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Alexandre · Guest

Hi,

I've been messing with the idea of using DDBs to speed the drawing of an
alpha-blended image to a canvas surface. This has come to my mind because
of the speed I would gain copying from a DDB to the screen, however I want
to know how much is this gain and if it is worth it. Does anyone has some
measurement of this kind?
I did some informal tests and it was indeed faster using a DDB to draw to
a form surface, however when it was stretched it was much slower then the
DIB equivalent. Is that a problem with the way Delphi handles DDBs (by the
way, is a DDB in a TBitmap a pure ddb? I saw a lot of calls to dib handles
in TBitmap without any checking if it is a DIB or not) or just the way
they work with Windows?

I have asked a lot, but what I really want to know is when are DDBs faster
or slower?
And I will be using the AlphaBlend function of Windows, does it has speed
advantages against other methods (Graphics32 for instance), because of
hardware-accelerated functions for instance?

Thanks,
Alexandre Rosenfeld