2 @c This is part of the GNU Emacs Lisp Reference Manual.
3 @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2001,
4 @c 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
5 @c See the file elisp.texi for copying conditions.
6 @setfilename ../../info/frames
7 @node Frames, Positions, Windows, Top
11 A @dfn{frame} is a screen object that contains one or more Emacs
12 windows (@pxref{Windows}). It is the kind of object called a
13 ``window'' in the terminology of graphical environments; but we can't
14 call it a ``window'' here, because Emacs uses that word in a different
15 way. In Emacs Lisp, a @dfn{frame object} is a Lisp object that
16 represents a frame on the screen. @xref{Frame Type}.
18 A frame initially contains a single main window and/or a minibuffer
19 window; you can subdivide the main window vertically or horizontally
20 into smaller windows. @xref{Splitting Windows}.
23 A @dfn{terminal} is a display device capable of displaying one or
24 more Emacs frames. In Emacs Lisp, a @dfn{terminal object} is a Lisp
25 object that represents a terminal. @xref{Terminal Type}.
27 @cindex terminal frame
29 There are two classes of terminals: text-only terminals and
30 graphical terminals. Text-only terminals are non-graphics-capable
31 display devices, including ``terminal emulators'' such as xterm. On
32 text-only terminals, each frame occupies the entire terminal screen;
33 although you can create additional frames and switch between them,
34 only one frame can be shown at any given time. We refer to frames on
35 text-only terminals as @dfn{terminal frames}. Graphical terminals, on
36 the other hand, are graphics-capable windowing systems, such as the X
37 Window System. On a graphical terminal, Emacs can display multiple
38 frames simultaneously. We refer to such frames as @dfn{window
41 On GNU and Unix systems, you can create additional frames on any
42 available terminal, within a single Emacs session, regardless of
43 whether Emacs was started on a text-only or graphical terminal. Emacs
44 can display on both graphical and text-only terminals simultaneously.
45 This comes in handy, for instance, when you connect to the same
46 session from several remote locations. @xref{Multiple Terminals}.
49 This predicate returns a non-@code{nil} value if @var{object} is a
50 frame, and @code{nil} otherwise. For a frame, the value indicates which
51 kind of display the frame uses:
55 The frame is displayed in an X window.
57 A terminal frame on a character display.
59 The frame is displayed on MS-Windows 9X/NT.
61 The frame is displayed on a GNUstep or Macintosh Cocoa display.
63 The frame is displayed on an MS-DOS terminal.
67 @defun frame-terminal &optional frame
68 This function returns the terminal object that displays @var{frame}.
69 If @var{frame} is @code{nil} or unspecified, it defaults to the
73 @defun terminal-live-p object
74 This predicate returns a non-@code{nil} value if @var{object} is a
75 terminal that is alive (i.e.@: was not deleted), and @code{nil}
76 otherwise. For live terminals, the return value indicates what kind
77 of frames are displayed on that terminal; the list of possible values
78 is the same as for @code{framep} above.
82 * Creating Frames:: Creating additional frames.
83 * Multiple Terminals:: Displaying on several different devices.
84 * Frame Parameters:: Controlling frame size, position, font, etc.
85 * Terminal Parameters:: Parameters common for all frames on terminal.
86 * Frame Titles:: Automatic updating of frame titles.
87 * Deleting Frames:: Frames last until explicitly deleted.
88 * Finding All Frames:: How to examine all existing frames.
89 * Frames and Windows:: A frame contains windows;
90 display of text always works through windows.
91 * Minibuffers and Frames:: How a frame finds the minibuffer to use.
92 * Input Focus:: Specifying the selected frame.
93 * Visibility of Frames:: Frames may be visible or invisible, or icons.
94 * Raising and Lowering:: Raising a frame makes it hide other windows;
95 lowering it makes the others hide it.
96 * Frame Configurations:: Saving the state of all frames.
97 * Mouse Tracking:: Getting events that say when the mouse moves.
98 * Mouse Position:: Asking where the mouse is, or moving it.
99 * Pop-Up Menus:: Displaying a menu for the user to select from.
100 * Dialog Boxes:: Displaying a box to ask yes or no.
101 * Pointer Shape:: Specifying the shape of the mouse pointer.
102 * Window System Selections:: Transferring text to and from other X clients.
103 * Drag and Drop:: Internals of Drag-and-Drop implementation.
104 * Color Names:: Getting the definitions of color names.
105 * Text Terminal Colors:: Defining colors for text-only terminals.
106 * Resources:: Getting resource values from the server.
107 * Display Feature Testing:: Determining the features of a terminal.
110 @node Creating Frames
111 @section Creating Frames
113 To create a new frame, call the function @code{make-frame}.
115 @defun make-frame &optional alist
116 This function creates and returns a new frame, displaying the current
119 The @var{alist} argument is an alist that specifies frame parameters
120 for the new frame. @xref{Frame Parameters}. If you specify the
121 @code{terminal} parameter in @var{alist}, the new frame is created on
122 that terminal. Otherwise, if you specify the @code{window-system}
123 frame parameter in @var{alist}, that determines whether the frame
124 should be displayed on a text-only or graphical terminal.
125 @xref{Window Systems}. If neither is specified, the new frame is
126 created in the same terminal as the selected frame.
128 Any parameters not mentioned in @var{alist} default to the values in
129 the alist @code{default-frame-alist} (@pxref{Initial Parameters});
130 parameters not specified there default from the X resources or its
131 equivalent on your operating system (@pxref{X Resources,, X Resources,
132 emacs, The GNU Emacs Manual}). After the frame is created, Emacs
133 applies any parameters listed in @code{frame-inherited-parameters}
134 (see below) and not present in the argument, taking the values from
135 the frame that was selected when @code{make-frame} was called.
137 This function itself does not make the new frame the selected frame.
138 @xref{Input Focus}. The previously selected frame remains selected.
139 On graphical terminals, however, the windowing system may select the
140 new frame for its own reasons.
143 @defvar before-make-frame-hook
144 A normal hook run by @code{make-frame} before it creates the frame.
147 @defvar after-make-frame-functions
148 An abnormal hook run by @code{make-frame} after it creates the frame.
149 Each function in @code{after-make-frame-functions} receives one argument, the
153 @defvar frame-inherited-parameters
154 This variable specifies the list of frame parameters that a newly
155 created frame inherits from the currently selected frame. For each
156 parameter (a symbol) that is an element in the list and is not present
157 in the argument to @code{make-frame}, the function sets the value of
158 that parameter in the created frame to its value in the selected
162 @node Multiple Terminals
163 @section Multiple Terminals
164 @cindex multiple terminals
166 @cindex multiple X displays
167 @cindex displays, multiple
169 Emacs represents each terminal, whether graphical or text-only, as a
170 @dfn{terminal object} data type (@pxref{Terminal Type}). On GNU and
171 Unix systems, Emacs can use multiple terminals simultaneously in each
172 session. On other systems, it can only use a single terminal. Each
173 terminal object has the following attributes:
177 The name of the device used by the terminal (e.g., @samp{:0.0} or
181 The terminal and keyboard coding systems used on the terminal.
182 @xref{Terminal I/O Encoding}.
185 The kind of display associated with the terminal. This is the symbol
186 returned by the function @code{terminal-live-p} (i.e., @code{x},
187 @code{t}, @code{w32}, @code{ns}, or @code{pc}). @xref{Frames}.
190 A list of terminal parameters. @xref{Terminal Parameters}.
193 There is no primitive for creating terminal objects. Emacs creates
194 them as needed, such as when you call @code{make-frame-on-display}
195 (which is described below).
197 @defun terminal-name &optional terminal
198 This function returns the file name of the device used by
199 @var{terminal}. If @var{terminal} is omitted or @code{nil}, it
200 defaults to the selected frame's terminal. @var{terminal} can also be
201 a frame, meaning that frame's terminal.
205 This function returns a list of all terminal objects currently in use.
208 @defun get-device-terminal device
209 This function returns a terminal whose device name is given by
210 @var{device}. If @var{device} is a string, it can be either the file
211 name of a terminal device, or the name of an X display of the form
212 @samp{@var{host}:@var{server}.@var{screen}}. If @var{device} is a
213 frame, this function returns that frame's terminal; @code{nil} means
214 the selected frame. Finally, if @var{device} is a terminal object
215 that represents a live terminal, that terminal is returned. The
216 function signals an error if its argument is none of the above.
219 @defun delete-terminal &optional terminal force
220 This function deletes all frames on @var{terminal} and frees the
221 resources used by it. It runs the abnormal hook
222 @code{delete-terminal-functions}, passing @var{terminal} as the
223 argument to each function.
225 If @var{terminal} is omitted or @code{nil}, it defaults to the
226 selected frame's terminal. @var{terminal} can also be a frame,
227 meaning that frame's terminal.
229 Normally, this function signals an error if you attempt to delete the
230 sole active terminal, but if @var{force} is non-@code{nil}, you are
231 allowed to do so. Emacs automatically calls this function when the
232 last frame on a terminal is deleted (@pxref{Deleting Frames}).
235 @defvar delete-terminal-functions
236 An abnormal hook run by @code{delete-terminal}. Each function
237 receives one argument, the @var{terminal} argument passed to
238 @code{delete-terminal}. Due to technical details, the functions may
239 be called either just before the terminal is deleted, or just
243 @cindex terminal-local variables
244 A few Lisp variables are @dfn{terminal-local}; that is, they have a
245 separate binding for each terminal. The binding in effect at any time
246 is the one for the terminal that the currently selected frame belongs
247 to. These variables include @code{default-minibuffer-frame},
248 @code{defining-kbd-macro}, @code{last-kbd-macro}, and
249 @code{system-key-alist}. They are always terminal-local, and can
250 never be buffer-local (@pxref{Buffer-Local Variables}).
252 On GNU and Unix systems, each X display is a separate graphical
253 terminal. When Emacs is started from within the X window system, it
254 uses the X display chosen with the @code{DISPLAY} environment
255 variable, or with the @samp{--display} option. @xref{Initial
256 Options,,, emacs, The GNU Emacs Manual}. Emacs can connect to other X
257 displays via the command @code{make-frame-on-display}. Each X display
258 has its own selected frame and its own minibuffer windows; however,
259 only one of those frames is ``@emph{the} selected frame'' at any given
260 moment (@pxref{Input Focus}). Emacs can even connect to other
261 text-only terminals, by interacting with the @command{emacsclient}
262 program. @xref{Emacs Server,,, emacs, The GNU Emacs Manual}.
264 A single X server can handle more than one display. Each X display
265 has a three-part name, @samp{@var{host}:@var{server}.@var{screen}}.
266 The first two parts, @var{host} and @var{server}, identify the X
267 server; the third part, @var{screen}, identifies a screen number on
268 that X server. When you use two or more screens belonging to one
269 server, Emacs knows by the similarity in their names that they share a
272 On some ``multi-monitor'' setups, a single X display outputs to more
273 than one monitor. Currently, there is no way for Emacs to distinguish
274 between the different physical monitors.
276 @deffn Command make-frame-on-display display &optional parameters
277 This function creates and returns a new frame on @var{display}, taking
278 the other frame parameters from the alist @var{parameters}.
