Non-clipping clips(wasRe: [cairo] Alpha masks)

[Bill Spitzak]

On Thursday 06 January 2005 05:05 pm, Keith Packard wrote:
> Around 19 o'clock on Jan 6, Owen Taylor wrote:
> > The intuitively expected definition of how the clip operates follows
> > from that:
> >
> >  ((src Op dest) In clip) Add (dest Out clip)
>
> I like it.  It has a nice 'obviousness' about it.

Yes if operations are allowed to modify where alpha is zero, this is exactly 
what I would expect. Anything else is pretty useless. I certainly want to be 
able to clip, draw anything that does not do a grestore, and be certain that 
it did not modify outside the clip region.

-- 
                   ,~,~,~,~ ~ ~ ~ ~
     /\_       _|_========___         Bill Spitzak
 ~~~/\/\\~~~~~~\____________/~~~~~~~~ spitzak at d2.com