(see below) and not present in the argument, taking the values from
the frame that was selected when @code{make-frame} was called.
+Note that on multi-monitor displays (@pxref{Multiple Terminals}), the
+window manager might position the frame differently than specified by
+the positional parameters in @var{alist} (@pxref{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 @dfn{dominating} monitor).
+
This function itself does not make the new frame the selected frame.
@xref{Input Focus}. The previously selected frame remains selected.
On graphical terminals, however, the windowing system may select the
terminals, by interacting with the @command{emacsclient} program.
@xref{Emacs Server,,, emacs, The GNU Emacs Manual}.
+@cindex X display names
+@cindex display name on X
A single X server can handle more than one display. Each X display
-has a three-part name, @samp{@var{host}:@var{server}.@var{screen}}.
-The first two parts, @var{host} and @var{server}, identify the X
-server; the third part, @var{screen}, identifies a screen number 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.
+has a three-part name,
+@samp{@var{hostname}:@var{displaynumber}.@var{screennumber}}. The
+first part, @var{hostname}, specifies the name of the machine to which
+the display is physically connected. The second part,
+@var{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,
+@var{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 @samp{w32}, and exists for compatibility, so that
+you could pass it to functions that expect a display name.
@deffn Command make-frame-on-display display &optional parameters
This function creates and returns a new frame on @var{display}, taking
@defun display-monitor-attributes-list &optional display
This function returns a list of physical monitor attributes on
-@var{display}, which defaults to that of the selected frame.
-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:
+@var{display}, which can be a display name (a string), a terminal, or
+a frame; if omitted or @code{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:
@table @samp
@item geometry
-Position and size in pixels as @samp{(@var{x} @var{y}
-@var{width} @var{height})}.
+Position of the top-left corner of the monitor's screen and its size,
+in pixels, as @samp{(@var{x} @var{y} @var{width} @var{height})}. Note
+that, if the monitor is not the primary monitor, some of the
+coordinates might be negative.
@item workarea
-Position and size of the work area in pixels as
-@samp{(@var{x} @var{y} @var{width} @var{height})}.
+Position of the top-left corner and size of the work area in pixels as
+@samp{(@var{x} @var{y} @var{width} @var{height})}. This is different
+from @samp{geometry} in that the various system windows, such as the
+task bar and side bar, are excluded from the work area. Note that, if
+the monitor is not the primary monitor, some of the coordinates might
+be negative.
@item mm-size
Width and height in millimeters as @samp{(@var{width} @var{height})}
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:
+
+@smalllisp
+ (display-monitor-attributes-list)
+ @result{}
+ (((geometry 0 0 1920 1080) ;; Left hand monitor
+ (workarea 0 0 1920 1050) ;; Bottom of screen used for task bar
+ task bar
+ (mm-size 677 381)
+ (name . "\\\\.\\DISPLAY1")
+ (frames #<frame emacs@@host *foo* 0000000005BBDC48>
+ #<frame emacs@@host *scratch* 000000008179D370>))
+ ((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)))
+@end smalllisp
+
@end defun
@defun frame-monitor-attributes &optional frame
@vindex display, a frame parameter
@item display
The display on which to open this frame. It should be a string of the
-form @code{"@var{host}:@var{dpy}.@var{screen}"}, just like the
-@env{DISPLAY} environment variable.
+form @samp{@var{host}:@var{dpy}.@var{screen}}, just like the
+@env{DISPLAY} environment variable. @xref{Multiple Terminals}, for
+more details about display names.
@vindex display-type, a frame parameter
@item display-type
@item @code{(+ @var{pos})}
This specifies the position of the left frame edge relative to the left
screen edge. The integer @var{pos} may be positive or negative; a
-negative value specifies a position outside the screen.
+negative value specifies a position outside the screen or on a monitor
+other than the primary one (for multi-monitor displays).
@item @code{(- @var{pos})}
This specifies the position of the right frame edge relative to the right
screen edge. The integer @var{pos} may be positive or negative; a
-negative value specifies a position outside the screen.
+negative value specifies a position outside the screen or on a monitor
+other than the primary one (for multi-monitor displays).
