how to access the mask bits of an icon?
lazarus / 39-Graphics

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march · 2011-02-26 09:25

I have a 32x32 16-color icon:
Aicon := TIcon.Create;
Aicon.LoadFromLazarusResource('arrow');

The image pixels are available from:
Aicon.Canvas.Colors[X,Y]
The transparent pixels are just black here, which I think is normal.

Now I need to see the mask pixels to identify the transparent areas.
Aicon.Masked is true.
Aicon.MaskHandle : HBitmap is available.
Can I use that somehow to find a mask[x,y] array?

FPC 2.2.4  Lazarus 0.9.28.2  WinXP (portable code)

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circular · 2011-02-26 17:37

Maybe if you create another TBitmap and assign the mask handle to the
bitmap handle.

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march · 2011-02-27 01:54

Yes, with the following:
MaskBitmap := TBitmap.Create;
MaskBitmap.Handle := Aicon.MaskHandle;

then only the non-transparent pixels have:
MaskBitmap.Canvas.Pixels[X,Y] = clBlack

It would be nice to see direct access to mask bits with a TIcon
property.
Maybe that will be a future addition, but for now this method does the
job.