[cairo] Problems with the gtk-x11 interface

Carl Worth cworth at cworth.org
Tue Dec 21 14:02:45 PST 2004

On Sun, 19 Dec 2004 19:47:10 -0500, Ashwin Bharambe wrote:
> I downloaded and compiled the latest cvs version of libcairo. I was
> testing the cairo-knockout.py example from pycairo and I find that,
> although the initial output is very beautiful, refresh (expose) events
> are not handled properly! :(  After exposing the window again, the
> output becomes erratic.

I've just duplicated this bug with cairo/pycairo checked out from CVS
today, (gtk 2.4.14 and pygtk 2.4.0).

The "erratic" output I see is that the red, green, and blue circles
are always drawn in the correct locations, but where the black circle
and the checkered background are supposed to appear often only the
background color appears.

> Is there anything I am doing wrong here?

I don't think so. :-)

The original C/Xlib demo (cairo-demo/X11/cairo-knockout.c) has no such
problems, so I don't think the bug is in core cairo.

Also, the other pycairo demos I tried did not show the same
problems. Notably, even when I threw an SVG file at svgview.py[*] with
gradients and group opacity, (which should trigger most of the same
code paths as cairo-knockout.py), it did everything fine.

So, this may just be a bug in cairo-knockout.py, otherwise it is
probably in pycairo somewhere.


[*] PS. Steve, thanks so much for the python bindings to libsvg-cairo!
This should be a lot of fun.

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