Add support for CMYK, HSL anf HSV colors

 # 1.2.0
 * Change license to Apache 2.0
 * Improve PdfRect
+* Add support for CMYK, HSL anf HSV colors
 
 # 1.1.1
 * Improve PdfPoint and PdfRect

@@ -67,5 +67,219 @@ class PdfColor {
           (((b * 255.0).round() & 0xff) << 0)) &
       0xFFFFFFFF;
 
+  PdfColorCmyk toCmyk() {
+    return PdfColorCmyk.fromRgb(r, g, b, a);
+  }
+
+  PdfColorHsv toHsv() {
+    return PdfColorHsv.fromRgb(r, g, b, a);
+  }
+
+  PdfColorHsl toHsl() {
+    return PdfColorHsl.fromRgb(r, g, b, a);
+  }
+
+  static double _linearizeColorComponent(double component) {
+    if (component <= 0.03928) return component / 12.92;
+    return math.pow((component + 0.055) / 1.055, 2.4);
+  }
+
+  double get luminance {
+    final double R = _linearizeColorComponent(r);
+    final double G = _linearizeColorComponent(g);
+    final double B = _linearizeColorComponent(b);
+    return 0.2126 * R + 0.7152 * G + 0.0722 * B;
+  }
+
   String toString() => "$runtimeType($r, $g, $b, $a)";
 }
+
+class PdfColorCmyk extends PdfColor {
+  final double c;
+  final double m;
+  final double y;
+  final double k;
+
+  const PdfColorCmyk(this.c, this.m, this.y, this.k, [double a = 1.0])
+      : super(
+          (1.0 - c) * (1.0 - k),
+          (1.0 - m) * (1.0 - k),
+          (1.0 - y) * (1.0 - k),
+        );
+
+  const PdfColorCmyk.fromRgb(double r, double g, double b, [double a = 1.0])
+      : k = 1.0 - r > g ? r : g > b ? r > g ? r : g : b,
+        c = (1.0 - r - (1.0 - r > g ? r : g > b ? r > g ? r : g : b)) /
+            (1.0 - (1.0 - r > g ? r : g > b ? r > g ? r : g : b)),
+        m = (1.0 - g - (1.0 - r > g ? r : g > b ? r > g ? r : g : b)) /
+            (1.0 - (1.0 - r > g ? r : g > b ? r > g ? r : g : b)),
+        y = (1.0 - b - (1.0 - r > g ? r : g > b ? r > g ? r : g : b)) /
+            (1.0 - (1.0 - r > g ? r : g > b ? r > g ? r : g : b)),
+        super(r, g, b, a);
+
+  @override
+  PdfColorCmyk toCmyk() {
+    return this;
+  }
+
+  String toString() => "$runtimeType($c, $m, $y, $k, $a)";
+}
+
+double _getHue(
+    double red, double green, double blue, double max, double delta) {
+  double hue;
+  if (max == 0.0) {
+    hue = 0.0;
+  } else if (max == red) {
+    hue = 60.0 * (((green - blue) / delta) % 6);
+  } else if (max == green) {
+    hue = 60.0 * (((blue - red) / delta) + 2);
+  } else if (max == blue) {
+    hue = 60.0 * (((red - green) / delta) + 4);
+  }
+
+  /// Set hue to 0.0 when red == green == blue.
+  hue = hue.isNaN ? 0.0 : hue;
+  return hue;
+}
+
+class PdfColorHsv extends PdfColor {
+  final double hue;
+  final double saturation;
+  final double value;
+
+  const PdfColorHsv._(this.hue, this.saturation, this.value, double red,
+      double green, double blue, double alpha)
+      : super(red, green, blue, alpha);
+
+  factory PdfColorHsv(double hue, double saturation, double value,
+      [double alpha = 1.0]) {
+    final double chroma = saturation * value;
+    final double secondary =
+        chroma * (1.0 - (((hue / 60.0) % 2.0) - 1.0).abs());
+    final double match = value - chroma;
+
+    double red;
+    double green;
+    double blue;
+    if (hue < 60.0) {
+      red = chroma;
+      green = secondary;
+      blue = 0.0;
+    } else if (hue < 120.0) {
+      red = secondary;
+      green = chroma;
+      blue = 0.0;
+    } else if (hue < 180.0) {
+      red = 0.0;
+      green = chroma;
+      blue = secondary;
+    } else if (hue < 240.0) {
+      red = 0.0;
+      green = secondary;
+      blue = chroma;
+    } else if (hue < 300.0) {
+      red = secondary;
+      green = 0.0;
+      blue = chroma;
+    } else {
+      red = chroma;
+      green = 0.0;
+      blue = secondary;
+    }
+
+    return PdfColorHsv._(hue, saturation, value, red + match, green + match,
+        blue + match, alpha);
+  }
+
+  factory PdfColorHsv.fromRgb(double red, double green, double blue,
+      [double alpha]) {
+    final double max = math.max(red, math.max(green, blue));
+    final double min = math.min(red, math.min(green, blue));
+    final double delta = max - min;
+
+    final hue = _getHue(red, green, blue, max, delta);
+    final double saturation = max == 0.0 ? 0.0 : delta / max;
+
+    return PdfColorHsv._(hue, saturation, max, red, green, blue, alpha);
+  }
+
+  @override
+  PdfColorHsv toHsv() {
+    return this;
+  }
+
+  String toString() => "$runtimeType($hue, $saturation, $value, $a)";
+}
+
+class PdfColorHsl extends PdfColor {
+  final double hue;
+  final double saturation;
+  final double lightness;
+
+  const PdfColorHsl._(this.hue, this.saturation, this.lightness, double alpha,
+      double red, double green, double blue)
+      : super(red, green, blue, alpha);
+
+  factory PdfColorHsl(double hue, double saturation, double lightness,
+      [double alpha]) {
+    final double chroma = (1.0 - (2.0 * lightness - 1.0).abs()) * saturation;
+    final double secondary =
+        chroma * (1.0 - (((hue / 60.0) % 2.0) - 1.0).abs());
+    final double match = lightness - chroma / 2.0;
+
+    double red;
+    double green;
+    double blue;
+    if (hue < 60.0) {
+      red = chroma;
+      green = secondary;
+      blue = 0.0;
+    } else if (hue < 120.0) {
+      red = secondary;
+      green = chroma;
+      blue = 0.0;
+    } else if (hue < 180.0) {
+      red = 0.0;
+      green = chroma;
+      blue = secondary;
+    } else if (hue < 240.0) {
+      red = 0.0;
+      green = secondary;
+      blue = chroma;
+    } else if (hue < 300.0) {
+      red = secondary;
+      green = 0.0;
+      blue = chroma;
+    } else {
+      red = chroma;
+      green = 0.0;
+      blue = secondary;
+    }
+    return PdfColorHsl._(hue, saturation, lightness, alpha, red + match,
+        green + match, blue + match);
+  }
+
+  factory PdfColorHsl.fromRgb(double red, double green, double blue,
+      [double alpha]) {
+    final double max = math.max(red, math.max(green, blue));
+    final double min = math.min(red, math.min(green, blue));
+    final double delta = max - min;
+
+    final double hue = _getHue(red, green, blue, max, delta);
+    final double lightness = (max + min) / 2.0;
+    // Saturation can exceed 1.0 with rounding errors, so clamp it.
+    final double saturation = lightness == 1.0
+        ? 0.0
+        : (delta / (1.0 - (2.0 * lightness - 1.0).abs())).clamp(0.0, 1.0);
+    return PdfColorHsl._(hue, saturation, lightness, alpha, red, green, blue);
+  }
+
+  @override
+  PdfColorHsl toHsl() {
+    return this;
+  }
+
+  @override
+  String toString() => '$runtimeType($hue, $saturation, $lightness, $a)';
+}

