ColorWheel and ValueBar implementation including color mapping routines.

These components will allow us to implement a color selection dialog.

1 files changed, 138 insertions, 0 deletions

diff --git a/src/gui/fpg_colormapping.pas b/src/gui/fpg_colormapping.pas
new file mode 100644
index 00000000..9f486bbf
--- /dev/null
+++ b/src/gui/fpg_colormapping.pas
@@ -0,0 +1,138 @@
+{
+    fpGUI  -  Free Pascal GUI Library
+
+    Copyright (C) 2006 - 2009 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: TRGBTriple;
+begin
+  rgb   := fpgColorToRGBTriple(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:     TRGBTriple;
+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 := RGBTripleTofpgColor(rgb);
+end;
+
+
+end.
+