[cairo] Overflow bug painting from PixBuf?

Chris Wilson chris at chris-wilson.co.uk
Wed Oct 14 17:01:49 PDT 2009

Excerpts from Arjen Nienhuis's message of Thu Oct 15 00:24:14 +0100 2009:
> I'm using cairo 1.8.8 and python to create some png files.


> This works fine until dst_x / scale > 32000. Then garbage is copied to
> ctx. This also occurs with the PDF backend.
> This means I cannot put a small thumbnail on the right side of an
> image. (see attachment, the last photo is missing)
> Is this a known bug? Is there anything I can do? Pre-scaling the
> pixbuf might work.

It is a known bug, a limitation of the fixed-point 16.16 matrix that we
use to transform images with pixman. In cairo-1.9.2, we have a
workaround that takes advantage of the fact that we can do the
translation independently of the matrix that extends our operating range
a bit (but still leaves worse than desired inaccuracies). In short, try
1.9.2, it's probably good enough for the task at hand.

Hope this helps, and you have fun with cairo!
Chris Wilson, Intel Open Source Technology Centre

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