of the buffer. | |
| 1214 | |
| 1215 Some people have urged that the opposite convention be used: they | |
| 1216 imagine that the window moves over text that remains in place. Then | |
| 1217 ``down'' commands would take you to the end of the buffer. This view is | |
| 1218 more consistent with the actual relationship between windows and the | |
| 1219 text in the buffer, but it is less like what the user sees. The | |
| 1220 position of a window on the terminal does not move, and short scrolling | |
| 1221 commands clearly move the text up or down on the screen. We have chosen | |
| 1222 names that fit the user's point of view. | |
| 1223 | |
| 1224 The scrolling functions (aside from @code{scroll-other-window}) have | |
| 1225 unpredictable results if the current buffer is different from the buffer | |
| 1226 that is displayed in the selected window. @xref{Current Buffer}. | |
| 1227 | |
| 1228 @deffn Command scroll-up &optional count | |
| 1229 This function scrolls the text in the selected window upward | |
| 1230 @var{count} lines. If @var{count} is negative, scrolling is actually | |
| 1231 downward. | |
| 1232 | |
| 1233 If @var{count} is @code{nil} (or omitted), then the length of scroll | |
| 1234 is @code{next-screen-context-lines} lines less than the usable height of | |
| 1235 the window (not counting its modeline). | |
| 1236 | |
| 1237 @code{scroll-up} returns @code{nil}. | |
| 1238 @end deffn | |
| 1239 | |
| 1240 @deffn Command scroll-down &optional count | |
| 1241 This function scrolls the text in the selected window downward | |
| 1242 @var{count} lines. If @var{count} is negative, scrolling is actually | |
| 1243 upward. | |
| 1244 | |
| 1245 If @var{count} is omitted or @code{nil}, then the length of the scroll | |
| 1246 is @code{next-screen-context-lines} lines less than the usable height of | |
| 1247 the window (not counting its mode line). | |
| 1248 | |
| 1249 @code{scroll-down} returns @code{nil}. | |
| 1250 @end deffn | |
| 1251 | |
| 1252 @deffn Command scroll-other-window &optional count | |
| 1253 This function scrolls the text in another window upward @var{count} | |
| 1254 lines. Negative values of @var{count}, or @code{nil}, are handled | |
| 1255 as in @code{scroll-up}. | |
| 1256 | |
| 1257 You can specify a buffer to scroll with the variable | |
| 1258 @code{other-window-scroll-buffer}. When the selected window is the | |
| 1259 minibuffer, the next window is normally the one at the top left corner. | |
| 1260 You can specify a different window to scroll with the variable | |
| 1261 @code{minibuffer-scroll-window}. This variable has no effect when any | |
| 1262 other window is selected. @xref{Minibuffer Misc}. | |
| 1263 | |
| 1264 When the minibuffer is active, it is the next window if the selected | |
| 1265 window is the one at the bottom right corner. In this case, | |
| 1266 @code{scroll-other-window} attempts to scroll the minibuffer. If the | |
| 1267 minibuffer contains just one line, it has nowhere to scroll to, so the | |
| 1268 line reappears after the echo area momentarily displays the message | |
| 1269 ``Beginning of buffer''. | |
| 1270 @end deffn | |
| 1271 | |
| 1272 @c Emacs 19 feature | |
| 1273 @defvar other-window-scroll-buffer | |
| 1274 If this variable is non-@code{nil}, it tells @code{scroll-other-window} | |
| 1275 which buffer to scroll. | |
| 1276 @end defvar | |
| 1277 | |
| 1278 @defopt scroll-step | |
| 1279 This variable controls how scrolling is done automatically when point | |
| 1280 moves off the screen. If the value is zero, then redisplay scrolls the | |
| 1281 text to center point vertically in the window. If the value is a | |
| 1282 positive integer @var{n}, then redisplay brings point back on screen by | |
| 1283 scrolling @var{n} lines in either direction, if possible; otherwise, it | |
| 1284 centers point. The default value is zero. | |
| 1285 @end defopt | |
| 1286 | |
| 1287 @defopt next-screen-context-lines | |
| 1288 The value of this variable is the number of lines of continuity to | |
