15.07.2011 2:10, cobines пишет:
2011/6/8 cobines<[email protected]>:
Hello everyone.
I want to convert an icon retrieved by Windows API to a TBitmap saving
transparency. As I understand transparency can be achieved by:
- using an additional Mask bitmap
- using 32bpp TBitmap with alpha channel
Having the handle to an icon from WINAPI, I convert it to TBitmap the
following way:
function IconToBitmap(h: HICON): TBitmap;
var
icon: TIcon;
begin
icon := TIcon.Create;
icon.Handle := h;
Result := TBitmap.Create;
Result.Assign(icon);
icon.Free;
end;
But this does not preserve transparency. I have to add:
Result.Mask(Result.TransparentColor);
Is this the correct way?
Why Icon does not automatically have a Mask? It does have
TransparentMode and TransparentColor correctly assigned.
TransparentColor is copied to TBitmap but the Mask is not copied or
not automatically created.
I finally had time to do some digging.
Turns out Mask bitmap exists in both TIcon and TBitmap (mask image is
copied). Problem is Masked is False in TBitmap. This is because in
procedure TRasterImage.Assign(Source: TPersistent);
there is line
FMasked := SrcImage.FMasked;
which is wrong. It should be :
FMasked := SrcImage.Masked;
FMasked is never set to True for TCustomIcon. Instead Masked property
is overridden to always return True. Therefore after
TBitmap.Assign(TIcon) FMasked is False, while it should be True.
Please create a bug report.
Also a question:
Why TIcon always has Masked=True?
Icons with alpha channel don't work properly with TIcon and they don't
use Mask. Is support for alpha channel icons simply not implemented?
--
Best regards,
Maxim Ganetsky mailto:[email protected]
--
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