A supposedly patent-free suggestion/solution to the curious subpixel rendering in Fedora

Adam Jackson ajax at redhat.com
Mon Mar 23 14:51:46 UTC 2009


On Sun, 2009-03-22 at 18:18 -0400, Jud Craft wrote:

> So here's the idea:  perhaps Fedora could petition Pango (I think
> that's the system GTK uses to render glyphs) to include the
> Qt-filtering style in their own upstream code.  This would mean that
> both GUI toolkits on the Linux desktop would then have patent-free,
> non-color-fringing, subpixel rendering by default.

freetype.  pango does glyph layout.  freetype does glyph rendering.

> And today currently, keep in mind that Qt on Fedora already has this
> new filtering, so I don't think there are any patent-problems with it:
>  Qt's solution seems to be a simple blur of their own ingenuity, and
> nothing related to Cleartype.  (Otherwise Fedora wouldn't ship it, I'd
> assume).

Not that I am in any way giving legal advice here (besides being just an
engineer, I've read neither the patents in question, nor the qt code),
but the other possibility is that someone does actually check the qt
code against the patents, and finds that it's infringing.

Not that bringing it to freetype is a bad idea, just that it may not get
you what you want.

Vetting _any_ software for patent clearance is already a barely
tractable problem.  Assuming that something is patent-clear just because
we're already shipping it is fallacious.  We've had to remove encumbered
code in the past and we'll probably have to do it in the future too.

(ObDisclaimer: I'm not aware of any current patent infringements in
fedora; I'm also in no particularly special place to _be_ aware of them.
For actual legal advice, find a lawyer and exchange money for service.)

- ajax
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