[cairo] cairo-gl glyph rendering performance
spitzak at gmail.com
Tue May 3 12:07:36 PDT 2011
I think it was probably done because they are using a+b-ab to composite
the glyphs together, which is what I expected cairo to do as well, and
this makes the artifacts as small as possible. There will always be a
small artifact in the antialiased edge due to the two
partially-transparent pixels compositing but this avoids a white line
between them, and also allows the renderer to be somewhat inaccurate.
Using MAX would remove the artifacts for these overlapping ones, but it
does mean they must overlap by at least 1 pixel. Possibly they are doing
In any case it might be worthwhile to investigate what Microsoft is
doing, since the fonts are probably going to be designed to work with
that. Might want to check Cocoa as well.
Jonathan Morton wrote:
> On Mon, 2011-05-02 at 21:34 -0400, Behdad Esfahbod wrote:
>> However, Microsoft recommends that Arabic glyphs should have their
>> baseline connection slightly bleed outside the glyph boundary.
> Clearly, whoever at Microsoft thought that up was not thinking of
> efficient antialiasing. It does work for a brute-force supersampling,
> but not the way XRender does it which takes less memory and less compute
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