| 1289 retain when scrolling by full screens. For example, @code{scroll-up} | |
| 1290 with an argument of @code{nil} scrolls so that this many lines at the | |
| 1291 bottom of the window appear instead at the top. The default value is | |
| 1292 @code{2}. | |
| 1293 @end defopt | |
| 1294 | |
| 1295 @deffn Command recenter &optional count | |
| 1296 @cindex centering point | |
| 1297 This function scrolls the selected window to put the text where point | |
| 1298 is located at a specified vertical position within the window. | |
| 1299 | |
| 1300 If @var{count} is a nonnegative number, it puts the line containing | |
| 1301 point @var{count} lines down from the top of the window. If @var{count} | |
| 1302 is a negative number, then it counts upward from the bottom of the | |
| 1303 window, so that @minus{}1 stands for the last usable line in the window. | |
| 1304 If @var{count} is a non-@code{nil} list, then it stands for the line in | |
| 1305 the middle of the window. | |
| 1306 | |
| 1307 If @var{count} is @code{nil}, @code{recenter} puts the line containing | |
| 1308 point in the middle of the window, then clears and redisplays the entire | |
| 1309 selected frame. | |
| 1310 | |
| 1311 When @code{recenter} is called interactively, @var{count} is the raw | |
| 1312 prefix argument. Thus, typing @kbd{C-u} as the prefix sets the | |
| 1313 @var{count} to a non-@code{nil} list, while typing @kbd{C-u 4} sets | |
| 1314 @var{count} to 4, which positions the current line four lines from the | |
| 1315 top. | |
| 1316 | |
| 1317 With an argument of zero, @code{recenter} positions the current line at | |
| 1318 the top of the window. This action is so handy that some people make a | |
| 1319 separate key binding to do this. For example, | |
| 1320 | |
| 1321 @example | |
| 1322 @group | |
| 1323 (defun line-to-top-of-window () | |
| 1324 "Scroll current line to top of window. | |
| 1325 Replaces three keystroke sequence C-u 0 C-l." | |
| 1326 (interactive) | |
| 1327 (recenter 0)) | |
| 1328 | |
| 1329 (global-set-key [kp-multiply] 'line-to-top-of-window) | |
| 1330 @end group | |
| 1331 @end example | |
| 1332 @end deffn | |
| 1333 | |
| 1334 @node Horizontal Scrolling | |
| 1335 @section Horizontal Scrolling | |
| 1336 @cindex horizontal scrolling | |
| 1337 | |
| 1338 Because we read English first from top to bottom and second from left | |
| 1339 to right, horizontal scrolling is not like vertical scrolling. Vertical | |
| 1340 scrolling involves selection of a contiguous portion of text to display. | |
| 1341 Horizontal scrolling causes part of each line to go off screen. The | |
| 1342 amount of horizontal scrolling is therefore specified as a number of | |
| 1343 columns rather than as a position in the buffer. It has nothing to do | |
| 1344 with the display-start position returned by @code{window-start}. | |
| 1345 | |
| 1346 Usually, no horizontal scrolling is in effect; then the leftmost | |
| 1347 column is at the left edge of the window. In this state, scrolling to | |
| 1348 the right is meaningless, since there is no data to the left of the | |
| 1349 screen to be revealed by it; so this is not allowed. Scrolling to the | |
| 1350 left is allowed; it scrolls the first columns of text off the edge of | |
| 1351 the window and can reveal additional columns on the right that were | |
| 1352 truncated before. Once a window has a nonzero amount of leftward | |
| 1353 horizontal scrolling, you can scroll it back to the right, but only so | |
| 1354 far as to reduce the net horizontal scroll to zero. There is no limit | |
| 1355 to how far left you can scroll, but eventually all the text will | |
| 1356 disappear off the left edge. | |
| 1357 | |
| 1358 @deffn Command scroll-left count | |
| 1359 This function scrolls the selected window @var{count} columns to the | |
| 1360 left (or to the right if @var{count} is negative). The return value is | |
| 1361 the total amount of leftward horizontal scrolling in effect after the | |
