[cairo] RFC the idea of n-plane color support

Carl Worth cworth at cworth.org
Fri Oct 29 14:08:19 PDT 2004

On Sun, 20 Jun 2004 20:51:16 -0400, Ross McFarland wrote:
> attached is a patch that changes the color path in cairo allowing
> arbitrary data to be passed through.

Hi Ross,

I'm sorry for the very late reply, but I'm trying to push through my
backlog. Hopefully I won't have to get so far behind in the future. And
I do want people to know that patches they have submitted have not been

> my thoughts are that cairo doesn't know or care anything about color, it
> just passes it through, so why not have a generic path so that any type
> of color could be passed through. (leave it up to the app and the
> backend to determine how the data is interpreted.) 

In the recent teleconference we discussed the issue of color spaces. I
agree that we need a system by which any color can be expressed. Keith
recommends that the cairo RGB API be specified to be sRGB but that it
allows negative values. I'm assured that this approach will allow all
colors to be expressed. It also has the benefit of doing the right thing
when users naïvely pass in RGB values.

But I'm not interested in an API addition that provides backend-specific
colors to be passed in. One of the goals of cairo is to enable you to
switch backends and get matching results without changing the
application code. If I understood the intent of your patch, it would
violate that property.

What do you think of this approach?



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