Frames
A frame is a screen object that contains one or more Emacs windows (Windows). It is the kind of object called a "window" in the terminology of graphical environments; but we can't call it a "window" here, because Emacs uses that word in a different way. In Emacs Lisp, a frame object is a Lisp object that represents a frame on the screen. Frame Type. A frame initially contains a single main window and/or a minibuffer window; you can subdivide the main window vertically or horizontally into smaller windows. Splitting Windows. A terminal is a display device capable of displaying one or more Emacs frames. In Emacs Lisp, a terminal object is a Lisp object that represents a terminal. Terminal Type. There are two classes of terminals: text terminals and graphical terminals. Text terminals are non-graphics-capable displays, including xterm and other terminal emulators. On a text terminal, each Emacs frame occupies the terminal's entire screen; although you can create additional frames and switch between them, the terminal only shows one frame at a time. Graphical terminals, on the other hand, are managed by graphical display systems such as the X Window System, which allow Emacs to show multiple frames simultaneously on the same display. On GNU and Unix systems, you can create additional frames on any available terminal, within a single Emacs session, regardless of whether Emacs was started on a text or graphical terminal. Emacs can display on both graphical and text terminals simultaneously. This comes in handy, for instance, when you connect to the same session from several remote locations. Multiple Terminals.
-
framep - This predicate returns a non-
nilvalue if object is a frame, andnilotherwise. For a frame, the value indicates which kind of display the frame uses: -
t - The frame is displayed on a text terminal.
-
x - The frame is displayed on an X graphical terminal.
-
w32 - The frame is displayed on a MS-Windows graphical terminal.
-
ns - The frame is displayed on a GNUstep or Macintosh Cocoa graphical terminal.
-
pc - The frame is displayed on an MS-DOS terminal.
-
pgtk - The frame is displayed using pure GTK facilities.
-
frame-terminal - This function returns the terminal object that displays frame. If frame is
nilor unspecified, it defaults to the selected frame. -
terminal-live-p - This predicate returns a non-
nilvalue if object is a terminal that is live (i.e., not deleted), andnilotherwise. For live terminals, the return value indicates what kind of frames are displayed on that terminal; the list of possible values is the same as forframepabove.
On a graphical terminal we distinguish two types of frames: A normal top-level frame is a frame whose window-system window is a child of the window-system's root window for that terminal. A child frame is a frame whose window-system window is the child of the window-system window of another Emacs frame. Child Frames.
Creating Frames
To create a new frame, call the function make-frame.
-
Command make-frame - This function creates and returns a new frame, displaying the current buffer. The parameters argument is an alist that specifies frame parameters for the new frame. Frame Parameters. If you specify the
terminalparameter in parameters, the new frame is created on that terminal. Otherwise, if you specify thewindow-systemframe parameter in parameters, that determines whether the frame should be displayed on a text terminal or a graphical terminal. Window Systems. If neither is specified, the new frame is created in the same terminal as the selected frame. Any parameters not mentioned in parameters default to the values in the alistdefault-frame-alist(Initial Parameters); parameters not specified there default from the X resources or its equivalent on your operating system (X Resources). After the frame is created, this function applies any parameters specified inframe-inherited-parameters(see below) it has no assigned yet, taking the values from the frame that was selected whenmake-framewas called. Note that on multi-monitor displays (Multiple Terminals), the window manager might position the frame differently than specified by the positional parameters in parameters (Position Parameters). For example, some window managers have a policy of displaying the frame on the monitor that contains the largest part of the window (a.k.a. the dominating monitor). This function itself does not make the new frame the selected frame. Input Focus. The previously selected frame remains selected. On graphical terminals, however, the window system may select the new frame for its own reasons. -
before-make-frame-hook - A normal hook run by
make-framebefore it creates the frame. -
after-make-frame-functions - An abnormal hook run by
make-frameafter it created the frame. Each function inafter-make-frame-functionsreceives one argument, the frame just created.
Note that any functions added to these hooks by your initial file are usually not run for the initial frame, since Emacs reads the initial file only after creating that frame. However, if the initial frame is specified to use a separate minibuffer frame (Minibuffers and Frames), the functions will be run for both, the minibuffer-less and the minibuffer frame. Alternatively, you can add functions to these hooks in your "early init file" (Init File), in which case they will be in effect for the initial frame as well.
-
frame-inherited-parameters - This variable specifies the list of frame parameters that a newly created frame inherits from the currently selected frame. For each parameter (a symbol) that is an element in this list and has not been assigned earlier when processing
make-frame, the function sets the value of that parameter in the created frame to its value in the selected frame. -
server-after-make-frame-hook - A normal hook run when the Emacs server starts using a client frame. When this hook is called, the client frame is the selected one. Note that, depending on how
emacsclientwas invoked (Invoking emacsclient), this client frame could be a new frame created for the client, or it could be an existing frame that the server reused for handling the client commands. Emacs Server.
Multiple Terminals
Emacs represents each terminal as a terminal object data type (Terminal Type). On GNU and Unix systems, Emacs can use multiple terminals simultaneously in each session. On other systems, it can only use a single terminal. Each terminal object has the following attributes:
- The name of the device used by the terminal (e.g.,
:0.0or/dev/tty). - The terminal and keyboard coding systems used on the terminal. Terminal I/O Encoding.
- The kind of display associated with the terminal. This is the symbol returned by the function
terminal-live-p(i.e.,x,t,w32,ns,pc,haiku, orpgtk). Frames. - A list of terminal parameters. Terminal Parameters.
There is no primitive for creating terminal objects. Emacs creates them as needed, such as when you call make-frame-on-display (described below).
-
terminal-name - This function returns the file name of the device used by terminal. If terminal is omitted or
nil, it defaults to the selected frame's terminal. terminal can also be a frame, meaning that frame's terminal. -
terminal-list - This function returns a list of all live terminal objects.
-
get-device-terminal - This function returns a terminal whose device name is given by device. If device is a string, it can be either the file name of a terminal device, or the name of an X display of the form
HOST:SERVER.SCREEN. If device is a frame, this function returns that frame's terminal;nilmeans the selected frame. Finally, if device is a terminal object that represents a live terminal, that terminal is returned. The function signals an error if its argument is none of the above. -
delete-terminal - This function deletes all frames on terminal and frees the resources used by it. It runs the abnormal hook
delete-terminal-functions, passing terminal as the argument to each function. If terminal is omitted ornil, it defaults to the selected frame's terminal. terminal can also be a frame, meaning that frame's terminal. Normally, this function signals an error if you attempt to delete the sole active terminal, but if force is non-nil, you are allowed to do so. Emacs automatically calls this function when the last frame on a terminal is deleted (Deleting Frames). -
delete-terminal-functions - An abnormal hook run by
delete-terminal. Each function receives one argument, the terminal argument passed todelete-terminal. Due to technical details, the functions may be called either just before the terminal is deleted, or just afterwards.
A few Lisp variables are terminal-local; that is, they have a separate binding for each terminal. The binding in effect at any time is the one for the terminal that the currently selected frame belongs to. These variables include default-minibuffer-frame, defining-kbd-macro, last-kbd-macro, and system-key-alist. They are always terminal-local, and can never be buffer-local (Buffer-Local Variables). On GNU and Unix systems, each X display is a separate graphical terminal. When Emacs is started from within the X window system, it uses the X display specified by the DISPLAY environment variable, or by the --display option (Initial Options). Emacs can connect to other X displays via the command make-frame-on-display. Each X display has its own selected frame and its own minibuffer windows; however, only one of those frames is the selected frame at any given moment (Input Focus). Emacs can even connect to other text terminals, by interacting with the emacsclient program. Emacs Server. A single X server can handle more than one display. Each X display has a three-part name, HOSTNAME:DISPLAYNUMBER.SCREENNUMBER. The first part, hostname, specifies the name of the machine to which the display is physically connected. The second part, displaynumber, is a zero-based number that identifies one or more monitors connected to that machine that share a common keyboard and pointing device (mouse, tablet, etc.). The third part, screennumber, identifies a zero-based screen number (a separate monitor) that is part of a single monitor collection on that X server. When you use two or more screens belonging to one server, Emacs knows by the similarity in their names that they share a single keyboard. Systems that don't use the X window system, such as MS-Windows, don't support the notion of X displays, and have only one display on each host. The display name on these systems doesn't follow the above 3-part format; for example, the display name on MS-Windows systems is a constant string w32, and exists for compatibility, so that you could pass it to functions that expect a display name.
-
Command make-frame-on-display - This function creates and returns a new frame on display, taking the other frame parameters from the alist parameters. display should be the name of an X display (a string). Before creating the frame, this function ensures that Emacs is set up to display graphics. For instance, if Emacs has not processed X resources (e.g., if it was started on a text terminal), it does so at this time. In all other respects, this function behaves like
make-frame(Creating Frames). -
x-display-list - This function returns a list that indicates which X displays Emacs has a connection to. The elements of the list are strings, and each one is a display name.
-
x-open-connection - This function opens a connection to the X display display, without creating a frame on that display. Normally, Emacs Lisp programs need not call this function, as
make-frame-on-displaycalls it automatically. The only reason for calling it is to check whether communication can be established with a given X display. The optional argument xrm-string, if notnil, is a string of resource names and values, in the same format used in the.Xresourcesfile. X Resources. These values apply to all Emacs frames created on this display, overriding the resource values recorded in the X server. Here's an example of what this string might look like:
"*BorderWidth: 3\n*InternalBorder: 2\n"
If must-succeed is non-nil, failure to open the connection terminates Emacs. Otherwise, it is an ordinary Lisp error.
-
x-close-connection - This function closes the connection to display display. Before you can do this, you must first delete all the frames that were open on that display (Deleting Frames).
On some multi-monitor setups, a single X display outputs to more than one physical monitor. You can use the functions display-monitor-attributes-list and frame-monitor-attributes to obtain information about such setups.
-
display-monitor-attributes-list - This function returns a list of physical monitor attributes on display, which can be a display name (a string), a terminal, or a frame; if omitted or
nil, it defaults to the selected frame's display. Each element of the list is an association list, representing the attributes of a physical monitor. The first element corresponds to the primary monitor. The attribute keys and values are: -
geometry - Position of the top-left corner of the monitor's screen and its size, in pixels, as
(X Y WIDTH HEIGHT). Note that, if the monitor is not the primary monitor, some of the coordinates might be negative. -
workarea - Position of the top-left corner and size of the work area (usable space) in pixels as
(X Y WIDTH HEIGHT). This may be different fromgeometryin that space occupied by various window manager features (docks, taskbars, etc.) may be excluded from the work area. Whether or not such features actually subtract from the work area depends on the platform and environment. Again, if the monitor is not the primary monitor, some of the coordinates might be negative. -
mm-size - Width and height in millimeters as
(WIDTH HEIGHT) -
frames - List of frames that this physical monitor dominates (see below).
-
name - Name of the physical monitor as string.
-
source - Source of the multi-monitor information as string; e.g.,
XRandR 1.5,XRandrorXinerama.
x, y, width, and height are integers. name and source may be absent. A frame is dominated by a physical monitor when either the largest area of the frame resides in that monitor, or (if the frame does not intersect any physical monitors) that monitor is the closest to the frame. Every (non-tooltip) frame (whether visible or not) in a graphical display is dominated by exactly one physical monitor at a time, though the frame can span multiple (or no) physical monitors. Here's an example of the data produced by this function on a 2-monitor display:
(display-monitor-attributes-list)
=>
(((geometry 0 0 1920 1080) ;; Left-hand
(workarea 0 0 1920 1050) ;; A taskbar occupies some of the height
(mm-size 677 381)
(name . "DISPLAY1")
(frames #<frame emacs@host *Messages* 0x11578c0>
#<frame emacs@host *scratch* 0x114b838>))
((geometry 1920 0 1680 1050) ;; Right-hand monitor
(workarea 1920 0 1680 1050) ;; Whole screen can be used
(mm-size 593 370)
(name . "DISPLAY2")
(frames)))-
frame-monitor-attributes - This function returns the attributes of the physical monitor dominating (see above) frame, which defaults to the selected frame.
On multi-monitor displays it is possible to use the command make-frame-on-monitor to make frames on the specified monitor.
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Command make-frame-on-monitor - This function creates and returns a new frame on monitor located on display, taking the other frame parameters from the alist parameters. monitor should be the name of the physical monitor, the same string as returned by the function
display-monitor-attributes-listin the attributename. display should be the name of an X display (a string). -
display-monitors-changed-functions - This variable is an abnormal hook run when the monitor configuration changes, which can happen if a monitor is rotated, moved, added or removed from a multiple-monitor setup, if the primary monitor changes, or if the resolution of a monitor changes. It is called with a single argument consisting of the terminal on which the monitor configuration changed. Programs should call
display-monitor-attributes-listwith the terminal as the argument to retrieve the new monitor configuration on that terminal.
Frame Geometry
The geometry of a frame depends on the toolkit that was used to build this instance of Emacs and the terminal that displays the frame. This chapter describes these dependencies and some of the functions to deal with them. Note that the frame argument of all of these functions has to specify a live frame (Deleting Frames). If omitted or nil, it specifies the selected frame (Input Focus).
Frame Layout
A visible frame occupies a rectangular area on its terminal's display. This area may contain a number of nested rectangles, each serving a different purpose. The drawing below sketches the layout of a frame on a graphical terminal:
<------------ Outer Frame Width ----------->
____________________________________________
^(0) ________ External/Outer Border _______ |
| | |_____________ Title Bar ______________| |
| | (1)_____________ Menu Bar ______________| | ^
| | (2)_____________ Tool Bar ______________| | ^
| | (3)_____________ Tab Bar _______________| | ^
| | | _________ Internal Border ________ | | ^
| | | | ^ | | | |
| | | | | | | | |
Outer | | | Inner | | | Native
Frame | | | Frame | | | Frame
Height | | | Height | | | Height
| | | | | | | | |
| | | |<--+--- Inner Frame Width ------->| | | |
| | | | | | | | |
| | | |___v______________________________| | | |
| | |___________ Internal Border __________| | v
v |___________ External/Outer Border __________|
<-------- Native Frame Width -------->
In practice not all of the areas shown in the drawing will or may be present. The meaning of these areas is described below.