| 1362 change---just like the value returned by @code{window-hscroll} (below). | |
| 1363 @end deffn | |
| 1364 | |
| 1365 @deffn Command scroll-right count | |
| 1366 This function scrolls the selected window @var{count} columns to the | |
| 1367 right (or to the left if @var{count} is negative). The return value is | |
| 1368 the total amount of leftward horizontal scrolling in effect after the | |
| 1369 change---just like the value returned by @code{window-hscroll} (below). | |
| 1370 | |
| 1371 Once you scroll a window as far right as it can go, back to its normal | |
| 1372 position where the total leftward scrolling is zero, attempts to scroll | |
| 1373 any farther right have no effect. | |
| 1374 @end deffn | |
| 1375 | |
| 1376 @defun window-hscroll &optional window | |
| 1377 This function returns the total leftward horizontal scrolling of | |
| 1378 @var{window}---the number of columns by which the text in @var{window} | |
| 1379 is scrolled left past the left margin. | |
| 1380 | |
| 1381 The value is never negative. It is zero when no horizontal scrolling | |
| 1382 has been done in @var{window} (which is usually the case). | |
| 1383 | |
| 1384 If @var{window} is @code{nil}, the selected window is used. | |
| 1385 | |
| 1386 @example | |
| 1387 @group | |
| 1388 (window-hscroll) | |
| 1389 @result{} 0 | |
| 1390 @end group | |
| 1391 @group | |
| 1392 (scroll-left 5) | |
| 1393 @result{} 5 | |
| 1394 @end group | |
| 1395 @group | |
| 1396 (window-hscroll) | |
| 1397 @result{} 5 | |
| 1398 @end group | |
| 1399 @end example | |
| 1400 @end defun | |
| 1401 | |
| 1402 @defun set-window-hscroll window columns | |
| 1403 This function sets the number of columns from the left margin that | |
| 1404 @var{window} is scrolled to the value of @var{columns}. The argument | |
| 1405 @var{columns} should be zero or positive; if not, it is taken as zero. | |
| 1406 | |
| 1407 The value returned is @var{columns}. | |
| 1408 | |
| 1409 @example | |
| 1410 @group | |
| 1411 (set-window-hscroll (selected-window) 10) | |
| 1412 @result{} 10 | |
| 1413 @end group | |
| 1414 @end example | |
| 1415 @end defun | |
| 1416 | |
| 1417 Here is how you can determine whether a given position @var{position} | |
| 1418 is off the screen due to horizontal scrolling: | |
| 1419 | |
| 1420 @example | |
| 1421 @group | |
| 1422 (defun hscroll-on-screen (window position) | |
| 1423 (save-excursion | |
| 1424 (goto-char position) | |
| 1425 (and | |
| 1426 (>= (- (current-column) (window-hscroll window)) 0) | |
| 1427 (< (- (current-column) (window-hscroll window)) | |
| 1428 (window-width window))))) | |
| 1429 @end group | |
| 1430 @end example | |
| 1431 @node Size of Window | |
| 1432 @section The Size of a Window | |
| 1433 @cindex window size | |
| 1434 @cindex size of window | |
| 1435 | |
| 1436 An Emacs window is rectangular, and its size information consists of | |
| 1437 the height (in lines or pixels) and the width (in character positions | |
| 1438 or pixels). The modeline is included in the height. The pixel | |
| 1439 width and height values include scrollbars and margins, while the | |
| 1440 line/character-position values do not. | |
| 1441 | |
| 1442 Note that the height in lines, and the width in characters, are | |
| 1443 determined by dividing the corresponding pixel value by the height or | |
| 1444 width of the default font in that window (if this is a variable-width | |
| 1445 font, the average width is used). The resulting values may or may not | |
| 1446 represent the actual number of lines in the window, or the actual number | |
| 1447 of character positions in any particular line, esp. if there are pixmaps | |
| 1448 or various different fonts in the window. | |
| 1449 | |
| 1450 The following functions return size information about a window: | |
| 1451 | |
| 1452 @defun window-height &optional window | |
| 1453 This function returns the number of lines in @var{window}, including | |
| 1454 its modeline but not including the horizontal scrollbar, if any (this | |