279 @var{display} should be the name of an X display (a string).
281 Before creating the frame, this function ensures that Emacs is ``set
282 up'' to display graphics. For instance, if Emacs has not processed X
283 resources (e.g., if it was started on a text-only terminal), it does
284 so at this time. In all other respects, this function behaves like
285 @code{make-frame} (@pxref{Creating Frames}).
288 @defun x-display-list
289 This function returns a list that indicates which X displays Emacs has
290 a connection to. The elements of the list are strings, and each one
294 @defun x-open-connection display &optional xrm-string must-succeed
295 This function opens a connection to the X display @var{display},
296 without creating a frame on that display. Normally, Emacs Lisp
297 programs need not call this function, as @code{make-frame-on-display}
298 calls it automatically. The only reason for calling it is to check
299 whether communication can be established with a given X display.
301 The optional argument @var{xrm-string}, if not @code{nil}, is a string
302 of resource names and values, in the same format used in the
303 @file{.Xresources} file. @xref{X Resources,, X Resources, emacs, The
304 GNU Emacs Manual}. These values apply to all Emacs frames created on
305 this display, overriding the resource values recorded in the X server.
306 Here's an example of what this string might look like:
309 "*BorderWidth: 3\n*InternalBorder: 2\n"
312 If @var{must-succeed} is non-@code{nil}, failure to open the connection
313 terminates Emacs. Otherwise, it is an ordinary Lisp error.
316 @defun x-close-connection display
317 This function closes the connection to display @var{display}. Before
318 you can do this, you must first delete all the frames that were open
319 on that display (@pxref{Deleting Frames}).
322 @node Frame Parameters
323 @section Frame Parameters
324 @cindex frame parameters
326 A frame has many parameters that control its appearance and behavior.
327 Just what parameters a frame has depends on what display mechanism it
330 Frame parameters exist mostly for the sake of window systems. A
331 terminal frame has a few parameters, mostly for compatibility's sake;
332 only the @code{height}, @code{width}, @code{name}, @code{title},
333 @code{menu-bar-lines}, @code{buffer-list} and @code{buffer-predicate}
334 parameters do something special. If the terminal supports colors, the
335 parameters @code{foreground-color}, @code{background-color},
336 @code{background-mode} and @code{display-type} are also meaningful.
337 If the terminal supports frame transparency, the parameter
338 @code{alpha} is also meaningful.
340 You can use frame parameters to define frame-local bindings for
341 variables. @xref{Frame-Local Variables}.
344 * Parameter Access:: How to change a frame's parameters.
345 * Initial Parameters:: Specifying frame parameters when you make a frame.
346 * Window Frame Parameters:: List of frame parameters for window systems.
347 * Size and Position:: Changing the size and position of a frame.
348 * Geometry:: Parsing geometry specifications.
351 @node Parameter Access
352 @subsection Access to Frame Parameters
354 These functions let you read and change the parameter values of a
357 @defun frame-parameter frame parameter
358 This function returns the value of the parameter @var{parameter} (a
359 symbol) of @var{frame}. If @var{frame} is @code{nil}, it returns the
360 selected frame's parameter. If @var{frame} has no setting for
361 @var{parameter}, this function returns @code{nil}.
364 @defun frame-parameters &optional frame
365 The function @code{frame-parameters} returns an alist listing all the
366 parameters of @var{frame} and their values. If @var{frame} is
367 @code{nil} or omitted, this returns the selected frame's parameters
370 @defun modify-frame-parameters frame alist
371 This function alters the parameters of frame @var{frame} based on the
372 elements of @var{alist}. Each element of @var{alist} has the form
373 @code{(@var{parm} . @var{value})}, where @var{parm} is a symbol naming a
374 parameter. If you don't mention a parameter in @var{alist}, its value
375 doesn't change. If @var{frame} is @code{nil}, it defaults to the selected
378 You can use this function to define frame-local bindings for
379 variables, see @ref{Frame-Local Variables}.
382 @defun set-frame-parameter frame parm value
383 This function sets the frame parameter @var{parm} to the specified
384 @var{value}. If @var{frame} is @code{nil}, it defaults to the
388 @defun modify-all-frames-parameters alist
389 This function alters the frame parameters of all existing frames
390 according to @var{alist}, then modifies @code{default-frame-alist}
391 (and, if necessary, @code{initial-frame-alist}) to apply the same
392 parameter values to frames that will be created henceforth.
395 @node Initial Parameters
396 @subsection Initial Frame Parameters
398 You can specify the parameters for the initial startup frame
399 by setting @code{initial-frame-alist} in your init file (@pxref{Init File}).
401 @defvar initial-frame-alist
402 This variable's value is an alist of parameter values used when creating
403 the initial window frame. You can set this variable to specify the
404 appearance of the initial frame without altering subsequent frames.
405 Each element has the form:
408 (@var{parameter} . @var{value})
411 Emacs creates the initial frame before it reads your init
412 file. After reading that file, Emacs checks @code{initial-frame-alist},
413 and applies the parameter settings in the altered value to the already
414 created initial frame.
416 If these settings affect the frame geometry and appearance, you'll see
417 the frame appear with the wrong ones and then change to the specified
418 ones. If that bothers you, you can specify the same geometry and
419 appearance with X resources; those do take effect before the frame is
420 created. @xref{X Resources,, X Resources, emacs, The GNU Emacs Manual}.
422 X resource settings typically apply to all frames. If you want to
423 specify some X resources solely for the sake of the initial frame, and
424 you don't want them to apply to subsequent frames, here's how to achieve
425 this. Specify parameters in @code{default-frame-alist} to override the
426 X resources for subsequent frames; then, to prevent these from affecting
427 the initial frame, specify the same parameters in
428 @code{initial-frame-alist} with values that match the X resources.
431 If these parameters specify a separate minibuffer-only frame with
432 @code{(minibuffer . nil)}, and you have not created one, Emacs creates
435 @defvar minibuffer-frame-alist
436 This variable's value is an alist of parameter values used when creating
437 an initial minibuffer-only frame---if such a frame is needed, according
438 to the parameters for the main initial frame.
441 @defvar default-frame-alist
442 This is an alist specifying default values of frame parameters for all
443 Emacs frames---the first frame, and subsequent frames. When using the X
444 Window System, you can get the same results by means of X resources
447 Setting this variable does not affect existing frames.
450 Functions that display a buffer in a separate frame can override the
451 default parameters by supplying their own parameters. @xref{Definition
452 of special-display-frame-alist}.
454 If you use options that specify window appearance when you invoke Emacs,
455 they take effect by adding elements to @code{default-frame-alist}. One
456 exception is @samp{-geometry}, which adds the specified position to
457 @code{initial-frame-alist} instead. @xref{Emacs Invocation,, Command
458 Line Arguments for Emacs Invocation, emacs, The GNU Emacs Manual}.
460 @node Window Frame Parameters
461 @subsection Window Frame Parameters
463 Just what parameters a frame has depends on what display mechanism
464 it uses. This section describes the parameters that have special
465 meanings on some or all kinds of terminals. Of these, @code{name},
466 @code{title}, @code{height}, @code{width}, @code{buffer-list} and
467 @code{buffer-predicate} provide meaningful information in terminal
468 frames, and @code{tty-color-mode} is meaningful @emph{only} in
472 * Basic Parameters:: Parameters that are fundamental.
473 * Position Parameters:: The position of the frame on the screen.
474 * Size Parameters:: Frame's size.
475 * Layout Parameters:: Size of parts of the frame, and
476 enabling or disabling some parts.
477 * Buffer Parameters:: Which buffers have been or should be shown.
478 * Management Parameters:: Communicating with the window manager.
479 * Cursor Parameters:: Controlling the cursor appearance.
480 * Font and Color Parameters:: Fonts and colors for the frame text.
483 @node Basic Parameters
484 @subsubsection Basic Parameters
486 These frame parameters give the most basic information about the
487 frame. @code{title} and @code{name} are meaningful on all terminals.
491 The display on which to open this frame. It should be a string of the
492 form @code{"@var{host}:@var{dpy}.@var{screen}"}, just like the
493 @code{DISPLAY} environment variable.
496 This parameter describes the range of possible colors that can be used
497 in this frame. Its value is @code{color}, @code{grayscale} or
501 If a frame has a non-@code{nil} title, it appears in the window
502 system's title bar at the top of the frame, and also in the mode line
503 of windows in that frame if @code{mode-line-frame-identification} uses
504 @samp{%F} (@pxref{%-Constructs}). This is normally the case when
505 Emacs is not using a window system, and can only display one frame at
506 a time. @xref{Frame Titles}.
509 The name of the frame. The frame name serves as a default for the frame
510 title, if the @code{title} parameter is unspecified or @code{nil}. If
511 you don't specify a name, Emacs sets the frame name automatically
512 (@pxref{Frame Titles}).
514 If you specify the frame name explicitly when you create the frame, the
515 name is also used (instead of the name of the Emacs executable) when
516 looking up X resources for the frame.
519 @node Position Parameters
520 @subsubsection Position Parameters
522 Position parameters' values are normally measured in pixels, but on
523 text-only terminals they count characters or lines instead.
527 The position, in pixels, of the left (or right) edge of the frame with
528 respect to the left (or right) edge of the screen. The value may be:
532 A positive integer relates the left edge of the frame to the left edge
533 of the screen. A negative integer relates the right frame edge to the
536 @item @code{(+ @var{pos})}
537 This specifies the position of the left frame edge relative to the left
538 screen edge. The integer @var{pos} may be positive or negative; a
539 negative value specifies a position outside the screen.
541 @item @code{(- @var{pos})}
542 This specifies the position of the right frame edge relative to the right
543 screen edge. The integer @var{pos} may be positive or negative; a
544 negative value specifies a position outside the screen.
547 Some window managers ignore program-specified positions. If you want to
548 be sure the position you specify is not ignored, specify a
549 non-@code{nil} value for the @code{user-position} parameter as well.
552 The screen position of the top (or bottom) edge, in pixels, with respect
553 to the top (or bottom) edge of the screen. It works just like
554 @code{left}, except vertically instead of horizontally.
557 The screen position of the left edge @emph{of the frame's icon}, in
558 pixels, counting from the left edge of the screen. This takes effect if
559 and when the frame is iconified.
561 If you specify a value for this parameter, then you must also specify
562 a value for @code{icon-top} and vice versa. The window manager may
563 ignore these two parameters.
566 The screen position of the top edge @emph{of the frame's icon}, in
567 pixels, counting from the top edge of the screen. This takes effect if
568 and when the frame is iconified.
571 When you create a frame and specify its screen position with the
572 @code{left} and @code{top} parameters, use this parameter to say whether
573 the specified position was user-specified (explicitly requested in some
574 way by a human user) or merely program-specified (chosen by a program).
