Batch Watermark with Delphi part I

As a novice photographer, always upload my pictures on flickr and the other day someone told me about putting watermarks to the pictures just in case (in order to protect my pictures). Well, said and done, here you can find one of my last applications: Thundax batch watermark. A simple application that lets you upload a set of jpeg images and a bitmap watermark and then embed the mark in each of the images by merging the pixels.

Imagine that we have this picture:


And We've designed the following watermark:

Then with my application, we can merge this pictures in an aesthetical way:

And the result:

The way to achieve this is by playing with the TJPEGImage and TBitmap classes. Here you can see the source code that I've used to implement this solution:

procedure BatchPictures();
var
  jpg: TJPEGImage;
  bmp: TBitmap;
  i: integer;
  sFile: string;
begin
  for i := 0 to ListView1.Items.Count - 1 do
    begin
      if ListView1.Items[i].Checked then
      begin
        bmp := TBitmap.Create;
        jpg := TJPEGImage.Create;
        jpg.LoadFromFile(ListView1.Items[i].Caption);
        bmp.Assign(jpg);
        jpg.Destroy;
        bmp.PixelFormat := pf24bit;
        AddWatermark(bmp, SpinEdit1.Value / 100);
        Jpg := TJPEGImage.Create;
        Jpg.Assign(Bmp);
        sFile := ExtractFileName(ListView1.Items[i].Caption);
        jpg.SaveToFile(Edit1.text + '\out' + sFile);
        bmp.Destroy;
        jpg.Destroy;
      end;
    end;
end;

the function:

procedure AddToImageWaterMark(bitmap: TBitmap; alpha: single);
procedure ColorToRGB(iColor: TColor; var R, G, B: Byte);
function HexToInt(const Value: string): Integer;
begin
Result := StrToInt('$' + Value);
end;
var
s: string;
begin
s := inttohex(iColor, 6);
R := HexToInt(AnsiRightStr(s, 2));
G := HexToInt(AnsiLeftStr(AnsiRightStr(s, 4), 2));
B := HexToInt(AnsiLeftStr(s, 2));
end;
type
TRGB = array[0..1023] of TRGBTriple;
var
waterMark: TBitmap;
sourceX, sourceY, distanceX, distanceY: integer;
linesDestination, linesSource: ^TRGB;
R,G,B : Byte;
begin
waterMark := TBitmap.Create;
waterMark.LoadFromFile(Edit2.text);

distanceY := 0;
distanceX := 0;

if rightBottom.Checked then
distanceY := bitmap.Height - waterMark.Height - 10
else if LeftTop.Checked then
distanceY := 10
else if righttop.Checked then
distanceY := 10
else if leftBottom.Checked then
distanceY := bitmap.Height - waterMark.Height - 10;

for sourceY := 0 to waterMark.Height - 1 do
begin
linesSource := waterMark.ScanLine[sourceY];
linesDestination := bitmap.ScanLine[distanceY];

if rightBottom.Checked then
distanceX := bitmap.Width - waterMark.Width - 10
else if LeftTop.Checked then
distanceX := 10
else if righttop.Checked then
distanceX := bitmap.Width - waterMark.Width - 10
else if leftBottom.Checked then
distanceX := 10;

for sourceX := 0 to waterMark.Width - 1 do
begin
ColorToRGB(ColorBox1.Selected, R, G, B);
if (linesSource[sourceX].rgbtRed = R)
and (linesSource[sourceX].rgbtGreen = G)
and (linesSource[sourceX].rgbtBlue = B) then
begin
linesDestination[distanceX].rgbtRed := linesDestination[distanceX].rgbtRed;
linesDestination[distanceX].rgbtGreen := linesDestination[distanceX].rgbtGreen;
linesDestination[distanceX].rgbtBlue := linesDestination[distanceX].rgbtBlue;
end
else
begin
linesDestination[distanceX].rgbtRed := trunc(linesDestination[distanceX].rgbtRed * (1 - alpha) + linesSource[sourceX].rgbtRed * alpha);
linesDestination[distanceX].rgbtGreen := trunc(linesDestination[distanceX].rgbtGreen * (1 - alpha) + linesSource[sourceX].rgbtGreen * alpha);
linesDestination[distanceX].rgbtBlue := trunc(linesDestination[distanceX].rgbtBlue * (1 - alpha) + linesSource[sourceX].rgbtBlue * alpha);
end;
inc(distanceX);
end;
distanceY := distanceY + 1;
end;
waterMark.Destroy;
end;

end.

I hope you enjoy!. Comments are welcome.!