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.