[cairo] Re: new clipping change patch

[Owen Taylor]

On Wed, 2005-05-25 at 10:56 -0700, Keith Packard wrote:

> On Wed, 2005-05-25 at 09:49 -0400, Owen Taylor wrote:
> 
> > What the function does is gets the extents of the mask operation.
> > (mask in the name is a verb, not a noun.) The mask argument isn't 
> > currently used, but would be needed for the useful optimization:
> > 
> >  - If the mask is a surface pattern, with extend=NONE and the 
> >    operator does nothing for transparent source (OVER, say)
> >    then the size of the intermediate surface is bounded by the
> >    size of the (transformed mask)
> 
> Ok, so the function is just incomplete.
> > 
> > (This optimization can be done for the source as well)
> > 
> > Yes, your patch doesn't change the end result of the function, my
> > comment was that with the patch we end up doing:
> 
> I think the patch just demonstrates how silly the original code was.  If
> you have a suggestion for what it should look like, I'd love to see it.
> Otherwise, I'll attempt to figure out the intended algorithm and
> implemen that.

There's nothing fancy about the intended algorithm ... leaving aside
the optimization mentioned above, what it is supposed to do is return
a rectangle which is the bounding box of the intersection of:

 - The surface extents
 - The clip region
 - The extents of the clip surface, if any. (surface->clip.rect)
 
(Careful, you can have *both* a clip region and a clip surface)

_cairo_gstate_clip_extents() could do all of that itself. It didn't
before and still doesn't.

Regards,
							Owen

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