[cairo] [PATCH] Clip rectangles are not necessarily YSorted

Chris Wilson chris at chris-wilson.co.uk
Tue Dec 6 10:18:35 PST 2011

On Tue,  6 Dec 2011 09:58:18 -0800, Keith Packard <keithp at keithp.com> wrote:
> None of the cairo clipping computations guarantee that the resulting
> list of rectangles are constructed in any particular order. Promising
> that they are results in an X error (BadMatch) which generally causes
> applications to crash.
> I suspect this may well be implicated in many (many) bug reports about
> applications which use cairo.
> Signed-off-by: Keith Packard <keithp at keithp.com>

Ouch. Thanks Keith for pointing out my stupidity in not only forgetting
just how the rectangles are generated (the lazy emission breaks all
sorting guarrantees) and that YSorted simply causes the Xserver to do
extra work for no benefit.


Chris Wilson, Intel Open Source Technology Centre

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