[cairo] Can't draw more

Carl Worth cworth at cworth.org
Sat Nov 24 09:23:31 PST 2007


On Sat, 24 Nov 2007 08:50:16 -0500, Gary Jaffe wrote:
> Is drawing on a working pixmap and then transferring the modified part
> of the pixmap to a cairo surface a reasonable way to go?

"Drawing on a working pixmap" is the same as "drawing to a cairo
surface". That is, you can use cairo to draw to a pixmap just fine,
(just use cairo_xlib_surface_create or its python equivalent and away
you go).

But if your question is whether it's appropriate to draw to a "backing
pixmap" outside of the expose event and to then do nothing in the
expose event but copy from that pixmap to the final destination---yes,
that can be a perfectly valid way to structure a program. And you can
use cairo for both the drawing and copying operations.

And if you do this, you can even turn off GTK+'s double buffering
since you're doing double buffering yourself this way.

-Carl
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