[OpenJDK 2D-Dev] Problems with lcd-antialiased glyphs

Clemens Eisserer linuxhippy at gmail.com
Mon Jun 9 20:24:33 UTC 2008


I started working on lcd-antialiased text now that grayscale and
non-AA case works fine (http://linuxhippy.blogspot.com), however I
experience some problems.
I know the basics, and how it basically works - but I have a hard time
understanding the insights.
I am running a bit out of time, so I hope I don't bother anybody by
asking on this list.

XRender provides (only) component alpha for subpixel-antialiasing.
The glyph is uploaded to an ARGB surface which is used as mask, each
component acts as mask for its counterpart

I tried uploading the glyph-images produced by Java2D directly into an
ARGB-glyphcache and using that, but the results are (of course) not
It seems the concepts do not match 100%, e.g. java2d does not provide
an alpha-component.
I tried setting the alpha-value manually but the results are really
strange - for 100% alpha the background suddenly turns into yellow
(with black used as src over white as background)
And what is the LUT-Table for, why doesn't XRender need it?
Has the XRender approach disavantages, and/or what is the cause the
Java2D uses a more complex approach?

Thank you for your patience and help, Clemens

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