| 1455 is different from @code{window-pixel-height}). If @var{window} is | |
| 1456 @code{nil}, the function uses the selected window. | |
| 1457 | |
| 1458 @example | |
| 1459 @group | |
| 1460 (window-height) | |
| 1461 @result{} 40 | |
| 1462 @end group | |
| 1463 @group | |
| 1464 (split-window-vertically) | |
| 1465 @result{} #<window on "windows.texi" 0x679b> | |
| 1466 @end group | |
| 1467 @group | |
| 1468 (window-height) | |
| 1469 @result{} 20 | |
| 1470 @end group | |
| 1471 @end example | |
| 1472 @end defun | |
| 1473 | |
| 1474 @defun window-width &optional window | |
| 1475 This function returns the number of columns in @var{window}, not | |
| 1476 including any left margin, right margin, or vertical scrollbar (this is | |
| 1477 different from @code{window-pixel-width}). If @var{window} is | |
| 1478 @code{nil}, the function uses the selected window. | |
| 1479 | |
| 1480 @example | |
| 1481 @group | |
| 1482 (window-width) | |
| 1483 @result{} 80 | |
| 1484 @end group | |
| 1485 @group | |
| 1486 (window-height) | |
| 1487 @result{} 40 | |
| 1488 @end group | |
| 1489 @group | |
| 1490 (split-window-horizontally) | |
| 1491 @result{} #<window on "windows.texi" 0x7538> | |
| 1492 @end group | |
| 1493 @group | |
| 1494 (window-width) | |
| 1495 @result{} 39 | |
| 1496 @end group | |
| 1497 @end example | |
| 1498 @end defun | |
| 1499 | |
| 1500 Note that after splitting the window into two side-by-side windows, | |
| 1501 the width of each window is less the half the width of the original | |
| 1502 window because a vertical scrollbar appeared between the windows, | |
| 1503 occupying two columns worth of space. Also, the height shrunk by | |
| 1504 one because horizontal scrollbars appeared that weren't there | |
| 1505 before. (Horizontal scrollbars appear only when lines are | |
| 1506 truncated, not when they wrap. This is usually the case for | |
| 1507 horizontally split windows but not for full-frame windows. You | |
| 1508 can change this using the variables @code{truncate-lines} and | |
| 1509 @code{truncate-partial-width-windows}.) | |
| 1510 | |
| 1511 @defun window-pixel-height &optional window | |
| 1512 This function returns the height of @var{window} in pixels, including | |
| 1513 its modeline and horizontal scrollbar, if any. If @var{window} is | |
| 1514 @code{nil}, the function uses the selected window. | |
| 1515 | |
| 1516 @example | |
| 1517 @group | |
| 1518 (window-pixel-height) | |
| 1519 @result{} 600 | |
| 1520 @end group | |
| 1521 @group | |
| 1522 (split-window-vertically) | |
| 1523 @result{} #<window on "windows.texi" 0x68a6> | |
| 1524 @end group | |
| 1525 @group | |
| 1526 (window-pixel-height) | |
| 1527 @result{} 300 | |
| 1528 @end group | |
| 1529 @end example | |
| 1530 @end defun | |
| 1531 | |
| 1532 @defun window-pixel-width &optional window | |
| 1533 This function returns the width of @var{window} in pixels, including | |
| 1534 any left margin, right margin, or vertical scrollbar that may be | |
| 1535 displayed alongside it. If @var{window} is @code{nil}, the function | |
| 1536 uses the selected window. | |
| 1537 | |
| 1538 @example | |
| 1539 @group | |
| 1540 (window-pixel-width) | |
| 1541 @result{} 735 | |
| 1542 @end group | |
| 1543 @group | |
| 1544 (window-pixel-height) | |
| 1545 @result{} 600 | |
| 1546 @end group | |
| 1547 @group | |
| 1548 (split-window-horizontally) | |
| 1549 @result{} #<window on "windows.texi" 0x7538> | |
| 1550 @end group | |
| 1551 @group | |
| 1552 (window-pixel-width) | |
| 1553 @result{} 367 | |
| 1554 @end group | |
| 1555 @group | |
| 1556 (window-pixel-height) | |
| 1557 @result{} 600 | |
| 1558 @end group | |
| 1559 @end example | |
| 1560 @end defun | |
| 1561 | |
| 1562 @node Position of Window | |
| 1563 @section The Position of a Window | |
| 1564 @cindex window position | |
| 1565 @cindex position of window | |
| 1566 | |
| 1567 XEmacs provides functions to determine the absolute location of windows | |
