[Cairo] Color transforms

[Keith Packard]

Around 0 o'clock on Jul 17, Trevor Woerner wrote:

> IMHO, if multi-platform is what everyone wants, it would be slightly 
> better to have less functionality but be consistent with the API and 
> capabilities, than to have the potential of some capabilities on some 
> systems but not on others.

Every system can support raster images, so there's no reason to consider 
limited functionality anywhere; we can always dump images.  That's going 
to be necessary for PostScript in any case as it doesn't support 
translucency.  Other systems recognize when the output cannot be generated 
with higher level primitives and fall back to rasterization automatically, 
I think we can manage the same in cairo.

Device-independent should mean that the API have no limitations caused by 
the rasterization engine for a particular device, but we will still need 
some media-specific functionality (like 'showpage').  Getting a PS driver 
running is a high priority mostly to make sure the API works for printing, 
not to make sure we can generate postscript (that's the easy part).

-keith