- Outer Frame
- The outer frame is a rectangle comprising all areas shown in the drawing. The edges of that rectangle are called the outer edges of the frame. Together, the outer width and outer height of the frame specify the outer size of that rectangle. Knowing the outer size of a frame is useful for fitting a frame into the working area of its display (Multiple Terminals) or for placing two frames adjacent to each other on the screen. Usually, the outer size of a frame is available only after the frame has been mapped (made visible, Visibility of Frames) at least once. For the initial frame or a frame that has not been created yet, the outer size can be only estimated or must be calculated from the window-system's or window manager's defaults. One workaround is to obtain the differences of the outer and native (see below) sizes of a mapped frame and use them for calculating the outer size of the new frame. The position of the upper left corner of the outer frame (indicated by
(0)in the drawing above) is the outer position of the frame. The outer position of a graphical frame is also referred to as "the position" of the frame because it usually remains unchanged on its display whenever the frame is resized or its layout is changed. The outer position is specified by and can be set via theleftandtopframe parameters (Position Parameters). For a normal, top-level frame these parameters usually represent its absolute position (see below) with respect to its display's origin. For a child frame (Child Frames) these parameters represent its position relative to the native position (see below) of its parent frame. For frames on text terminals the values of these parameters are meaningless and always zero. - External Border
- The external border is part of the decorations supplied by the window manager. It is typically used for resizing the frame with the mouse and is therefore not shown on "fullboth" and maximized frames (Size Parameters). Its width is determined by the window manager and cannot be changed by Emacs' functions. External borders don't exist on text terminal frames. For graphical frames, their display can be suppressed by setting the
override-redirectorundecoratedframe parameter (Management Parameters). - Outer Border
- The outer border is a separate border whose width can be specified with the
border-widthframe parameter (Layout Parameters). In practice, either the external or the outer border of a frame are displayed but never both at the same time. Usually, the outer border is shown only for special frames that are not (fully) controlled by the window manager like tooltip frames (Tooltips), child frames (Child Frames) andundecoratedoroverride-redirectframes (Management Parameters). Outer borders are never shown on text terminal frames and on frames generated by GTK+ routines. On MS-Windows, the outer border is emulated with the help of a one pixel wide external border. Non-toolkit builds on X allow to change the color of the outer border by setting theborder-colorframe parameter (Layout Parameters). - Title Bar
- The title bar, a.k.a.@ caption bar, is also part of the window manager's decorations and typically displays the title of the frame (Frame Titles) as well as buttons for minimizing, maximizing and deleting the frame. It can be also used for dragging the frame with the mouse. The title bar is usually not displayed for fullboth (Size Parameters), tooltip (Tooltips) and child frames (Child Frames) and doesn't exist for terminal frames. Display of the title bar can be suppressed by setting the
override-redirector theundecoratedframe parameters (Management Parameters). - Menu Bar
- The menu bar (Menu Bar) can be either internal (drawn by Emacs itself) or external (drawn by the toolkit). Most builds (GTK+, Lucid, Motif and MS-Windows) rely on an external menu bar. NS also uses an external menu bar which, however, is not part of the outer frame. Non-toolkit builds can provide an internal menu bar. On text terminal frames, the menu bar is part of the frame's root window (Windows and Frames). As a rule, menu bars are never shown on child frames (Child Frames). Display of the menu bar can be suppressed by setting the
menu-bar-linesparameter (Layout Parameters) to zero. Whether the menu bar is wrapped or truncated whenever its width becomes too large to fit on its frame depends on the toolkit . Usually, only Motif and MS-Windows builds can wrap the menu bar. When they (un-)wrap the menu bar, they try to keep the outer height of the frame unchanged, so the native height of the frame (see below) will change instead. - Tool Bar
- Like the menu bar, the tool bar (Tool Bar) can be either internal (drawn by Emacs itself) or external (drawn by a toolkit). The GTK+ and NS builds have the tool bar drawn by the toolkit. The remaining builds use internal tool bars. With GTK+ the tool bar can be located on either side of the frame, immediately outside the internal border, see below. Tool bars are usually not shown for child frames (Child Frames). Display of the tool bar can be suppressed by setting the
tool-bar-linesparameter (Layout Parameters) to zero. If the variableauto-resize-tool-barsis non-nil, Emacs wraps the internal tool bar when its width becomes too large for its frame. If and when Emacs (un-)wraps the internal tool bar, it by default keeps the outer height of the frame unchanged, so the native height of the frame (see below) will change instead. Emacs built with GTK+, on the other hand, never wraps the tool bar but may automatically increase the outer width of a frame in order to accommodate an overlong tool bar. - Tab Bar
- The tab bar (Tab Bars) is always drawn by Emacs itself. The tab bar appears above the tool bar in Emacs built with an internal tool bar, and below the tool bar in builds with an external tool bar. Display of the tab bar can be suppressed by setting the
tab-bar-linesparameter (Layout Parameters) to zero. - Native Frame
- The native frame is a rectangle located entirely within the outer frame. It excludes the areas occupied by an external or outer border, the title bar and any external menu or tool bar. The edges of the native frame are called the native edges of the frame. Together, the native width and native height of a frame specify the native size of the frame. The native size of a frame is the size Emacs passes to the window-system or window manager when creating or resizing the frame from within Emacs. It is also the size Emacs receives from the window-system or window manager whenever these resize the frame's window-system window, for example, after maximizing the frame by clicking on the corresponding button in the title bar or when dragging its external border with the mouse. The position of the top left corner of the native frame specifies the native position of the frame. (1)–(3) in the drawing above indicate that position for the various builds:
- (1) non-toolkit, Haiku, and terminal frames
- (2) Lucid, Motif, and MS-Windows frames
- (3) GTK+ and NS frames
- Accordingly, the native height of a frame may include the height of the tool bar but not that of the menu bar (Lucid, Motif, MS-Windows) or those of the menu bar and the tool bar (non-toolkit and text terminal frames). The native position of a frame is the reference position for functions that set or return the current position of the mouse (Mouse Position) and for functions dealing with the position of windows like
window-edges,window-atorcoordinates-in-window-p(Coordinates and Windows). It also specifies the (0, 0) origin for locating and positioning child frames within this frame (Child Frames). Note also that the native position of a frame usually remains unaltered on its display when removing or adding the window manager decorations by changing the frame'soverride-redirectorundecoratedparameter (Management Parameters). - Internal Border
- The internal border is a border drawn by Emacs around the inner frame (see below). The specification of its appearance depends on whether or not the given frame is a child frame (Child Frames). For normal frames its width is specified by the
internal-border-widthframe parameter (Layout Parameters), and its color is specified by the background of theinternal-borderface. For child frames its width is specified by thechild-frame-border-widthframe parameter (but will use theinternal-border-widthparameter as fallback), and its color is specified by the background of thechild-frame-borderface. - Inner Frame
- The inner frame is the rectangle reserved for the frame's windows. It's enclosed by the internal border which, however, is not part of the inner frame. Its edges are called the inner edges of the frame. The inner width and inner height specify the inner size of the rectangle. The inner frame is sometimes also referred to as the display area of the frame. As a rule, the inner frame is subdivided into the frame's root window (Windows and Frames) and the frame's minibuffer window (Minibuffer Windows). There are two notable exceptions to this rule: A minibuffer-less frame contains a root window only and does not contain a minibuffer window. A minibuffer-only frame contains only a minibuffer window which also serves as that frame's root window. See Initial Parameters for how to create such frame configurations.
- Text Area
- The text area of a frame is a somewhat fictitious area that can be embedded in the native frame. Its position is unspecified. Its width can be obtained by removing from that of the native width the widths of the internal border, one vertical scroll bar, and one left and one right fringe if they are specified for this frame, see Layout Parameters. Its height can be obtained by removing from that of the native height the widths of the internal border and the heights of the frame's internal menu and tool bars, the tab bar and one horizontal scroll bar if specified for this frame.
The absolute position of a frame is given as a pair (X, Y) of horizontal and vertical pixel offsets relative to an origin (0, 0) of the frame's display. Correspondingly, the absolute edges of a frame are given as pixel offsets from that origin. Note that with multiple monitors, the origin of the display does not necessarily coincide with the top-left corner of the entire usable display area of the terminal. Hence the absolute position of a frame can be negative in such an environment even when that frame is completely visible. By convention, vertical offsets increase "downwards". This means that the height of a frame is obtained by subtracting the offset of its top edge from that of its bottom edge. Horizontal offsets increase "rightwards", as expected, so a frame's width is calculated by subtracting the offset of its left edge from that of its right edge. For a frame on a graphical terminal the following function returns the sizes of the areas described above:
-
frame-geometry - This function returns geometric attributes of frame. The return value is an association list of the attributes listed below. All coordinate, height and width values are integers counting pixels. Note that if frame has not been mapped yet, (Visibility of Frames) some of the return values may only represent approximations of the actual values—those that can be seen after the frame has been mapped.
-
outer-position - A cons representing the absolute position of the outer frame, relative to the origin at position (0, 0) of frame's display.
-
outer-size - A cons of the outer width and height of frame.
-
external-border-size - A cons of the horizontal and vertical width of frame's external borders as supplied by the window manager. If the window manager doesn't supply these values, Emacs will try to guess them from the coordinates of the outer and inner frame.
-
outer-border-width - The width of the outer border of frame. The value is meaningful for non-GTK+ X builds only.
-
title-bar-size - A cons of the width and height of the title bar of frame as supplied by the window manager or operating system. If both of them are zero, the frame has no title bar. If only the width is zero, Emacs was not able to retrieve the width information.
-
menu-bar-external - If non-
nil, this means the menu bar is external (not part of the native frame of frame). -
menu-bar-size - A cons of the width and height of the menu bar of frame.
-
tool-bar-external - If non-
nil, this means the tool bar is external (not part of the native frame of frame). -
tool-bar-position - This tells on which side the tool bar on frame is and can be one of
left,top,rightorbottom. The only toolkit that currently supports a value other thantopis GTK+. -
tool-bar-size - A cons of the width and height of the tool bar of frame.
-
internal-border-width - The width of the internal border of frame.
The following function can be used to retrieve the edges of the outer, native and inner frame.
-
frame-edges - This function returns the absolute edges of the outer, native or inner frame of frame. frame must be a live frame and defaults to the selected one. The returned list has the form
(LEFT TOP RIGHT BOTTOM)where all values are in pixels relative to the origin of frame's display. For terminal frames the values returned for left and top are always zero. Optional argument type specifies the type of the edges to return:outer-edgesmeans to return the outer edges of frame,native-edges(ornil) means to return its native edges andinner-edgesmeans to return its inner edges. By convention, the pixels of the display at the values returned for left and top are considered to be inside (part of) frame. Hence, if left and top are both zero, the pixel at the display's origin is part of frame. The pixels at bottom and right, on the other hand, are considered to lie immediately outside frame. This means that if you have, for example, two side-by-side frames positioned such that the right outer edge of the frame on the left equals the left outer edge of the frame on the right, the pixels at that edge show a part of the frame on the right.
Frame Font
Each frame has a default font which specifies the default character size for that frame. This size is meant when retrieving or changing the size of a frame in terms of columns or lines (Size Parameters). It is also used when resizing (Window Sizes) or splitting (Splitting Windows) windows. The terms line height and canonical character height are sometimes used instead of "default character height". Similarly, the terms column width and canonical character width are used instead of "default character width".
-
frame-char-height - @defunx frame-char-width &optional frame These functions return the default height and width of a character in frame, measured in pixels. Together, these values establish the size of the default font on frame. The values depend on the choice of font for frame, see Font and Color Parameters.
The default font can be also set directly with the following function:
-
Command set-frame-font - This sets the default font to font. When called interactively, it prompts for the name of a font, and uses that font on the selected frame. When called from Lisp, font should be a font name (a string), a font object, font entity, or a font spec. If the optional argument keep-size is
nil, this keeps the number of frame lines and columns fixed. (If non-nil, the optionframe-inhibit-implied-resizedescribed in the next section will override this.) If keep-size is non-nil(or with a prefix argument), it tries to keep the size of the display area of the current frame fixed by adjusting the number of lines and columns. If the optional argument frames isnil, this applies the font to the selected frame only. If frames is non-nil, it should be a list of frames to act upon, ortmeaning all existing and all future graphical frames.
Frame Position
On graphical systems, the position of a normal top-level frame is specified as the absolute position of its outer frame (Frame Geometry). The position of a child frame (Child Frames) is specified via pixel offsets of its outer edges relative to the native position of its parent frame. You can access or change the position of a frame using the frame parameters left and top (Position Parameters). Here are two additional functions for working with the positions of an existing, visible frame. For both functions, the argument frame must denote a live frame and defaults to the selected frame.
-
frame-position - For a normal, non-child frame this function returns a cons of the pixel coordinates of its outer position (Frame Layout) with respect to the origin
(0of its display. For a child frame (Child Frames) this function returns the pixel coordinates of its outer position with respect to an origin(0at the native position of frame's parent. Negative values never indicate an offset from the right or bottom edge of frame's display or parent frame. Rather, they mean that frame's outer position is on the left and/or above the origin of its display or the native position of its parent frame. This usually means that frame is only partially visible (or completely invisible). However, on systems where the display's origin does not coincide with its top-left corner, the frame may be visible on a secondary monitor. On a text terminal frame both values are zero. -
set-frame-position - This function sets the outer frame position of frame to (x, y). The latter arguments specify pixels and normally count from the origin at the position (0, 0) of frame's display. For child frames, they count from the native position of frame's parent frame. Negative parameter values position the right edge of the outer frame by -x pixels left from the right edge of the screen (or the parent frame's native rectangle) and the bottom edge by -y pixels up from the bottom edge of the screen (or the parent frame's native rectangle). Note that negative values do not permit to align the right or bottom edge of frame exactly at the right or bottom edge of its display or parent frame. Neither do they allow to specify a position that does not lie within the edges of the display or parent frame. The frame parameters
leftandtop(Position Parameters) allow to do that, but may still fail to provide good results for the initial or a new frame. This function has no effect on text terminal frames. -
move-frame-functions - This hook specifies the functions that are run when an Emacs frame is moved (assigned a new position) by the window-system or window manager. The functions are run with one argument, the frame that moved. For a child frame (Child Frames), the functions are run only when the position of the frame changes in relation to that of its parent frame.
Frame Size
The canonical way to specify the size of a frame from within Emacs is by specifying its text size—a tuple of the width and height of the frame's text area (Frame Layout). It can be measured either in pixels or in terms of the frame's canonical character size (Frame Font). For frames with an internal menu or tool bar, the frame's native height cannot be told exactly before the frame has been actually drawn. This means that in general you cannot use the native size to specify the initial size of a frame. As soon as you know the native size of a visible frame, you can calculate its outer size (Frame Layout) by adding in the remaining components from the return value of frame-geometry. For invisible frames or for frames that have yet to be created, however, the outer size can only be estimated. This also means that calculating an exact initial position of a frame specified via offsets from the right or bottom edge of the screen (Frame Position) is impossible. The text size of any frame can be set and retrieved with the help of the height and width frame parameters (Size Parameters). The text size of the initial frame can be also set with the help of an X-style geometry specification. Command Line Arguments for Emacs Invocation. Below we list some functions to access and set the size of an existing, visible frame, by default the selected one.
-
frame-height - @defunx frame-width &optional frame These functions return the height and width of the text area of frame, measured in units of the default font height and width of frame (Frame Font). These functions are plain shorthands for writing
(frame-parameter frame 'height)and(frame-parameter frame 'width). If the text area of frame measured in pixels is not a multiple of its default font size, the values returned by these functions are rounded down to the number of characters of the default font that fully fit into the text area.
The functions following next return the pixel widths and heights of the native, outer and inner frame and the text area (Frame Layout) of a given frame. For a text terminal, the results are in characters rather than pixels.
-
frame-outer-width - @defunx frame-outer-height &optional frame These functions return the outer width and height of frame in pixels.
-
frame-native-height - @defunx frame-native-width &optional frame These functions return the native width and height of frame in pixels.
-
frame-inner-width - @defunx frame-inner-height &optional frame These functions return the inner width and height of frame in pixels.
-
frame-text-width - @defunx frame-text-height &optional frame These functions return the width and height of the text area of frame in pixels.
On window systems that support it, Emacs tries by default to make the text size of a frame measured in pixels a multiple of the frame's character size. This, however, usually means that a frame can be resized only in character size increments when dragging its external borders. It also may break attempts to truly maximize the frame or making it "fullheight" or "fullwidth" (Size Parameters) leaving some empty space below and/or on the right of the frame. The following option may help in that case.
-
frame-resize-pixelwise - If this option is
nil(the default), a frame's text pixel size is usually rounded to a multiple of the current values of that frame'sframe-char-heightandframe-char-widthwhenever the frame is resized. If this is non-nil, no rounding occurs, hence frame sizes can increase/decrease by one pixel. Setting this variable usually causes the next resize operation to pass the corresponding size hints to the window manager. This means that this variable should be set only in a user's initial file; applications should never bind it temporarily. The precise meaning of a value ofnilfor this option depends on the toolkit used. Dragging the external border with the mouse is done character-wise provided the window manager is willing to process the corresponding size hints. Callingset-frame-size(see below) with arguments that do not specify the frame size as an integer multiple of its character size, however, may: be ignored, cause a rounding (GTK+), or be accepted (Lucid, Motif, MS-Windows). With some window managers you may have to set this to non-nilin order to make a frame appear truly maximized or full-screen. -
set-frame-size - This function sets the size of the text area of frame, measured in terms of the canonical height and width of a character on frame (Frame Font). The optional argument pixelwise non-
nilmeans to measure the new width and height in units of pixels instead. Note that ifframe-resize-pixelwiseisnil, some toolkits may refuse to truly honor the request if it does not increase/decrease the frame size to a multiple of its character size. -
set-frame-height - This function resizes the text area of frame to a height of height lines. The sizes of existing windows in frame are altered proportionally to fit. If pretend is non-
nil, then Emacs displays height lines of output in frame, but does not change its value for the actual height of the frame. This is only useful on text terminals. Using a smaller height than the terminal actually implements may be useful to reproduce behavior observed on a smaller screen, or if the terminal malfunctions when using its whole screen. Setting the frame height directly does not always work, because knowing the correct actual size may be necessary for correct cursor positioning on text terminals. The optional fourth argument pixelwise non-nilmeans that frame should be height pixels high. Note that ifframe-resize-pixelwiseisnil, some window managers may refuse to truly honor the request if it does not increase/decrease the frame height to a multiple of its character height. When used interactively, this command will ask the user for the number of lines to set the height of the currently selected frame. You can also provide this value with a numeric prefix. -
set-frame-width - This function sets the width of the text area of frame, measured in characters. The argument pretend has the same meaning as in
set-frame-height. The optional fourth argument pixelwise non-nilmeans that frame should be width pixels wide. Note that ifframe-resize-pixelwiseisnil, some window managers may refuse to fully honor the request if it does not increase/decrease the frame width to a multiple of its character width. When used interactively, this command will ask the user for the number of columns to set the width of the currently selected frame. You can also provide this value with a numeric prefix.