| 1568 within a frame, and the relative location of a window in comparison to | |
| 1569 other windows in the same frame. | |
| 1570 | |
| 1571 @defun window-pixel-edges &optional window | |
| 1572 This function returns a list of the pixel edge coordinates of | |
| 1573 @var{window}. If @var{window} is @code{nil}, the selected window is | |
| 1574 used. | |
| 1575 | |
| 1576 The order of the list is @code{(@var{left} @var{top} @var{right} | |
| 1577 @var{bottom})}, all elements relative to 0, 0 at the top left corner of | |
| 1578 the frame. The element @var{right} of the value is one more than the | |
| 1579 rightmost pixel used by @var{window} (including any left margin, right | |
| 1580 margin, or vertical scrollbar displayed alongside it), and | |
| 1581 @var{bottom} is one more than the bottommost pixel used by @var{window} | |
| 1582 (including any modeline or horizontal scrollbar displayed above | |
| 1583 or below it). The frame area does not include any frame menubars or | |
| 1584 toolbars that may be displayed; thus, for example, if there is only | |
| 1585 one window on the frame, the values for @var{left} and @var{top} will | |
| 1586 always be 0. | |
| 1587 | |
| 1588 If @var{window} is at the upper left corner of its frame, @var{right} | |
| 1589 and @var{bottom} are the same as the values returned by | |
| 1590 @code{(window-pixel-width)} and @code{(window-pixel-height)} | |
| 1591 respectively, and @var{top} and @var{bottom} are zero. | |
| 1592 @end defun | |
| 1593 | |
| 1594 There is no longer a function @code{window-edges} because it does not | |
| 1595 make sense in a world with variable-width and variable-height lines, | |
| 1596 as are allowed in XEmacs. | |
| 1597 | |
| 1598 @defun window-highest-p window | |
| 1599 This function returns non-@code{nil} if @var{window} is along the | |
| 1600 top of its frame. | |
| 1601 @end defun | |
| 1602 | |
| 1603 @defun window-lowest-p window | |
| 1604 This function returns non-@code{nil} if @var{window} is along the | |
| 1605 bottom of its frame. | |
| 1606 @end defun | |
| 1607 | |
| 1608 @node Resizing Windows | |
| 1609 @section Changing the Size of a Window | |
| 1610 @cindex window resizing | |
| 1611 @cindex changing window size | |
| 1612 @cindex window size, changing | |
| 1613 | |
| 1614 The window size functions fall into two classes: high-level commands | |
| 1615 that change the size of windows and low-level functions that access | |
| 1616 window size. XEmacs does not permit overlapping windows or gaps between | |
| 1617 windows, so resizing one window affects other windows. | |
| 1618 | |
| 1619 @deffn Command enlarge-window size &optional horizontal | |
| 1620 This function makes the selected window @var{size} lines taller, | |
| 1621 stealing lines from neighboring windows. It takes the lines from one | |
| 1622 window at a time until that window is used up, then takes from another. | |
| 1623 If a window from which lines are stolen shrinks below | |
| 1624 @code{window-min-height} lines, that window disappears. | |
| 1625 | |
| 1626 If @var{horizontal} is non-@code{nil}, this function makes | |
| 1627 @var{window} wider by @var{size} columns, stealing columns instead of | |
| 1628 lines. If a window from which columns are stolen shrinks below | |
| 1629 @code{window-min-width} columns, that window disappears. | |
| 1630 | |
| 1631 If the requested size would exceed that of the window's frame, then the | |
| 1632 function makes the window occupy the entire height (or width) of the | |
| 1633 frame. | |
| 1634 | |
| 1635 If @var{size} is negative, this function shrinks the window by | |
| 1636 @minus{}@var{size} lines or columns. If that makes the window smaller | |
| 1637 than the minimum size (@code{window-min-height} and | |
| 1638 @code{window-min-width}), @code{enlarge-window} deletes the window. | |
| 1639 | |
| 1640 @code{enlarge-window} returns @code{nil}. | |
| 1641 @end deffn | |
| 1642 | |
| 1643 @deffn Command enlarge-window-horizontally columns | |