575 A non-@code{nil} value says the position was user-specified.
577 Window managers generally heed user-specified positions, and some heed
578 program-specified positions too. But many ignore program-specified
579 positions, placing the window in a default fashion or letting the user
580 place it with the mouse. Some window managers, including @code{twm},
581 let the user specify whether to obey program-specified positions or
584 When you call @code{make-frame}, you should specify a non-@code{nil}
585 value for this parameter if the values of the @code{left} and @code{top}
586 parameters represent the user's stated preference; otherwise, use
590 @node Size Parameters
591 @subsubsection Size Parameters
593 Size parameters' values are normally measured in pixels, but on
594 text-only terminals they count characters or lines instead.
598 The height of the frame contents, in characters. (To get the height in
599 pixels, call @code{frame-pixel-height}; see @ref{Size and Position}.)
602 The width of the frame contents, in characters. (To get the width in
603 pixels, call @code{frame-pixel-width}; see @ref{Size and Position}.)
606 This does for the size parameters @code{height} and @code{width} what
607 the @code{user-position} parameter (see above) does for the position
608 parameters @code{top} and @code{left}.
611 Specify that width, height or both shall be set to the size of the screen.
612 The value @code{fullwidth} specifies that width shall be the size of the
613 screen. The value @code{fullheight} specifies that height shall be the
614 size of the screen. The value @code{fullboth} specifies that both the
615 width and the height shall be set to the size of the screen.
618 @node Layout Parameters
619 @subsubsection Layout Parameters
621 These frame parameters enable or disable various parts of the
622 frame, or control their sizes.
626 The width in pixels of the frame's border.
628 @item internal-border-width
629 The distance in pixels between text (or fringe) and the frame's border.
631 @item vertical-scroll-bars
632 Whether the frame has scroll bars for vertical scrolling, and which side
633 of the frame they should be on. The possible values are @code{left},
634 @code{right}, and @code{nil} for no scroll bars.
637 @item horizontal-scroll-bars
638 Whether the frame has scroll bars for horizontal scrolling
639 (non-@code{nil} means yes). Horizontal scroll bars are not currently
643 @item scroll-bar-width
644 The width of vertical scroll bars, in pixels, or @code{nil} meaning to
645 use the default width.
649 The default width of the left and right fringes of windows in this
650 frame (@pxref{Fringes}). If either of these is zero, that effectively
651 removes the corresponding fringe. A value of @code{nil} stands for
652 the standard fringe width, which is the width needed to display the
655 The combined fringe widths must add up to an integral number of
656 columns, so the actual default fringe widths for the frame may be
657 larger than the specified values. The extra width needed to reach an
658 acceptable total is distributed evenly between the left and right
659 fringe. However, you can force one fringe or the other to a precise
660 width by specifying that width as a negative integer. If both widths are
661 negative, only the left fringe gets the specified width.
664 The number of lines to allocate at the top of the frame for a menu
665 bar. The default is 1. A value of @code{nil} means don't display a
666 menu bar. @xref{Menu Bar}. (The X toolkit and GTK allow at most one
667 menu bar line; they treat larger values as 1.)
670 The number of lines to use for the tool bar. A value of @code{nil}
671 means don't display a tool bar. (GTK and Nextstep allow at most one
672 tool bar line; they treat larger values as 1.)
675 Additional space to leave below each text line, in pixels (a positive
676 integer). @xref{Line Height}, for more information.
679 @node Buffer Parameters
680 @subsubsection Buffer Parameters
682 These frame parameters, meaningful on all kinds of terminals, deal
683 with which buffers have been, or should, be displayed in the frame.
687 Whether this frame has its own minibuffer. The value @code{t} means
688 yes, @code{nil} means no, @code{only} means this frame is just a
689 minibuffer. If the value is a minibuffer window (in some other frame),
690 the new frame uses that minibuffer.
692 @item buffer-predicate
693 The buffer-predicate function for this frame. The function
694 @code{other-buffer} uses this predicate (from the selected frame) to
695 decide which buffers it should consider, if the predicate is not
696 @code{nil}. It calls the predicate with one argument, a buffer, once for
697 each buffer; if the predicate returns a non-@code{nil} value, it
698 considers that buffer.
701 A list of buffers that have been selected in this frame,
702 ordered most-recently-selected first.
705 If non-@code{nil}, this frame's window is never split automatically.
708 @node Management Parameters
709 @subsubsection Window Management Parameters
710 @cindex window manager, and frame parameters
712 These frame parameters, meaningful only on window system displays,
713 interact with the window manager.
717 The state of visibility of the frame. There are three possibilities:
718 @code{nil} for invisible, @code{t} for visible, and @code{icon} for
719 iconified. @xref{Visibility of Frames}.
722 Whether selecting the frame raises it (non-@code{nil} means yes).
725 Whether deselecting the frame lowers it (non-@code{nil} means yes).
728 The type of icon to use for this frame when it is iconified. If the
729 value is a string, that specifies a file containing a bitmap to use.
730 Any other non-@code{nil} value specifies the default bitmap icon (a
731 picture of a gnu); @code{nil} specifies a text icon.
734 The name to use in the icon for this frame, when and if the icon
735 appears. If this is @code{nil}, the frame's title is used.
738 The number of the window-system window used by the frame
739 to contain the actual Emacs windows.
741 @item outer-window-id
742 The number of the outermost window-system window used for the whole frame.
745 If non-@code{nil}, tell Xt to wait for the window manager to confirm
746 geometry changes. Some window managers, including versions of Fvwm2
747 and KDE, fail to confirm, so Xt hangs. Set this to @code{nil} to
748 prevent hanging with those window managers.
752 @c ??? Not yet working.
753 The X window number of the window that should be the parent of this one.
754 Specifying this lets you create an Emacs window inside some other
755 application's window. (It is not certain this will be implemented; try
756 it and see if it works.)
760 @node Cursor Parameters
761 @subsubsection Cursor Parameters
763 This frame parameter controls the way the cursor looks.
767 How to display the cursor. Legitimate values are:
771 Display a filled box. (This is the default.)
773 Display a hollow box.
775 Don't display a cursor.
777 Display a vertical bar between characters.
778 @item (bar . @var{width})
779 Display a vertical bar @var{width} pixels wide between characters.
781 Display a horizontal bar.
782 @item (hbar . @var{height})
783 Display a horizontal bar @var{height} pixels high.
788 The buffer-local variable @code{cursor-type} overrides the value of
789 the @code{cursor-type} frame parameter, but if it is @code{t}, that
790 means to use the cursor specified for the frame.
792 @defvar blink-cursor-alist
793 This variable specifies how to blink the cursor. Each element has the
794 form @code{(@var{on-state} . @var{off-state})}. Whenever the cursor
795 type equals @var{on-state} (comparing using @code{equal}), the
796 corresponding @var{off-state} specifies what the cursor looks like
797 when it blinks ``off.'' Both @var{on-state} and @var{off-state}
798 should be suitable values for the @code{cursor-type} frame parameter.
800 There are various defaults for how to blink each type of cursor, if
801 the type is not mentioned as an @var{on-state} here. Changes in this
802 variable do not take effect immediately, only when you specify the
803 @code{cursor-type} frame parameter.
806 @defvar cursor-in-non-selected-windows
807 This variable controls how the cursor looks in a window that is not
808 selected. It supports the same values as the @code{cursor-type} frame
809 parameter; also, @code{nil} means don't display a cursor in
810 nonselected windows, and @code{t} (the default) means use a standard
811 modificatoin of the usual cursor type (solid box becomes hollow box,
812 and bar becomes a narrower bar).
815 @node Font and Color Parameters
816 @subsubsection Font and Color Parameters
818 These frame parameters control the use of fonts and colors.
822 A list of symbols, specifying the @dfn{font backends} to use for
823 drawing fonts in the frame, in order of priority. On X, there are
824 currently two available font backends: @code{x} (the X core font
825 driver) and @code{xft} (the Xft font driver). On other systems, there
826 is only one available font backend, so it does not make sense to
827 modify this frame parameter.
829 @item background-mode
830 This parameter is either @code{dark} or @code{light}, according
831 to whether the background color is a light one or a dark one.
834 @cindex standard colors for character terminals
835 This parameter overrides the terminal's color support as given by the
836 system's terminal capabilities database in that this parameter's value
837 specifies the color mode to use in terminal frames. The value can be
838 either a symbol or a number. A number specifies the number of colors
839 to use (and, indirectly, what commands to issue to produce each
840 color). For example, @code{(tty-color-mode . 8)} specifies use of the
841 ANSI escape sequences for 8 standard text colors. A value of -1 turns
844 If the parameter's value is a symbol, it specifies a number through
845 the value of @code{tty-color-mode-alist}, and the associated number is
849 @cindex gamma correction
850 If this is a number, Emacs performs ``gamma correction'' which adjusts
851 the brightness of all colors. The value should be the screen gamma of
852 your display, a floating point number.
854 Usual PC monitors have a screen gamma of 2.2, so color values in
855 Emacs, and in X windows generally, are calibrated to display properly
856 on a monitor with that gamma value. If you specify 2.2 for
857 @code{screen-gamma}, that means no correction is needed. Other values
858 request correction, designed to make the corrected colors appear on
859 your screen the way they would have appeared without correction on an
860 ordinary monitor with a gamma value of 2.2.
862 If your monitor displays colors too light, you should specify a
863 @code{screen-gamma} value smaller than 2.2. This requests correction
864 that makes colors darker. A screen gamma value of 1.5 may give good
865 results for LCD color displays.
868 @cindex opacity, frame
869 @cindex transparency, frame
870 @vindex frame-alpha-lower-limit
871 This parameter specifies the opacity of the frame, on graphical
872 displays that support variable opacity. It should be an integer
873 between 0 and 100, where 0 means completely transparent and 100 means
874 completely opaque. It can also have a @code{nil} value, which tells
875 Emacs not to set the frame opacity (leaving it to the window manager).
877 To prevent the frame from disappearing completely from view, the
878 variable @code{frame-alpha-lower-limit} defines a lower opacity limit.
879 If the value of the frame parameter is less than the value of this
880 variable, Emacs uses the latter. By default,
881 @code{frame-alpha-lower-limit} is 20.
883 The @code{alpha} frame parameter can also be a cons cell
884 @code{(@samp{active} . @samp{inactive})}, where @samp{active} is the
885 opacity of the frame when it is selected, and @samp{inactive} is the
886 opactity when it is not selected.
889 The following frame parameters are semi-obsolete in that they are
890 automatically equivalent to particular face attributes of particular
891 faces (@pxref{Standard Faces,,, emacs, The Emacs Manual}):
895 The name of the font for displaying text in the frame. This is a
896 string, either a valid font name for your system or the name of an Emacs
897 fontset (@pxref{Fontsets}). It is equivalent to the @code{font}
898 attribute of the @code{default} face.
900 @item foreground-color
901 The color to use for the image of a character. It is equivalent to
902 the @code{:foreground} attribute of the @code{default} face.
904 @item background-color
905 The color to use for the background of characters. It is equivalent to
906 the @code{:background} attribute of the @code{default} face.
909 The color for the mouse pointer. It is equivalent to the @code{:background}
910 attribute of the @code{mouse} face.
913 The color for the cursor that shows point. It is equivalent to the
914 @code{:background} attribute of the @code{cursor} face.
917 The color for the border of the frame. It is equivalent to the
918 @code{:background} attribute of the @code{border} face.