None of these three functions will make a frame smaller than needed to display all of its windows together with their scroll bars, fringes, margins, dividers, mode and header lines. This contrasts with requests by the window manager triggered, for example, by dragging the external border of a frame with the mouse. Such requests are always honored by clipping, if necessary, portions that cannot be displayed at the right, bottom corner of the frame. The parameters min-width and min-height (Size Parameters) can be used to obtain a similar behavior when changing the frame size from within Emacs. The abnormal hook window-size-change-functions (Window Hooks) tracks all changes of the inner size of a frame including those induced by request of the window-system or window manager. To rule out false positives that might occur when changing only the sizes of a frame's windows without actually changing the size of the inner frame, use the following function.
-
frame-size-changed-p - This function returns non-
nilwhen the inner width or height of frame has changed sincewindow-size-change-functionswas run the last time for frame. It always returnsnilimmediately after runningwindow-size-change-functionsfor frame.
Implied Frame Resizing
By default, Emacs tries to keep the number of lines and columns of a frame's text area unaltered when, for example, toggling its menu or tool bar, changing its default font or setting the width of any of its scroll bars. This means that in such case Emacs must ask the window manager to resize the frame's window in order to accommodate the size change. Occasionally, such implied frame resizing may be unwanted, for example, when a frame has been maximized or made full-screen (where it's turned off by default). In general, users can disable implied resizing with the following option:
-
frame-inhibit-implied-resize - If this option is
nil, changing a frame's font, menu bar, tool bar, internal borders, fringes or scroll bars may resize its outer frame in order to keep the number of columns or lines of its text area unaltered. If this option ist, no such resizing is done. The value of this option can be also a list of frame parameters. In that case, implied resizing is inhibited for the change of a parameter that appears in this list. Parameters currently handled by this option arefont,font-backend,internal-border-width,menu-bar-linesandtool-bar-lines. Changing any of thescroll-bar-width,scroll-bar-height,vertical-scroll-bars,horizontal-scroll-bars,left-fringeandright-fringeframe parameters is handled as if the frame contained just one live window. This means, for example, that removing vertical scroll bars on a frame containing several side by side windows will shrink the outer frame width by the width of one scroll bar provided this option isniland keep it unchanged if this option istor a list containingvertical-scroll-bars. The default value is(tab-bar-lines tool-bar-lines)for Lucid, Motif and MS-Windows (which means that adding/removing a tool or tab bar there does not change the outer frame height),(tab-bar-lines)on all other window systems including GTK+ (which means that changing any of the parameters listed above with the exception oftab-bar-linesmay change the size of the outer frame), andtotherwise (which means the outer frame size never changes implicitly when there's no window system support). Note that when a frame is not large enough to accommodate a change of any of the parameters listed above, Emacs may try to enlarge the frame even if this option is non-nil. Note also that window managers usually do not ask for resizing a frame when they change the number of lines occupied by an external menu or tool bar. Typically, such "wrappings" occur when a user shrinks a frame horizontally, making it impossible to display all elements of its menu or tool bar. They may also result from a change of the major mode altering the number of items of a menu or tool bar. Any such wrappings may implicitly alter the number of lines of a frame's text area and are unaffected by the setting of this option.
Frame Parameters
A frame has many parameters that control its appearance and behavior. Just what parameters a frame has depends on what display mechanism it uses. Frame parameters exist mostly for the sake of graphical displays. Most frame parameters have no effect when applied to a frame on a text terminal; only the height, width, name, title, menu-bar-lines, buffer-list and buffer-predicate parameters do something special. If the terminal supports colors, the parameters foreground-color, background-color, background-mode and display-type are also meaningful. If the terminal supports frame transparency, the parameter alpha is also meaningful. By default, frame parameters are saved and restored by the desktop library functions (Desktop Save Mode) when the variable desktop-restore-frames is non-nil. It's the responsibility of applications that their parameters are included in frameset-persistent-filter-alist to avoid that they get meaningless or even harmful values in restored sessions.
Access to Frame Parameters
These functions let you read and change the parameter values of a frame.
-
frame-parameter - This function returns the value of the parameter parameter (a symbol) of frame. If frame is
nil, it returns the selected frame's parameter. If frame has no setting for parameter, this function returnsnil. -
frame-parameters - The function
frame-parametersreturns an alist listing all the parameters of frame and their values. If frame isnilor omitted, this returns the selected frame's parameters -
modify-frame-parameters - This function alters the frame frame based on the elements of alist. Each element of alist has the form
(PARM . VALUE), where parm is a symbol naming a parameter. If you don't mention a parameter in alist, its value doesn't change. If frame isnil, it defaults to the selected frame. Some parameters are only meaningful for frames on certain kinds of display (Frames). If alist includes parameters that are not meaningful for the frame's display, this function will change its value in the frame's parameter list, but will otherwise ignore it. When alist specifies more than one parameter whose value can affect the new size of frame, the final size of the frame may differ according to the toolkit used. For example, specifying that a frame should from now on have a menu and/or tool bar instead of none and simultaneously specifying the new height of the frame will inevitably lead to a recalculation of the frame's height. Conceptually, in such case, this function will try to have the explicit height specification prevail. It cannot be excluded, however, that the addition (or removal) of the menu or tool bar, when eventually performed by the toolkit, will defeat this intention. Sometimes, bindingframe-inhibit-implied-resize(Implied Frame Resizing) to a non-nilvalue around calls to this function may fix the problem sketched here. Sometimes, however, exactly such binding may be hit by the problem. -
set-frame-parameter - This function sets the frame parameter parm to the specified value. If frame is
nil, it defaults to the selected frame. -
modify-all-frames-parameters - This function alters the frame parameters of all existing frames according to alist, then modifies
default-frame-alist(and, if necessary,initial-frame-alist) to apply the same parameter values to frames that will be created henceforth.
Initial Frame Parameters
You can specify the parameters for the initial startup frame by setting initial-frame-alist in your init file (Init File).
-
initial-frame-alist - This variable's value is an alist of parameter values used when creating the initial frame. You can set this variable to specify the appearance of the initial frame without altering subsequent frames. Each element has the form:
(PARAMETER . VALUE)
Emacs creates the initial frame before it reads your init file. After reading that file, Emacs checks initial-frame-alist, and applies the parameter settings in the altered value to the already created initial frame. If these settings affect the frame geometry and appearance, you'll see the frame appear with the wrong ones and then change to the specified ones. If that bothers you, you can specify the same geometry and appearance with X resources; those do take effect before the frame is created. X Resources. X resource settings typically apply to all frames. If you want to specify some X resources solely for the sake of the initial frame, and you don't want them to apply to subsequent frames, here's how to achieve this. Specify parameters in default-frame-alist to override the X resources for subsequent frames; then, to prevent these from affecting the initial frame, specify the same parameters in initial-frame-alist with values that match the X resources. If these parameters include (minibuffer . nil), that indicates that the initial frame should have no minibuffer. In this case, Emacs creates a separate minibuffer-only frame as well.
-
minibuffer-frame-alist - This variable's value is an alist of parameter values used when creating an initial minibuffer-only frame (i.e., the minibuffer-only frame that Emacs creates if
initial-frame-alistspecifies a frame with no minibuffer). -
default-frame-alist - This is an alist specifying default values of frame parameters for all Emacs frames—the first frame, and subsequent frames. When using the X Window System, you can get the same results by means of X resources in many cases. Setting this variable does not affect existing frames. Furthermore, functions that display a buffer in a separate frame may override the default parameters by supplying their own parameters.
If you invoke Emacs with command-line options that specify frame appearance, those options take effect by adding elements to either initial-frame-alist or default-frame-alist. Options which affect just the initial frame, such as --geometry and --maximized, add to initial-frame-alist; the others add to default-frame-alist. Command Line Arguments for Emacs Invocation.
Window Frame Parameters
Just what parameters a frame has depends on what display mechanism it uses. This section describes the parameters that have special meanings on some or all kinds of terminals. Of these, name, title, height, width, buffer-list and buffer-predicate provide meaningful information in terminal frames, and tty-color-mode is meaningful only for frames on text terminals.
Basic Parameters
These frame parameters give the most basic information about the frame. title and name are meaningful on all terminals.
-
display - The display on which to open this frame. It should be a string of the form
HOST:DPY.SCREEN, just like theDISPLAYenvironment variable. Multiple Terminals, for more details about display names. -
display-type - This parameter describes the range of possible colors that can be used in this frame. Its value is
color,grayscaleormono. -
title - If a frame has a non-
niltitle, that title appears in the window system's title bar at the top of the frame, and also in the mode line of windows in that frame ifmode-line-frame-identificationuses%F(%-Constructs). This is normally the case when Emacs is not using a window system, and can only display one frame at a time. When Emacs is using a window system, this parameter, if non-nil, overrides the title determined by thenameparameter and the implicit title calculated according toframe-title-format. It also overrides the title determined byicon-title-formatfor iconified frames. Frame Titles. -
name - The name of the frame. If you don't specify a name via this parameter, Emacs sets the frame name automatically, as specified by
frame-title-formatandicon-title-format, and that is the frame's title that will appear on display when Emacs uses a window system (unless thetitleparameter overrides it). If you specify the frame name explicitly when you create the frame, the name is also used (instead of the name of the Emacs executable) when looking up X resources for the frame. -
explicit-name - If the frame name was specified explicitly when the frame was created, this parameter will be that name. If the frame wasn't explicitly named, this parameter will be
nil.
Position Parameters
Parameters describing the X- and Y-offsets of a frame are always measured in pixels. For a normal, non-child frame they specify the frame's outer position (Frame Geometry) relative to its display's origin. For a child frame (Child Frames) they specify the frame's outer position relative to the native position of the frame's parent frame. (Note that none of these parameters is meaningful on TTY frames.)
-
left - The position, in pixels, of the left outer edge of the frame with respect to the left edge of the frame's display or parent frame. It can be specified in one of the following ways.
-
an integer - A positive integer always relates the left edge of the frame to the left edge of its display or parent frame. A negative integer relates the right frame edge to the right edge of the display or parent frame.
-
(+ POS) - This specifies the position of the left frame edge relative to the left edge of its display or parent frame. The integer pos may be positive or negative; a negative value specifies a position outside the screen or parent frame or on a monitor other than the primary one (for multi-monitor displays).
-
(- POS) - This specifies the position of the right frame edge relative to the right edge of the display or parent frame. The integer pos may be positive or negative; a negative value specifies a position outside the screen or parent frame or on a monitor other than the primary one (for multi-monitor displays).
-
a floating-point value - A floating-point value in the range 0.0 to 1.0 specifies the left edge's offset via the left position ratio of the frame—the ratio of the left edge of its outer frame to the width of the frame's workarea (Multiple Terminals) or its parent's native frame (Child Frames) minus the width of the outer frame. Thus, a left position ratio of 0.0 flushes a frame to the left, a ratio of 0.5 centers it and a ratio of 1.0 flushes it to the right of its display or parent frame. Similarly, the top position ratio of a frame is the ratio of the frame's top position to the height of its workarea or parent frame minus the height of the frame. Emacs will try to keep the position ratios of a child frame unaltered if that frame has a non-
nilkeep-ratioparameter (Frame Interaction Parameters) and its parent frame is resized. Since the outer size of a frame (Frame Geometry) is usually unavailable before a frame has been made visible, it is generally not advisable to use floating-point values when creating decorated frames. Floating-point values are more suited for ensuring that an (undecorated) child frame is positioned nicely within the area of its parent frame. Some window managers ignore program-specified positions. If you want to be sure the position you specify is not ignored, specify a non-nilvalue for theuser-positionparameter as in the following example: (modify-frame-parameters nil '((user-position . t) (left . (+ -4)))) In general, it is not a good idea to position a frame relative to the right or bottom edge of its display. Positioning the initial or a new frame is either not accurate (because the size of the outer frame is not yet fully known before the frame has been made visible) or will cause additional flicker (if the frame has to be repositioned after becoming visible). Note also, that positions specified relative to the right/bottom edge of a display, workarea or parent frame as well as floating-point offsets are stored internally as integer offsets relative to the left/top edge of the display, workarea or parent frame edge. They are also returned as such by functions likeframe-parametersand restored as such by the desktop saving routines. -
top - The screen position of the top (or bottom) edge, in pixels, with respect to the top (or bottom) edge of the display or parent frame. It works just like
left, except vertically instead of horizontally. -
icon-left - The screen position of the left edge of the frame's icon, in pixels, counting from the left edge of the screen. This takes effect when the frame is iconified, if the window manager supports this feature. If you specify a value for this parameter, then you must also specify a value for
icon-topand vice versa. -
icon-top - The screen position of the top edge of the frame's icon, in pixels, counting from the top edge of the screen. This takes effect when the frame is iconified, if the window manager supports this feature.
-
user-position - When you create a frame and specify its screen position with the
leftandtopparameters, use this parameter to say whether the specified position was user-specified (explicitly requested in some way by a human user) or merely program-specified (chosen by a program). A non-nilvalue says the position was user-specified. Window managers generally heed user-specified positions, and some heed program-specified positions too. But many ignore program-specified positions, placing the window in a default fashion or letting the user place it with the mouse. Some window managers, includingtwm, let the user specify whether to obey program-specified positions or ignore them. When you callmake-frame, you should specify a non-nilvalue for this parameter if the values of theleftandtopparameters represent the user's stated preference; otherwise, usenil. -
z-group - This parameter specifies a relative position of the frame's window-system window in the stacking (Z-) order of the frame's display. If this is
above, the window-system will display the window that corresponds to the frame above all other window-system windows that do not have theaboveproperty set. If this isnil, the frame's window is displayed below all windows that have theaboveproperty set and above all windows that have thebelowproperty set. If this isbelow, the frame's window is displayed below all windows that do not have thebelowproperty set. To position the frame above or below a specific other frame use the functionframe-restack(Raising and Lowering).
Size Parameters
Frame parameters usually specify frame sizes in character units. On graphical displays, the default face determines the actual pixel sizes of these character units (Face Attributes).
-
width - This parameter specifies the width of the frame. It can be specified as in the following ways:
-
an integer - A positive integer specifies the width of the frame's text area (Frame Geometry) in characters.
-
a cons cell - If this is a cons cell with the symbol
text-pixelsin its CAR, the CDR of that cell specifies the width of the frame's text area in pixels. -
a floating-point value - A floating-point number between 0.0 and 1.0 can be used to specify the width of a frame via its width ratio—the ratio of its outer width (Frame Geometry) to the width of the frame's workarea (Multiple Terminals) or its parent frame's (Child Frames) native frame. Thus, a value of 0.5 makes the frame occupy half of the width of its workarea or parent frame, a value of 1.0 the full width. Similarly, the height ratio of a frame is the ratio of its outer height to the height of its workarea or its parent's native frame. Emacs will try to keep the width and height ratio of a child frame unaltered if that frame has a non-
nilkeep-ratioparameter (Frame Interaction Parameters) and its parent frame is resized. Since the outer size of a frame is usually unavailable before a frame has been made visible, it is generally not advisable to use floating-point values when creating decorated frames. Floating-point values are more suited to ensure that a child frame always fits within the area of its parent frame as, for example, when customizingdisplay-buffer-alist(Choosing Window) viadisplay-buffer-in-child-frame. Regardless of how this parameter was specified, functions reporting the value of this parameter likeframe-parametersalways report the width of the frame's text area in characters as an integer rounded, if necessary, to a multiple of the frame's default character width. That value is also used by the desktop saving routines. -
height - This parameter specifies the height of the frame. It works just like
width, except vertically instead of horizontally. -
user-size - This does for the size parameters
heightandwidthwhat theuser-positionparameter (user-position) does for the position parameterstopandleft. -
min-width - This parameter specifies the minimum native width (Frame Geometry) of the frame, in characters. Normally, the functions that establish a frame's initial width or resize a frame horizontally make sure that all the frame's windows, vertical scroll bars, fringes, margins and vertical dividers can be displayed. This parameter, if non-
nilallows to make a frame narrower than that with the consequence that any components that do not fit will be clipped by the window manager. -
min-height - This parameter specifies the minimum native height (Frame Geometry) of the frame, in characters. Normally, the functions that establish a frame's initial size or resize a frame make sure that all the frame's windows, horizontal scroll bars and dividers, mode and header lines, the echo area and the internal menu and tool bar can be displayed. This parameter, if non-
nilallows to make a frame smaller than that with the consequence that any components that do not fit will be clipped by the window manager. -
fullscreen - This parameter specifies whether to maximize the frame's width, height or both. Its value can be
fullwidth,fullheight,fullboth, ormaximized.(On PGTK frames) A fullwidth frame is as wide as possible, a fullheight frame is as tall as possible, and a fullboth frame is both as wide and as tall as possible. A maximized frame is like a "fullboth" frame, except that it usually keeps its title bar and the buttons for resizing and closing the frame. Also, maximized frames typically avoid hiding any task bar or panels displayed on the desktop. A "fullboth" frame, on the other hand, usually omits the title bar and occupies the entire available screen space. Full-height and full-width frames are more similar to maximized frames in this regard. However, these typically display an external border which might be absent with maximized frames. Hence the heights of maximized and full-height frames and the widths of maximized and full-width frames often differ by a few pixels. With some window managers you may have to customize the variableframe-resize-pixelwise(Frame Size) in order to make a frame truly appear maximized or full-screen. Moreover, some window managers might not support smooth transition between the various full-screen or maximization states. Customizing the variablex-frame-normalize-before-maximizecan help to overcome that. Full-screen on macOS hides both the tool-bar and the menu-bar, however both will be displayed if the mouse pointer is moved to the top of the screen. -
fullscreen-restore - This parameter specifies the desired fullscreen state of the frame after invoking the
toggle-frame-fullscreencommand (Frame Commands) in the "fullboth" state. Normally this parameter is installed automatically by that command when toggling the state to fullboth. If, however, you start Emacs in the "fullboth" state, you have to specify the desired behavior in your initial file as, for example (setq default-frame-alist '((fullscreen . fullboth) (fullscreen-restore . fullheight))) This will give a new frame full height after typing in itF11for the first time. -
fit-frame-to-buffer-margins - This parameter allows to override the value of the option
fit-frame-to-buffer-marginswhen fitting this frame to the buffer of its root window withfit-frame-to-buffer(Resizing Windows). -
fit-frame-to-buffer-sizes - This parameter allows to override the value of the option
fit-frame-to-buffer-sizeswhen fitting this frame to the buffer of its root window withfit-frame-to-buffer(Resizing Windows).
