[Pixman] fast-scale branch performance improvements

Alexander Larsson alexl at redhat.com
Mon Mar 15 13:51:49 PDT 2010

On Mon, 2010-03-15 at 03:25 +0200, Siarhei Siamashka wrote:

> But before it gets committed, some problems with potential fixed point
> overflows when dealing with large images need to be addressed. I have
> made a test program which can expose some of these problems:
> http://cgit.freedesktop.org/~siamashka/pixman/log/?h=largescaling-test

I pushed a new version of my branch, rebased on:
on (as before):

This has a new flag FAST_PATH_16BIT_SAFE which handles this problem (and
it runs your test successfully.

I also rebased 

on this.

> And for the case of scaling without repeat, function
> 'image_samples_covers'
> also needs to be verified with the regards to how it behaves in corner
> cases and extreme image size ranges.

I have not done this, but there is some level of limitation on size
since the FAST_PATH_SAMPLES_COVERS_CLIP flag requires the src region to
fit in 16 bits.

 Alexander Larsson                                            Red Hat, Inc 
       alexl at redhat.com            alexander.larsson at gmail.com 
He's an underprivileged albino astronaut from the Mississippi delta. She's a 
cold-hearted thirtysomething stripper in the wrong place at the wrong time. 
They fight crime! 

More information about the Pixman mailing list