920 @item scroll-bar-foreground
921 If non-@code{nil}, the color for the foreground of scroll bars. It is
922 equivalent to the @code{:foreground} attribute of the
923 @code{scroll-bar} face.
925 @item scroll-bar-background
926 If non-@code{nil}, the color for the background of scroll bars. It is
927 equivalent to the @code{:background} attribute of the
928 @code{scroll-bar} face.
931 @node Size and Position
932 @subsection Frame Size And Position
933 @cindex size of frame
938 You can read or change the size and position of a frame using the
939 frame parameters @code{left}, @code{top}, @code{height}, and
940 @code{width}. Whatever geometry parameters you don't specify are chosen
941 by the window manager in its usual fashion.
943 Here are some special features for working with sizes and positions.
944 (For the precise meaning of ``selected frame'' used by these functions,
945 see @ref{Input Focus}.)
947 @defun set-frame-position frame left top
948 This function sets the position of the top left corner of @var{frame} to
949 @var{left} and @var{top}. These arguments are measured in pixels, and
950 normally count from the top left corner of the screen.
952 Negative parameter values position the bottom edge of the window up from
953 the bottom edge of the screen, or the right window edge to the left of
954 the right edge of the screen. It would probably be better if the values
955 were always counted from the left and top, so that negative arguments
956 would position the frame partly off the top or left edge of the screen,
957 but it seems inadvisable to change that now.
960 @defun frame-height &optional frame
961 @defunx frame-width &optional frame
962 These functions return the height and width of @var{frame}, measured in
963 lines and columns. If you don't supply @var{frame}, they use the
969 These functions are old aliases for @code{frame-height} and
970 @code{frame-width}. When you are using a non-window terminal, the size
971 of the frame is normally the same as the size of the terminal screen.
974 @defun frame-pixel-height &optional frame
975 @defunx frame-pixel-width &optional frame
976 These functions return the height and width of the main display area
977 of @var{frame}, measured in pixels. If you don't supply @var{frame},
978 they use the selected frame.
980 These values include the internal borders, and windows' scroll bars
981 and fringes (which belong to individual windows, not to the frame
982 itself), but do not include menu bars or tool bars (except when using
983 X without an X toolkit).
986 @defun frame-char-height &optional frame
987 @defunx frame-char-width &optional frame
988 These functions return the height and width of a character in
989 @var{frame}, measured in pixels. The values depend on the choice of
990 font. If you don't supply @var{frame}, these functions use the selected
994 @defun set-frame-size frame cols rows
995 This function sets the size of @var{frame}, measured in characters;
996 @var{cols} and @var{rows} specify the new width and height.
998 To set the size based on values measured in pixels, use
999 @code{frame-char-height} and @code{frame-char-width} to convert
1000 them to units of characters.
1003 @defun set-frame-height frame lines &optional pretend
1004 This function resizes @var{frame} to a height of @var{lines} lines. The
1005 sizes of existing windows in @var{frame} are altered proportionally to
1008 If @var{pretend} is non-@code{nil}, then Emacs displays @var{lines}
1009 lines of output in @var{frame}, but does not change its value for the
1010 actual height of the frame. This is only useful for a terminal frame.
1011 Using a smaller height than the terminal actually implements may be
1012 useful to reproduce behavior observed on a smaller screen, or if the
1013 terminal malfunctions when using its whole screen. Setting the frame
1014 height ``for real'' does not always work, because knowing the correct
1015 actual size may be necessary for correct cursor positioning on a
1019 @defun set-frame-width frame width &optional pretend
1020 This function sets the width of @var{frame}, measured in characters.
1021 The argument @var{pretend} has the same meaning as in
1022 @code{set-frame-height}.
1025 @findex set-screen-height
1026 @findex set-screen-width
1027 The older functions @code{set-screen-height} and
1028 @code{set-screen-width} were used to specify the height and width of the
1029 screen, in Emacs versions that did not support multiple frames. They
1030 are semi-obsolete, but still work; they apply to the selected frame.
1033 @subsection Geometry
1035 Here's how to examine the data in an X-style window geometry
1038 @defun x-parse-geometry geom
1039 @cindex geometry specification
1040 The function @code{x-parse-geometry} converts a standard X window
1041 geometry string to an alist that you can use as part of the argument to
1044 The alist describes which parameters were specified in @var{geom}, and
1045 gives the values specified for them. Each element looks like
1046 @code{(@var{parameter} . @var{value})}. The possible @var{parameter}
1047 values are @code{left}, @code{top}, @code{width}, and @code{height}.
1049 For the size parameters, the value must be an integer. The position
1050 parameter names @code{left} and @code{top} are not totally accurate,
1051 because some values indicate the position of the right or bottom edges
1052 instead. The @var{value} possibilities for the position parameters are:
1053 an integer, a list @code{(+ @var{pos})}, or a list @code{(- @var{pos})};
1054 as previously described (@pxref{Position Parameters}).
1059 (x-parse-geometry "35x70+0-0")
1060 @result{} ((height . 70) (width . 35)
1061 (top - 0) (left . 0))
1065 @node Terminal Parameters
1066 @section Terminal Parameters
1067 @cindex terminal parameters
1069 Each terminal has a list of associated parameters. These
1070 @dfn{terminal parameters} are mostly a convenient way of storage for
1071 terminal-local variables, but some terminal parameters have a special
1074 This section describes functions to read and change the parameter values
1075 of a terminal. They all accept as their argument either a terminal or
1076 a frame; the latter means use that frame's terminal. An argument of
1077 @code{nil} means the selected frame's terminal.
1079 @defun terminal-parameters &optional terminal
1080 This function returns an alist listing all the parameters of
1081 @var{terminal} and their values.
1084 @defun terminal-parameter terminal parameter
1085 This function returns the value of the parameter @var{parameter} (a
1086 symbol) of @var{terminal}. If @var{terminal} has no setting for
1087 @var{parameter}, this function returns @code{nil}.
1090 @defun set-terminal-parameter terminal parameter value
1091 This function sets the parameter @var{parm} of @var{terminal} to the
1092 specified @var{value}, and returns the previous value of that
1096 Here's a list of a few terminal parameters that have a special
1100 @item background-mode
1101 The classification of the terminal's background color, either
1102 @code{light} or @code{dark}.
1103 @item normal-erase-is-backspace
1104 Value is either 1 or 0, depending on whether
1105 @code{normal-erase-is-backspace-mode} is turned on or off on this
1106 terminal. @xref{DEL Does Not Delete,,, emacs, The Emacs Manual}.
1107 @item terminal-initted
1108 After the terminal is initialized, this is set to the
1109 terminal-specific initialization function.
1113 @section Frame Titles
1116 Every frame has a @code{name} parameter; this serves as the default
1117 for the frame title which window systems typically display at the top of
1118 the frame. You can specify a name explicitly by setting the @code{name}
1121 Normally you don't specify the name explicitly, and Emacs computes the
1122 frame name automatically based on a template stored in the variable
1123 @code{frame-title-format}. Emacs recomputes the name each time the
1124 frame is redisplayed.
1126 @defvar frame-title-format
1127 This variable specifies how to compute a name for a frame when you have
1128 not explicitly specified one. The variable's value is actually a mode
1129 line construct, just like @code{mode-line-format}, except that the
1130 @samp{%c} and @samp{%l} constructs are ignored. @xref{Mode Line
1134 @defvar icon-title-format
1135 This variable specifies how to compute the name for an iconified frame,
1136 when you have not explicitly specified the frame title. This title
1137 appears in the icon itself.
1140 @defvar multiple-frames
1141 This variable is set automatically by Emacs. Its value is @code{t} when
1142 there are two or more frames (not counting minibuffer-only frames or
1143 invisible frames). The default value of @code{frame-title-format} uses
1144 @code{multiple-frames} so as to put the buffer name in the frame title
1145 only when there is more than one frame.
1147 The value of this variable is not guaranteed to be accurate except
1148 while processing @code{frame-title-format} or
1149 @code{icon-title-format}.
1152 @node Deleting Frames
1153 @section Deleting Frames
1154 @cindex deleting frames
1156 Frames remain potentially visible until you explicitly @dfn{delete}
1157 them. A deleted frame cannot appear on the screen, but continues to
1158 exist as a Lisp object until there are no references to it.
1160 @deffn Command delete-frame &optional frame force
1161 @vindex delete-frame-functions
1162 This function deletes the frame @var{frame}. Unless @var{frame} is a
1163 tooltip, it first runs the hook @code{delete-frame-functions} (each
1164 function gets one argument, @var{frame}). By default, @var{frame} is
1167 A frame cannot be deleted if its minibuffer is used by other frames.
1168 Normally, you cannot delete a frame if all other frames are invisible,
1169 but if @var{force} is non-@code{nil}, then you are allowed to do so.
1172 @defun frame-live-p frame
1173 The function @code{frame-live-p} returns non-@code{nil} if the frame
1174 @var{frame} has not been deleted. The possible non-@code{nil} return
1175 values are like those of @code{framep}. @xref{Frames}.
1178 Some window managers provide a command to delete a window. These work
1179 by sending a special message to the program that operates the window.
1180 When Emacs gets one of these commands, it generates a
1181 @code{delete-frame} event, whose normal definition is a command that
1182 calls the function @code{delete-frame}. @xref{Misc Events}.
1184 @node Finding All Frames
1185 @section Finding All Frames
1186 @cindex frames, scanning all
1189 The function @code{frame-list} returns a list of all the live frames,
1190 i.e.@: those that have not been deleted. It is analogous to
1191 @code{buffer-list} for buffers, and includes frames on all terminals.
1192 The list that you get is newly created, so modifying the list doesn't
1193 have any effect on the internals of Emacs.
1196 @defun visible-frame-list
1197 This function returns a list of just the currently visible frames.
1198 @xref{Visibility of Frames}. (Terminal frames always count as
1199 ``visible,'' even though only the selected one is actually displayed.)
1202 @defun next-frame &optional frame minibuf
1203 The function @code{next-frame} lets you cycle conveniently through all
1204 the frames on the current display from an arbitrary starting point. It
1205 returns the ``next'' frame after @var{frame} in the cycle. If
1206 @var{frame} is omitted or @code{nil}, it defaults to the selected frame
1207 (@pxref{Input Focus}).
1209 The second argument, @var{minibuf}, says which frames to consider:
1213 Exclude minibuffer-only frames.
1214 @item @code{visible}
1215 Consider all visible frames.
1217 Consider all visible or iconified frames.
1219 Consider only the frames using that particular window as their
1222 Consider all frames.
1226 @defun previous-frame &optional frame minibuf
1227 Like @code{next-frame}, but cycles through all frames in the opposite
1231 See also @code{next-window} and @code{previous-window}, in @ref{Cyclic
1234 @node Frames and Windows
1235 @section Frames and Windows
1237 Each window is part of one and only one frame; you can get that frame
1238 with @code{window-frame}.
1240 @defun window-frame window
1241 This function returns the frame that @var{window} is on.
1244 All the non-minibuffer windows in a frame are arranged in a cyclic
1245 order. The order runs from the frame's top window, which is at the
1246 upper left corner, down and to the right, until it reaches the window at
1247 the lower right corner (always the minibuffer window, if the frame has
1248 one), and then it moves back to the top. @xref{Cyclic Window Ordering}.
