How to create transparent bitmap?
lazarus / 39-Graphics

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haword · 2007-05-22 09:47

example:
var
 bmp: TBitmap;
begin
  bmp:=TBitmap.Create;
  bmp.PixelFormat:= pf24bit;
  bmp.Height:=16;
  bmp.Width:=16;
  bmp.TransparentColor:=clBlack;
  bmp.Transparent:=true;
  bmp.Canvas.Brush.Color:=clBlack;
  bmp.Canvas.FillRect(bmp.Canvas.ClipRect);

  SpeedButton1.Glyph.TransparentColor:=clBlack;
  SpeedButton1.Glyph.Transparent:=true;
  SpeedButton1.Glyph.Assign(bmp);

  SpeedButton1.Glyph.SaveToFile('test.bmp');
  SpeedButton2.Glyph.LoadFromFile('test.bmp');

  bmp.Free;

SpeedButton1 show black box, SpeedButton2 show empty, how to create
transparent bitmap and show this to SpeedButton1?

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Marc · 2007-05-22 09:52

at this moment is is not possible to draw transparent yet. This will
be added in the near future

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theo · 2007-05-22 10:44

You could do it with OpBitmap like this:

var bmp:TBitmap;
 opb:TCanvasOPBitmap;
begin
bmp:=TBitmap.create;
opb:=TCanvasOPBitmap.create;
opb.width:=16;
opb.height:=16;
opb.Canvas.Brush.color:=clRed;
opb.Canvas.FillRect(Rect(0,0,16,16));
opb.Canvas.Brush.color:=clBlack;
opb.Canvas.FillRect(Rect(1,1,15,15));
opb.TransparentColor:=opb.Pixels[8,8];
AssignOpBitmapToBitmap(opb,bmp);
opb.free;
SpeedButton1.Glyph.Assign(Bmp);
bmp.free;

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haword · 2007-05-22 11:08

Quote from: "theo"You could do it with OpBitmap like this:

var bmp:TBitmap;
 opb:TCanvasOPBitmap;
begin
bmp:=TBitmap.create;
opb:=TCanvasOPBitmap.create;
opb.width:=16;
opb.height:=16;
opb.Canvas.Brush.color:=clRed;
opb.Canvas.FillRect(Rect(0,0,16,16));
opb.Canvas.Brush.color:=clBlack;
opb.Canvas.FillRect(Rect(1,1,15,15));
opb.TransparentColor:=opb.Pixels[8,8];
AssignOpBitmapToBitmap(opb,bmp);
opb.free;
SpeedButton1.Glyph.Assign(Bmp);
bmp.free;
Hi Theo! Thanks. I and did earlier. But wished to make a transparency
without usage TCanvasOPBitmap. Use only internal resources Lzarus.

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Marc · 2007-05-22 16:18

What is a OPBitmap ?

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theo · 2007-05-22 19:11

Quote from: "Marc"What is a OPBitmap ?

OPBitmap itself is sort of a VCL compatibility layer.
You can reuse code working with scanline accesss, pixelformat
conversions etc the way you're used to from the VCL.

http://www.theo.ch/lazarus/opbitmap1_5.zip