How to make a 32bits PNG image without transparency
lazarus / 39-Graphics

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phabyam · 2012-11-16 05:43

Hola amigos!

I need to generate a 32bits png image without transparent pixels, I'm
doing this

Code: [Select]procedure TForm1.Button1Click(Sender: TObject);
var
  Png : TPortableNetworkGraphic;
begin
  Png := TPortableNetworkGraphic.Create;

  Png.PixelFormat:=pf32bit;
  Png.Transparent:=False;
  //Png.TransparentColor:=clNone;
  Png.SetSize(256,256);

  Png.Canvas.Brush.Color:=clBlue;
  Png.Canvas.FillRect(0,0,256,256);

  Png.Canvas.Brush.Color:=clYellow;
  Png.Canvas.Ellipse(10,10,246,246);

  Png.SaveToFile('E:\Archivos\Escritorio\DrawTest.png');
  Png.Free;
end;  
but the saved image have transparent pixels, check this
http://i.imgur.com/75MmE.png 

when I change   Png.PixelFormat:=pf32bit; to pf24bits the saved image
is OK , check this  http://i.imgur.com/hDqX8.png, but unfortunately I
need the image in 32bits pixel format

Helpme guys,

sorry my poor english

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Imants · 2012-11-16 07:09

try something like this

  lazimg := TLazIntfImage.Create(256, 256);
  drawer := TLazCanvas.create(lazimg);
  drawer.Rectangle(0, 0, 255, 255);
  FStream := TFileStream.Create('C:\test.png', fmOpenWrite);

  FWrite := TFPWriterPNG.create;
  FWrite.UseAlpha := False;
  FWrite.WordSized := False;
  lazimg.SaveToStream(FStream, FWrite); 

  drawer.Free;
  FStream .Free;
  FWrite.Free;
  lazimg.Free;

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circular · 2012-11-16 07:43

What do you mean by 32 bits ? If it's RGB each 8 bits, then it means
that there is an implicit alpha channel. So you need to fill it with
zeroes for example with something like "for each pixel, get color,
change alpha color to zero and set color"