Problem to save image (in PNG) with transparency

[carlejt]

Problem to save image (in PNG) with transparency;
I do not know how to do it, I tried this (but have not had the expected result):

Code: [Select]


procedure TForm1.Button1Click(Sender: TObject);

var png: TPortableNetworkGraphic;

begin

  png:=TPortableNetworkGraphic.Create;
  png.Width:=200;
  png.Height:=200;

  png.Transparent:=true;
  png.TransparentColor:=clYellow;  // transparent color

  png.Canvas.Brush.Color:=clblue;
  png.Canvas.FillRect(0,0,199,199);
  png.Canvas.Brush.Color:=clyellow;
  png.Canvas.FillRect(50,50,150,150);

  png.SaveToFile('image.png');    // why the image has no transparency?

end;



How to save the image in PNG with transparency?, Is it possible?, What is the solution?

Thanks.

[Wodzu]

Strange, I've played with it for a while and also could not get transparency to work.

Interesting thing is that when you modify PixelFormat property to 32bit, the blue border is getting transparent.