[cairo] propsal for blur-API in cairo

Bill Spitzak spitzak at gmail.com
Wed Jun 17 18:54:34 PDT 2009

Instead of having a blur version of every call, the blur (well
actually the filter) could be part of the graphics state, just like
the color is.

Being able to blur the path/etc is pretty interesting but has
implementation difficulties. Most proposals I have seen involve
blurring a source image instead (I think this is your other proposal).
That is probably a lot easier to implement, also it is more likely to
produce the desired result, such as when two filled shapes touch along
an edge and then you blur the result, if they were blurred
individually you would get a transparent area between them.

Like the pen the blur should be specified by a 2x2 matrix. The actual
blur shape is a 1x1 circle distorted by this matrix, though at low
quality it would be two axis-aligned 1xn blurs. I don't think any
"blur object" is needed, just pass the desired blur matrix and quality

On Wed, Jun 17, 2009 at 1:23 PM, Mirco Müller<macslow at bangang.de> wrote:
> Greetings cairo-lovers!
>        I've spent some time thinking of what an API-addition for blurring in
> cairo should look like. I tried to stick to the pattern used by the API
> used for gradients.

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