1250 @defun frame-first-window &optional frame
1251 This returns the topmost, leftmost window of frame @var{frame}.
1252 If omitted or @code{nil}, @var{frame} defaults to the selected frame.
1255 At any time, exactly one window on any frame is @dfn{selected within the
1256 frame}. The significance of this designation is that selecting the
1257 frame also selects this window. Conversely, selecting a window for
1258 Emacs with @code{select-window} also makes that window selected within
1259 its frame. @xref{Selecting Windows}.
1261 @defun frame-selected-window &optional frame
1262 This function returns the window on @var{frame} that is selected
1263 within @var{frame}. If omitted or @code{nil}, @var{frame} defaults to
1267 @defun set-frame-selected-window frame window &optional norecord
1268 This sets the selected window of frame @var{frame} to @var{window}.
1269 If @var{frame} is @code{nil}, it operates on the selected frame. If
1270 @var{frame} is the selected frame, this makes @var{window} the
1271 selected window. This function returns @var{window}.
1273 Optional argument @var{norecord} non-@code{nil} means to neither change
1274 the order of recently selected windows nor the buffer list (@pxref{The
1278 Another function that (usually) returns one of the windows in a given
1279 frame is @code{minibuffer-window}. @xref{Definition of minibuffer-window}.
1281 @node Minibuffers and Frames
1282 @section Minibuffers and Frames
1284 Normally, each frame has its own minibuffer window at the bottom, which
1285 is used whenever that frame is selected. If the frame has a minibuffer,
1286 you can get it with @code{minibuffer-window} (@pxref{Definition of
1287 minibuffer-window}).
1289 However, you can also create a frame with no minibuffer. Such a frame
1290 must use the minibuffer window of some other frame. When you create the
1291 frame, you can specify explicitly the minibuffer window to use (in some
1292 other frame). If you don't, then the minibuffer is found in the frame
1293 which is the value of the variable @code{default-minibuffer-frame}. Its
1294 value should be a frame that does have a minibuffer.
1296 If you use a minibuffer-only frame, you might want that frame to raise
1297 when you enter the minibuffer. If so, set the variable
1298 @code{minibuffer-auto-raise} to @code{t}. @xref{Raising and Lowering}.
1300 @defvar default-minibuffer-frame
1301 This variable specifies the frame to use for the minibuffer window, by
1302 default. It does not affect existing frames. It is always local to
1303 the current terminal and cannot be buffer-local. @xref{Multiple
1308 @section Input Focus
1310 @c @cindex selected frame Duplicates selected-frame
1312 At any time, one frame in Emacs is the @dfn{selected frame}. The selected
1313 window always resides on the selected frame.
1315 When Emacs displays its frames on several terminals (@pxref{Multiple
1316 Terminals}), each terminal has its own selected frame. But only one
1317 of these is ``@emph{the} selected frame'': it's the frame that belongs
1318 to the terminal from which the most recent input came. That is, when
1319 Emacs runs a command that came from a certain terminal, the selected
1320 frame is the one of that terminal. Since Emacs runs only a single
1321 command at any given time, it needs to consider only one selected
1322 frame at a time; this frame is what we call @dfn{the selected frame}
1323 in this manual. The display on which the selected frame is shown is
1324 the @dfn{selected frame's display}.
1326 @defun selected-frame
1327 This function returns the selected frame.
1330 Some window systems and window managers direct keyboard input to the
1331 window object that the mouse is in; others require explicit clicks or
1332 commands to @dfn{shift the focus} to various window objects. Either
1333 way, Emacs automatically keeps track of which frame has the focus. To
1334 explicitly switch to a different frame from a Lisp function, call
1335 @code{select-frame-set-input-focus}.
1337 Lisp programs can also switch frames ``temporarily'' by calling the
1338 function @code{select-frame}. This does not alter the window system's
1339 concept of focus; rather, it escapes from the window manager's control
1340 until that control is somehow reasserted.
1342 When using a text-only terminal, only one frame can be displayed at a
1343 time on the terminal, so after a call to @code{select-frame}, the next
1344 redisplay actually displays the newly selected frame. This frame
1345 remains selected until a subsequent call to @code{select-frame}. Each
1346 terminal frame has a number which appears in the mode line before the
1347 buffer name (@pxref{Mode Line Variables}).
1349 @defun select-frame-set-input-focus frame
1350 This function selects @var{frame}, raises it (should it happen to be
1351 obscured by other frames) and tries to give it the X server's focus. On
1352 a text-only terminal, the next redisplay displays the new frame on the
1353 entire terminal screen. The return value of this function is not
1357 @c ??? This is not yet implemented properly.
1358 @defun select-frame frame &optional norecord
1359 This function selects frame @var{frame}, temporarily disregarding the
1360 focus of the X server if any. The selection of @var{frame} lasts until
1361 the next time the user does something to select a different frame, or
1362 until the next time this function is called. (If you are using a
1363 window system, the previously selected frame may be restored as the
1364 selected frame after return to the command loop, because it still may
1365 have the window system's input focus.)
1367 The specified @var{frame} becomes the selected frame, as explained
1368 above, and the terminal that @var{frame} is on becomes the selected
1369 terminal. The window selected within @var{frame} becomes the selected
1370 window. This function returns @var{frame}, or @code{nil} if @var{frame}
1373 Optional argument @var{norecord} non-@code{nil} means to neither change
1374 the order of recently selected windows nor the buffer list. @xref{The
1377 In general, you should never use @code{select-frame} in a way that could
1378 switch to a different terminal without switching back when you're done.
1381 Emacs cooperates with the window system by arranging to select frames as
1382 the server and window manager request. It does so by generating a
1383 special kind of input event, called a @dfn{focus} event, when
1384 appropriate. The command loop handles a focus event by calling
1385 @code{handle-switch-frame}. @xref{Focus Events}.
1387 @deffn Command handle-switch-frame frame
1388 This function handles a focus event by selecting frame @var{frame}.
1390 Focus events normally do their job by invoking this command.
1391 Don't call it for any other reason.
1394 @defun redirect-frame-focus frame &optional focus-frame
1395 This function redirects focus from @var{frame} to @var{focus-frame}.
1396 This means that @var{focus-frame} will receive subsequent keystrokes and
1397 events intended for @var{frame}. After such an event, the value of
1398 @code{last-event-frame} will be @var{focus-frame}. Also, switch-frame
1399 events specifying @var{frame} will instead select @var{focus-frame}.
1401 If @var{focus-frame} is omitted or @code{nil}, that cancels any existing
1402 redirection for @var{frame}, which therefore once again receives its own
1405 One use of focus redirection is for frames that don't have minibuffers.
1406 These frames use minibuffers on other frames. Activating a minibuffer
1407 on another frame redirects focus to that frame. This puts the focus on
1408 the minibuffer's frame, where it belongs, even though the mouse remains
1409 in the frame that activated the minibuffer.
1411 Selecting a frame can also change focus redirections. Selecting frame
1412 @code{bar}, when @code{foo} had been selected, changes any redirections
1413 pointing to @code{foo} so that they point to @code{bar} instead. This
1414 allows focus redirection to work properly when the user switches from
1415 one frame to another using @code{select-window}.
1417 This means that a frame whose focus is redirected to itself is treated
1418 differently from a frame whose focus is not redirected.
1419 @code{select-frame} affects the former but not the latter.
1421 The redirection lasts until @code{redirect-frame-focus} is called to
1425 @defopt focus-follows-mouse
1426 This option is how you inform Emacs whether the window manager transfers
1427 focus when the user moves the mouse. Non-@code{nil} says that it does.
1428 When this is so, the command @code{other-frame} moves the mouse to a
1429 position consistent with the new selected frame.
1432 @node Visibility of Frames
1433 @section Visibility of Frames
1434 @cindex visible frame
1435 @cindex invisible frame
1436 @cindex iconified frame
1437 @cindex frame visibility
1439 A window frame may be @dfn{visible}, @dfn{invisible}, or
1440 @dfn{iconified}. If it is visible, you can see its contents, unless
1441 other windows cover it. If it is iconified, the frame's contents do
1442 not appear on the screen, but an icon does. (Note: because of the
1443 way in which some window managers implement the concept of multiple
1444 workspaces, or desktops, all frames on other workspaces may appear to
1445 Emacs to be iconified.) If the frame is invisible, it doesn't show on
1446 the screen, not even as an icon.
1448 Visibility is meaningless for terminal frames, since only the selected
1449 one is actually displayed in any case.
1451 @deffn Command make-frame-visible &optional frame
1452 This function makes frame @var{frame} visible. If you omit
1453 @var{frame}, it makes the selected frame visible. This does not raise
1454 the frame, but you can do that with @code{raise-frame} if you wish
1455 (@pxref{Raising and Lowering}).
1458 @deffn Command make-frame-invisible &optional frame force
1459 This function makes frame @var{frame} invisible. If you omit
1460 @var{frame}, it makes the selected frame invisible.
1462 Unless @var{force} is non-@code{nil}, this function refuses to make
1463 @var{frame} invisible if all other frames are invisible..
1466 @deffn Command iconify-frame &optional frame
1467 This function iconifies frame @var{frame}. If you omit @var{frame}, it
1468 iconifies the selected frame.
1471 @defun frame-visible-p frame
1472 This returns the visibility status of frame @var{frame}. The value is
1473 @code{t} if @var{frame} is visible, @code{nil} if it is invisible, and
1474 @code{icon} if it is iconified.
1476 On a text-only terminal, all frames are considered visible, whether
1477 they are currently being displayed or not, and this function returns
1478 @code{t} for all frames.
1481 The visibility status of a frame is also available as a frame
1482 parameter. You can read or change it as such. @xref{Management
1485 The user can iconify and deiconify frames with the window manager.
1486 This happens below the level at which Emacs can exert any control, but
1487 Emacs does provide events that you can use to keep track of such
1488 changes. @xref{Misc Events}.
1490 @node Raising and Lowering
1491 @section Raising and Lowering Frames
1493 Most window systems use a desktop metaphor. Part of this metaphor is
1494 the idea that windows are stacked in a notional third dimension
1495 perpendicular to the screen surface, and thus ordered from ``highest''
1496 to ``lowest.'' Where two windows overlap, the one higher up covers
1497 the one underneath. Even a window at the bottom of the stack can be
1498 seen if no other window overlaps it.
1500 @c @cindex raising a frame redundant with raise-frame
1501 @cindex lowering a frame
1502 A window's place in this ordering is not fixed; in fact, users tend
1503 to change the order frequently. @dfn{Raising} a window means moving
1504 it ``up,'' to the top of the stack. @dfn{Lowering} a window means
1505 moving it to the bottom of the stack. This motion is in the notional
1506 third dimension only, and does not change the position of the window
1509 With Emacs, frames constitute the windows in the metaphor sketched
1510 above. You can raise and lower frames using these functions:
1512 @deffn Command raise-frame &optional frame
1513 This function raises frame @var{frame} (default, the selected frame).
1514 If @var{frame} is invisible or iconified, this makes it visible.
1517 @deffn Command lower-frame &optional frame
1518 This function lowers frame @var{frame} (default, the selected frame).
1521 @defopt minibuffer-auto-raise
1522 If this is non-@code{nil}, activation of the minibuffer raises the frame
1523 that the minibuffer window is in.
