Managing Alpha channels
lazarus / 39-Graphics

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torbente · 2014-09-13 01:14

I need do some hark work with alpha channeled images. Are there any
unit or package to make this easier? Basically, i need store a lot of
small images (Imagelist maybe?) and then paste it in a TImage in all
posibble ways and combinations. AFAIK, canvas draw do not work since
it do not keep transparencys.

Thanks a lot.

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torbente · 2014-09-13 13:02

Trying to paste many different images fron a imagelist to one Timage
picture

Image1: TImage;
ImageList1: TImageList;
image1.picture.bitmap := nil;
Image1.Picture.Bitmap.TransparentMode := tmFixed;
Image1.Picture.Bitmap.TransparentColor := clblack;

Imagelist1 have 23 different images stored. I want be able to paste
different images from it to the image1.picture at different positions.

For example:

imagelist1.draw(image1.picture.bitmap.canvas,20,20,0);
imagelist1.draw(image1.picture.bitmap.canvas,10,10,1);

But it do not works, the TImage remains totally transparent

Please, any help is really apreciated.

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engkin · 2014-09-13 14:13

I don't think you can use Bitmap without first setting its size,
something like:
Code: [Select]Image1.Picture.Bitmap.SetSize(..., ...);

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torbente · 2014-09-13 16:07

if i set de size, the bitmap becomes totally black and im able to
paste images from the imagelist, but still it is not transparent. what
im missing?

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engkin · 2014-09-13 16:22

Maybe:
Code: [Select]Image1.Picture.Bitmap.Transparent := True;
?

Edit:
Don't know, but maybe imagelist1.DrawingStyle should be dsTransparent?

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torbente · 2014-09-14 02:16

Ok, i solved this problem with a workaround, but i guess is a bug in
the IDE.

If i just assign an all transparent image to Timage in the IDE, with
just one black pixel, everything works ok.