further work on new color manipulation code

2 files changed, 260 insertions, 6 deletions

diff --git a/libs/canvas/canvas/colors.h b/libs/canvas/canvas/colors.h
index 80d57c698f..17e93cf128 100644
--- a/libs/canvas/canvas/colors.h
+++ b/libs/canvas/canvas/colors.h
@@ -17,19 +17,85 @@
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
 
+#ifndef __ardour_canvas_colors_h__
+#define __ardour_canvas_colors_h__
+
 #include <cairomm/context.h>
 
 #include "canvas/visibility.h"
 #include "canvas/types.h"
 
-namespace ArdourCanvas {
+namespace ArdourCanvas 
+{
+
+struct LIBCANVAS_API HSV;
+struct LIBCANVAS_API HSVA;
+
+extern LIBCANVAS_API Color hsv_to_color (double h, double s, double v, double a = 1.0);
+extern LIBCANVAS_API Color hsv_to_color (const HSV&, double a = 1.0);
+extern LIBCANVAS_API Color hsva_to_color (const HSVA&);
+extern LIBCANVAS_API void  color_to_hsv (Color color, double& h, double& s, double& v);
+
+extern LIBCANVAS_API void  color_to_rgba (Color, double& r, double& g, double& b, double& a);
+extern LIBCANVAS_API Color rgba_to_color (double r, double g, double b, double a);
+
+uint32_t LIBCANVAS_API contrasting_text_color (uint32_t c);
+
+struct LIBCANVAS_API HSV 
+{
+	HSV ();
+	HSV (double h, double s, double v);
+	HSV (Color);
+	virtual ~HSV() {}
+
+	double h;
+	double s;
+	double v;
+
+	bool is_gray() const { return s == 0; }
+
+	operator Color() const { return hsv_to_color (*this); }
+
+	HSV operator+ (const HSV&) const;
+	HSV operator- (const HSV&) const;
+	HSV operator* (double) const;
+
+	HSV darker (double factor = 1.3) const { return shade (factor); }
+	HSV lighter (double factor = 0.7) const { return shade (factor); }
 
-	extern LIBCANVAS_API void color_to_hsv (Color color, double& h, double& s, double& v);
-	extern LIBCANVAS_API Color hsv_to_color (double h, double s, double v, double a);
+	HSV shade (double factor) const;
+	HSV mix (const HSV& other, double amt) const;
 
-	extern LIBCANVAS_API void color_to_rgba (Color, double& r, double& g, double& b, double& a);
-	extern LIBCANVAS_API Color rgba_to_color (double r, double g, double b, double a);
+	void print (std::ostream&) const;
+
+  protected:
+	virtual void clamp();
+};
+
+
+
+struct LIBCANVAS_API HSVA : public HSV
+{
+	HSVA ();
+	HSVA (double h, double s, double v, double a);
+	HSVA (Color);
+
+	double a;
+
+	operator Color() const { return hsva_to_color (*this); }
+
+	HSVA operator+ (const HSVA&) const;
+	HSVA operator- (const HSVA&) const;
+
+	void print (std::ostream&) const;
+
+  protected:
+	void clamp ();
+};
 
-        uint32_t LIBCANVAS_API contrasting_text_color (uint32_t c);
 }
 
+std::ostream& operator<<(std::ostream& o, const ArdourCanvas::HSV& hsv);
+std::ostream& operator<<(std::ostream& o, const ArdourCanvas::HSVA& hsva);
+
+#endif /* __ardour_canvas_colors_h__ */
diff --git a/libs/canvas/colors.cc b/libs/canvas/colors.cc
index 3c638935ec..a3a7565fc8 100644
--- a/libs/canvas/colors.cc
+++ b/libs/canvas/colors.cc
@@ -77,7 +77,12 @@ ArdourCanvas::color_to_hsv (Color color, double& h, double& s, double& v)
 	} else {
 		s = delta / cmax;
 	}
+}
 
+ArdourCanvas::Color
+ArdourCanvas::hsv_to_color (const HSV& hsv, double a)
+{
+	return hsv_to_color (hsv.h, hsv.s, hsv.v, a);
 }
 