1526 You can also enable auto-raise (raising automatically when a frame is
1527 selected) or auto-lower (lowering automatically when it is deselected)
1528 for any frame using frame parameters. @xref{Management Parameters}.
1530 @node Frame Configurations
1531 @section Frame Configurations
1532 @cindex frame configuration
1534 A @dfn{frame configuration} records the current arrangement of frames,
1535 all their properties, and the window configuration of each one.
1536 (@xref{Window Configurations}.)
1538 @defun current-frame-configuration
1539 This function returns a frame configuration list that describes
1540 the current arrangement of frames and their contents.
1543 @defun set-frame-configuration configuration &optional nodelete
1544 This function restores the state of frames described in
1545 @var{configuration}. However, this function does not restore deleted
1548 Ordinarily, this function deletes all existing frames not listed in
1549 @var{configuration}. But if @var{nodelete} is non-@code{nil}, the
1550 unwanted frames are iconified instead.
1553 @node Mouse Tracking
1554 @section Mouse Tracking
1555 @cindex mouse tracking
1556 @c @cindex tracking the mouse Duplicates track-mouse
1558 Sometimes it is useful to @dfn{track} the mouse, which means to display
1559 something to indicate where the mouse is and move the indicator as the
1560 mouse moves. For efficient mouse tracking, you need a way to wait until
1561 the mouse actually moves.
1563 The convenient way to track the mouse is to ask for events to represent
1564 mouse motion. Then you can wait for motion by waiting for an event. In
1565 addition, you can easily handle any other sorts of events that may
1566 occur. That is useful, because normally you don't want to track the
1567 mouse forever---only until some other event, such as the release of a
1570 @defspec track-mouse body@dots{}
1571 This special form executes @var{body}, with generation of mouse motion
1572 events enabled. Typically, @var{body} would use @code{read-event} to
1573 read the motion events and modify the display accordingly. @xref{Motion
1574 Events}, for the format of mouse motion events.
1576 The value of @code{track-mouse} is that of the last form in @var{body}.
1577 You should design @var{body} to return when it sees the up-event that
1578 indicates the release of the button, or whatever kind of event means
1579 it is time to stop tracking.
1582 The usual purpose of tracking mouse motion is to indicate on the screen
1583 the consequences of pushing or releasing a button at the current
1586 In many cases, you can avoid the need to track the mouse by using
1587 the @code{mouse-face} text property (@pxref{Special Properties}).
1588 That works at a much lower level and runs more smoothly than
1589 Lisp-level mouse tracking.
1592 @c These are not implemented yet.
1594 These functions change the screen appearance instantaneously. The
1595 effect is transient, only until the next ordinary Emacs redisplay. That
1596 is OK for mouse tracking, since it doesn't make sense for mouse tracking
1597 to change the text, and the body of @code{track-mouse} normally reads
1598 the events itself and does not do redisplay.
1600 @defun x-contour-region window beg end
1601 This function draws lines to make a box around the text from @var{beg}
1602 to @var{end}, in window @var{window}.
1605 @defun x-uncontour-region window beg end
1606 This function erases the lines that would make a box around the text
1607 from @var{beg} to @var{end}, in window @var{window}. Use it to remove
1608 a contour that you previously made by calling @code{x-contour-region}.
1611 @defun x-draw-rectangle frame left top right bottom
1612 This function draws a hollow rectangle on frame @var{frame} with the
1613 specified edge coordinates, all measured in pixels from the inside top
1614 left corner. It uses the cursor color, the one used for indicating the
1618 @defun x-erase-rectangle frame left top right bottom
1619 This function erases a hollow rectangle on frame @var{frame} with the
1620 specified edge coordinates, all measured in pixels from the inside top
1621 left corner. Erasure means redrawing the text and background that
1622 normally belong in the specified rectangle.
1626 @node Mouse Position
1627 @section Mouse Position
1628 @cindex mouse position
1629 @cindex position of mouse
1631 The functions @code{mouse-position} and @code{set-mouse-position}
1632 give access to the current position of the mouse.
1634 @defun mouse-position
1635 This function returns a description of the position of the mouse. The
1636 value looks like @code{(@var{frame} @var{x} . @var{y})}, where @var{x}
1637 and @var{y} are integers giving the position in characters relative to
1638 the top left corner of the inside of @var{frame}.
1641 @defvar mouse-position-function
1642 If non-@code{nil}, the value of this variable is a function for
1643 @code{mouse-position} to call. @code{mouse-position} calls this
1644 function just before returning, with its normal return value as the
1645 sole argument, and it returns whatever this function returns to it.
1647 This abnormal hook exists for the benefit of packages like
1648 @file{xt-mouse.el} that need to do mouse handling at the Lisp level.
1651 @defun set-mouse-position frame x y
1652 This function @dfn{warps the mouse} to position @var{x}, @var{y} in
1653 frame @var{frame}. The arguments @var{x} and @var{y} are integers,
1654 giving the position in characters relative to the top left corner of the
1655 inside of @var{frame}. If @var{frame} is not visible, this function
1656 does nothing. The return value is not significant.
1659 @defun mouse-pixel-position
1660 This function is like @code{mouse-position} except that it returns
1661 coordinates in units of pixels rather than units of characters.
1664 @defun set-mouse-pixel-position frame x y
1665 This function warps the mouse like @code{set-mouse-position} except that
1666 @var{x} and @var{y} are in units of pixels rather than units of
1667 characters. These coordinates are not required to be within the frame.
1669 If @var{frame} is not visible, this function does nothing. The return
1670 value is not significant.
1676 @section Pop-Up Menus
1678 When using a window system, a Lisp program can pop up a menu so that
1679 the user can choose an alternative with the mouse.
1681 @defun x-popup-menu position menu
1682 This function displays a pop-up menu and returns an indication of
1683 what selection the user makes.
1685 The argument @var{position} specifies where on the screen to put the
1686 top left corner of the menu. It can be either a mouse button event
1687 (which says to put the menu where the user actuated the button) or a
1691 ((@var{xoffset} @var{yoffset}) @var{window})
1695 where @var{xoffset} and @var{yoffset} are coordinates, measured in
1696 pixels, counting from the top left corner of @var{window}. @var{window}
1697 may be a window or a frame.
1699 If @var{position} is @code{t}, it means to use the current mouse
1700 position. If @var{position} is @code{nil}, it means to precompute the
1701 key binding equivalents for the keymaps specified in @var{menu},
1702 without actually displaying or popping up the menu.
1704 The argument @var{menu} says what to display in the menu. It can be a
1705 keymap or a list of keymaps (@pxref{Menu Keymaps}). In this case, the
1706 return value is the list of events corresponding to the user's choice.
1707 (This list has more than one element if the choice occurred in a
1708 submenu.) Note that @code{x-popup-menu} does not actually execute the
1709 command bound to that sequence of events.
1711 Alternatively, @var{menu} can have the following form:
1714 (@var{title} @var{pane1} @var{pane2}...)
1718 where each pane is a list of form
1721 (@var{title} @var{item1} @var{item2}...)
1724 Each item should normally be a cons cell @code{(@var{line} . @var{value})},
1725 where @var{line} is a string, and @var{value} is the value to return if
1726 that @var{line} is chosen. An item can also be a string; this makes a
1727 non-selectable line in the menu.
1729 If the user gets rid of the menu without making a valid choice, for
1730 instance by clicking the mouse away from a valid choice or by typing
1731 keyboard input, then this normally results in a quit and
1732 @code{x-popup-menu} does not return. But if @var{position} is a mouse
1733 button event (indicating that the user invoked the menu with the
1734 mouse) then no quit occurs and @code{x-popup-menu} returns @code{nil}.
1737 @strong{Usage note:} Don't use @code{x-popup-menu} to display a menu
1738 if you could do the job with a prefix key defined with a menu keymap.
1739 If you use a menu keymap to implement a menu, @kbd{C-h c} and @kbd{C-h
1740 a} can see the individual items in that menu and provide help for them.
1741 If instead you implement the menu by defining a command that calls
1742 @code{x-popup-menu}, the help facilities cannot know what happens inside
1743 that command, so they cannot give any help for the menu's items.
1745 The menu bar mechanism, which lets you switch between submenus by
1746 moving the mouse, cannot look within the definition of a command to see
1747 that it calls @code{x-popup-menu}. Therefore, if you try to implement a
1748 submenu using @code{x-popup-menu}, it cannot work with the menu bar in
1749 an integrated fashion. This is why all menu bar submenus are
1750 implemented with menu keymaps within the parent menu, and never with
1751 @code{x-popup-menu}. @xref{Menu Bar}.
1753 If you want a menu bar submenu to have contents that vary, you should
1754 still use a menu keymap to implement it. To make the contents vary, add
1755 a hook function to @code{menu-bar-update-hook} to update the contents of
1756 the menu keymap as necessary.
1759 @section Dialog Boxes
1760 @cindex dialog boxes
1762 A dialog box is a variant of a pop-up menu---it looks a little
1763 different, it always appears in the center of a frame, and it has just
1764 one level and one or more buttons. The main use of dialog boxes is
1765 for asking questions that the user can answer with ``yes,'' ``no,''
1766 and a few other alternatives. With a single button, they can also
1767 force the user to acknowledge important information. The functions
1768 @code{y-or-n-p} and @code{yes-or-no-p} use dialog boxes instead of the
1769 keyboard, when called from commands invoked by mouse clicks.
1771 @defun x-popup-dialog position contents &optional header
1772 This function displays a pop-up dialog box and returns an indication of
1773 what selection the user makes. The argument @var{contents} specifies
1774 the alternatives to offer; it has this format:
1777 (@var{title} (@var{string} . @var{value})@dots{})
1781 which looks like the list that specifies a single pane for
1782 @code{x-popup-menu}.
1784 The return value is @var{value} from the chosen alternative.
1786 As for @code{x-popup-menu}, an element of the list may be just a
1787 string instead of a cons cell @code{(@var{string} . @var{value})}.
1788 That makes a box that cannot be selected.
1790 If @code{nil} appears in the list, it separates the left-hand items from
1791 the right-hand items; items that precede the @code{nil} appear on the
1792 left, and items that follow the @code{nil} appear on the right. If you
1793 don't include a @code{nil} in the list, then approximately half the
1794 items appear on each side.
1796 Dialog boxes always appear in the center of a frame; the argument
1797 @var{position} specifies which frame. The possible values are as in
1798 @code{x-popup-menu}, but the precise coordinates or the individual
1799 window don't matter; only the frame matters.
1801 If @var{header} is non-@code{nil}, the frame title for the box is
1802 @samp{Information}, otherwise it is @samp{Question}. The former is used
1803 for @code{message-box} (@pxref{message-box}).
