procedure TForm1.Image1DragDrop(Sender, Source: TObject; X, Y: Integer);
begin

if (Source is Timage) and (Sender is TImage) then
begin
  // 비트맵 받고
   Bitmap.Assign((Sender as TImage).Picture.Bitmap);
   // 비트맵 바꾸고
   (Sender as TImage).Picture := (Source as TImage).Picture;
   // 바꾼거 주고
   (Source as TImage).Picture.Bitmap.Assign(Bitmap);
end;

end;