1 files changed, 148 insertions, 0 deletions
diff --git a/src/GraphicObjects/TestCairoPatch.cs b/src/GraphicObjects/TestCairoPatch.cs
new file mode 100644
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+++ b/src/GraphicObjects/TestCairoPatch.cs
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+//
+// TestCairoPatch.cs
+//
+// Author:
+//       jp <>
+//
+// Copyright (c) 2013-2017 Jean-Philippe Bruyère
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+using Cairo;
+
+namespace Crow
+{
+	public class TestCairoPatch : GraphicObject
+	{
+		void computeControlPoints (
+			double xc, double yc,
+			double x1, double y1,
+			out double x2, out double y2,
+			out double x3, out double y3,
+			double x4, double y4){
+			double ax = x1 - xc;
+			double ay = y1 - yc;
+			double bx = x4 - xc;
+			double byy = y4 - yc;
+			double q1 = ax * ax + ay * ay;
+			double q2 = q1 + ax * bx + ay * byy;
+			double k2 = 4.0/3.0 * (Math.Sqrt(2.0 * q1 * q2) - q2) / (ax * byy - ay * bx);
+
+
+			x2 = xc + ax - k2 * ay;
+			y2 = yc + ay + k2 * ax;
+			x3 = xc + bx + k2 * byy;
+			y3 = yc + byy - k2 * bx;
+		}
+		protected override void onDraw (Context gr)
+		{
+			base.onDraw (gr);
+
+			double radius = 100;
+
+			double pi3 = Math.PI / 3.0;
+
+			MeshPattern mp = new MeshPattern ();
+
+			double x1 = radius,y1 = 0,
+			x2 = 0, y2 = 0, x3 = 0, y3 = 0, x4 = 0, y4 = 0,
+			xc = radius,yc = radius;
+
+			double dx = Math.Sin (pi3) * radius;
+			double dy = Math.Cos (pi3) * radius;
+
+			mp.BeginPatch ();
+			mp.MoveTo (xc, yc);
+			mp.LineTo (x1, y1);
+			x4 = xc + dx;
+			y4 = yc - dy;
+			computeControlPoints (xc, yc, x1, y1, out x2, out y2, out x3, out y3, x4, y4);
+			mp.CurveTo (x2, y2, x3, y3, x4, y4);
+
+			mp.SetCornerColorRGB (0, 1, 1, 1);
+			mp.SetCornerColorRGB (1, 1, 0, 0);
+			mp.SetCornerColorRGB (2, 1, 1, 0);
+
+			x1 = x4;
+			y1 = y4;
+			y4 = yc + dy;
+
+			computeControlPoints (xc, yc, x1, y1, out x2, out y2, out x3, out y3, x4, y4);
+			mp.CurveTo (x2, y2, x3, y3, x4, y4);
+
+			mp.SetCornerColorRGB (3, 0, 1, 0);
+			mp.EndPatch ();
+
+			x1 = x4;
+			y1 = y4;
+			x4 = xc;
+			y4 = yc * 2.0;
+
+			mp.BeginPatch ();
+			mp.MoveTo (xc, yc);
+			mp.LineTo (x1, y1);
+			computeControlPoints (xc, yc, x1, y1, out x2, out y2, out x3, out y3, x4, y4);
+			mp.CurveTo (x2, y2, x3, y3, x4, y4);
+
+			mp.SetCornerColorRGB (0, 1, 1, 1);
+			mp.SetCornerColorRGB (1, 0, 1, 0);
+			mp.SetCornerColorRGB (2, 0, 1, 1);
+
+			x1 = x4;
+			y1 = y4;
+			x4 = xc-dx;
+			y4 = yc+dy;
+
+			computeControlPoints (xc, yc, x1, y1, out x2, out y2, out x3, out y3, x4, y4);
+			mp.CurveTo (x2, y2, x3, y3, x4, y4);
+
+			mp.SetCornerColorRGB (3, 0, 0, 1);
+			mp.EndPatch ();
+
+			x1 = x4;
+			y1 = y4;
+			y4 = yc - dy;
+
+			mp.BeginPatch ();
+			mp.MoveTo (xc, yc);
+			mp.LineTo (x1, y1);
+			computeControlPoints (xc, yc, x1, y1, out x2, out y2, out x3, out y3, x4, y4);
+			mp.CurveTo (x2, y2, x3, y3, x4, y4);
+
+			mp.SetCornerColorRGB (0, 1, 1, 1);
+			mp.SetCornerColorRGB (1, 0, 0, 1);
+			mp.SetCornerColorRGB (2, 1, 0, 1);
+
+			x1 = x4;
+			y1 = y4;
+			x4 = radius;
+			y4 = 0;
+
+			computeControlPoints (xc, yc, x1, y1, out x2, out y2, out x3, out y3, x4, y4);
+			mp.CurveTo (x2, y2, x3, y3, x4, y4);
+
+			mp.SetCornerColorRGB (3, 1, 0, 0);
+			mp.EndPatch ();
+
+			gr.SetSource (mp);
+			gr.Paint ();
+		}
+	}
+}
+