1805 In some configurations, Emacs cannot display a real dialog box; so
1806 instead it displays the same items in a pop-up menu in the center of the
1809 If the user gets rid of the dialog box without making a valid choice,
1810 for instance using the window manager, then this produces a quit and
1811 @code{x-popup-dialog} does not return.
1815 @section Pointer Shape
1816 @cindex pointer shape
1817 @cindex mouse pointer shape
1819 You can specify the mouse pointer style for particular text or
1820 images using the @code{pointer} text property, and for images with the
1821 @code{:pointer} and @code{:map} image properties. The values you can
1822 use in these properties are @code{text} (or @code{nil}), @code{arrow},
1823 @code{hand}, @code{vdrag}, @code{hdrag}, @code{modeline}, and
1824 @code{hourglass}. @code{text} stands for the usual mouse pointer
1825 style used over text.
1827 Over void parts of the window (parts that do not correspond to any
1828 of the buffer contents), the mouse pointer usually uses the
1829 @code{arrow} style, but you can specify a different style (one of
1830 those above) by setting @code{void-text-area-pointer}.
1832 @defvar void-text-area-pointer
1833 This variable specifies the mouse pointer style for void text areas.
1834 These include the areas after the end of a line or below the last line
1835 in the buffer. The default is to use the @code{arrow} (non-text)
1839 When using X, you can specify what the @code{text} pointer style
1840 really looks like by setting the variable @code{x-pointer-shape}.
1842 @defvar x-pointer-shape
1843 This variable specifies the pointer shape to use ordinarily in the
1844 Emacs frame, for the @code{text} pointer style.
1847 @defvar x-sensitive-text-pointer-shape
1848 This variable specifies the pointer shape to use when the mouse
1849 is over mouse-sensitive text.
1852 These variables affect newly created frames. They do not normally
1853 affect existing frames; however, if you set the mouse color of a
1854 frame, that also installs the current value of those two variables.
1855 @xref{Font and Color Parameters}.
1857 The values you can use, to specify either of these pointer shapes, are
1858 defined in the file @file{lisp/term/x-win.el}. Use @kbd{M-x apropos
1859 @key{RET} x-pointer @key{RET}} to see a list of them.
1861 @node Window System Selections
1862 @section Window System Selections
1863 @cindex selection (for window systems)
1865 The X server records a set of @dfn{selections} which permit transfer of
1866 data between application programs. The various selections are
1867 distinguished by @dfn{selection types}, represented in Emacs by
1868 symbols. X clients including Emacs can read or set the selection for
1871 @deffn Command x-set-selection type data
1872 This function sets a ``selection'' in the X server. It takes two
1873 arguments: a selection type @var{type}, and the value to assign to it,
1874 @var{data}. If @var{data} is @code{nil}, it means to clear out the
1875 selection. Otherwise, @var{data} may be a string, a symbol, an integer
1876 (or a cons of two integers or list of two integers), an overlay, or a
1877 cons of two markers pointing to the same buffer. An overlay or a pair
1878 of markers stands for text in the overlay or between the markers.
1880 The argument @var{data} may also be a vector of valid non-vector
1883 Each possible @var{type} has its own selection value, which changes
1884 independently. The usual values of @var{type} are @code{PRIMARY},
1885 @code{SECONDARY} and @code{CLIPBOARD}; these are symbols with upper-case
1886 names, in accord with X Window System conventions. If @var{type} is
1887 @code{nil}, that stands for @code{PRIMARY}.
1889 This function returns @var{data}.
1892 @defun x-get-selection &optional type data-type
1893 This function accesses selections set up by Emacs or by other X
1894 clients. It takes two optional arguments, @var{type} and
1895 @var{data-type}. The default for @var{type}, the selection type, is
1898 The @var{data-type} argument specifies the form of data conversion to
1899 use, to convert the raw data obtained from another X client into Lisp
1900 data. Meaningful values include @code{TEXT}, @code{STRING},
1901 @code{UTF8_STRING}, @code{TARGETS}, @code{LENGTH}, @code{DELETE},
1902 @code{FILE_NAME}, @code{CHARACTER_POSITION}, @code{NAME},
1903 @code{LINE_NUMBER}, @code{COLUMN_NUMBER}, @code{OWNER_OS},
1904 @code{HOST_NAME}, @code{USER}, @code{CLASS}, @code{ATOM}, and
1905 @code{INTEGER}. (These are symbols with upper-case names in accord
1906 with X conventions.) The default for @var{data-type} is
1911 The X server also has a set of eight numbered @dfn{cut buffers} which can
1912 store text or other data being moved between applications. Cut buffers
1913 are considered obsolete, but Emacs supports them for the sake of X
1914 clients that still use them. Cut buffers are numbered from 0 to 7.
1916 @defun x-get-cut-buffer &optional n
1917 This function returns the contents of cut buffer number @var{n}.
1918 If omitted @var{n} defaults to 0.
1921 @defun x-set-cut-buffer string &optional push
1922 @anchor{Definition of x-set-cut-buffer}
1923 This function stores @var{string} into the first cut buffer (cut buffer
1924 0). If @var{push} is @code{nil}, only the first cut buffer is changed.
1925 If @var{push} is non-@code{nil}, that says to move the values down
1926 through the series of cut buffers, much like the way successive kills in
1927 Emacs move down the kill ring. In other words, the previous value of
1928 the first cut buffer moves into the second cut buffer, and the second to
1929 the third, and so on through all eight cut buffers.
1932 @defvar selection-coding-system
1933 This variable specifies the coding system to use when reading and
1934 writing selections or the clipboard. @xref{Coding
1935 Systems}. The default is @code{compound-text-with-extensions}, which
1936 converts to the text representation that X11 normally uses.
1939 @cindex clipboard support (for MS-Windows)
1940 When Emacs runs on MS-Windows, it does not implement X selections in
1941 general, but it does support the clipboard. @code{x-get-selection}
1942 and @code{x-set-selection} on MS-Windows support the text data type
1943 only; if the clipboard holds other types of data, Emacs treats the
1946 @defopt x-select-enable-clipboard
1947 If this is non-@code{nil}, the Emacs yank functions consult the
1948 clipboard before the primary selection, and the kill functions store in
1949 the clipboard as well as the primary selection. Otherwise they do not
1950 access the clipboard at all. The default is @code{nil} on most systems,
1951 but @code{t} on MS-Windows.
1955 @section Drag and Drop
1957 @vindex x-dnd-test-function
1958 @vindex x-dnd-known-types
1959 When a user drags something from another application over Emacs, that other
1960 application expects Emacs to tell it if Emacs can handle the data that is
1961 dragged. The variable @code{x-dnd-test-function} is used by Emacs to determine
1962 what to reply. The default value is @code{x-dnd-default-test-function}
1963 which accepts drops if the type of the data to be dropped is present in
1964 @code{x-dnd-known-types}. You can customize @code{x-dnd-test-function} and/or
1965 @code{x-dnd-known-types} if you want Emacs to accept or reject drops based
1966 on some other criteria.
1968 @vindex x-dnd-types-alist
1969 If you want to change the way Emacs handles drop of different types
1970 or add a new type, customize @code{x-dnd-types-alist}. This requires
1971 detailed knowledge of what types other applications use for drag and
1974 @vindex dnd-protocol-alist
1975 When an URL is dropped on Emacs it may be a file, but it may also be
1976 another URL type (ftp, http, etc.). Emacs first checks
1977 @code{dnd-protocol-alist} to determine what to do with the URL. If
1978 there is no match there and if @code{browse-url-browser-function} is
1979 an alist, Emacs looks for a match there. If no match is found the
1980 text for the URL is inserted. If you want to alter Emacs behavior,
1981 you can customize these variables.
1984 @section Color Names
1987 @cindex specify color
1988 @cindex numerical RGB color specification
1989 A color name is text (usually in a string) that specifies a color.
1990 Symbolic names such as @samp{black}, @samp{white}, @samp{red}, etc.,
1991 are allowed; use @kbd{M-x list-colors-display} to see a list of
1992 defined names. You can also specify colors numerically in forms such
1993 as @samp{#@var{rgb}} and @samp{RGB:@var{r}/@var{g}/@var{b}}, where
1994 @var{r} specifies the red level, @var{g} specifies the green level,
1995 and @var{b} specifies the blue level. You can use either one, two,
1996 three, or four hex digits for @var{r}; then you must use the same
1997 number of hex digits for all @var{g} and @var{b} as well, making
1998 either 3, 6, 9 or 12 hex digits in all. (See the documentation of the
1999 X Window System for more details about numerical RGB specification of
2002 These functions provide a way to determine which color names are
2003 valid, and what they look like. In some cases, the value depends on the
2004 @dfn{selected frame}, as described below; see @ref{Input Focus}, for the
2005 meaning of the term ``selected frame.''
2007 To read user input of color names with completion, use
2008 @code{read-color} (@pxref{High-Level Completion, read-color}).
2010 @defun color-defined-p color &optional frame
2011 This function reports whether a color name is meaningful. It returns
2012 @code{t} if so; otherwise, @code{nil}. The argument @var{frame} says
2013 which frame's display to ask about; if @var{frame} is omitted or
2014 @code{nil}, the selected frame is used.
2016 Note that this does not tell you whether the display you are using
2017 really supports that color. When using X, you can ask for any defined
2018 color on any kind of display, and you will get some result---typically,
2019 the closest it can do. To determine whether a frame can really display
2020 a certain color, use @code{color-supported-p} (see below).
2022 @findex x-color-defined-p
2023 This function used to be called @code{x-color-defined-p},
2024 and that name is still supported as an alias.
2027 @defun defined-colors &optional frame
2028 This function returns a list of the color names that are defined
2029 and supported on frame @var{frame} (default, the selected frame).
2030 If @var{frame} does not support colors, the value is @code{nil}.
2032 @findex x-defined-colors
2033 This function used to be called @code{x-defined-colors},
2034 and that name is still supported as an alias.
2037 @defun color-supported-p color &optional frame background-p
2038 This returns @code{t} if @var{frame} can really display the color
2039 @var{color} (or at least something close to it). If @var{frame} is
2040 omitted or @code{nil}, the question applies to the selected frame.
2042 Some terminals support a different set of colors for foreground and
2043 background. If @var{background-p} is non-@code{nil}, that means you are
2044 asking whether @var{color} can be used as a background; otherwise you
2045 are asking whether it can be used as a foreground.
2047 The argument @var{color} must be a valid color name.
2050 @defun color-gray-p color &optional frame
2051 This returns @code{t} if @var{color} is a shade of gray, as defined on
2052 @var{frame}'s display. If @var{frame} is omitted or @code{nil}, the
2053 question applies to the selected frame. If @var{color} is not a valid
2054 color name, this function returns @code{nil}.