Layout Parameters
These frame parameters enable or disable various parts of the frame, or control their sizes.
-
border-width - The width in pixels of the frame's outer border (Frame Geometry).
-
internal-border-width - The width in pixels of the frame's internal border (Frame Geometry).
-
child-frame-border-width - The width in pixels of the frame's internal border (Frame Geometry) if the given frame is a child frame (Child Frames). If this is
nil, the value specified by theinternal-border-widthparameter is used instead. -
vertical-scroll-bars - Whether the frame has scroll bars (Scroll Bars) for vertical scrolling, and which side of the frame they should be on. The possible values are
left,right, andnilfor no scroll bars. -
horizontal-scroll-bars - Whether the frame has scroll bars for horizontal scrolling (
tandbottommean yes,nilmeans no). -
scroll-bar-width - The width of vertical scroll bars, in pixels, or
nilmeaning to use the default width. -
scroll-bar-height - The height of horizontal scroll bars, in pixels, or
nilmeaning to use the default height. -
left-fringe,right-fringe - The default width of the left and right fringes of windows in this frame (Fringes). If either of these is zero, that effectively removes the corresponding fringe. When you use
frame-parameterto query the value of either of these two frame parameters, the return value is always an integer. When usingset-frame-parameter, passing anilvalue imposes an actual default value of 8 pixels. -
right-divider-width - The width (thickness) reserved for the right divider (Window Dividers) of any window on the frame, in pixels. A value of zero means to not draw right dividers.
-
bottom-divider-width - The width (thickness) reserved for the bottom divider (Window Dividers) of any window on the frame, in pixels. A value of zero means to not draw bottom dividers.
-
menu-bar-lines - The number of lines to allocate at the top of the frame for a menu bar (Menu Bar). The default is one if Menu Bar mode is enabled and zero otherwise. Menu Bars. For an external menu bar (Frame Layout), this value remains unchanged even when the menu bar wraps to two or more lines. In that case, the
menu-bar-sizevalue returned byframe-geometry(Frame Geometry) allows to derive whether the menu bar actually occupies one or more lines. -
tool-bar-lines - The number of lines to use for the tool bar (Tool Bar). The default is one if Tool Bar mode is enabled and zero otherwise. Tool Bars. This value may change whenever the tool bar wraps (Frame Layout).
-
tool-bar-position - The position of the tool bar when Emacs was built with GTK+. Its value can be one of
top,bottomleft,right. The default istop. -
tab-bar-lines - The number of lines to use for the tab bar (Tab Bars). The default is one if Tab Bar mode is enabled and zero otherwise. This value may change whenever the tab bar wraps (Frame Layout).
-
line-spacing - Additional space to leave below each text line, in pixels (a positive integer). Line Height, for more information.
-
no-special-glyphs - If this is non-
nil, it suppresses the display of any truncation (Truncation) and continuation glyphs for all the buffers displayed by this frame. This is useful to eliminate such glyphs when fitting a frame to its buffer viafit-frame-to-buffer(Resizing Windows). This frame parameter has effect only for GUI frames shown on graphical displays, and only if the fringes are disabled. This parameter is intended as a purely-presentation feature, and in particular should not be used for frames where the user can interactively insert text, or more generally where the cursor is shown. A notable example of frames where this is used is tooltip frames (Tooltips).
Buffer Parameters
These frame parameters, meaningful on all kinds of terminals, deal with which buffers have been, or should, be displayed in the frame.
-
minibuffer - Whether this frame has its own minibuffer. The value
tmeans yes,nilmeans no,onlymeans this frame is just a minibuffer. If the value is a minibuffer window (in some other frame), the frame uses that minibuffer. This parameter takes effect when the frame is created. If specified asnil, Emacs will try to set it to the minibuffer window ofdefault-minibuffer-frame(Minibuffers and Frames). For an existing frame, this parameter can be used exclusively to specify another minibuffer window. It is not allowed to change it from a minibuffer window totand vice-versa, or fromttonil. If the parameter specifies a minibuffer window already, setting it tonilhas no effect. The special valuechild-framemeans to make a minibuffer-only child frame (Child Frames) whose parent becomes the frame created. As if specified asnil, Emacs will set this parameter to the minibuffer window of the child frame but will not select the child frame after its creation. -
buffer-predicate - The buffer-predicate function for this frame. The function
other-bufferuses this predicate (from the selected frame) to decide which buffers it should consider, if the predicate is notnil. It calls the predicate with one argument, a buffer, once for each buffer; if the predicate returns a non-nilvalue, it considers that buffer. -
buffer-list - A list of buffers that have been selected in this frame, ordered most-recently-selected first.
-
unsplittable - If non-
nil, this frame's window is never split automatically.
Frame Interaction Parameters
These parameters supply forms of interactions between different frames.
-
parent-frame - If non-
nil, this means that this frame is a child frame (Child Frames), and this parameter specifies its parent frame. Ifnil, this means that this frame is a normal, top-level frame. -
delete-before - If non-
nil, this parameter specifies another frame whose deletion will automatically trigger the deletion of this frame. Deleting Frames. -
mouse-wheel-frame - If non-
nil, this parameter specifies the frame whose windows will be scrolled whenever the mouse wheel is scrolled with the mouse pointer hovering over this frame, see Mouse Commands. -
no-other-frame - If this is non-
nil, then this frame is not eligible as candidate for the functionsnext-frame,previous-frame(Finding All Frames) andother-frame, see Frame Commands. -
auto-hide-function - When this parameter specifies a function, that function will be called instead of the function specified by the variable
frame-auto-hide-functionwhen quitting the frame's only window (Quitting Windows) and there are other frames left. -
minibuffer-exit - When this parameter is non-
nil, Emacs will by default make this frame invisible whenever the minibuffer (Minibuffers) is exited. Alternatively, it can specify the functionsiconify-frameanddelete-frame. This parameter is useful to make a child frame disappear automatically (similar to how Emacs deals with a window) when exiting the minibuffer. -
keep-ratio - This parameter is currently meaningful for child frames (Child Frames) only. If it is non-
nil, then Emacs will try to keep the frame's size (width and height) ratios (Size Parameters) as well as its left and right position ratios (Position Parameters) unaltered whenever its parent frame is resized. If the value of this parameter isnil, the frame's position and size remain unaltered when the parent frame is resized, so the position and size ratios may change. If the value of this parameter ist, Emacs will try to preserve the frame's size and position ratios, hence the frame's size and position relative to its parent frame may change. More individual control is possible by using a cons cell: In that case the frame's width ratio is preserved if the CAR of the cell is eithertorwidth-only. The height ratio is preserved if the CAR of the cell is eithertorheight-only. The left position ratio is preserved if the CDR of the cell is eithertorleft-only. The top position ratio is preserved if the CDR of the cell is eithertortop-only.
Mouse Dragging Parameters
The parameters described below provide support for resizing a frame by dragging its internal borders with the mouse. They also allow moving a frame with the mouse by dragging the header or tab line of its topmost or the mode line of its bottommost window. These parameters are mostly useful for child frames (Child Frames) that come without window manager decorations. If necessary, they can be used for undecorated top-level frames as well.
-
drag-internal-border - If non-
nil, the frame can be resized by dragging its internal borders, if present, with the mouse. -
drag-with-header-line - If non-
nil, the frame can be moved with the mouse by dragging the header line of its topmost window. -
drag-with-tab-line - If non-
nil, the frame can be moved with the mouse by dragging the tab line of its topmost window. -
drag-with-mode-line - If non-
nil, the frame can be moved with the mouse by dragging the mode line of its bottommost window. Note that such a frame is not allowed to have its own minibuffer window. -
snap-width - A frame that is moved with the mouse will "snap" at the border(s) of the display or its parent frame whenever it is dragged as near to such an edge as the number of pixels specified by this parameter.
-
top-visible - If this parameter is a number, the top edge of the frame never appears above the top edge of its display or parent frame. Moreover, as many pixels of the frame as specified by that number will remain visible when the frame is moved against any of the remaining edges of its display or parent frame. Setting this parameter is useful to guard against dragging a child frame with a non-
nildrag-with-header-lineparameter completely out of the area of its parent frame. -
bottom-visible - If this parameter is a number, the bottom edge of the frame never appears below the bottom edge of its display or parent frame. Moreover, as many pixels of the frame as specified by that number will remain visible when the frame is moved against any of the remaining edges of its display or parent frame. Setting this parameter is useful to guard against dragging a child frame with a non-
nildrag-with-mode-lineparameter completely out of the area of its parent frame.
Window Management Parameters
The following frame parameters control various aspects of the frame's interaction with the window manager or window system. They have no effect on text terminals.
-
visibility - The state of visibility of the frame. There are three possibilities:
nilfor invisible,tfor visible, andiconfor iconified. Visibility of Frames. -
auto-raise - If non-
nil, Emacs automatically raises the frame when it is selected. Some window managers do not allow this. -
auto-lower - If non-
nil, Emacs automatically lowers the frame when it is deselected. Some window managers do not allow this. -
icon-type - The type of icon to use for this frame. If the value is a string, that specifies a file containing a bitmap to use;
nilspecifies no icon (in which case the window manager decides what to show); any other non-nilvalue specifies the default Emacs icon. -
icon-name - The name to use in the icon for this frame, when and if the icon appears. If this is
nil, the frame's title is used. -
window-id - The ID number which the graphical display uses for this frame. Emacs assigns this parameter when the frame is created; changing the parameter has no effect on the actual ID number.
-
outer-window-id - The ID number of the outermost window-system window in which the frame exists. As with
window-id, changing this parameter has no actual effect. -
wait-for-wm - If non-
nil, tell Xt to wait for the window manager to confirm geometry changes. Some window managers, including versions of Fvwm2 and KDE, fail to confirm, so Xt hangs. Set this tonilto prevent hanging with those window managers. -
sticky - If non-
nil, the frame is visible on all virtual desktops on systems with virtual desktops. -
shaded - If non-
nil, tell the window manager to display the frame in a way that its contents are hidden, leaving only the title bar. -
use-frame-synchronization - If non-
nil, synchronize the frame redisplay with the refresh rate of the monitor to avoid graphics tearing. At present, this is only implemented on Haiku and the X window system inside no-toolkit and X toolkit builds, does not work correctly with toolkit scroll bars, and requires a compositing manager supporting the relevant display synchronization protocols. ThesynchronizeResizeX resource must also be set to the string"extended". -
inhibit-double-buffering - If non-
nil, the frame is drawn to the screen without double buffering. Emacs normally attempts to use double buffering, where available, to reduce flicker. Set this property if you experience display bugs or pine for that retro, flicker-y feeling. -
skip-taskbar - If non-
nil, this tells the window manager to remove the frame's icon from the taskbar associated with the frame's display and inhibit switching to the frame's window via the combinationAlt-TAB. On MS-Windows, iconifying such a frame will "roll in" its window-system window at the bottom of the desktop. Some window managers may not honor this parameter. -
no-focus-on-map - If non-
nil, this means that the frame does not want to receive input focus when it is mapped (Visibility of Frames). Some window managers may not honor this parameter. -
no-accept-focus - If non-
nil, this means that the frame does not want to receive input focus via explicit mouse clicks or when moving the mouse into it either viafocus-follows-mouse(Input Focus) ormouse-autoselect-window(Mouse Window Auto-selection). This may have the unwanted side-effect that a user cannot scroll a non-selected frame with the mouse. Some window managers may not honor this parameter. On Haiku, it also has the side-effect that the window will not be able to receive any keyboard input from the user, not even if the user switches to the frame using the key combinationAlt-TAB. -
undecorated - If non-
nil, this frame's window-system window is drawn without decorations, like the title, minimize/maximize boxes and external borders. This usually means that the window cannot be dragged, resized, iconified, maximized or deleted with the mouse. Ifnil, the frame's window is usually drawn with all the elements listed above unless their display has been suspended via window manager settings. Under X, Emacs uses the Motif window manager hints to turn off decorations. Some window managers may not honor these hints. NS builds consider the tool bar to be a decoration, and therefore hide it on an undecorated frame. -
override-redirect - If non-
nil, this means that this is an override redirect frame—a frame not handled by window managers under X. Override redirect frames have no window manager decorations, can be positioned and resized only via Emacs' positioning and resizing functions and are usually drawn on top of all other frames. Setting this parameter has no effect on MS-Windows. -
ns-appearance - Only available on macOS, if set to
darkdraw this frame's window-system window using the "vibrant dark" theme, and if set tolightuse the "aqua" theme, otherwise use the system default. The "vibrant dark" theme can be used to set the toolbar and scrollbars to a dark appearance when using an Emacs theme with a dark background. -
ns-transparent-titlebar - Only available on macOS, if non-
nil, set the titlebar and toolbar to be transparent. This effectively sets the background color of both to match the Emacs background color.
Cursor Parameters
This frame parameter controls the way the cursor looks.
-
cursor-type - How to display the cursor. Legitimate values are:
-
box - Display a filled box. (This is the default.)
-
(box . SIZE) - Display a filled box. However, display it as a hollow box if point is under masked image larger than size pixels in either dimension.
-
hollow - Display a hollow box.
-
nil - Don't display a cursor.
-
bar - Display a vertical bar between characters.
-
(bar . WIDTH) - Display a vertical bar width pixels wide between characters.
-
hbar - Display a horizontal bar.
-
(hbar . HEIGHT) - Display a horizontal bar height pixels high.
The cursor-type frame parameter may be overridden by the variables cursor-type and cursor-in-non-selected-windows:
-
cursor-type - This buffer-local variable controls how the cursor looks in a selected window showing the buffer. If its value is
t, that means to use the cursor specified by thecursor-typeframe parameter. Otherwise, the value should be one of the cursor types listed above, and it overrides thecursor-typeframe parameter. -
cursor-in-non-selected-windows - This buffer-local variable controls how the cursor looks in a window that is not selected. It supports the same values as the
cursor-typeframe parameter; also,nilmeans don't display a cursor in nonselected windows, andt(the default) means use a standard modification of the usual cursor type (solid box becomes hollow box, and bar becomes a narrower bar). -
x-stretch-cursor - This variable controls the width of the block cursor displayed on extra-wide glyphs such as a tab or a stretch of white space. By default, the block cursor is only as wide as the font's default character, and will not cover all of the width of the glyph under it if that glyph is extra-wide. A non-
nilvalue of this variable means draw the block cursor as wide as the glyph under it. The default value isnil. This variable has no effect on text-mode frames, since the text-mode cursor is drawn by the terminal out of Emacs's control. -
blink-cursor-alist - This variable specifies how to blink the cursor. Each element has the form
(ON-STATE . OFF-STATE). Whenever the cursor type equals on-state (comparing usingequal), the corresponding off-state specifies what the cursor looks like when it blinks off. Both on-state and off-state should be suitable values for thecursor-typeframe parameter. There are various defaults for how to blink each type of cursor, if the type is not mentioned as an on-state here. Changes in this variable do not take effect immediately, only when you specify thecursor-typeframe parameter.
