Автор: http://www.swissdelphicenter.ch

{
  Here's some function that returns the lighter or darker color of a TColor.
  You can use it, for example, to design a bevel or something like that.
 }

 {=======================================}

function Min(a, b: Longint): Longint;
begin
  if a > b then
    Result := b
  else
    Result := a;
end;

function Max(a, b: Longint): Longint;
begin
  if a > b then
    Result := a
  else
    Result := b;
end;

{=======================================}

function GetHighlightColor(BaseColor: TColor): TColor;
begin
  Result := RGB(Min(GetRValue(ColorToRGB(BaseColor)) + 64, 255),
    Min(GetGValue(ColorToRGB(BaseColor)) + 64, 255),
    Min(GetBValue(ColorToRGB(BaseColor)) + 64, 255));
end;

function GetShadowColor(BaseColor: TColor): TColor;
begin
  Result := RGB(Max(GetRValue(ColorToRGB(BaseColor)) - 64, 0),
    Max(GetGValue(ColorToRGB(BaseColor)) - 64, 0),
    Max(GetBValue(ColorToRGB(BaseColor)) - 64, 0));
end;