@end table
Some window managers ignore program-specified positions. If you want to
(defun display-screens (&optional display)
"Return the number of screens associated with DISPLAY.
+DISPLAY should be either a frame or a display name (a string).
If DISPLAY is omitted or nil, it defaults to the selected frame's display."
(let ((frame-type (framep-on-display display)))
(cond
(defun display-pixel-height (&optional display)
"Return the height of DISPLAY's screen in pixels.
+DISPLAY can be a display name or a frame.
If DISPLAY is omitted or nil, it defaults to the selected frame's display.
For character terminals, each character counts as a single pixel.
(defun display-pixel-width (&optional display)
"Return the width of DISPLAY's screen in pixels.
+DISPLAY can be a display name or a frame.
If DISPLAY is omitted or nil, it defaults to the selected frame's display.
For character terminals, each character counts as a single pixel.
(defun display-mm-height (&optional display)
"Return the height of DISPLAY's screen in millimeters.
If the information is unavailable, this function returns nil.
+DISPLAY can be a display name or a frame.
If DISPLAY is omitted or nil, it defaults to the selected frame's display.
You can override what the system thinks the result should be by
(defun display-mm-width (&optional display)
"Return the width of DISPLAY's screen in millimeters.
If the information is unavailable, this function returns nil.
+DISPLAY can be a display name or a frame.
If DISPLAY is omitted or nil, it defaults to the selected frame's display.
You can override what the system thinks the result should be by
"Return the backing store capability of DISPLAY's screen.
The value may be `always', `when-mapped', `not-useful', or nil if
the question is inapplicable to a certain kind of display.
+DISPLAY can be a display name or a frame.
If DISPLAY is omitted or nil, it defaults to the selected frame's display."
(let ((frame-type (framep-on-display display)))
(cond
(defun display-save-under (&optional display)
"Return non-nil if DISPLAY's screen supports the SaveUnder feature.
+DISPLAY can be a display name or a frame.
If DISPLAY is omitted or nil, it defaults to the selected frame's display."
(let ((frame-type (framep-on-display display)))
(cond
(defun display-planes (&optional display)
"Return the number of planes supported by DISPLAY.
+DISPLAY can be a display name or a frame.
If DISPLAY is omitted or nil, it defaults to the selected frame's display."
(let ((frame-type (framep-on-display display)))
(cond
(defun display-color-cells (&optional display)
"Return the number of color cells supported by DISPLAY.
+DISPLAY can be a display name or a frame.
If DISPLAY is omitted or nil, it defaults to the selected frame's display."
(let ((frame-type (framep-on-display display)))
(cond
"Return the visual class of DISPLAY.
The value is one of the symbols `static-gray', `gray-scale',
`static-color', `pseudo-color', `true-color', or `direct-color'.
+DISPLAY can be a display name or a frame.
If DISPLAY is omitted or nil, it defaults to the selected frame's display."
(let ((frame-type (framep-on-display display)))
(cond
(defun display-monitor-attributes-list (&optional display)
"Return a list of physical monitor attributes on DISPLAY.
+DISPLAY can be a display name, a terminal name, or a frame.
If DISPLAY is omitted or nil, it defaults to the selected frame's display.
Each element of the list represents the attributes of a physical
monitor. The first element corresponds to the primary monitor.
geometry -- Position and size in pixels in the form of (X Y WIDTH HEIGHT)
workarea -- Position and size of the work area in pixels in the
- form of (X Y WIDTH HEIGHT)
+ form of (X Y WIDTH HEIGHT); this excludes task bar etc.
mm-size -- Width and height in millimeters in the form of
(WIDTH HEIGHT)
frames -- List of frames dominated by the physical monitor
name (*) -- Name of the physical monitor as a string
-where X, Y, WIDTH, and HEIGHT are integers. Keys labeled
-with (*) are optional.
+where X, Y, WIDTH, and HEIGHT are integers, which might be negative
+for monitors other than the primary one. X and Y are coordinates
+of the top-left corner of the rectange. Keys labeled with (*) are
+optional.
A frame is dominated by a physical monitor when either the
largest area of the frame resides in the monitor, or the monitor
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