[cairo] Cairo equivalent of Photoshop Overlay?

[Benjamin Otte]

On 10/27/07, Jeff Muizelaar <jeff at infidigm.net> wrote:
> > There isn't in cairo HEAD but there is in this tree:
> > http://gitweb.freedesktop.org/?p=users/company/cairo.git;a=summary
>
> Which makes me ask: do we have any good reasons not to merge this stuff?
> We have certainly have applications that want it (poppler, swfdec,
> librsvg?). I guess it would probably be a good idea to do a branch of
> poppler against that tree to ensure that it meets the needs of PDF.
>
> Benjamin, what is your opinion on the mergeability of that tree?
>
The code that is used by Swfdec - that is all the operators that are
part of Flash - works fine. What is missing, and I guess that's the
reason for why it's not merged, is someone to check that the operators
that are only part of SVG work fine. These are COLOR_DODGE,
COLOR_BURN, SOFT_LIGHT and EXCLUSION. I just copied them from
Emmanuel's work as they were.

Another thing I wasn't sure about is if the 2 Flash-specific operators
(SUBTRACT and INVERT) can be implemented using the SVG operators, but
I couldn't come up with a way to do it. That would certainly ease up
implementation of operators for some backends, in particular the SVG
one.

Cheers,
Benjamin