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{
fpGUI - Free Pascal GUI Toolkit
Copyright (C) 2006 - 2010 See the file AUTHORS.txt, included in this
distribution, for details of the copyright.
See the file COPYING.modifiedLGPL, included in this distribution,
for details about redistributing fpGUI.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Description:
This unit contains some color conversion/mapping functions.
}
unit fpg_ColorMapping;
{$mode objfpc}{$H+}
interface
uses
Classes, fpg_base;
// IN these functions the following definitions apply:
// Hue: 0 - 1535
// red = 0 green = 512 blue = 1024
// Saturation: 0 - 1
// grey (no color) = 0 max color = 1
// Value: 0 - 1
// black =0 max brightness = 1
procedure RGBToHSV(C: TfpgColor; out Hue: longint; out Saturation, Value: double);
function HSVToRGB(const H: longint; const S, V: double): TfpgColor;
implementation
uses
Math;
procedure RGBToHSV(C: TfpgColor; out Hue: longint; out Saturation, Value: double);
var
r, g, b: longint;
hi, lo: longint;
d: longint;
rgb: TFPColor;
begin
rgb := fpgColorToFPColor(C);
r := rgb.Red;
g := rgb.Green;
b := rgb.Blue;
hi := max(max(r, g), b);
lo := min(min(r, g), b);
d := hi - lo;
Value := hi / 256;
if d > 0 then
begin
if r = hi then
Hue := 256 * (g - b) div d
else if g = hi then
Hue := 512 + 256 * (b - r) div d
else
Hue := 1024 + 256 * (r - g) div d;
if Hue < 0 then
Hue := Hue + 1536;
end
else
Hue := 0; // doesn't matter (grey: Sat = 0)
if hi > 0 then
Saturation := d / hi
else
Saturation := 0; // doesn't matter (black: Val = 0
end;
function HSVToRGB(const H: longint; const S, V: double): TfpgColor;
var
r, g, b: longint;
rgb: TFPColor;
begin
if (h < 0) or (h > 1535) or (S < 0) or (S > 1) or (V < 0) or (V > 1) then
begin
// Invalid value, use black
Result := 0;
exit;
end;
case h div 256 of
0:
begin
r := 255;
g := h;
b := 0;
end;
1:
begin
r := 511 - h;
g := 255;
b := 0;
end;
2:
begin
r := 0;
g := 255;
b := h - 512;
end;
3:
begin
r := 0;
g := 1023 - h;
b := 255;
end;
4:
begin
r := h - 1024;
g := 0;
b := 255;
end;
5:
begin
r := 255;
g := 0;
b := 1535 - h;
end;
end;
r := Trunc(V * (255 - S * (255 - r)));
g := Trunc(V * (255 - S * (255 - g)));
b := Trunc(V * (255 - S * (255 - b)));
rgb.Red := r;
rgb.Green := g;
rgb.Blue := b;
Result := FPColorTofpgColor(rgb);
end;
end.
|
