50.2.4.1 Image Instance Types

Image instances come in a number of different types. The type of an image instance specifies the nature of the image: Whether it is a text string, a mono pixmap, a color pixmap, etc.

The valid image instance types are

nothing

Nothing is displayed.

text

Displayed as text. The foreground and background colors and the font of the text are specified independent of the pixmap. Typically these attributes will come from the face of the surrounding text, unless a face is specified for the glyph in which the image appears.

mono-pixmap

Displayed as a mono pixmap (a pixmap with only two colors where the foreground and background can be specified independent of the pixmap; typically the pixmap assumes the foreground and background colors of the text around it, unless a face is specified for the glyph in which the image appears).

color-pixmap

Displayed as a color pixmap.

pointer

Used as the mouse pointer for a window.

subwindow

A child window that is treated as an image. This allows (e.g.) another program to be responsible for drawing into the window. Not currently implemented.

widget

An active GUI element implemented as a “widget” or “control” of the underlying window system.

The following functions are used to check whether an image instance type is valid in the running SXEmacs.

Function: valid-image-instance-type-p type

This function returns non-nil if type is a valid image instance type.

Function: image-instance-type-list

This function returns a list of the valid image instance types.

The following functions are used to determine the type of an image instance.

Function: image-instance-type image-instance

Return the type of the given image instance. The return value will be one of nothing, text, mono-pixmap, color-pixmap, pointer, subwindow, or widget.

Function: text-image-instance-p object

Return non-nil if object is an image instance of type text.

Function: mono-pixmap-image-instance-p object

Return non-nil if object is an image instance of type mono-pixmap.

Function: color-pixmap-image-instance-p object

Return non-nil if object is an image instance of type color-pixmap.

Function: pointer-image-instance-p object

Return non-nil if object is an image instance of type pointer.

Function: subwindow-image-instance-p object

Return non-nil if object is an image instance of type subwindow.

Function: nothing-image-instance-p object

Return non-nil if object is an image instance of type nothing.

Function: widget-image-instance-p object

Return non-nil if object is an image instance of type widget.