How to blend 2 TColor's together with a specified strength (Opacity).
function BlendColors(Color1, Color2: TColor; Opacity: Byte): TColor;
var
I : Integer;
Val1,
Val2 : Byte;
RGB1,
RGB2 : PByteArray;
begin
//First make sure they are RGB rather than a windows colour
Color1 := ColorToRGB(Color1);
Color2 := ColorToRGB(Color2);
//Point our Byte arrays to the 2 colours
RGB1 := @Color1;
RGB2 := @Color2;
//Blend the B,G,R
for I:=0 to 2 do
begin
Val1 := RGB1[I] * (255 - Opacity) div 255;
Val2 := RGB2[I] * Opacity div 255;
RGB1[I] := Val1 + Val2;
end;
//Set the colour flag to specify $01 = actual RGB colour
RGB1[3] := 1;
Result := Color1;
end