[cairo] Extending XRender to support non-blurry edges for transformations(?)

Carl Worth cworth at cworth.org
Wed Jul 30 14:23:24 PDT 2008

On Wed, 2008-07-30 at 16:14 +0200, Clemens Eisserer wrote:
> What do you think about extending XRender with support for restricting
> filter to source picture only?

Various people have made proposals similar to this before. But no
proposal has ever been very compelling.

One objection is that there's a "layering violation" in your
description. Cairo and Render have separate controls for filtering modes
and sampling modes, but what you're describing here is a mode that
somehow intermingles sampling and filtering in ways that would prevent
them from being separate, (conceptually or in the implementation).

Beyond that, though, there's an issue of what do you actually want? You
mentioned wanting to draw a rotated image without using PAD sampling and
a mask. And you do want BILINEAR filtering internal to the image, but
not on the edges. Do you see that you are necessarily asking for a
non-antialiased result around the edge of the image? Is this what you
really want?

Please let us know if you have a concrete proposal that goes beyond
these objections, (where others have not in the past).



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