[cairo-bugs] [Bug 11529] Performance of cairo is not good without XRender extension

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Wed Jul 25 12:35:33 PDT 2007


------- Comment #15 from cworth at cworth.org  2007-07-25 12:35 PST -------
Neyond making the blit faster, you'll want to make sure it's doing no
more than necessary.

Everytime you hit a fallback within cairo it will be doing a sequence

        Allocate temorary image surface
        XGetImage from X to surface
        Do software rendering on surface
        XPutImage from surface to X
        Discard temporary surface

and doing that many times in a loop can be quite damaging to
performance, (copying the same data over and over). So an improved
version would keep a persistent image surface around and not copy data
that hasn't changed.

But at that point you might as well just make the application
explicitly use cairo's image surface backend directly and explicitly
do the XPutImage when results are complete.

Or, as mentioned before, just fix the broken X server so that it
implements Render itself and cairo never needs to do any fallbacks for

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