2D antialiasing?

Glynn Clements glynn at gclements.plus.com
Wed Dec 10 12:23:02 PST 2008

McDonald, Michael-p7438c wrote:

> One of our customers thinks X has 2D antialiasing. In the old days, X
> had very specific pixelization rules which pretty much prohibited
> antialiasing for general graphics. Is there any supposrt for 2D
> antialiasing? The only thing I can find is using Xrender for
> antialiasing fonts. Anything else?

The core X11 API doesn't support anti-aliasing.

Anti-aliasing requires being able to interpolate pixel values, and the
core X11 API treats pixel values as just numbers, without any
consideration of how they map to colours (the rendering doesn't pay
any attention to Visuals; if you're rendering to a Pixmap, there isn't
even a Visual to pay attention to). Also, anti-aliasing tends to do
the wrong thing if the GC's function and plane-mask aren't GXcopy and
AllPlanes respectively.

Programs which perform anti-aliasing will either be using XRender (or
maybe OpenGL), or rendering client-side and blitting the end result.

Glynn Clements <glynn at gclements.plus.com>

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