[cairo] LCD filtering in cairo, use default filter?

Behdad Esfahbod behdad at behdad.org
Sun Jan 13 14:18:57 PST 2008

On Sun, 2008-01-13 at 10:41 -0500, Sylvain Pasche wrote:
> Right now there is no link between fontconfig and the LCD filter option yet.

Right.  And I believe I told you that first step to get this patch into
cairo is to work with Keith Packard to get this element in fontconfig.
If you are quick enough, you can make this happen and released in
fontconfig 2.6 pretty soon.

> Before going further, I'm wondering if it makes sense to make this value 
> configurable or if we should just always use the default filter.

Of course it should be configurable.  No doubt about that.

> When 
> using the bytecode interpreter there is not much difference and it can 
> improve the output when using the autohinter.

One thing that would be interesting and very helpful is to make
fontconfig export an element in the font patterns determining whether
autohinter or bytecode interpretter will be used to render glyphs.  Then
one can write sophisticated per-font configuration to choose the best
filter or hinting settings for example.

> I think each approaches have their advantages and disadvantage, I'm 
> starting the discussion to decide what would be the best way to take.

I don't see any advantage in "no configurability" option.  And no
disadvantage in "configurability" option.  Worst case you can ignore the
configurability and act as if it wasn't there.

> Note that the same choice can be made for Xft, which hasn't integrated 
> the LCD filtering patch yet.


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 Temporary Safety, deserve neither Liberty nor Safety."
        -- Benjamin Franklin, 1759

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