@@ -182,10 +182,34 @@ class PdfGraphics {
   ///
   /// @param c Color to use
   void setColor(PdfColor color) {
-    buf.putNumList(<double>[color.r, color.g, color.b]);
-    buf.putString(" rg ");
-    buf.putNumList(<double>[color.r, color.g, color.b]);
-    buf.putString(" RG\n");
+    setFillColor(color);
+    setStrokeColor(color);
+  }
+
+  /// Sets the fill color for drawing
+  ///
+  /// @param c Color to use
+  void setFillColor(PdfColor color) {
+    if (color is PdfColorCmyk) {
+      buf.putNumList(<double>[color.c, color.m, color.y, color.k]);
+      buf.putString(" k\n");
+    } else {
+      buf.putNumList(<double>[color.r, color.g, color.b]);
+      buf.putString(" rg\n");
+    }
+  }
+
+  /// Sets the stroke color for drawing
+  ///
+  /// @param c Color to use
+  void setStrokeColor(PdfColor color) {
+    if (color is PdfColorCmyk) {
+      buf.putNumList(<double>[color.c, color.m, color.y, color.k]);
+      buf.putString(" K\n");
+    } else {
+      buf.putNumList(<double>[color.r, color.g, color.b]);
+      buf.putString(" RG\n");
+    }
   }
 
   /// Set the transformation Matrix