Font and Color Parameters
These frame parameters control the use of fonts and colors.
-
font-backend - A list of symbols, specifying the font backends to use for drawing characters on the frame, in order of priority. In Emacs built without Cairo drawing on X, there are currently three potentially available font backends:
x(the X core font driver),xft(the Xft font driver), andxfthb(the Xft font driver with HarfBuzz text shaping). If built with Cairo drawing, there are also three potentially available font backends on X:x,ftcr(the FreeType font driver on Cairo), andftcrhb(the FreeType font driver on Cairo with HarfBuzz text shaping). When Emacs is built with HarfBuzz, the default font driver isftcrhb, although use of theftcrdriver is still possible, but not recommended. On MS-Windows, there are currently three available font backends:gdi(the core MS-Windows font driver),uniscribe(font driver for OTF and TTF fonts with text shaping by the Uniscribe engine), andharfbuzz(font driver for OTF and TTF fonts with HarfBuzz text shaping) (Windows Fonts). Theharfbuzzdriver is similarly recommended. On Haiku, there can be several font drivers (Haiku Fonts). On other systems, there is only one available font backend, so it does not make sense to modify this frame parameter. -
background-mode - This parameter is either
darkorlight, according to whether the background color is a light one or a dark one. -
tty-color-mode - This parameter overrides the terminal's color support as given by the system's terminal capabilities database in that this parameter's value specifies the color mode to use on a text terminal. The value can be either a symbol or a number. A number specifies the number of colors to use (and, indirectly, what commands to issue to produce each color). For example,
(tty-color-mode . 8)specifies use of the ANSI escape sequences for 8 standard text colors. A value of −1 turns off color support. If the parameter's value is a symbol, it specifies a number through the value oftty-color-mode-alist, and the associated number is used instead. -
screen-gamma - If this is a number, Emacs performs gamma correction which adjusts the brightness of all colors. The value should be the screen gamma of your display. Usual PC monitors have a screen gamma of 2.2, so color values in Emacs, and in X windows generally, are calibrated to display properly on a monitor with that gamma value. If you specify 2.2 for
screen-gamma, that means no correction is needed. Other values request correction, designed to make the corrected colors appear on your screen the way they would have appeared without correction on an ordinary monitor with a gamma value of 2.2. If your monitor displays colors too light, you should specify ascreen-gammavalue smaller than 2.2. This requests correction that makes colors darker. A screen gamma value of 1.5 may give good results for LCD color displays. -
alpha - This parameter specifies the opacity of the frame, on graphical displays that support variable opacity. It should be an integer between 0 and 100, where 0 means completely transparent and 100 means completely opaque. It can also have a
nilvalue, which tells Emacs not to set the frame opacity (leaving it to the window manager). To prevent the frame from disappearing completely from view, the variableframe-alpha-lower-limitdefines a lower opacity limit. If the value of the frame parameter is less than the value of this variable, Emacs uses the latter. By default,frame-alpha-lower-limitis 20. Thealphaframe parameter can also be a cons cell(ACTIVE . INACTIVE), where active is the opacity of the frame when it is selected, and inactive is the opacity when it is not selected. Some window systems do not support thealphaparameter for child frames (Child Frames). -
alpha-background - Sets the background transparency of the frame. Unlike the
alphaframe parameter, this only controls the transparency of the background while keeping foreground elements such as text fully opaque. It should be an integer between 0 and 100, where 0 means completely transparent and 100 means completely opaque (default).
The following frame parameters are semi-obsolete in that they are automatically equivalent to particular face attributes of particular faces (Standard Faces):
-
font - The name of the font for displaying text in the frame. This is a string, either a valid font name for your system or the name of an Emacs fontset (Fontsets). It is equivalent to the
fontattribute of thedefaultface. -
foreground-color - The color to use for characters. It is equivalent to the
:foregroundattribute of thedefaultface. -
background-color - The color to use for the background of characters. It is equivalent to the
:backgroundattribute of thedefaultface. -
mouse-color - The color for the mouse pointer. It is equivalent to the
:backgroundattribute of themouseface. -
cursor-color - The color for the cursor that shows point. It is equivalent to the
:backgroundattribute of thecursorface. -
border-color - The color for the border of the frame. It is equivalent to the
:backgroundattribute of theborderface. -
scroll-bar-foreground - If non-
nil, the color for the foreground of scroll bars. It is equivalent to the:foregroundattribute of thescroll-barface. -
scroll-bar-background - If non-
nil, the color for the background of scroll bars. It is equivalent to the:backgroundattribute of thescroll-barface.
Geometry
Here's how to examine the data in an X-style window geometry specification:
-
x-parse-geometry - The function
x-parse-geometryconverts a standard X window geometry string to an alist that you can use as part of the argument tomake-frame. The alist describes which parameters were specified in geom, and gives the values specified for them. Each element looks like(PARAMETER . VALUE). The possible parameter values areleft,top,width, andheight. For the size parameters, the value must be an integer. The position parameter namesleftandtopare not totally accurate, because some values indicate the position of the right or bottom edges instead. The value possibilities for the position parameters are: an integer, a list(+ POS), or a list(- POS); as previously described (Position Parameters). Here is an example:
(x-parse-geometry "35x70+0-0")
=> ((height . 70) (width . 35)
(top - 0) (left . 0))
Terminal Parameters
Each terminal has a list of associated parameters. These terminal parameters are mostly a convenient way of storage for terminal-local variables, but some terminal parameters have a special meaning. This section describes functions to read and change the parameter values of a terminal. They all accept as their argument either a terminal or a frame; the latter means use that frame's terminal. An argument of nil means the selected frame's terminal.
-
terminal-parameters - This function returns an alist listing all the parameters of terminal and their values.
-
terminal-parameter - This function returns the value of the parameter parameter (a symbol) of terminal. If terminal has no setting for parameter, this function returns
nil. -
set-terminal-parameter - This function sets the parameter parameter of terminal to the specified value, and returns the previous value of that parameter.
Here's a list of a few terminal parameters that have a special meaning:
-
background-mode - The classification of the terminal's background color, either
lightordark. -
normal-erase-is-backspace - Value is either 1 or 0, depending on whether
normal-erase-is-backspace-modeis turned on or off on this terminal. DEL Does Not Delete. -
terminal-initted - After the terminal is initialized, this is set to the terminal-specific initialization function.
-
tty-mode-set-strings - When present, a list of strings containing escape sequences that Emacs will output while configuring a tty for rendering. Emacs emits these strings only when configuring a terminal: if you want to enable a mode on a terminal that is already active (for example, while in
tty-setup-hook), explicitly output the necessary escape sequence usingsend-string-to-terminalin addition to adding the sequence totty-mode-set-strings. -
tty-mode-reset-strings - When present, a list of strings that undo the effects of the strings in
tty-mode-set-strings. Emacs emits these strings when exiting, deleting a terminal, or suspending itself.
Frame Titles
Every frame has a name parameter; this serves as the default for the frame title which window systems typically display at the top of the frame. You can specify a name explicitly by setting the name frame property. Normally you don't specify the name explicitly, and Emacs computes the frame name automatically based on a template stored in the variable frame-title-format. Emacs recomputes the name each time the frame is redisplayed.
-
frame-title-format - This variable specifies how to compute a name for a frame when you have not explicitly specified one (via the frame's parameters; Basic Parameters). The variable's value is actually a mode line construct, just like
mode-line-format, except that the%c,%C, and%lconstructs are ignored. Mode Line Data. -
icon-title-format - This variable specifies how to compute the name for an iconified frame when you have not explicitly specified the frame's name via the frame's parameters. The resulting title appears in the frame's icon itself. If the value is a string, is should be a mode line construct like that of
frame-title-format. The value can also bet, which means to useframe-title-formatinstead; this avoids problems with some window managers and desktop environments, where a change in a frame's title (when a frame is iconified) is interpreted as a request to raise the frame and/or give it input focus. It is also useful if you want the frame's title to be the same no matter if the frame is iconified or not. The default value is a string identical to the default value offrame-title-format. -
multiple-frames - This variable is set automatically by Emacs. Its value is
twhen there are two or more frames (not counting minibuffer-only frames or invisible frames). The default value offrame-title-formatusesmultiple-framesso as to put the buffer name in the frame title only when there is more than one frame. The value of this variable is not guaranteed to be accurate except while processingframe-title-formatoricon-title-format.
Deleting Frames
A live frame is one that has not been deleted. When a frame is deleted, it is removed from its terminal display, although it may continue to exist as a Lisp object until there are no more references to it.
-
Command delete-frame - This function deletes the frame frame. The argument frame must specify a live frame (see below) and defaults to the selected frame. It first deletes any child frame of frame (Child Frames) and any frame whose
delete-beforeframe parameter (Frame Interaction Parameters) specifies frame. All such deletions are performed recursively; so this step makes sure that no other frames with frame as their ancestor will exist. Then, unless frame specifies a tooltip, this function runs the hookdelete-frame-functions(each function getting one argument, frame) before actually killing the frame. After actually killing the frame and removing the frame from the frame list,delete-framerunsafter-delete-frame-functions. Note that a frame cannot be deleted as long as its minibuffer serves as surrogate minibuffer for another frame (Minibuffers and Frames). Normally, you cannot delete a frame if all other frames are invisible, but if force is non-nil, then you are allowed to do so. -
frame-live-p - This function returns non-
nilif the frame frame has not been deleted. The possible non-nilreturn values are like those offramep. Frames.
Some window managers provide a command to delete a window. These work by sending a special message to the program that operates the window. When Emacs gets one of these commands, it generates a delete-frame event, whose normal definition is a command that calls the function delete-frame. Misc Events.
-
Command delete-other-frames - This command deletes all frames on frame's terminal, except frame. If frame uses another frame's minibuffer, that minibuffer frame is left untouched. The argument frame must specify a live frame and defaults to the selected frame. Internally, this command works by calling
delete-framewith forcenilfor all frames that shall be deleted. This function does not delete any of frame's child frames (Child Frames). If frame is a child frame, it deletes frame's siblings only. With the prefix argument iconify, the frames are iconified rather than deleted.
Finding All Frames
-
frame-list - This function returns a list of all the live frames, i.e., those that have not been deleted. It is analogous to
buffer-listfor buffers, and includes frames on all terminals. The list that you get is newly created, so modifying the list doesn't have any effect on the internals of Emacs. -
visible-frame-list - This function returns a list of just the currently visible frames. Visibility of Frames. Frames on text terminals always count as visible, even though only the selected one is actually displayed.
-
frame-list-z-order - This function returns a list of Emacs' frames, in Z (stacking) order (Raising and Lowering). The optional argument display specifies which display to poll. display should be either a frame or a display name (a string). If omitted or
nil, that stands for the selected frame's display. It returnsnilif display contains no Emacs frame. Frames are listed from topmost (first) to bottommost (last). As a special case, if display is non-niland specifies a live frame, it returns the child frames of that frame in Z (stacking) order. This function is not meaningful on text terminals. -
next-frame - This function lets you cycle conveniently through all the frames on a specific terminal from an arbitrary starting point. It returns the frame following frame, in the list of all live frames, on frame's terminal. The argument frame must specify a live frame and defaults to the selected frame. It never returns a frame whose
no-other-frameparameter (Frame Interaction Parameters) is non-nil. The second argument, minibuf, says which frames to consider when deciding what the next frame should be: -
nil - Consider all frames except minibuffer-only frames.
-
visible - Consider only visible frames.
- 0
- Consider only visible or iconified frames.
- a window
- Consider only the frames using that particular window as their minibuffer window.
- anything else
- Consider all frames.
-
previous-frame - Like
next-frame, but cycles through all frames in the opposite direction.
See also next-window and previous-window, in Cyclic Window Ordering. Some Lisp programs need to find one or more frames that satisfy a given criteria. The function filtered-frame-list is provided for this purpose.
-
filtered-frame-list - This function returns the list of all the live frames which satisfy the specified predicate. The argument predicate must be a function of one argument, a frame to be tested against the filtering criteria, and should return non-
nilif the frame satisfies the criteria.
Minibuffers and Frames
Normally, each frame has its own minibuffer window at the bottom, which is used whenever that frame is selected. You can get that window with the function minibuffer-window (Minibuffer Windows). However, you can also create a frame without a minibuffer. Such a frame must use the minibuffer window of some other frame. That other frame will serve as surrogate minibuffer frame for this frame and cannot be deleted via delete-frame (Deleting Frames) as long as this frame is live. When you create the frame, you can explicitly specify its minibuffer window (in some other frame) with the minibuffer frame parameter (Buffer Parameters). If you don't, then the minibuffer is found in the frame which is the value of the variable default-minibuffer-frame. Its value should be a frame that does have a minibuffer. If you use a minibuffer-only frame, you might want that frame to raise when you enter the minibuffer. If so, set the variable minibuffer-auto-raise to t. Raising and Lowering.
-
default-minibuffer-frame - This variable specifies the frame to use for the minibuffer window, by default. It does not affect existing frames. It is always local to the current terminal and cannot be buffer-local. Multiple Terminals.
Input Focus
At any time, one frame in Emacs is the selected frame. The selected window (Selecting Windows) always resides on the selected frame. When Emacs displays its frames on several terminals (Multiple Terminals), each terminal has its own selected frame. But only one of these is the selected frame: it's the frame that belongs to the terminal from which the most recent input came. That is, when Emacs runs a command that came from a certain terminal, the selected frame is the one of that terminal. Since Emacs runs only a single command at any given time, it needs to consider only one selected frame at a time; this frame is what we call the selected frame in this manual. The display on which the selected frame is shown is the selected frame's display.
-
selected-frame - This function returns the selected frame.
Some window systems and window managers direct keyboard input to the window object that the mouse is in; others require explicit clicks or commands to shift the focus to various window objects. Either way, Emacs automatically keeps track of which frames have focus. To explicitly switch to a different frame from a Lisp function, call select-frame-set-input-focus. The plural "frames" in the previous paragraph is deliberate: while Emacs itself has only one selected frame, Emacs can have frames on many different terminals (recall that a connection to a window system counts as a terminal), and each terminal has its own idea of which frame has input focus. Under the X Window System, where user input is organized into individual "seats" of input, each seat in turn can have its own specific input focus. When you set the input focus to a frame, you set the focus for that frame's terminal on the last seat which interacted with Emacs, but frames on other terminals and seats may still remain focused. If the input focus is set before any user interaction has occurred on the specified terminal, then the X server picks a random seat (normally the one with the lowest number) and sets the input focus there. Lisp programs can switch frames temporarily by calling the function select-frame. This does not alter the window system's concept of focus; rather, it escapes from the window manager's control until that control is somehow reasserted. When using a text terminal, only one frame can be displayed at a time on the terminal, so after a call to select-frame, the next redisplay actually displays the newly selected frame. This frame remains selected until a subsequent call to select-frame. Each frame on a text terminal has a number which appears in the mode line before the buffer name (Mode Line Variables).
-
select-frame-set-input-focus - This function selects frame, raises it (should it happen to be obscured by other frames) and tries to give it the window system's focus. On a text terminal, the next redisplay displays the new frame on the entire terminal screen. The optional argument norecord has the same meaning as for
select-frame(see below). The return value of this function is not significant.
Ideally, the function described next should focus a frame without also raising it above other frames. Unfortunately, many window-systems or window managers may refuse to comply.
-
x-focus-frame - This function gives frame the focus of the X server without necessarily raising it. frame
nilmeans use the selected frame. Under X, the optional argument noactivate, if non-nil, means to avoid making frame's window-system window the "active" window which should insist a bit more on avoiding to raise frame above other frames. On MS-Windows the noactivate argument has no effect. However, if frame is a child frame (Child Frames), this function usually focuses frame without raising it above other child frames. If there is no window system support, this function does nothing. -
Command select-frame - This function selects frame frame, temporarily disregarding the focus of the X server if any. The selection of frame lasts until the next time the user does something to select a different frame, or until the next time this function is called. (If you are using a window system, the previously selected frame may be restored as the selected frame after return to the command loop, because it still may have the window system's input focus.) The specified frame becomes the selected frame, and its terminal becomes the selected terminal. This function then calls
select-windowas a subroutine, passing the window selected within frame as its first argument and norecord as its second argument (hence, if norecord is non-nil, this avoids changing the order of recently selected windows and the buffer list). Selecting Windows. This function returns frame, ornilif frame has been deleted. In general, you should never useselect-framein a way that could switch to a different terminal without switching back when you're done.
