Windows (or even pixmaps, in some cases) may not sit at the origin of
the containing pixmap, so any coordinates relative to the drawable
must be adjusted. For destinations and untransformed sources, the
operation coordinates are adjusted. For transformed sources, the
transform matrix is adjusted.
Signed-off-by: Keith Packard <keithp@keithp.com>
Acked-by: Soeren Sandmann <sandmann@daimi.au.dk>