[cairo] [patch] pixman rectangular clipping fix

[c99drn at cs.umu.se]

Quoting graydon hoare <graydon at redhat.com>:
> hi,
> 
> I noticed today in cairo_gstate.c that the rectangular clipping
> fast path has been disabled. since this fast path is very important
> when rendering GUIs with cairo I investigated the source of the
> bug; it is actually localized to the image backend, and can be
> corrected with the following patch.
> 
> is it OK to commit this? I must admit the multiple layers of
> clipping in pixman are quite confusing, so I am not *certain* this
> is correct; it does seem to follow the intention of the function
> however (compute the correct compositing clipping region).
> 
> also, if this is OK, may I re-enable the cairo fast path?
> 
> -graydon
> 
> 
> --- icimage.c	2004-05-10 16:41:40.000000000 -0400
> +++ icimage.c	2004-09-17 14:40:06.945495992 -0400
> @@ -603,6 +603,12 @@
>   	pixman_region_destroy (region);
>   	return 0;
>       }
> +
> +    if (iDst->clientClipType != CT_NONE && iDst->clientClip != NULL)
> +    {
> +	pixman_region_intersect (region, iDst->clientClip, region);
> +    }
> +
>       if (iDst->alphaMap)
>       {
>   	if (!IcClipImageReg (region, iDst->alphaMap->pCompositeClip,

I've already committed I fix for that a few days ago. I never re-enabled the
fast path for clipping in cairo so you can go a head and do that if you like.
I've also changed so that libpixman is now making a copy of region passed to
pixman_image_set_clip_region, so a copy of the region should no longer be made
in cairo_image_surface_set_clip_region. You should fix that as well if you
re-enabled the fast clipping.

- David