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SelectClipRgn and TransparentBlt - which is fastest?

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Paolo Severini

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Feb 14, 2001, 4:51:44 AM2/14/01
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Hi,

I need to blit non-rectangular bitmap regions on the screen.
Should I use TransparentBlt() or should I build an HRGN
and call SelectClipRgn() and BitBlt()?
Which is the fastest of these two methods ?

Furthermore, TransparentBlt() isn't supported in Win95/NT
but can be emulated with a sequence of BitBlt calls.
But in this case, it's faster than SelectClipRgn?

Thanks in advance very much.

-- Paolo Severini


Feng Yuan

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Feb 14, 2001, 10:16:44 PM2/14/01
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It depends on the complexity of the region.

If the region is extremely complex, for example, every alternative pixesl,
using clipping takes much more take.
If the region is quite simple, for example two rectangles, using clipping
takes less time.

If you're printing, using clipping with complex region could generate huge
printer data.

BTW: TransparentBlt support on Windows 98 is reported to be resource
leaking.

Feng Yuan ( for the GDI book to read, check www.fengyuan.com )


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