 ArdourCanvas::Color
@@ -191,3 +196,186 @@ ArdourCanvas::contrasting_text_color (uint32_t c)
 
 	return (luminance (c) < 0.50) ? white : black;
 }
+
+HSV::HSV ()
+	: h (1.0)
+	, s (1.0)
+	, v (1.0)
+{
+}
+
+HSV::HSV (double hh, double ss, double vv)
+	: h (hh)
+	, s (ss)
+	, v (vv)
+{
+}
+
+HSV::HSV (Color c)
+{
+	color_to_hsv (c, h, s, v);
+}
+
+void
+HSV::clamp ()
+{
+	s = min (s, 1.0);
+	v = min (v, 1.0);
+	h = min (255.0, h);
+}
+
+HSV
+HSV::operator+ (const HSV& operand) const
+{
+	HSV hsv;
+	hsv.h = h + operand.h;
+	hsv.s = s + operand.s;
+	hsv.v = v + operand.v;
+	hsv.clamp();
+	return hsv;
+}
+
+HSV
+HSV::operator- (const HSV& operand) const
+{
+	HSV hsv;
+	hsv.h = h - operand.h;
+	hsv.s = s - operand.s;
+	hsv.v = v - operand.v;
+	hsv.clamp();
+	return hsv;
+}
+
+HSV
+HSV::operator* (double d) const
+{
+	HSV hsv;
+	hsv.h = h * d;
+	hsv.s = s * d;
+	hsv.v = v * d;
+	hsv.clamp();
+	return hsv;
+}
+
+HSV
+HSV::shade (double factor) const
+{
+	HSV hsv (*this);
+	
+	/* algorithm derived from a google palette website
+	   and analysis of their color palettes.
+
+	   basic rule: to make a color darker, increase its saturation 
+	   until it reaches 88%, but then additionally reduce value/lightness 
+	   by a larger amount.
+
+	   invert rule to make a color lighter.
+	*/
+
+	if (factor > 1.0) {
+		if (s < 88) {
+			hsv.v *= 1.0/(factor/10.0);
+		} else {
+			hsv.s *= factor;
+		}
+	} else {
+		if (s < 88) {
+			hsv.v *= 1.0/factor;
+		} else {
+			hsv.s *= factor;
+		}
+	}
+
+	hsv.clamp();
+
+	return hsv;
+}
+
+HSV
+HSV::mix (const HSV& other, double amount) const
+{
+	HSV hsv;
+
+	hsv.h = h + (amount * (other.h - h));
+	hsv.v = v + (amount * (other.s - s));
+	hsv.s = s + (amount * (other.v - v));
+
+	hsv.clamp();
+
+	return hsv;
+}
+
+void
+HSV::print (std::ostream& o) const
+{
+	if (!is_gray()) {
+		o << "hsv " << h << '|' << s << '|' << v;
+	} else {
+		o << "hsv gray";
+	}
+}
+
+HSVA::HSVA ()
+	: a (1.0) 
+{
+}
+
+HSVA::HSVA (double hh, double ss, double vv, double aa)
+	: HSV (hh, ss, vv)
+	, a (aa) 
+{
+}
+
+HSVA::HSVA (Color c)
+{
+	color_to_hsv (c, h, s, v);
+	a = c & 0xff;
+}
+
+void
+HSVA::clamp ()
+{
+	HSV::clamp ();
+	a = min (1.0, a);
+}
+
+HSVA
+HSVA::operator+ (const HSVA& operand) const
+{
+	HSVA hsv;
+	hsv.h = h + operand.h;
+	hsv.s = s + operand.s;
+	hsv.v = v + operand.v;
+	hsv.a = a + operand.a;
+	return hsv;
+}
+
+HSVA
+HSVA::operator- (const HSVA& operand) const
+{
+	HSVA hsv;
+	hsv.h = h - operand.h;
+	hsv.s = s - operand.s;
+	hsv.a = a - operand.a;
+	return hsv;
+}
+
+void
+HSVA::print (std::ostream& o) const
+{
+	if (!is_gray()) {
+		o << "hsva " << h << '|' << s << '|' << v << '|' << a;
+	} else {
+		o << "hsva gray";
+	}
+}
+
+
+ArdourCanvas::Color
+ArdourCanvas::hsva_to_color (const HSVA& hsva)
+{
+	return hsv_to_color (hsva.h, hsva.s, hsva.v, hsva.a);
+}
+
+std::ostream& operator<<(std::ostream& o, const ArdourCanvas::HSV& hsv) { hsv.print (o); return o; }
+std::ostream& operator<<(std::ostream& o, const ArdourCanvas::HSVA& hsva) { hsva.print (o); return o; }