[haiku-development] Re: Optimizing Painter::_DrawBitmapBilinearCopy32
- From: Christian Packmann <Christian.Packmann@xxxxxx>
- To: haiku-development@xxxxxxxxxxxxx
- Date: Fri, 13 Mar 2009 12:39:13 +0100
Stephan Aßmus - 2009-03-11 17:00 :
We need definitely both. We want fast B_OP_COPY for MediaPlayer and fast
B_OP_ALPHA/OVER for Showimage displaying images with alpha channel.
Therefor we need at least those two routines. In B_OP_COPY mode, you can
calculate alpha if that's easier for you, but you need to write 255 as
result and perform no blending.
I've adjusted my code for this.
In B_OP_ALPHA mode, you would
additionally perform blending when writing the result. Blending with
screen contents, but alpha always results in 255. Screen alpha is to be
assumed 255 already in the blending calculations (simplifying them).
I'll wait with this until there is a C reference routine. But adaption of
the B_OP_COPY SSE/MMX code shouldn't be hard. And vector code should
really shine here, the relative speedup gets higher the more arithmetic
instructions you perform on the same data.
Christian
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