CLIM 2 User Guide

3.5 Pixmaps in CLIM
A pixmap can be thought of as an off-screen window, that is, a medium that can be used for graphical output,
but is not visible on any display device. Pixmaps are provided to allow a programmer to generate a piece of
output associated with some display device that can then later be rapidly drawn on a real display device.
For example, an electrical CAD system might generate a pixmap that corresponds to a complex, frequently
used part in a VLSI schematic, and then use draw-pixmap or copy-from-pixmap to draw the part
as needed.
The exact representation of a pixmap is explicitly unspecified.
Note that there is no interaction between the pixmap operations and output recording, that
is, displaying a pixmap on a sheet is a pure drawing operation that affects only the display, not the
output history. Some mediums may not support pixmaps (such as PostScript mediums); in this
case, an error will be signaled.
copy-to-pixmap
Arguments: medium medium-x medium-y width height
&optional pixmap (pixmap-x 0) (pixmap-y 0)
(boole-fun boole-1)
[Function]
■ Copies the pixels from the medium medium starting at the position specified by (mediumx,medium-y)
into the pixmap pixmap at the position specified by (pixmap-x,pixmap-y). A
rectangle whose width and height is specified by width and height is copied. medium-x and
medium-y are specified in user coordinates. (If medium is a sheet or a stream, then medium-x
and medium-y are transformed by the user transformation.)
If pixmap is not supplied, a new pixmap will be allocated. Otherwise, pixmap must be an
object returned by allocate-pixmap that has the appropriate characteristics for medium.
The pixels are copied as if with the boolean operation specified by boole-fun. The value of
that argument should one of the boole-xxx constants and defaults to boole-1, meaning that the
source bits are set into the destination.
Note that copy-to-pixmap does not record any information on an output record. drawpixmap
and draw-pixmap* both do add to the output record.
■ The returned value is the pixmap.
copy-from-pixmap
[Function]
Arguments: pixmap pixmap-x pixmap-y width height medium medium-x
medium-y &optional (boole-fun boole-1)
■ Copies the pixels from the pixmap pixmap starting at the position specified by (pixmapx,pixmap-y)
into the medium medium at the position (medium-x,medium-y). A rectangle
whose width and height is specified by width and height is copied. medium-x and mediumy
are specified in user coordinates. (If medium is a sheet or a stream, then medium-x and
medium-y are transformed by the user transformation.)
pixmap must be an object returned by allocate-pixmap that has the appropriate characteristics
for medium.
As for copy-to-pixmap, the pixels are copied as if with the boolean operation specified by
boole-fun. The value of that argument should one of the boole-xxx constants and defaults to
boole-1, meaning that the source bits are set into the destination.
■ The returned value is the pixmap.
40 CLIM 2.2 User Guide