TColor 調整亮度

procedure pr_BrightenColor(var Color: TColor; Brightness: Integer);
var R, G, B: Byte;
begin
  R := GetRValue(Color);
  G := GetGValue(Color);
  B := GetBValue(Color);

  R := Min(255, R + Brightness);
  G := Min(255, G + Brightness);
  B := Min(255, B + Brightness);

  Color := RGB(R, G, B);
end;