Emacs cooperates with the window system by arranging to select frames as the server and window manager request. When a window system informs Emacs that one of its frames has been selected, Emacs internally generates a focus-in event. When an Emacs frame is displayed on a text-terminal emulator, such as xterm, which supports reporting of focus-change notification, the focus-in and focus-out events are available even for text-mode frames. Focus events are normally handled by handle-focus-in.
-
Command handle-focus-in - This function handles focus-in events from window systems and terminals that support explicit focus notifications. It updates the per-frame focus flags that
frame-focus-statequeries and callsafter-focus-change-function. In addition, it generates aswitch-frameevent in order to switch the Emacs notion of the selected frame to the frame most recently focused in some terminal. It's important to note that this switching of the Emacs selected frame to the most recently focused frame does not mean that other frames do not continue to have the focus in their respective terminals. Do not invoke this function yourself: instead, attach logic toafter-focus-change-function. -
Command handle-switch-frame - This function handles a switch-frame event, which Emacs generates for itself upon focus notification or under various other circumstances involving an input event arriving at a different frame from the last event. Do not invoke this function yourself.
-
redirect-frame-focus - This function redirects focus from frame to focus-frame. This means that focus-frame will receive subsequent keystrokes and events intended for frame. After such an event, the value of
last-event-framewill be focus-frame. Also, switch-frame events specifying frame will instead select focus-frame. If focus-frame is omitted ornil, that cancels any existing redirection for frame, which therefore once again receives its own events. One use of focus redirection is for frames that don't have minibuffers. These frames use minibuffers on other frames. Activating a minibuffer on another frame redirects focus to that frame. This puts the focus on the minibuffer's frame, where it belongs, even though the mouse remains in the frame that activated the minibuffer. Selecting a frame can also change focus redirections. Selecting framebar, whenfoohad been selected, changes any redirections pointing tofooso that they point tobarinstead. This allows focus redirection to work properly when the user switches from one frame to another usingselect-window. This means that a frame whose focus is redirected to itself is treated differently from a frame whose focus is not redirected.select-frameaffects the former but not the latter. The redirection lasts untilredirect-frame-focusis called to change it. -
frame-focus-state - This function retrieves the last known focus state of frame. It returns
nilif the frame is known not to be focused,tif the frame is known to be focused, orunknownif Emacs does not know the focus state of the frame. (You may see this last state in TTY frames running on terminals that do not support explicit focus notifications.) -
after-focus-change-function - This function is called with no arguments when Emacs notices that a frame may have gotten or lost focus. Focus events are delivered asynchronously, and may not be delivered in the expected order, so code that wants to do something depending on the state of focused frames have go through all the frames and check. For instance, here's a simple example function that sets the background color based on whether the frame has focus or not:
(add-function :after after-focus-change-function
#'my-change-background)
(defun my-change-background ()
(dolist (frame (frame-list))
(pcase (frame-focus-state frame)
(`t (set-face-background 'default "black" frame))
(`nil (set-face-background 'default "#404040" frame)))))
Multiple frames may appear to have input focus simultaneously due to focus event delivery differences, the presence of multiple Emacs terminals, and other factors, and code should be robust in the face of this situation. Depending on window system, focus events may also be delivered repeatedly and with different focus states before settling to the expected values. Code relying on focus notifications should "debounce" any user-visible updates arising from focus changes, perhaps by deferring work until redisplay. This function may be called in arbitrary contexts, including from inside read-event, so take the same care as you might when writing a process filter.
-
focus-follows-mouse - This option informs Emacs whether and how the window manager transfers focus when you move the mouse pointer into a frame. It can have three meaningful values:
-
nil - The default value
nilshould be used when your window manager follows a "click-to-focus" policy where you have to click the mouse inside of a frame in order for that frame to gain focus. -
t - The value
tshould be used when your window manager has the focus automatically follow the position of the mouse pointer but a frame that gains focus is not raised automatically and may even remain occluded by other window-system windows. -
auto-raise - The value
auto-raiseshould be used when your window manager has the focus automatically follow the position of the mouse pointer and a frame that gains focus is raised automatically.
If this option is non-nil, Emacs moves the mouse pointer to the frame selected by select-frame-set-input-focus. That function is used by a number of commands like, for example, other-frame and pop-to-buffer. The distinction between the values t and auto-raise is not needed for "normal" frames because the window manager usually takes care of raising them. It is useful to automatically raise child frames via mouse-autoselect-window (Mouse Window Auto-selection). Note that this option does not distinguish "sloppy" focus (where the frame that previously had focus retains focus as long as the mouse pointer does not move into another window-system window) from "strict" focus (where a frame immediately loses focus when it's left by the mouse pointer). Neither does it recognize whether your window manager supports delayed focusing or auto-raising where you can explicitly specify the time until a new frame gets focus or is auto-raised. You can supply a "focus follows mouse" policy for individual Emacs windows by customizing the variable mouse-autoselect-window (Mouse Window Auto-selection).
Visibility of Frames
A frame on a graphical display may be visible, invisible, or iconified. If it is visible, its contents are displayed in the usual manner. If it is iconified, its contents are not displayed, but there is a little icon somewhere to bring the frame back into view (some window managers refer to this state as minimized rather than iconified, but from Emacs' point of view they are the same thing). If a frame is invisible, it is not displayed at all. The concept of visibility is strongly related to that of (un-)mapped frames. A frame (or, more precisely, its window-system window) is and becomes mapped when it is displayed for the first time and whenever it changes its state of visibility from iconified or invisible to visible. Conversely, a frame is and becomes unmapped whenever it changes its status from visible to iconified or invisible. Visibility is meaningless on text terminals, since only the selected frame is actually displayed in any case.
-
frame-visible-p - This function returns the visibility status of frame frame. The value is
tif frame is visible,nilif it is invisible, andiconif it is iconified. On a text terminal, all frames are considered visible for the purposes of this function, even though only one frame is displayed. Raising and Lowering. -
Command iconify-frame - This function iconifies frame frame. If you omit frame, it iconifies the selected frame. This usually makes all child frames of frame (and their descendants) invisible (Child Frames).
-
Command make-frame-visible - This function makes frame frame visible. If you omit frame, it makes the selected frame visible. This does not raise the frame, but you can do that with
raise-frameif you wish (Raising and Lowering). Making a frame visible usually makes all its child frames (and their descendants) visible as well (Child Frames). -
Command make-frame-invisible - This function makes frame frame invisible. If you omit frame, it makes the selected frame invisible. Usually, this makes all child frames of frame (and their descendants) invisible too (Child Frames). Unless force is non-
nil, this function refuses to make frame invisible if all other frames are invisible.
The visibility status of a frame is also available as a frame parameter. You can read or change it as such. Management Parameters. The user can also iconify and deiconify frames with the window manager. This happens below the level at which Emacs can exert any control, but Emacs does provide events that you can use to keep track of such changes. Misc Events.
-
x-double-buffered-p - This function returns non-
nilif frame is currently being rendered with double buffering. frame defaults to the selected frame.
Raising, Lowering and Restacking Frames
Most window systems use a desktop metaphor. Part of this metaphor is the idea that system-level windows (representing, e.g., Emacs frames) are stacked in a notional third dimension perpendicular to the screen surface. The order induced by stacking is total and usually referred to as stacking (or Z-) order. Where the areas of two windows overlap, the one higher up in that order will (partially) cover the one underneath. You can raise a frame to the top of that order or lower a frame to its bottom by using the functions raise-frame and lower-frame. You can restack a frame directly above or below another frame using the function frame-restack. Note that all functions described below will respect the adherence of frames (and all other window-system windows) to their respective z-group (Position Parameters). For example, you usually cannot lower a frame below that of the desktop window and you cannot raise a frame whose z-group parameter is nil above the window-system's taskbar or tooltip window.
-
Command raise-frame - This function raises frame frame (default, the selected frame) above all other frames belonging to the same or a lower z-group as frame. If frame is invisible or iconified, this makes it visible. If frame is a child frame (Child Frames), this raises frame above all other child frames of its parent.
-
Command lower-frame - This function lowers frame frame (default, the selected frame) below all other frames belonging to the same or a higher z-group as frame. If frame is a child frame (Child Frames), this lowers frame below all other child frames of its parent.
-
frame-restack - This function restacks frame1 below frame2. This implies that if both frames are visible and their display areas overlap, frame2 will (partially) obscure frame1. If the optional third argument above is non-
nil, this function restacks frame1 above frame2. This means that if both frames are visible and their display areas overlap, frame1 will (partially) obscure frame2. Technically, this function may be thought of as an atomic action performed in two steps: The first step removes frame1's window-system window from the display. The second step reinserts frame1's window into the display below (above if above is true) that of frame2. Hence the position of frame2 in its display's Z (stacking) order relative to all other frames excluding frame1 remains unaltered. Some window managers may refuse to restack windows.
Note that the effect of restacking will only hold as long as neither of the involved frames is iconified or made invisible. You can use the z-group (Position Parameters) frame parameter to add a frame to a group of frames permanently shown above or below other frames. As long as a frame belongs to one of these groups, restacking it will only affect its relative stacking position within that group. The effect of restacking frames belonging to different z-groups is undefined. You can list frames in their current stacking order with the function frame-list-z-order (Finding All Frames).
-
minibuffer-auto-raise - If this is non-
nil, activation of the minibuffer raises the frame that the minibuffer window is in.
On window systems, you can also enable auto-raising (on frame selection) or auto-lowering (on frame deselection) using frame parameters. Management Parameters. The concept of raising and lowering frames also applies to text terminal frames. On each text terminal, only the top frame is displayed at any one time.
-
tty-top-frame - This function returns the top frame on terminal. terminal should be a terminal object, a frame (meaning that frame's terminal), or
nil(meaning the selected frame's terminal). If it does not refer to a text terminal, the return value isnil.
Frame Configurations
A frame configuration records the current arrangement of frames, all their properties, and the window configuration of each one. (Window Configurations.)
-
current-frame-configuration - This function returns a frame configuration list that describes the current arrangement of frames and their contents.
-
set-frame-configuration - This function restores the state of frames described in configuration. However, this function does not restore deleted frames. Ordinarily, this function deletes all existing frames not listed in configuration. But if nodelete is non-
nil, the unwanted frames are iconified instead.
Child Frames
Child frames are objects halfway between windows (Windows) and "normal" frames. Like windows, they are attached to an owning frame. Unlike windows, they may overlap each other—changing the size or position of one child frame does not change the size or position of any of its sibling child frames. By design, operations to make or modify child frames are implemented with the help of frame parameters (Frame Parameters) without any specialized functions or customizable variables. Note that child frames are meaningful on graphical terminals only. To create a new child frame or to convert a normal frame into a child frame, set that frame's parent-frame parameter (Frame Interaction Parameters) to that of an already existing frame. The frame specified by that parameter will then be the frame's parent frame as long as the parameter is not changed or reset. Technically, this makes the child frame's window-system window a child window of the parent frame's window-system window. The parent-frame parameter can be changed at any time. Setting it to another frame reparents the child frame. Setting it to another child frame makes the frame a nested child frame. Setting it to nil restores the frame's status as a top-level frame—a frame whose window-system window is a child of its display's root window.(On Haiku) Since child frames can be arbitrarily nested, a frame can be both a child and a parent frame. Also, the relative roles of child and parent frame may be reversed at any time (though it's usually a good idea to keep the size of a child frame sufficiently smaller than that of its parent). An error will be signaled for the attempt to make a frame an ancestor of itself. Most window-systems clip a child frame at the native edges (Frame Geometry) of its parent frame—everything outside these edges is usually invisible. A child frame's left and top parameters specify a position relative to the top-left corner of its parent's native frame. When the parent frame is resized, this position remains conceptually unaltered. NS builds do not clip child frames at the parent frame's edges, allowing them to be positioned so they do not obscure the parent frame while still being visible themselves. Usually, moving a parent frame moves along all its child frames and their descendants as well, keeping their relative positions unaltered. Note that the hook move-frame-functions (Frame Position) is run for a child frame only when the position of the child frame relative to its parent frame changes. When a parent frame is resized, its child frames conceptually retain their previous sizes and their positions relative to the left upper corner of the parent. This means that a child frame may become (partially) invisible when its parent frame shrinks. The parameter keep-ratio (Frame Interaction Parameters) can be used to resize and reposition a child frame proportionally whenever its parent frame is resized. This may avoid obscuring parts of a frame when its parent frame is shrunk. A visible child frame always appears on top of its parent frame thus obscuring parts of it, except on NS builds where it may be positioned beneath the parent. This is comparable to the window-system window of a top-level frame which also always appears on top of its parent window—the desktop's root window. When a parent frame is iconified or made invisible (Visibility of Frames), its child frames are made invisible. When a parent frame is deiconified or made visible, its child frames are made visible. When a parent frame is about to be deleted (Deleting Frames), its child frames are recursively deleted before it. There is one exception to this rule: When the child frame serves as a surrogate minibuffer frame (Minibuffers and Frames) for another frame, it is retained until the parent frame has been deleted. If, at this time, no remaining frame uses the child frame as its minibuffer frame, Emacs will try to delete the child frame too. If that deletion fails for whatever reason, the child frame is made a top-level frame. Whether a child frame can have a menu or tool bar is window-system or window manager dependent. Most window-systems explicitly disallow menu bars for child frames. It seems advisable to disable both, menu and tool bars, via the frame's initial parameters settings. Usually, child frames do not exhibit window manager decorations like a title bar or external borders (Frame Geometry). When the child frame does not show a menu or tool bar, any other of the frame's borders (Layout Parameters) can be used instead of the external borders. In particular, under X (but not when building with GTK+), the frame's outer border can be used. On MS-Windows, specifying a non-zero outer border width will show a one-pixel wide external border. Under all window-systems, the internal border can be used. In either case, it's advisable to disable a child frame's window manager decorations with the undecorated frame parameter (Management Parameters). To resize or move an undecorated child frame with the mouse, special frame parameters (Mouse Dragging Parameters) have to be used. The internal border of a child frame, if present, can be used to resize the frame with the mouse, provided that frame has a non-nil drag-internal-border parameter. If set, the snap-width parameter indicates the number of pixels where the frame snaps at the respective edge or corner of its parent frame. There are two ways to drag an entire child frame with the mouse: The drag-with-mode-line parameter, if non-nil, allows to drag a frame without minibuffer window (Minibuffer Windows) via the mode line area of its bottommost window. The drag-with-header-line parameter, if non-nil, allows to drag the frame via the header line area of its topmost window. In order to give a child frame a draggable header or mode line, the window parameters mode-line-format and header-line-format are handy (Window Parameters). These allow to remove an unwanted mode line (when drag-with-header-line is chosen) and to remove mouse-sensitive areas which might interfere with frame dragging. When the user drags a frame with a mouse and overshoots, it's easy to drag a frame out of the screen area of its parent. Retrieving such a frame can be hairy once the mouse button has been released. To prevent such a situation, it is advisable to set the frame's top-visible or bottom-visible parameter (Mouse Dragging Parameters). Set the top-visible parameter of a child frame to a number when you intend to allow the user dragging that frame by its header line. Setting top-visible to a number inhibits dragging the top edge of the child frame above the top edge of its parent. Set the bottom-visible parameter to a number when you intend to drag that frame via its mode line; this inhibits dragging the bottom edge of the child frame beneath the bottom edge of its parent. In either case, that number also specifies width and height (in pixels) of the area of the child frame that remains visible during dragging. When a child frame is used for displaying a buffer via display-buffer-in-child-frame (Buffer Display Action Functions), the frame's auto-hide-function parameter (Frame Interaction Parameters) can be set to a function, in order to appropriately deal with the frame when the window displaying the buffer shall be quit. When a child frame is used during minibuffer interaction, for example, to display completions in a separate window, the minibuffer-exit parameter (Frame Interaction Parameters) is useful in order to deal with the frame when the minibuffer is exited. The behavior of child frames deviates from that of top-level frames in a number of other ways as well. Here we sketch a few of them:
- The semantics of maximizing and iconifying child frames is highly window-system dependent. As a rule, applications should never invoke these operations on child frames. By default, invoking
iconify-frameon a child frame will try to iconify the top-level frame corresponding to that child frame instead. To obtain a different behavior, users may customize the optioniconify-child-framedescribed below. - Raising, lowering and restacking child frames (Raising and Lowering) or changing the
z-group(Position Parameters) of a child frame changes only the stacking order of child frames with the same parent. - Many window-systems are not able to change the opacity (Font and Color Parameters) of child frames.
- Transferring focus from a child frame to an ancestor that is not its parent by clicking with the mouse in a visible part of that ancestor's window may fail with some window-systems. You may have to click into the direct parent's window-system window first.
