1 files changed, 222 insertions, 0 deletions
diff --git a/libs/canvas/utils.cc b/libs/canvas/utils.cc
new file mode 100644
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--- /dev/null
+++ b/libs/canvas/utils.cc
@@ -0,0 +1,222 @@
+/*
+    Copyright (C) 2011-2013 Paul Davis
+    Author: Carl Hetherington <cth@carlh.net>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    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.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include <algorithm>
+#include <cmath>
+#include <stdint.h>
+#include <cairomm/context.h>
+#include "canvas/utils.h"
+
+using std::max;
+using std::min;
+
+void
+ArdourCanvas::color_to_hsv (Color color, double& h, double& s, double& v)
+{
+	double r, g, b, a;
+	double cmax;
+	double cmin;
+	double delta;
+	
+	color_to_rgba (color, r, g, b, a);
+	
+	if (r > g) {
+		cmax = max (r, b);
+	} else {
+		cmax = max (g, b);
+	}
+
+	if (r < g) {
+		cmin = min (r, b);
+	} else {
+		cmin = min (g, b);
+	}
+
+	v = cmax;
+
+	delta = cmax - cmin;
+
+	if (cmax == 0) {
+		// r = g = b == 0 ... v is undefined, s = 0
+		s = 0.0;  
+		h = -1.0;
+	}
+
+	if (delta != 0.0) {	
+		if (cmax == r) {
+			h = fmod ((g - b)/delta, 6.0);
+		} else if (cmax == g) {
+			h = ((b - r)/delta) + 2;
+		} else {
+			h = ((r - g)/delta) + 4;
+		}
+		
+		h *= 60.0;
+	}
+
+	if (delta == 0 || cmax == 0) {
+		s = 0;
+	} else {
+		s = delta / cmax;
+	}
+
+}
+
+ArdourCanvas::Color
+ArdourCanvas::hsv_to_color (double h, double s, double v, double a)
+{
+	s = min (1.0, max (0.0, s));
+	v = min (1.0, max (0.0, v));
+
+	if (s == 0) {
+		// achromatic (grey)
+		return rgba_to_color (v, v, v, a);
+	}
+
+	h = min (360.0, max (0.0, h));
+
+	double c = v * s;
+        double x = c * (1.0 - fabs(fmod(h / 60.0, 2) - 1.0));
+        double m = v - c;
+
+        if (h >= 0.0 && h < 60.0) {
+		return rgba_to_color (c + m, x + m, m, a);
+        } else if (h >= 60.0 && h < 120.0) {
+		return rgba_to_color (x + m, c + m, m, a);
+        } else if (h >= 120.0 && h < 180.0) {
+		return rgba_to_color (m, c + m, x + m, a);
+        } else if (h >= 180.0 && h < 240.0) {
+		return rgba_to_color (m, x + m, c + m, a);
+        } else if (h >= 240.0 && h < 300.0) {
+		return rgba_to_color (x + m, m, c + m, a);
+        } else if (h >= 300.0 && h < 360.0) {
+		return rgba_to_color (c + m, m, x + m, a);
+        } 
+	return rgba_to_color (m, m, m, a);
+}
+
+void
+ArdourCanvas::color_to_rgba (Color color, double& r, double& g, double& b, double& a)
+{
+	r = ((color >> 24) & 0xff) / 255.0;
+	g = ((color >> 16) & 0xff) / 255.0;
+	b = ((color >>  8) & 0xff) / 255.0;
+	a = ((color >>  0) & 0xff) / 255.0;
+}
+
+ArdourCanvas::Color
+ArdourCanvas::rgba_to_color (double r, double g, double b, double a)
+{
+	/* clamp to [0 .. 1] range */
+
+	r = min (1.0, max (0.0, r));
+	g = min (1.0, max (0.0, g));
+	b = min (1.0, max (0.0, b));
+	a = min (1.0, max (0.0, a));
+
+	/* convert to [0..255] range */
+
+	unsigned int rc, gc, bc, ac;
+	rc = rint (r * 255.0);
+	gc = rint (g * 255.0);
+	bc = rint (b * 255.0);
+	ac = rint (a * 255.0);
+
+	/* build-an-integer */
+
+	return (rc << 24) | (gc << 16) | (bc << 8) | ac;
+}
+
+void
+ArdourCanvas::set_source_rgba (Cairo::RefPtr<Cairo::Context> context, Color color)
