[squeak-dev] PNGReadWriter bug?
J. Vuletich (mail lists)
juanlists at jvuletich.org
Sat Jun 14 13:25:47 UTC 2014
Hi Tim,
Quoting tim Rowledge <tim at rowledge.org>:
> ...
>
> I think you’re right but it’s probably going to be ‘fun’ to fix. The
> Scratch code is handling forms with transparency pretty well in
> almost all cases (except this dratted banana bunch!) using ‘paint’.
> I’ll have to see if the ARM specific bitblt improvements allow me to
> use ‘blend’ without killing display performance. Hmm, maybe if I
> ‘blend’ it into another Form and ‘paint’ that?
That will most likely leave R, G and B alone, not zeroing them. A
rather crude hack you might use is calling #preMultiplyAlpha. This
will fix this case. But it will ruin any Form with alpha values other
than 0 or 255, i.e. actual translucency.
Something else that might work is blitting the Form on a new one, with
an appropriate ColorMap.
>
> tim
> --
> tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
> "Oh bother" said Pooh, as he reached for the reset button
Cheers,
Juan Vuletich
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