An External Image is an intermediate object. It is a representation of a graphic but is not associated with a port and cannot be used directly for drawing.
An object of type
is created by reading an image from a file, or by externalizing an
object, or by copying an existing
. Or, if you have the image bitmap data, you can create one directly as in the
contains the bitmap data, potentially compressed. You can copy
objects, or write them to file, or compress the data.
You cannot query the size of the image in an
object directly. To get the dimensions without actually drawing it on screen see Pixmap graphics ports.
If you create an
and want to externalize it to write it to file, follow this example:
(let ((image (gp:make-image-from-port pane 10 10 200 200)))
(gp:externalize-and-write-image pane image filename )
(gp:free-image pane image)))
CAPI User Guide (Unix version) - 30 Aug 2011