| 1644 This function makes the selected window @var{columns} wider. | |
| 1645 It could be defined as follows: | |
| 1646 | |
| 1647 @example | |
| 1648 @group | |
| 1649 (defun enlarge-window-horizontally (columns) | |
| 1650 (enlarge-window columns t)) | |
| 1651 @end group | |
| 1652 @end example | |
| 1653 @end deffn | |
| 1654 | |
| 1655 @deffn Command shrink-window size &optional horizontal | |
| 1656 This function is like @code{enlarge-window} but negates the argument | |
| 1657 @var{size}, making the selected window smaller by giving lines (or | |
| 1658 columns) to the other windows. If the window shrinks below | |
| 1659 @code{window-min-height} or @code{window-min-width}, then it disappears. | |
| 1660 | |
| 1661 If @var{size} is negative, the window is enlarged by @minus{}@var{size} | |
| 1662 lines or columns. | |
| 1663 @end deffn | |
| 1664 | |
| 1665 @deffn Command shrink-window-horizontally columns | |
| 1666 This function makes the selected window @var{columns} narrower. | |
| 1667 It could be defined as follows: | |
| 1668 | |
| 1669 @example | |
| 1670 @group | |
| 1671 (defun shrink-window-horizontally (columns) | |
| 1672 (shrink-window columns t)) | |
| 1673 @end group | |
| 1674 @end example | |
| 1675 @end deffn | |
| 1676 | |
| 1677 @cindex minimum window size | |
| 1678 The following two variables constrain the window-size-changing | |
| 1679 functions to a minimum height and width. | |
| 1680 | |
| 1681 @defopt window-min-height | |
| 1682 The value of this variable determines how short a window may become | |
| 1683 before it is automatically deleted. Making a window smaller than | |
| 1684 @code{window-min-height} automatically deletes it, and no window may be | |
| 1685 created shorter than this. The absolute minimum height is two (allowing | |
| 1686 one line for the mode line, and one line for the buffer display). | |
| 1687 Actions that change window sizes reset this variable to two if it is | |
| 1688 less than two. The default value is 4. | |
| 1689 @end defopt | |
| 1690 | |
| 1691 @defopt window-min-width | |
| 1692 The value of this variable determines how narrow a window may become | |
| 1693 before it automatically deleted. Making a window smaller than | |
| 1694 @code{window-min-width} automatically deletes it, and no window may be | |
| 1695 created narrower than this. The absolute minimum width is one; any | |
| 1696 value below that is ignored. The default value is 10. | |
| 1697 @end defopt | |
| 1698 | |
| 1699 @defvar window-size-change-functions | |
| 1700 This variable holds a list of functions to be called if the size of any | |
| 1701 window changes for any reason. The functions are called just once per | |
| 1702 redisplay, and just once for each frame on which size changes have | |
| 1703 occurred. | |
| 1704 | |
| 1705 Each function receives the frame as its sole argument. There is no | |
| 1706 direct way to find out which windows changed size, or precisely how; | |
| 1707 however, if your size-change function keeps track, after each change, of | |
| 1708 the windows that interest you, you can figure out what has changed by | |
| 1709 comparing the old size data with the new. | |
| 1710 | |
| 1711 Creating or deleting windows counts as a size change, and therefore | |
| 1712 causes these functions to be called. Changing the frame size also | |
| 1713 counts, because it changes the sizes of the existing windows. | |
| 1714 | |
| 1715 It is not a good idea to use @code{save-window-excursion} in these | |
| 1716 functions, because that always counts as a size change, and it would | |
| 1717 cause these functions to be called over and over. In most cases, | |
| 1718 @code{save-selected-window} is what you need here. | |
| 1719 @end defvar | |
| 1720 | |
| 1721 @node Window Configurations | |
| 1722 @section Window Configurations | |
| 1723 @cindex window configurations | |
| 1724 @cindex saving window information | |
| 1725 | |
| 1726 A @dfn{window configuration} records the entire layout of a | |
