Does Lazarus Suuport transparency with PNG
lazarus / 39-Graphics

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BenJones · 2013-05-09 05:01

Hi, I was wondering does lazarus support the saving of Transparent png
files. I tryed loading in a Bitmap with the transparent color set at
RGB 255,0,255, the png file saves but no transparency. any ideas of
how to get around this?

Here is a sniplet of code I use maybe you guys can see if I gone wrong
anywere.
Thanks

Code: [Select]var
  png : TPortableNetworkGraphic;
  bmp : TBitmap;
begin
  png := TPortableNetworkGraphic.Create;
  bmp := TBitmap.Create;
  bmp.LoadFromFile('c:\out\ben.bmp');
  png.PixelFormat := pf32bit;
  png.Transparent := True;
  png.TransparentColor := RGBToColor(255,0,255);
  png.Assign(bmp);
  png.SaveToFile('c:\out\hello.png');

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User137 · 2013-05-09 07:19

That didn't seem to work, but changing it a little did:
Code: [Select]var
  png : TPortableNetworkGraphic;
  bmp : TBitmap;
begin
  png := TPortableNetworkGraphic.Create;
  png.PixelFormat := pf32bit;
  bmp := TBitmap.Create;
  bmp.PixelFormat := pf32bit;
  bmp.Transparent := True;
  bmp.TransparentColor := RGBToColor(255,0,255);
  bmp.LoadFromFile('d:\netti\temp.bmp');
  png.SetSize(bmp.Width, bmp.Height);
  png.Canvas.Draw(0, 0, bmp);
  png.SaveToFile('d:\netti\temp.png');
  bmp.Free;
  png.Free;I got rid of assign(), and made the bmp transparent
instead.

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Dibo · 2013-05-09 11:03

Try with BGRABitmap. It has full support for PNG.
http://wiki.freepascal.org/BGRABitmap

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BenJones · 2013-05-09 19:24

Thanks User137 seems to work that now.
Dibo I also take a look at BGRABitmap
thanks agian.