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2 Display and Screens

— Function: x:open-display display-name

display-name Specifies the hardware display name, which determines the display and communications domain to be used. On a POSIX-conformant system, if the display-name is #f, it defaults to the value of the DISPLAY environment variable.

The encoding and interpretation of display-name is implementation-dependent. On POSIX-conformant systems, the display-name or DISPLAY environment variable can be a string in the format:

— Special Form: hostname:number.screen-number

hostname specifies the name of the host machine on which the display is physically attached. Follow the hostname with either a single colon (:) or a double colon (::).

number specifies the number of the display server on that host machine. You may optionally follow this display number with a period (.). A single CPU can have more than one display. Multiple displays are usually numbered starting with zero.

screen-number specifies the screen to be used on that server. Multiple screens can be controlled by a single X server. The screen-number sets an internal variable that can be accessed by using the x:default-screen procedure.

— Function: x:close display

display specifies the connection to the X server.

The x:close function closes the connection to the X server for the display specified and destroys all windows, resource IDs (Window, Font, Pixmap, Colormap, Cursor, and GContext), or other resources that the client has created on this display, unless the close-down mode of the resource has been changed (see x:set-close-down-mode). Therefore, these windows, resource IDs, and other resources should not be used again or an error will be generated. Before exiting, you should call x:close-display or x:flush explicitly so that any pending errors are reported.

— Function: x:protocol-version display

Returns cons of the major version number (11) of the X protocol associated with the connected display and the minor protocol revision number of the X server.

— Function: x:server-vendor display

Returns a string that provides some identification of the owner of the X server implementation. The contents of the string are implementation-dependent.

— Function: x:vendor-release display

Returns a number related to a vendor's release of the X server.

A display consists of one or more Screens. Each screen has a root-window, default-graphics-context, and colormap.

— Function: x:screen-count display

Returns the number of available screens.

— Function: x:default-screen display

Returns the default screen number specified by the x:open-display function. Use this screen number in applications which will use only a single screen.

— Function: x:root-window display screen-number
— Function: x:root-window display

screen-number, if givien, specifies the appropriate screen number on the host server. Otherwise the default-screen for display is used.

Returns the root window for the specified screen-number. Use x:root-window for functions that need a drawable of a particular screen or for creating top-level windows. — Function: x:root-window window

Returns the root window for the specified window's screen.

— Function: x:default-colormap display screen-number
— Function: x:default-colormap display
— Function: x:default-colormap window

Returns the default colormap of the specified screen.

— Function: x:default-ccc display screen-number
— Function: x:default-ccc display
— Function: x:default-ccc window

Returns the default Color-Conversion-Context (ccc) of the specified screen.

— Function: x:default-gc display screen-number
— Function: x:default-gc display
— Function: x:default-gc window

Returns the default graphics-context of the specified screen.

— Function: x:screen-depths display screen-number
— Function: x:screen-depths display
— Function: x:screen-depths window

Returns an array of depths supported by the specified screen.

The Visual type describes possible colormap depths and arrangements.

— Function: x:default-visual display screen-number
— Function: x:default-visual display
— Function: x:default-visual window

Returns the default Visual type for the specified screen.

— Function: x:make-visual display depth class
— Function: x:make-visual window depth class

The integer depth specifies the number of bits per pixel. The class argument specifies one of the possible visual classes for a screen:

X:make-visual returns a visual type for the screen specified by display or window if successful; #f if not.

— Function: x:visual-class visual
— Function: x:visual-class screen
— Function: x:visual-class display

Returns the (integer) visual class of its argument.

— Function: x:visual-geometry visual
— Function: x:visual-geometry screen
— Function: x:visual-geometry display

Returns a list of the:

— Function: x:screen-cells display screen-number
— Function: x:screen-cells display
— Function: x:screen-cells window

Returns the number of entries in the default colormap.

— Function: x:screen-depth display screen-number

Returns the depth of the root window of the specified screen. — Function: x:screen-depth display
— Function: x:screen-depth window
— Function: x:screen-depth visual

Returns the depth of argument.

The depth of a window or pixmap is the number of bits per pixel it has. The depth of a graphics context is the depth of the drawables it can be used in conjunction with graphics output.

— Function: x:screen-size display screen-number
— Function: x:screen-size display
— Function: x:screen-size window

Returns a list of integer height and width of the screen in pixels.

— Function: x:screen-dimensions display screen-number
— Function: x:screen-dimensions display
— Function: x:screen-dimensions window

Returns a list of integer height and width of the screen in millimeters.

— Function: x:screen-white display screen-number
— Function: x:screen-white display
— Function: x:screen-white window

Returns the white pixel value of the specified screen.

— Function: x:screen-black display screen-number
— Function: x:screen-black display
— Function: x:screen-black window

Returns the black pixel value of the specified screen.