+{
+	context->set_source_rgba (
+		((color >> 24) & 0xff) / 255.0,
+		((color >> 16) & 0xff) / 255.0,
+		((color >>  8) & 0xff) / 255.0,
+		((color >>  0) & 0xff) / 255.0
+		);
+}
+
+ArdourCanvas::Distance
+ArdourCanvas::distance_to_segment_squared (Duple const & p, Duple const & p1, Duple const & p2, double& t, Duple& at)
+{
+	static const double kMinSegmentLenSquared = 0.00000001;  // adjust to suit.  If you use float, you'll probably want something like 0.000001f
+	static const double kEpsilon = 1.0E-14;  // adjust to suit.  If you use floats, you'll probably want something like 1E-7f
+	double dx = p2.x - p1.x;
+	double dy = p2.y - p1.y;
+	double dp1x = p.x - p1.x;
+	double dp1y = p.y - p1.y;
+	const double segLenSquared = (dx * dx) + (dy * dy);
+
+	if (segLenSquared >= -kMinSegmentLenSquared && segLenSquared <= kMinSegmentLenSquared) {
+		// segment is a point.
+		at = p1;
+		t = 0.0;
+		return ((dp1x * dp1x) + (dp1y * dp1y));
+	} 
+
+
+	// Project a line from p to the segment [p1,p2].  By considering the line
+	// extending the segment, parameterized as p1 + (t * (p2 - p1)),
+	// we find projection of point p onto the line. 
+	// It falls where t = [(p - p1) . (p2 - p1)] / |p2 - p1|^2
+		
+	t = ((dp1x * dx) + (dp1y * dy)) / segLenSquared;
+
+	if (t < kEpsilon) {
+		// intersects at or to the "left" of first segment vertex (p1.x, p1.y).  If t is approximately 0.0, then
+		// intersection is at p1.  If t is less than that, then there is no intersection (i.e. p is not within
+		// the 'bounds' of the segment)
+		if (t > -kEpsilon) {
+			// intersects at 1st segment vertex
+			t = 0.0;
+		}
+		// set our 'intersection' point to p1.
+		at = p1;
+		// Note: If you wanted the ACTUAL intersection point of where the projected lines would intersect if
+		// we were doing PointLineDistanceSquared, then qx would be (p1.x + (t * dx)) and qy would be (p1.y + (t * dy)).
+
+	} else if (t > (1.0 - kEpsilon)) {
+		// intersects at or to the "right" of second segment vertex (p2.x, p2.y).  If t is approximately 1.0, then
+		// intersection is at p2.  If t is greater than that, then there is no intersection (i.e. p is not within
+		// the 'bounds' of the segment)
+		if (t < (1.0 + kEpsilon)) {
+			// intersects at 2nd segment vertex
+			t = 1.0;
+		}
+		// set our 'intersection' point to p2.
+		at = p2;
+		// Note: If you wanted the ACTUAL intersection point of where the projected lines would intersect if
+		// we were doing PointLineDistanceSquared, then qx would be (p1.x + (t * dx)) and qy would be (p1.y + (t * dy)).
+	} else {
+		// The projection of the point to the point on the segment that is perpendicular succeeded and the point
+		// is 'within' the bounds of the segment.  Set the intersection point as that projected point.
+		at = Duple (p1.x + (t * dx), p1.y + (t * dy));
+	}
+
+	// return the squared distance from p to the intersection point.  Note that we return the squared distance
+	// as an optimization because many times you just need to compare relative distances and the squared values
+	// works fine for that.  If you want the ACTUAL distance, just take the square root of this value.
+	double dpqx = p.x - at.x;
+	double dpqy = p.y - at.y;
+
+	return ((dpqx * dpqx) + (dpqy * dpqy));
+}
+