2057 @defun color-values color &optional frame
2059 This function returns a value that describes what @var{color} should
2060 ideally look like on @var{frame}. If @var{color} is defined, the
2061 value is a list of three integers, which give the amount of red, the
2062 amount of green, and the amount of blue. Each integer ranges in
2063 principle from 0 to 65535, but some displays may not use the full
2064 range. This three-element list is called the @dfn{rgb values} of the
2067 If @var{color} is not defined, the value is @code{nil}.
2070 (color-values "black")
2072 (color-values "white")
2073 @result{} (65280 65280 65280)
2074 (color-values "red")
2075 @result{} (65280 0 0)
2076 (color-values "pink")
2077 @result{} (65280 49152 51968)
2078 (color-values "hungry")
2082 The color values are returned for @var{frame}'s display. If
2083 @var{frame} is omitted or @code{nil}, the information is returned for
2084 the selected frame's display. If the frame cannot display colors, the
2085 value is @code{nil}.
2087 @findex x-color-values
2088 This function used to be called @code{x-color-values},
2089 and that name is still supported as an alias.
2092 @node Text Terminal Colors
2093 @section Text Terminal Colors
2094 @cindex colors on text-only terminals
2096 Text-only terminals usually support only a small number of colors,
2097 and the computer uses small integers to select colors on the terminal.
2098 This means that the computer cannot reliably tell what the selected
2099 color looks like; instead, you have to inform your application which
2100 small integers correspond to which colors. However, Emacs does know
2101 the standard set of colors and will try to use them automatically.
2103 The functions described in this section control how terminal colors
2106 Several of these functions use or return @dfn{rgb values}, described
2107 in @ref{Color Names}.
2109 These functions accept a display (either a frame or the name of a
2110 terminal) as an optional argument. We hope in the future to make Emacs
2111 support more than one text-only terminal at one time; then this argument
2112 will specify which terminal to operate on (the default being the
2113 selected frame's terminal; @pxref{Input Focus}). At present, though,
2114 the @var{frame} argument has no effect.
2116 @defun tty-color-define name number &optional rgb frame
2117 This function associates the color name @var{name} with
2118 color number @var{number} on the terminal.
2120 The optional argument @var{rgb}, if specified, is an rgb value, a list
2121 of three numbers that specify what the color actually looks like.
2122 If you do not specify @var{rgb}, then this color cannot be used by
2123 @code{tty-color-approximate} to approximate other colors, because
2124 Emacs will not know what it looks like.
2127 @defun tty-color-clear &optional frame
2128 This function clears the table of defined colors for a text-only terminal.
2131 @defun tty-color-alist &optional frame
2132 This function returns an alist recording the known colors supported by a
2135 Each element has the form @code{(@var{name} @var{number} . @var{rgb})}
2136 or @code{(@var{name} @var{number})}. Here, @var{name} is the color
2137 name, @var{number} is the number used to specify it to the terminal.
2138 If present, @var{rgb} is a list of three color values (for red, green,
2139 and blue) that says what the color actually looks like.
2142 @defun tty-color-approximate rgb &optional frame
2143 This function finds the closest color, among the known colors
2144 supported for @var{display}, to that described by the rgb value
2145 @var{rgb} (a list of color values). The return value is an element of
2146 @code{tty-color-alist}.
2149 @defun tty-color-translate color &optional frame
2150 This function finds the closest color to @var{color} among the known
2151 colors supported for @var{display} and returns its index (an integer).
2152 If the name @var{color} is not defined, the value is @code{nil}.
2156 @section X Resources
2158 @defun x-get-resource attribute class &optional component subclass
2159 The function @code{x-get-resource} retrieves a resource value from the X
2160 Window defaults database.
2162 Resources are indexed by a combination of a @dfn{key} and a @dfn{class}.
2163 This function searches using a key of the form
2164 @samp{@var{instance}.@var{attribute}} (where @var{instance} is the name
2165 under which Emacs was invoked), and using @samp{Emacs.@var{class}} as
2168 The optional arguments @var{component} and @var{subclass} add to the key
2169 and the class, respectively. You must specify both of them or neither.
2170 If you specify them, the key is
2171 @samp{@var{instance}.@var{component}.@var{attribute}}, and the class is
2172 @samp{Emacs.@var{class}.@var{subclass}}.
2175 @defvar x-resource-class
2176 This variable specifies the application name that @code{x-get-resource}
2177 should look up. The default value is @code{"Emacs"}. You can examine X
2178 resources for application names other than ``Emacs'' by binding this
2179 variable to some other string, around a call to @code{x-get-resource}.
2182 @defvar x-resource-name
2183 This variable specifies the instance name that @code{x-get-resource}
2184 should look up. The default value is the name Emacs was invoked with,
2185 or the value specified with the @samp{-name} or @samp{-rn} switches.
2188 To illustrate some of the above, suppose that you have the line:
2191 xterm.vt100.background: yellow
2195 in your X resources file (whose name is usually @file{~/.Xdefaults}
2196 or @file{~/.Xresources}). Then:
2200 (let ((x-resource-class "XTerm") (x-resource-name "xterm"))
2201 (x-get-resource "vt100.background" "VT100.Background"))
2205 (let ((x-resource-class "XTerm") (x-resource-name "xterm"))
2206 (x-get-resource "background" "VT100" "vt100" "Background"))
2211 @xref{X Resources,, X Resources, emacs, The GNU Emacs Manual}.
2213 @node Display Feature Testing
2214 @section Display Feature Testing
2215 @cindex display feature testing
2217 The functions in this section describe the basic capabilities of a
2218 particular display. Lisp programs can use them to adapt their behavior
2219 to what the display can do. For example, a program that ordinarily uses
2220 a popup menu could use the minibuffer if popup menus are not supported.
2222 The optional argument @var{display} in these functions specifies which
2223 display to ask the question about. It can be a display name, a frame
2224 (which designates the display that frame is on), or @code{nil} (which
2225 refers to the selected frame's display, @pxref{Input Focus}).
2227 @xref{Color Names}, @ref{Text Terminal Colors}, for other functions to
2228 obtain information about displays.
2230 @defun display-popup-menus-p &optional display
2231 This function returns @code{t} if popup menus are supported on
2232 @var{display}, @code{nil} if not. Support for popup menus requires that
2233 the mouse be available, since the user cannot choose menu items without
2237 @defun display-graphic-p &optional display
2238 This function returns @code{t} if @var{display} is a graphic display
2239 capable of displaying several frames and several different fonts at
2240 once. This is true for displays that use a window system such as X, and
2241 false for text-only terminals.
2244 @defun display-mouse-p &optional display
2245 @cindex mouse, availability
2246 This function returns @code{t} if @var{display} has a mouse available,
2250 @defun display-color-p &optional display
2251 @findex x-display-color-p
2252 This function returns @code{t} if the screen is a color screen.
2253 It used to be called @code{x-display-color-p}, and that name
2254 is still supported as an alias.
2257 @defun display-grayscale-p &optional display
2258 This function returns @code{t} if the screen can display shades of gray.
2259 (All color displays can do this.)
2262 @defun display-supports-face-attributes-p attributes &optional display
2263 @anchor{Display Face Attribute Testing}
2264 This function returns non-@code{nil} if all the face attributes in
2265 @var{attributes} are supported (@pxref{Face Attributes}).
2267 The definition of `supported' is somewhat heuristic, but basically
2268 means that a face containing all the attributes in @var{attributes},
2269 when merged with the default face for display, can be represented in a
2274 different in appearance than the default face, and
2277 `close in spirit' to what the attributes specify, if not exact.
2280 Point (2) implies that a @code{:weight black} attribute will be
2281 satisfied by any display that can display bold, as will
2282 @code{:foreground "yellow"} as long as some yellowish color can be
2283 displayed, but @code{:slant italic} will @emph{not} be satisfied by
2284 the tty display code's automatic substitution of a `dim' face for
2288 @defun display-selections-p &optional display
2289 This function returns @code{t} if @var{display} supports selections.
2290 Windowed displays normally support selections, but they may also be
2291 supported in some other cases.
2294 @defun display-images-p &optional display
2295 This function returns @code{t} if @var{display} can display images.
2296 Windowed displays ought in principle to handle images, but some
2297 systems lack the support for that. On a display that does not support
2298 images, Emacs cannot display a tool bar.
2301 @defun display-screens &optional display
2302 This function returns the number of screens associated with the display.
2305 @defun display-pixel-height &optional display
2306 This function returns the height of the screen in pixels.
2307 On a character terminal, it gives the height in characters.
2309 For graphical terminals, note that on ``multi-monitor'' setups this
2310 refers to the pixel width for all physical monitors associated with
2311 @var{display}. @xref{Multiple Terminals}.
2314 @defun display-pixel-width &optional display
2315 This function returns the width of the screen in pixels.
2316 On a character terminal, it gives the width in characters.
2318 For graphical terminals, note that on ``multi-monitor'' setups this
2319 refers to the pixel width for all physical monitors associated with
2320 @var{display}. @xref{Multiple Terminals}.
2323 @defun display-mm-height &optional display
2324 This function returns the height of the screen in millimeters,
2325 or @code{nil} if Emacs cannot get that information.
2328 @defun display-mm-width &optional display
2329 This function returns the width of the screen in millimeters,
2330 or @code{nil} if Emacs cannot get that information.
2333 @defvar display-mm-dimensions-alist
2334 This variable allows the user to specify the dimensions of graphical
2335 displays returned by @code{display-mm-height} and
2336 @code{display-mm-width} in case the system provides incorrect values.
2339 @defun display-backing-store &optional display
2340 This function returns the backing store capability of the display.
2341 Backing store means recording the pixels of windows (and parts of
2342 windows) that are not exposed, so that when exposed they can be
2343 displayed very quickly.
2345 Values can be the symbols @code{always}, @code{when-mapped}, or
2346 @code{not-useful}. The function can also return @code{nil}
2347 when the question is inapplicable to a certain kind of display.
2350 @defun display-save-under &optional display
2351 This function returns non-@code{nil} if the display supports the
2352 SaveUnder feature. That feature is used by pop-up windows
2353 to save the pixels they obscure, so that they can pop down
2357 @defun display-planes &optional display
2358 This function returns the number of planes the display supports.
2359 This is typically the number of bits per pixel.
2360 For a tty display, it is log to base two of the number of colors supported.
2363 @defun display-visual-class &optional display
2364 This function returns the visual class for the screen. The value is one
2365 of the symbols @code{static-gray}, @code{gray-scale},
2366 @code{static-color}, @code{pseudo-color}, @code{true-color}, and
2367 @code{direct-color}.
2370 @defun display-color-cells &optional display
2371 This function returns the number of color cells the screen supports.
2374 These functions obtain additional information specifically
2377 @defun x-server-version &optional display
2378 This function returns the list of version numbers of the X server
2379 running the display. The value is a list of three integers: the major
2380 and minor version numbers of the X protocol, and the
2381 distributor-specific release number of the X server software itself.
2384 @defun x-server-vendor &optional display
2385 This function returns the ``vendor'' that provided the X server
2386 software (as a string). Really this means whoever distributes the X
2389 When the developers of X labelled software distributors as
2390 ``vendors,'' they showed their false assumption that no system could
2391 ever be developed and distributed noncommercially.
2395 @defvar x-no-window-manager
2396 This variable's value is @code{t} if no X window manager is in use.
2402 The functions @code{x-pixel-width} and @code{x-pixel-height} return the
2403 width and height of an X Window frame, measured in pixels.
2408 arch-tag: 94977df6-3dca-4730-b57b-c6329e9282ba