[squeak-dev] Re: [Ann] Enhanced StrikeFonts (antiAliasing,
subPixel AA)
Andreas Raab
andreas.raab at gmx.de
Wed Aug 5 02:46:10 UTC 2009
Juan Vuletich wrote:
> You're right. It seems we need the second BitBlt pass even for black
> text. Just added that to the trunk. I also added a preference,
> #properAlphaForBlackText that defaults to true, but can be set to false
> if performance is more important that correctness.
Yeah, good choice. It turns out that there is a measurable performance
difference between single-pass and two-pass rendering (for example in
the browser benchmark). Is it possible to merge these specific two rules
into a single-pass rendering to retain the original single-pass performance?
> Note #1. This needs a rather recent VM, that includes my fixes to BitBlt
> done in April. Your latest Windows VM is ok.
>
> Note #2. If the trend is to fix the handling of alpha channel in the
> image, at some point the fix to ignore Display alpha must be removed
> from the Linux VM, to play well with composing window managers.
Yes, we should. It would be nice if we could actually control the alpha
correctly.
> Note #3. The second pass stuff is done in GrafPort, but not in BitBlt.
> Do you think it is better to move it up to BitBlt?
BitBlt, since it's used directly from StrikeFont and not via Canvas.
Cheers,
- Andreas
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