[GR32] How to blend two TBitmap32s

[WojTec]

@NamenLozer, this is black blured border on white background. I mean white color in multiply mode is neutral (not visible)

Here is test code:

Delphi-Quellcode:

function ColorAlgebra(F, B, M: TColor32): TColor32;
begin
//  BlendMode.Multiply(F, B, M);
//  Result := BlendRegEx(F, B, M);
  // 1. multiply
  Result := ColorModulate(F, B);
  // 2. blend
  Result := BlendRegEx(Result, B, M);
end;

procedure TForm18.Image321Click(Sender: TObject);
var
  ImageMap, ShapeMap, Blended: TBitmap32;
begin
  ImageMap := TBitmap32.Create;
  ShapeMap := TBitmap32.Create;
  Blended := TBitmap32.Create;
  try
    // Bitmap.SetSize(240, 180);
    // Bitmap.Clear(clWhite32);
    ImageMap.Assign(Image321.Bitmap);
    ShapeMap.SetSize(ImageMap.Width, ImageMap.Height);
    Blended.SetSize(ImageMap.Width, ImageMap.Height);
    // vignette is generated, can use existing img too
    [vignette code here, working on ShapeMap]

    Blended.MasterAlpha := 0;
    ImageMap.MasterAlpha := 0;
    ShapeMap.MasterAlpha := 0;
//    BlendTransfer(Blended, 0, 0, Blended.BoundsRect, ImageMap, ImageMap.BoundsRect,
//      ShapeMap, ShapeMap.BoundsRect, ColorAlgebra, 0
//    );
//    Image321.Bitmap.Assign(Blended);

    ImageMap.DrawMode := dmBlend;
    ImageMap.OnPixelCombine := BlendMode.Multiply;
    ImageMap.MasterAlpha := 0;
    ImageMap.DrawTo(ShapeMap, 0, 0);
    Image321.Bitmap.Assign(ShapeMap);
  finally
    ImageMap.Free;
    ShapeMap.Free;
    Blended.Free;
  end;
end;

Whats wrong with this?

Multiply() method supports alpha. In this way I realized blending and opacity in my layers (5).