[PATCH] Bug #25136: Revert "Fix clipping when windows are used as sources"

[Soeren Sandmann]

Keith Packard <keithp at keithp.com> writes:

> On 30 Nov 2009 15:52:20 +0100, Soeren Sandmann <sandmann at daimi.au.dk> wrote:
> 
> > If you clip to the screen pixmap, then you will need to adjust the
> > transformation to account for the coordinates of the drawable no
> > longer being right. Or ignore it, as you say.
> 
> That doesn't sound terribly difficult to me. It should just be a matter
> of adjusting the transform elements of the matrix (as the transform is
> From dest to source). Should take a couple of adds.

Don't you still need to apply the translation before the original
transformation? In either case, no, not terribly difficult.

> > The crash (and security hole - because you can write outside the
> > screen too) was introduced by reverting the copying patch. Before
> > that, with the Fedora patch, it was correct, just really slow in one
> > case.
> 
> I guess I'm still confused then -- at some point you have to restrict
> access to pixels within some pixmap; how is this getting skipped in this
> case?

There is not a one-to-one correspondence between pixmaps and pixman
images. Without the copying, a pixman image that points exactly at the
window bits is created. If some of those bits don't exist, then the
pixman image will contain bits that don't exist.



Soren