- Window managers might not bother to extend their focus follows mouse policy to child frames. Customizing
mouse-autoselect-windowcan help in this regard (Mouse Window Auto-selection). - Dropping (Drag and Drop) on child frames is not guaranteed to work on all window-systems. Some will drop the object on the parent frame or on some ancestor instead.
The following two functions can be useful when working with child and parent frames:
-
frame-parent - This function returns the parent frame of frame. The parent frame of frame is the Emacs frame whose window-system window is the parent window of frame's window-system window. If such a frame exists, frame is considered a child frame of that frame. This function returns
nilif frame has no parent frame. -
frame-ancestor-p - This functions returns non-
nilif ancestor is an ancestor of descendant. ancestor is an ancestor of descendant when it is either descendant's parent frame or it is an ancestor of descendant's parent frame. Both, ancestor and descendant must specify live frames.
Note also the function window-largest-empty-rectangle (Coordinates and Windows) which can be used to inscribe a child frame in the largest empty area of an existing window. This can be useful to avoid that a child frame obscures any text shown in that window. Customizing the following option can be useful to tweak the behavior of iconify-frame for child frames.
-
iconify-child-frame - This option tells Emacs how to proceed when it is asked to iconify a child frame. If it is
nil,iconify-framewill do nothing when invoked on a child frame. If it isiconify-top-level, Emacs will try to iconify the top-level frame that is the ancestor of this child frame instead. If it ismake-invisible, Emacs will try to make this child frame invisible instead of iconifying it. Any other value means to try iconifying the child frame. Since such an attempt may not be honored by all window managers and can even lead to making the child frame unresponsive to user actions, the default is to iconify the top level frame instead.
Mouse Tracking
Sometimes it is useful to track the mouse, which means to display something to indicate where the mouse is and move the indicator as the mouse moves. For efficient mouse tracking, you need a way to wait until the mouse actually moves. The convenient way to track the mouse is to ask for events to represent mouse motion. Then you can wait for motion by waiting for an event. In addition, you can easily handle any other sorts of events that may occur. That is useful, because normally you don't want to track the mouse forever—only until some other event, such as the release of a button.
-
track-mouse - This macro executes body, with generation of mouse motion events enabled. Typically, body would use
read-eventto read the motion events and modify the display accordingly. Motion Events, for the format of mouse motion events. The value oftrack-mouseis that of the last form in body. You should design body to return when it sees the up-event that indicates the release of the button, or whatever kind of event means it is time to stop tracking. Its value also controls how mouse events are reported while a mouse button is held down: if it isdroppingordrag-source, the motion events are reported relative to the frame underneath the pointer. If there is no such frame, the events will be reported relative to the frame the mouse buttons were first pressed on. In addition, theposn-windowof the mouse position list will benilif the value isdrag-source. This is useful to determine if a frame is not directly visible underneath the mouse pointer. Thetrack-mousemacro causes Emacs to generate mouse motion events by binding the variabletrack-mouseto a non-nilvalue. If that variable has the special valuedragging, it additionally instructs the display engine to refrain from changing the shape of the mouse pointer. This is desirable in Lisp programs that require mouse dragging across large portions of Emacs display, which might otherwise cause the mouse pointer to change its shape according to the display portion it hovers on (Pointer Shape). Therefore, Lisp programs that need the mouse pointer to retain its original shape during dragging should bindtrack-mouseto the valuedraggingat the beginning of their body.
The usual purpose of tracking mouse motion is to indicate on the screen the consequences of pushing or releasing a button at the current position. In many cases, you can avoid the need to track the mouse by using the mouse-face text property (Special Properties). That works at a much lower level and runs more smoothly than Lisp-level mouse tracking.
Mouse Position
The functions mouse-position and set-mouse-position give access to the current position of the mouse.
-
mouse-position - This function returns a description of the position of the mouse. The value looks like
(FRAME X . Y), where x and y are integers giving the (possibly rounded) position in multiples of the default character size of frame (Frame Font) relative to the native position of frame (Frame Geometry). -
mouse-position-function - If non-
nil, the value of this variable is a function formouse-positionto call.mouse-positioncalls this function just before returning, with its normal return value as the sole argument, and it returns whatever this function returns to it. This abnormal hook exists for the benefit of packages likext-mouse.elthat need to do mouse handling at the Lisp level. -
tty-menu-calls-mouse-position-function - If non-
nil, TTY menus will callmouse-position-functionas described above. This exists for cases wheremouse-position-functionis not safe to be called by the TTY menus, such as if it could trigger redisplay. -
set-mouse-position - This function warps the mouse to position x, y in frame frame. The arguments x and y are integers, giving the position in multiples of the default character size of frame (Frame Font) relative to the native position of frame (Frame Geometry). The resulting mouse position is constrained to the native frame of frame. If frame is not visible, this function does nothing. The return value is not significant.
-
mouse-pixel-position - This function is like
mouse-positionexcept that it returns coordinates in units of pixels rather than units of characters. -
set-mouse-pixel-position - This function warps the mouse like
set-mouse-positionexcept that x and y are in units of pixels rather than units of characters. The resulting mouse position is not constrained to the native frame of frame. If frame is not visible, this function does nothing. The return value is not significant.
On a graphical terminal the following two functions allow the absolute position of the mouse cursor to be retrieved and set.
-
mouse-absolute-pixel-position - This function returns a cons cell (x . y) of the coordinates of the mouse cursor position in pixels, relative to a position (0, 0) of the selected frame's display.
-
set-mouse-absolute-pixel-position - This function moves the mouse cursor to the position (x, y). The coordinates x and y are interpreted in pixels relative to a position (0, 0) of the selected frame's display.
The following function can tell whether the mouse cursor is currently visible on a frame:
-
frame-pointer-visible-p - This predicate function returns non-
nilif the mouse pointer displayed on frame is visible; otherwise it returnsnil. frame omitted ornilmeans the selected frame. This is useful whenmake-pointer-invisibleis set tot: it allows you to know if the pointer has been hidden. Mouse Avoidance.
Dialog Boxes
A dialog box is a variant of a pop-up menu—it looks a little different, it always appears in the center of a frame, and it has just one level and one or more buttons. The main use of dialog boxes is for asking questions that the user can answer with "yes", "no", and a few other alternatives. With a single button, they can also force the user to acknowledge important information. The functions y-or-n-p and yes-or-no-p use dialog boxes instead of the keyboard, when called from commands invoked by mouse clicks.
-
x-popup-dialog - This function displays a pop-up dialog box and returns an indication of what selection the user makes. The argument contents specifies the alternatives to offer; it has this format:
(TITLE (STRING . VALUE)...)
which looks like the list that specifies a single pane for x-popup-menu. The return value is value from the chosen alternative. As for x-popup-menu, an element of the list may be just a string instead of a cons cell (STRING . VALUE). That makes a box that cannot be selected. If nil appears in the list, it separates the left-hand items from the right-hand items; items that precede the nil appear on the left, and items that follow the nil appear on the right. If you don't include a nil in the list, then approximately half the items appear on each side. Dialog boxes always appear in the center of a frame; the argument position specifies which frame. The possible values are as in x-popup-menu, but the precise coordinates or the individual window don't matter; only the frame matters. If header is non-nil, the frame title for the box is Information, otherwise it is Question. The former is used for message-box (message-box). (On text terminals, the box title is not displayed.) In some configurations, Emacs cannot display a real dialog box; so instead it displays the same items in a pop-up menu in the center of the frame. If the user gets rid of the dialog box without making a valid choice, for instance using the window manager, then this produces a quit and x-popup-dialog does not return.
Pointer Shape
You can specify the mouse pointer style for particular text or images using the pointer text property, and for images with the :pointer and :map image properties. The values you can use in these properties are in the table below. The actual shapes may vary between systems; the descriptions are examples.
-
text,nil - The usual mouse pointer style used over text (an "I"-like shape).
-
arrow,vdrag,modeline - An arrow that points north-west.
-
hand - A hand that points upwards.
-
hdrag - A right-left arrow.
-
nhdrag - An up-down arrow.
-
hourglass - A rotating ring.
Over void parts of the window (parts that do not correspond to any of the buffer contents), the mouse pointer usually uses the arrow style, but you can specify a different style (one of those above) by setting void-text-area-pointer.
-
void-text-area-pointer - This variable specifies the mouse pointer style for void text areas. These include the areas after the end of a line or below the last line in the buffer. The default is to use the
arrow(non-text) pointer style.
When using some window systems, you can specify what the text pointer style really looks like by setting the variable x-pointer-shape.
-
x-pointer-shape - This variable specifies the pointer shape to use ordinarily in the Emacs frame, for the
textpointer style. -
x-sensitive-text-pointer-shape - This variable specifies the pointer shape to use when the mouse is over mouse-sensitive text.
These variables affect newly created frames. They do not normally affect existing frames; however, if you set the mouse color of a frame, that also installs the current value of those two variables. Font and Color Parameters. The values you can use, to specify either of these pointer shapes, are defined in the file lisp/term/x-win.el. Use M-x apropos RET x-pointer RET to see a list of them.
Window System Selections
In window systems, such as X, data can be transferred between different applications by means of selections. X defines an arbitrary number of selection types, each of which can store its own data; however, only three are commonly used: the clipboard, primary selection, and secondary selection. Other window systems support only the clipboard. Cut and Paste, for Emacs commands that make use of these selections. This section documents the low-level functions for reading and setting window-system selections.
-
Command gui-set-selection - This function sets a window-system selection. It takes two arguments: a selection type type, and the value to assign to it, data. type should be a symbol; it is usually one of
PRIMARY,SECONDARYorCLIPBOARD. These are symbols with upper-case names, in accord with X Window System conventions. If type isnil, that stands forPRIMARY. If data isnil, it means to clear out the selection. Otherwise, data may be a string, a symbol, an integer, an overlay, or a cons of two markers pointing to the same buffer. An overlay or a pair of markers stands for text in the overlay or between the markers. The argument data may also be a vector of valid non-vector selection values. If data is a string, then its text properties can specify values used for individual data types. For example, if data has a property namedtext/uri-list, then a call togui-get-selectionwith the data typetext/uri-listwill result in the value of that property being used instead of data itself. This function returns data. -
gui-get-selection - This function accesses selections set up by Emacs or by other programs. It takes two optional arguments, type and data-type. The default for type, the selection type, is
PRIMARY. The data-type argument specifies the form of data conversion to use, to convert the raw data obtained from another program into Lisp data. Meaningful values includeTEXT,STRING,UTF8_STRING,TARGETS,LENGTH,DELETE,FILE_NAME,CHARACTER_POSITION,NAME,LINE_NUMBER,COLUMN_NUMBER,OWNER_OS,HOST_NAME,USER,CLASS,ATOM, andINTEGER. (These are symbols with upper-case names in accord with X conventions.) The default for data-type isSTRING. Window systems other than X usually support only a small subset of these types, in addition toSTRING. -
selection-coding-system - This variable specifies the coding system to use when reading and writing selections or the clipboard. Coding Systems. The default is
compound-text-with-extensions, which converts to the text representation that X11 normally uses.
When Emacs runs on MS-Windows, it does not implement X selections in general, but it does support the clipboard. gui-get-selection and gui-set-selection on MS-Windows support the text data type only; if the clipboard holds other types of data, Emacs treats the clipboard as empty. The supported data type is STRING. For backward compatibility, there are obsolete aliases x-get-selection and x-set-selection, which were the names of gui-get-selection and gui-set-selection before Emacs 25.1.
Yanking Media
If you choose, for instance, "Copy Image" in a web browser, that image is put onto the clipboard, and Emacs can access it via gui-get-selection. But in general, inserting image data into an arbitrary buffer isn't very useful—you can't really do much with it by default. So Emacs has a system to let modes register handlers for these "complicated" selections.
-
yank-media-handler - types can be a MIME media type symbol, a regexp to match these, or a list of these symbols and regexps. For instance:
(yank-media-handler 'text/html #'my-html-handler) (yank-media-handler "image/.*" #'my-image-handler)
A mode can register as many handlers as required. The handler function is called with two parameters: The MIME media type symbol and the data (as a string). The handler should then insert the object into the buffer, or save it, or do whatever is appropriate for the mode. The yank-media command will consult the registered handlers in the current buffer, compare that with the available media types on the clipboard, and then pass on the matching selection to the handler (if any). If there's more than one matching selection, the user is queried first. The yank-media-types command can be used to explore the clipboard/primary selection. It lists all the media types that are currently available, and can be handy when creating handlers—to see what data is actually available. Some applications put a surprising amount of different data types on the clipboard.
Drag and Drop
When the user drops something from another application over Emacs, Emacs will try to insert any text and open any URL that was dropped. If text was dropped, then it will always be inserted at the location of the mouse pointer where the drop happened, or saved in the kill ring if insertion failed, which could happen if the buffer was read-only. If a URL was dropped instead, then Emacs will first try to call an appropriate handler function by matching the URL against regexps defined in the variable dnd-protocol-alist, and then against those defined in the variables browse-url-handlers and browse-url-default-handlers. Should no suitable handler be located, Emacs will fall back to inserting the URL as plain text.
-
dnd-protocol-alist - This variable is a list of cons cells of the form
(PATTERN . ACTION). pattern is a regexp that URLs are matched against after being dropped. action is a function that is called with two arguments, should a URL being dropped match pattern: the URL being dropped, and the action being performed for the drop, which is one of the symbolscopy,move,link,privateorask. If action is private, then it means the program that initiated the drop wants Emacs to perform an unspecified action with the URL; a reasonable action to perform in that case is to open the URL or copy its contents into the current buffer. Otherwise, action has the same meaning as the action argument todnd-begin-file-drag.
Emacs implements receiving text and URLs individually for each window system, and does not by default support receiving other kinds of data as drops. To support receiving other kinds of data, use the X-specific interface described below. When a user drags something from another application over Emacs under the X Window System, that other application expects Emacs to tell it if Emacs understands the data being dragged. The function in the variable x-dnd-test-function is called by Emacs to determine what to reply to any such inquiry. The default value is x-dnd-default-test-function, which accepts drops if the type of the data to be dropped is present in x-dnd-known-types. Changing the variables x-dnd-test-function and x-dnd-known-types can make Emacs accept or reject drops based on some other criteria. If you want to change the way Emacs receives drops of different data types, or you want to enable it to understand a new type, change the variable x-dnd-types-alist. Doing so correctly requires detailed knowledge of what data types other applications use for drag and drop. These data types are typically implemented as special data types that can be obtained from an X selection provided by the other application. In most cases, they are either the same data types that are typically accepted by gui-set-selection, or MIME types, depending on the specific drag-and-drop protocol being used. For example, the data type used for plain text may be either "STRING" or "text/plain". When Emacs runs on X window system, it supports the X Direct Save (XDS) protocol, which allows users to save a file by dragging and dropping it onto an Emacs window, such as a Dired window. To comply with the unique requirements of XDS, these drag-and-drop requests are processed specially: instead of being handled according to x-dnd-types-alist, they are handled by the direct-save function that is the value of the variable x-dnd-direct-save-function. The value should be a function of two arguments, need-name and filename. The XDS protocol uses a two-step procedure for dragging files:
- The application from which the file is dragged asks Emacs to provide the full file name under which to save the file. For this purpose, the direct-save function is called with its first argument need-name non-
nil, and the second argument filename set to the basename of the file to be saved. It should return the fully-expanded absolute file name under which to save the file. For example, if a file is dragged to a Dired window, the natural directory for the file is the directory of the file shown at location of the drop. If saving the file is not possible for some reason, the function should returnnil, which will cancel the drag-and-drop operation. - The application from which the file is dragged saves the file under the name returned by the first call to the direct-save function. If it succeeds in saving the file, the direct-save function is called again, this time with the first argument need-name set to
niland the second argument filename set to the full absolute name of the saved file. The function is then expected to do whatever is needed given the fact that file was saved. For example, Dired should update the directory on display by showing the new file there.
The default value of x-dnd-direct-save-function is x-dnd-save-direct.
-
x-dnd-save-direct - When called with the need-name argument non-
nil, this function prompts the user for the absolute file name under which it should be saved. If the specified file already exists, it additionally asks the user whether to overwrite it, and returns the absolute file name only if the user confirms the overwriting. When called with the need-name argumentnil, it reverts the Dired listing if the current buffer is in Dired mode or one of its descendants, and otherwise visits the file by callingfind-file(Visiting Functions). -
x-dnd-save-direct-immediately - This function works like
x-dnd-save-direct, but when called with its need-name argument non-nil, it doesn't prompt the user for the full name of the file to be saved; instead, it returns its argument filename expanded against the current buffer's default directory (File Name Expansion). (It still asks for confirmation if a file by that name already exists in the default directory.)