| 1727 frame---all windows, their sizes, which buffers they contain, what part | |
| 1728 of each buffer is displayed, and the values of point and the mark. You | |
| 1729 can bring back an entire previous layout by restoring a window | |
| 1730 configuration previously saved. | |
| 1731 | |
| 1732 If you want to record all frames instead of just one, use a frame | |
| 1733 configuration instead of a window configuration. @xref{Frame | |
| 1734 Configurations}. | |
| 1735 | |
| 1736 @defun current-window-configuration | |
| 1737 This function returns a new object representing XEmacs's current window | |
| 1738 configuration, namely the number of windows, their sizes and current | |
| 1739 buffers, which window is the selected window, and for each window the | |
| 1740 displayed buffer, the display-start position, and the positions of point | |
| 1741 and the mark. An exception is made for point in the current buffer, | |
| 1742 whose value is not saved. | |
| 1743 @end defun | |
| 1744 | |
| 1745 @defun set-window-configuration configuration | |
| 1746 This function restores the configuration of XEmacs's windows and | |
| 1747 buffers to the state specified by @var{configuration}. The argument | |
| 1748 @var{configuration} must be a value that was previously returned by | |
| 1749 @code{current-window-configuration}. | |
| 1750 | |
| 1751 This function always counts as a window size change and triggers | |
| 1752 execution of the @code{window-size-change-functions}. (It doesn't know | |
| 1753 how to tell whether the new configuration actually differs from the old | |
| 1754 one.) | |
| 1755 | |
| 1756 Here is a way of using this function to get the same effect | |
| 1757 as @code{save-window-excursion}: | |
| 1758 | |
| 1759 @example | |
| 1760 @group | |
| 1761 (let ((config (current-window-configuration))) | |
| 1762 (unwind-protect | |
| 1763 (progn (split-window-vertically nil) | |
| 1764 @dots{}) | |
| 1765 (set-window-configuration config))) | |
| 1766 @end group | |
| 1767 @end example | |
| 1768 @end defun | |
| 1769 | |
| 1770 @defspec save-window-excursion forms@dots{} | |
| 1771 This special form records the window configuration, executes @var{forms} | |
| 1772 in sequence, then restores the earlier window configuration. The window | |
| 1773 configuration includes the value of point and the portion of the buffer | |
| 1774 that is visible. It also includes the choice of selected window. | |
| 1775 However, it does not include the value of point in the current buffer; | |
| 1776 use @code{save-excursion} if you wish to preserve that. | |
| 1777 | |
| 1778 Don't use this construct when @code{save-selected-window} is all you need. | |
| 1779 | |
| 1780 Exit from @code{save-window-excursion} always triggers execution of the | |
| 1781 @code{window-size-change-functions}. (It doesn't know how to tell | |
| 1782 whether the restored configuration actually differs from the one in | |
| 1783 effect at the end of the @var{forms}.) | |
| 1784 | |
| 1785 The return value is the value of the final form in @var{forms}. | |
| 1786 For example: | |
| 1787 | |
| 1788 @example | |
| 1789 @group | |
| 1790 (split-window) | |
| 1791 @result{} #<window 25 on control.texi> | |
| 1792 @end group | |
| 1793 @group | |
| 1794 (setq w (selected-window)) | |
| 1795 @result{} #<window 19 on control.texi> | |
| 1796 @end group | |
| 1797 @group | |
| 1798 (save-window-excursion | |
| 1799 (delete-other-windows w) | |
| 1800 (switch-to-buffer "foo") | |
| 1801 'do-something) | |
| 1802 @result{} do-something | |
| 1803 ;; @r{The frame is now split again.} | |
| 1804 @end group | |
| 1805 @end example | |
| 1806 @end defspec | |
| 1807 | |
| 1808 @defun window-configuration-p object | |
| 1809 This function returns @code{t} if @var{object} is a window configuration. | |
| 1810 @end defun | |
| 1811 | |
| 1812 Primitives to look inside of window configurations would make sense, | |
| 1813 but none are implemented. It is not clear they are useful enough to be | |
| 1814 worth implementing. |