[cairo] Clip region problems

[Owen Taylor]

On Wed, 2005-04-27 at 08:59 -0700, Keith Packard wrote:
> On Wed, 2005-04-27 at 11:33 -0400, Owen Taylor wrote:
> > >  4. Only allow a surface to be used for a single thing at a same time
> > > 
> > >      - two cairo_t's cannot be active for the same target surface
> > >      - a surface that is the target of a cairo_t cannot be used
> > >        as a source.
> > > 
> > >     Pro: Simple
> > >     Con: Fairly big restriction
> 
> I don't mind limiting us to one cairo_t per surface, but it seems harsh
> to prohibit using a surface for both dest and source at the same time.
> What do we need to solve to make this possible?  Do we just need more
> state in the cairo_surface_t object?

Various things could be done 

 - The "nested use" proposal I just made should allow handling things
   as long as you don't want to use a surface as the source for drawing
   to itself. 

 - You could always use different pictures for source and dest

 - Complicated things outlined in my first mail
   (http://lists.freedesktop.org/archives/cairo/2005-March/003358.html)

Regards,
						Owen

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