On capable window systems, Emacs also supports dragging contents from its frames to windows of other applications.
-
dnd-begin-text-drag - This function begins dragging text from frame to another program (known as the drop target), and returns the result of drag-and-drop operation when the text is dropped or the drag-and-drop operation is canceled. text is the text that will be inserted by the drop target. action must be one of the symbols
copyormove, wherecopymeans that text should be inserted by the drop target, andmovemeans the same ascopy, but in addition the caller may have to delete text from its source as explained below. frame is the frame where the mouse is currently held down, ornil, which means to use the selected frame. This function may return immediately if no mouse buttons are held down, so it should be only called immediately after adown-mouse-1or similar event (Mouse Events), with frame set to the frame where that event was generated (Click Events). allow-same-frame specifies whether or not drops on top of frame itself are to be ignored. The return value specifies the action that the drop target actually performed, and optionally what the caller should do. It can be one of the following symbols: -
copy - The drop target inserted the dropped text.
-
move - The drop target inserted the dropped text, but in addition the caller should delete text from wherever it originated, such as its buffer.
-
private - The drop target performed some other unspecified action.
-
nil - The drag-and-drop operation was canceled.
-
dnd-begin-file-drag - This function begins dragging file from frame to another program, and returns the result of the drag-and-drop operation when the file is dropped or the drag-and-drop operation is canceled. If file is a remote file, then a temporary copy will be made. action must be one of the symbols
copy,moveorlink, wherecopymeans that file should be opened or copied by the drop target,movemeans the drop target should move the file to another location, andlinkmeans the drop target should create a symbolic link to file. It is an error to specifylinkas the action if file is a remote file. frame and allow-same-frame have the same meaning as indnd-begin-text-drag. The return value is the action that the drop target actually performed, which can be one of the following symbols: -
copy - The drop target opened or copied file to a different location.
-
move - The drop target moved file to a different location.
-
link - The drop target (usually a file manager) created a symbolic link to file.
-
private - The drop target performed some other unspecified action.
-
nil - The drag-and-drop operation was canceled.
-
dnd-begin-drag-files - This function is like
dnd-begin-file-drag, except that files is a list of files. If the drop target doesn't support dropping multiple files, then the first file will be used instead. -
dnd-direct-save - This function is similar to
dnd-begin-file-drag(with the default action of copy), but instead of specifying the action you specify the name of the copy created by the target program inname.
The high-level interfaces described above are implemented on top of a lower-level primitive. If you need to drag content other than files or text, use the low-level interface x-begin-drag instead. However, using it will require detailed knowledge of the data types and actions used by the programs to transfer content via drag-and-drop on each platform you want to support.
-
x-begin-drag - This function begins a drag from frame, and returns when the drag-and-drop operation ends, either because the drop was successful, or because the drop was rejected. The drop occurs when all mouse buttons are released on top of an X window other than frame (the drop target), or any X window if allow-current-frame is non-
nil. If no mouse buttons are held down when the drag-and-drop operation begins, this function may immediately returnnil. targets is a list of strings describing selection targets, much like the data-type argument togui-get-selection, that the drop target can request from Emacs (Window System Selections). action is a symbol describing the action recommended to the target. It can either beXdndActionCopy, which means to copy the contents of the selectionXdndSelectionto the drop target; orXdndActionMove, which means copy as withXdndActionCopy, and in addition the caller should delete whatever was stored in that selection after copying it. action may also be an alist which associates between symbols describing the available actions, and strings that the drop target is expected to present to the user to choose between the available actions. If return-frame is non-niland the mouse moves over an Emacs frame after first moving out of frame, then the frame to which the mouse moves will be returned immediately. If return-frame is the symbolnow, then any frame underneath the mouse pointer will be returned without waiting for the mouse to first move out of frame. return-frame is useful when you want to treat dragging content from one frame to another specially, while also being able to drag content to other programs, but it is not guaranteed to work on all systems and with all window managers. If follow-tooltip is non-nil, the position of any tooltip (such as one shown bytooltip-show) will follow the location of the mouse pointer whenever it moves during the drag-and-drop operation. The tooltip will be hidden once all mouse buttons are released. If the drop was rejected or no drop target was found, this function returnsnil. Otherwise, it returns a symbol describing the action the target chose to perform, which can differ from action if that isn't supported by the drop target.XdndActionPrivateis also a valid return value in addition toXdndActionCopyandXdndActionMove; it means that the drop target chose to perform an unspecified action, and no further processing is required by the caller. The caller must cooperate with the target to fully perform the action chosen by the target. For example, callers should delete the buffer text that was dragged if this function returnsXdndActionMove.
On X Windows, several different drag-and-drop protocols are supported by x-begin-drag. When dragging content that is known to not be supported by a specific drag-and-drop protocol, it might be desirable to turn that protocol off, by changing the values of the following variables:
-
x-dnd-disable-motif-protocol - When this is non-
nil, the Motif drag and drop protocols are disabled, and dropping onto programs that only understand them will not work. -
x-dnd-use-offix-drop - When this is
nil, the OffiX (old KDE) drag and drop protocol is disabled. When this is the symbolfiles, the OffiX protocol will only be used if"FILE_NAME"is one of the targets given tox-begin-drag. Any other value means to use the OffiX protocol to drop all supported content. -
x-dnd-use-unsupported-drop - When one of the
"STRING","UTF8_STRING","COMPOUND_TEXT"or"TEXT"targets is present in the list given tox-begin-drag, Emacs will try to use synthesized mouse events and the primary selection to insert the text if the drop target doesn't support any drag-and-drop protocol at all. A side effect is that Emacs will become the owner of the primary selection upon such a drop. If that is not desired, then the drop emulation can be disabled by setting this variable tonil.
Color Names
A color name is text (usually in a string) that specifies a color. Symbolic names such as black, white, red, etc., are allowed; use M-x list-colors-display to see a list of defined names. You can also specify colors numerically in forms such as #RGB and RGB:R/G/B, where r specifies the red level, g specifies the green level, and b specifies the blue level. You can use either one, two, three, or four hex digits for r; then you must use the same number of hex digits for all g and b as well, making either 3, 6, 9 or 12 hex digits in all. (See the documentation of the X Window System for more details about numerical RGB specification of colors.) These functions provide a way to determine which color names are valid, and what they look like. In some cases, the value depends on the selected frame, as described below; see Input Focus, for the meaning of the term "selected frame". To read user input of color names with completion, use read-color (read-color).
-
color-defined-p - This function reports whether a color name is meaningful. It returns
tif so; otherwise,nil. The argument frame says which frame's display to ask about; if frame is omitted ornil, the selected frame is used. Note that this does not tell you whether the display you are using really supports that color. When using X, you can ask for any defined color on any kind of display, and you will get some result—typically, the closest it can do. To determine whether a frame can really display a certain color, usecolor-supported-p(see below). This function used to be calledx-color-defined-p, and that name is still supported as an alias. -
defined-colors - This function returns a list of the color names that are defined and supported on frame frame (default, the selected frame). If frame does not support colors, the value is
nil. This function used to be calledx-defined-colors, and that name is still supported as an alias. -
color-supported-p - This returns
tif frame can really display the color color (or at least something close to it). If frame is omitted ornil, the question applies to the selected frame. Some terminals support a different set of colors for foreground and background. If background-p is non-nil, that means you are asking whether color can be used as a background; otherwise you are asking whether it can be used as a foreground. The argument color must be a valid color name. -
color-gray-p - This returns
tif color is a shade of gray, as defined on frame's display. If frame is omitted ornil, the question applies to the selected frame. If color is not a valid color name, this function returnsnil. -
color-values - This function returns a value that describes what color should ideally look like on frame. If color is defined, the value is a list of three integers, which give the amount of red, the amount of green, and the amount of blue. Each integer ranges in principle from 0 to 65535, but some displays may not use the full range. This three-element list is called the rgb values of the color. If color is not defined, the value is
nil.
(color-values "black")
=> (0 0 0)
(color-values "white")
=> (65535 65535 65535)
(color-values "red")
=> (65535 0 0)
(color-values "pink")
=> (65535 49344 52171)
(color-values "hungry")
=> nil
The color values are returned for frame's display. If frame is omitted or nil, the information is returned for the selected frame's display. If the frame cannot display colors, the value is nil. This function used to be called x-color-values, and that name is still supported as an alias.
-
color-name-to-rgb - This function does the same as
color-values, but it returns color values as floating-point numbers between 0.0 and 1.0 inclusive. -
color-dark-p - This function returns non-
nilif the color described by its RGB triplet rgb is more readable against white background than against dark background. The argument rgb should be a list of the form(R G B), with each component a floating-point number in the range 0.0 to 1.0 inclusive. You can usecolor-name-to-rgbto convert a color's name to such a list.
Text Terminal Colors
Text terminals usually support only a small number of colors, and the computer uses small integers to select colors on the terminal. This means that the computer cannot reliably tell what the selected color looks like; instead, you have to inform your application which small integers correspond to which colors. However, Emacs does know the standard set of colors and will try to use them automatically. The functions described in this section control how terminal colors are used by Emacs. Several of these functions use or return rgb values, described in Color Names. These functions accept a display (either a frame or the name of a terminal) as an optional argument. We hope in the future to make Emacs support different colors on different text terminals; then this argument will specify which terminal to operate on (the default being the selected frame's terminal; Input Focus). At present, though, the frame argument has no effect.
-
tty-color-define - This function associates the color name name with color number number on the terminal. The optional argument rgb, if specified, is an rgb value, a list of three numbers that specify what the color actually looks like. If you do not specify rgb, then this color cannot be used by
tty-color-approximateto approximate other colors, because Emacs will not know what it looks like. -
tty-color-clear - This function clears the table of defined colors for a text terminal.
-
tty-color-alist - This function returns an alist recording the known colors supported by a text terminal. Each element has the form
(NAME NUMBER . RGB)or(NAME NUMBER). Here, name is the color name, number is the number used to specify it to the terminal. If present, rgb is a list of three color values (for red, green, and blue) that says what the color actually looks like. -
tty-color-approximate - This function finds the closest color, among the known colors supported for display, to that described by the rgb value rgb (a list of color values). The return value is an element of
tty-color-alist. -
tty-color-translate - This function finds the closest color to color among the known colors supported for display and returns its index (an integer). If the name color is not defined, the value is
nil.
X Resources
This section describes some of the functions and variables for querying and using X resources, or their equivalent on your operating system. X Resources, for more information about X resources.
-
x-get-resource - The function
x-get-resourceretrieves a resource value from the X Window defaults database. Resources are indexed by a combination of a key and a class. This function searches using a key of the formINSTANCE.ATTRIBUTE(where instance is the name under which Emacs was invoked), and usingEmacs.CLASSas the class. The optional arguments component and subclass add to the key and the class, respectively. You must specify both of them or neither. If you specify them, the key isINSTANCE.COMPONENT.ATTRIBUTE, and the class isEmacs.CLASS.SUBCLASS. -
x-resource-class - This variable specifies the application name that
x-get-resourceshould look up. The default value is"Emacs". You can examine X resources for other application names by binding this variable to some other string, around a call tox-get-resource. -
x-resource-name - This variable specifies the instance name that
x-get-resourceshould look up. The default value is the name Emacs was invoked with, or the value specified with the-nameor-rnswitches.
To illustrate some of the above, suppose that you have the line:
xterm.vt100.background: yellow
in your X resources file (whose name is usually ~/.Xdefaults or ~/.Xresources). Then:
(let ((x-resource-class "XTerm") (x-resource-name "xterm"))
(x-get-resource "vt100.background" "VT100.Background"))
=> "yellow"
(let ((x-resource-class "XTerm") (x-resource-name "xterm"))
(x-get-resource "background" "VT100" "vt100" "Background"))
=> "yellow"
-
inhibit-x-resources - If this variable is non-
nil, Emacs does not look up X resources, and X resources do not have any effect when creating new frames.
Display Feature Testing
The functions in this section describe the basic capabilities of a particular display. Lisp programs can use them to adapt their behavior to what the display can do. For example, a program that ordinarily uses a popup menu could use the minibuffer if popup menus are not supported. The optional argument display in these functions specifies which display to ask the question about. It can be a display name, a frame (which designates the display that frame is on), or nil (which refers to the selected frame's display, Input Focus). Color Names, Text Terminal Colors, for other functions to obtain information about displays.
-
display-popup-menus-p - This function returns
tif popup menus are supported on display,nilif not. Support for popup menus requires that the mouse be available, since the menu is popped up by clicking the mouse on some portion of the Emacs display. -
display-graphic-p - This function returns
tif display is a graphic display capable of displaying several frames and several different fonts at once. This is true for displays that use a window system such as X, and false for text terminals. -
display-mouse-p - This function returns
tif display has a mouse available,nilif not. -
display-color-p - This function returns
tif the screen is a color screen. It used to be calledx-display-color-p, and that name is still supported as an alias. -
display-grayscale-p - This function returns
tif the screen can display shades of gray. (All color displays can do this.) -
display-supports-face-attributes-p - This function returns non-
nilif all the face attributes in attributes are supported (Face Attributes). The definition of "supported" is somewhat heuristic, but basically means that a face containing all the attributes in attributes, when merged with the default face for display, can be represented in a way that's
- different in appearance than the default face, and
- close in spirit to what the attributes specify, if not exact.
Point (2) implies that a :weight black attribute will be satisfied by any display that can display bold, as will :foreground "yellow" as long as some yellowish color can be displayed, but :slant italic will not be satisfied by the tty display code's automatic substitution of a dim face for italic.
-
display-selections-p - This function returns
tif display supports selections. Windowed displays normally support selections, but they may also be supported in some other cases. -
display-images-p - This function returns
tif display can display images. Windowed displays ought in principle to handle images, but some systems lack the support for that. On a display that does not support images, Emacs cannot display a tool bar. -
display-screens - This function returns the number of screens associated with the display.
-
display-pixel-height - This function returns the height of the screen in pixels. On a character terminal, it gives the height in characters. For graphical terminals, note that on multi-monitor setups this refers to the pixel height for all physical monitors associated with display. Multiple Terminals.
-
display-pixel-width - This function returns the width of the screen in pixels. On a character terminal, it gives the width in characters. For graphical terminals, note that on multi-monitor setups this refers to the pixel width for all physical monitors associated with display. Multiple Terminals.
-
display-mm-height - This function returns the height of the screen in millimeters, or
nilif Emacs cannot get that information. For graphical terminals, note that on multi-monitor setups this refers to the height for all physical monitors associated with display. Multiple Terminals. -
display-mm-width - This function returns the width of the screen in millimeters, or
nilif Emacs cannot get that information. For graphical terminals, note that on multi-monitor setups this refers to the width for all physical monitors associated with display. Multiple Terminals. -
display-mm-dimensions-alist - This variable allows the user to specify the dimensions of graphical displays returned by
display-mm-heightanddisplay-mm-widthin case the system provides incorrect values. -
display-backing-store - This function returns the backing store capability of the display. Backing store means recording the pixels of windows (and parts of windows) that are not exposed, so that when exposed they can be displayed very quickly. Values can be the symbols
always,when-mapped, ornot-useful. The function can also returnnilwhen the question is inapplicable to a certain kind of display. -
display-save-under - This function returns non-
nilif the display supports the SaveUnder feature. That feature is used by pop-up windows to save the pixels they obscure, so that they can pop down quickly. -
display-planes - This function returns the number of planes the display supports. This is typically the number of bits per pixel. For a tty display, it is log to base two of the number of colors supported.
-
display-visual-class - This function returns the visual class for the screen. The value is one of the symbols
static-gray(a limited, unchangeable number of grays),gray-scale(a full range of grays),static-color(a limited, unchangeable number of colors),pseudo-color(a limited number of colors),true-color(a full range of colors), anddirect-color(a full range of colors). -
display-color-cells - This function returns the number of color cells the screen supports.
These functions obtain additional information about the window system in use where Emacs shows the specified display. (Their names begin with x- for historical reasons.)
-
x-server-version - This function returns the list of version numbers of the GUI window system running on display, such as the X server on GNU and Unix systems. The value is a list of three integers: the major and minor version numbers of the protocol, and the distributor-specific release number of the window system software itself. On GNU and Unix systems, these are normally the version of the X protocol and the distributor-specific release number of the X server software. On MS-Windows, this is the version of the Windows OS.
-
x-server-vendor - This function returns the vendor that provided the window system software (as a string). On GNU and Unix systems this really means whoever distributes the X server. On MS-Windows this is the vendor ID string of the Windows OS (Microsoft). When the developers of X labeled software distributors as "vendors", they showed their false assumption that no system could ever be developed and distributed noncommercially.