Barcodes in BGRABitmap
lazarus / 39-Graphics

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99Percent · 2014-12-05 03:18

I am having trouble getting a barcode in a TBGRABitmap canvas.

I am using the barcode library.

Code: [Select]procedure TForm1.Button1Click(Sender: TObject);
var
  Bitmap,Photo : TBGRABitmap;
  Barcode : TBarcode;
begin
    Bitmap := TBGRABitmap.Create(661,1028,BGRAPixelTransparent);
     Photo :=TBGRABitmap.Create('somepicture.jpg');
     Barcode:=TBarcode.Create(self);
    try
       with Bitmap do begin
         StretchPutImage(Rect(40,400,440,830),Photo,dmDrawWithTranspar
ency,255);
         FontHeight:=40;
         FontAntialias:=True;
         FontStyle:= [fsBold];
         TextOut(240,950,'Name Last Name',BGRABlack,taCenter);
       end;
       with Barcode do begin
         Typ:=bcCode128A;
         Height:=80;
         Modul:=3;
         Text:='^01234';
         Barcode.
         Top:=850;
         Left:=40+((400-Width) div 2);
         DrawBarcode(Bitmap.Canvas);
       end;
         Bitmap.SaveToFile('credencial.png');
       Image1.Picture.Bitmap.Assign(Bitmap);
     finally
       Bitmap.Free;
       Photo.Free;
       Barcode.Free;
  end;
end;

It works fine in Linux but on Windows the black lines of the barcode
are gone, only the white lines show. I have tried drawing a polygon
directly to canvas and if I use any color except black it appears
fine. Only the black color seems to be causing this problem. What am I
missing?

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circular · 2014-12-05 15:00

The black color (clBlack) is used to specify a transparent color. To
have a black color, you need to use clBlackOpaque constant instead.

Alternatively, if you cannot change the color of the bar code, you can
use Bitmap.AlphaFill to set the alpha channel to 255 afterwards in the
desired area.