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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, voir la section Input Focus).
Voir la section Color Names, Text Terminal Colors, for other functions to obtain information about displays.
This function returns t if popup menus are supported on
display, nil if not. Support for popup menus requires that the
mouse be available, since the user cannot choose menu items without a mouse.
This function returns t if 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-only terminals.
This function returns t if display has a mouse available,
nil if not.
This function returns t if the screen is a color screen. It used to
be called x-display-color-p, and that name is still supported as an
alias.
This function returns t if the screen can display shades of gray.
(All color displays can do this.)
This function returns non-nil if all the face attributes in
attributes are supported (voir la section 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
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.
This function returns t if display supports selections.
Windowed displays normally support selections, but they may also be
supported in some other cases.
This function returns t if 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.
This function returns the number of screens associated with the display.
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 width for all physical monitors associated with display. Voir la section Multiple Displays.
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. Voir la section Multiple Displays.
This function returns the height of the screen in millimeters, or nil
if Emacs cannot get that information.
This function returns the width of the screen in millimeters, or nil
if Emacs cannot get that information.
This variable allows the user to specify the dimensions of graphical
displays returned by display-mm-height and display-mm-width in
case the system provides incorrect values.
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, or
not-useful. The function can also return nil when the
question is inapplicable to a certain kind of display.
This function returns non-nil if 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.
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.
This function returns the visual class for the screen. The value is one of
the symbols static-gray, gray-scale, static-color,
pseudo-color, true-color, and direct-color.
This function returns the number of color cells the screen supports.
These functions obtain additional information specifically about X displays.
This function returns the list of version numbers of the X server running the display. The value is a list of three integers: the major and minor version numbers of the X protocol, and the distributor-specific release number of the X server software itself.
This function returns the “vendor” that provided the X server software (as a string). Really this means whoever distributes the X server.
When the developers of X labelled software distributors as “vendors,” they showed their false assumption that no system could ever be developed and distributed noncommercially.
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Ce document a été généré par Eric Reinbold le 13 Octobre 2007 en utilisant texi2html 1.78.