[cairo] Path Gradients

Behdad Esfahbod behdad at behdad.org
Fri Jan 4 10:55:45 PST 2008

On Fri, 2008-01-04 at 10:26 -0800, Bill Spitzak wrote:
> > Another interesting feature of the path gradients in the links is
> that
> > one can also have color stop along the path (that is, along the
> circle),
> > not only from the center to the path.
> You are right, some of the examples show that. The center point was a 
> fixed color, but gradiated in straight lines to a different color at 
> each control point, with that end color interpolated between them.
> It was unclear what happens with multiple-step gradients, which some
> of 
> the examples show. Does it only change the last step, or is there an
> api 
> to change all the steps?

The actual radial stops where done in the code using a Blend object,
that's like just having stops for alpha value.  That is, instead of the
linear interpolation between the two ends, user can provide a detailed
blend function.  No separate color stops.

> I found it interesting that all the "real" examples did not use this 
> feature and kept a constant color. It may indicate that emulation of 
> this is not necessary.
> I am still very interested in any explanation why the path needs to
> be 
> specified twice and what happens if the two paths are different.

What do you mean by twice?  Where?


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