Function to generate darker color (clBtnFace -> clBtnShadow)

[indrahig]

Hi,
We all know about system color in Delphi:
clBtnFace and clBtnShadow.

clBtnShadow is always darker than clBtnFace.
clBtnShadow is generated by Windows automatically when we change the clBtnFace (through display properties in windows control panel)

Is there any function or API function to generate that kind of Color?
I mean, we provide a Color, then the function return a darker Color than the provided color. The input Color and the result color relationship is just like clBtnFace and clBtnShadow.

Anyone knows that?

 

[whosrdaddy]

Here ya go :

http://www.swissdelphicenter.ch/en/showcode.php?id=1411

Cheers,
Daddy

-----------------------------------------------------
What You See Is What You Get
Never underestimate tha powah of tha google!

 

[sggaunt]

Colours are stored as a binary value each colour represented as 8 bits.
In hex this looks like
$FFFFFF (white) $000000 (black), there is an upper control byte which we dont need to worry about.

So to darken a colour simply decrese all three bytes by the same amout.
e.g
$FFFFFF decrese to $EEEEEE is a light grey.
$E7E7E7 slightly darker grey.

darkrning can be achived like this, load the result into the color property of whatever you want to alter.
BColour := Bcolour - $111111;


Steve: Delphi a feersum engin indeed.

 

[indrahig]

wow, thanks whosrdaddy and sggaunt.
I'll try those and give you the result.

 

[indrahig]

Here it is,
I decided to use this code (after some experiment)

function ChangeColor(AColor: TColor; Lighten: boolean): TColor;
var
  r,g,b: extended;
  aRGBCol: integer;
begin
  aRGBCol:= ColorToRGB(AColor);
  r := GetRValue(aRGBCol);
  g := GetGValue(aRGBCol);
  b := GetBValue(aRGBCol);
  if Ligthen then
  begin
    if r = 0 then
      r:= 127
    else
      r := r+((r/255)*100);
    if g = 0 then
      g:= 127
    else
      g := g+((g/255)*100);
    if b = 0 then
      b:= 127
    else
      b := b+((b/255)*100);
  end
  else
  begin
    r := r-((r/255)*100);
    g := g-((g/255)*100);
    b := b-((b/255)*100);
  end;
  if r > 255 then r := 255;
  if r < 0 then r := 0;
  if g > 255 then g := 255;
  if g < 0 then g := 0;
  if b > 255 then b := 255;
  if b < 0 then b := 0;
  Result := RGB(byte(Round(r)),byte(Round(g)),byte(Round(b)));
end;