--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OrthancStone/Sources/Scene2D/Internals/CairoArrowRenderer.cpp	Fri Oct 30 16:26:39 2020 +0100
@@ -0,0 +1,77 @@
+/**
+ * Stone of Orthanc
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2020 Osimis S.A., Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation, either version 3 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program. If not, see
+ * <http://www.gnu.org/licenses/>.
+ **/
+
+
+#include "CairoArrowRenderer.h"
+
+#include "../ArrowSceneLayer.h"
+
+namespace OrthancStone
+{
+  namespace Internals
+  {
+    void CairoArrowRenderer::Render(const AffineTransform2D& transform,
+                                    unsigned int canvasWidth,
+                                    unsigned int canvasHeight)
+    {
+      const ArrowSceneLayer& layer = GetLayer<ArrowSceneLayer>();
+      
+      cairo_t* cr = GetCairoContext();
+
+      cairo_set_line_width(cr, layer.GetThickness());
+
+      const Color& color = layer.GetColor();
+      cairo_set_source_rgb(cr, color.GetRedAsFloat(),
+                           color.GetGreenAsFloat(),
+                           color.GetBlueAsFloat());
+
+      const double zoom = transform.ComputeZoom();
+
+      ScenePoint2D axis = layer.GetB() - layer.GetA();
+      double n = ScenePoint2D::SquaredMagnitude(axis);
+      
+      if (!LinearAlgebra::IsCloseToZero(n))
+      {
+        axis = axis * layer.GetArrowLength() / (sqrt(n) * zoom);
+
+        const ScenePoint2D a = layer.GetA().Apply(transform);
+        const ScenePoint2D b = layer.GetB().Apply(transform);
+
+        cairo_move_to(cr, a.GetX(), a.GetY());
+        cairo_line_to(cr, b.GetX(), b.GetY());
+
+        AffineTransform2D r1 = AffineTransform2D::CreateRotation(layer.GetArrowAngle());
+        const ScenePoint2D c = (layer.GetA() + axis.Apply(r1)).Apply(transform);
+        
+        AffineTransform2D r2 = AffineTransform2D::CreateRotation(-layer.GetArrowAngle());
+        const ScenePoint2D d = (layer.GetA() + axis.Apply(r2)).Apply(transform);
+        
+        cairo_move_to(cr, a.GetX(), a.GetY());
+        cairo_line_to(cr, c.GetX(), c.GetY());
+
+        cairo_move_to(cr, a.GetX(), a.GetY());
+        cairo_line_to(cr, d.GetX(), d.GetY());
+
+        cairo_stroke(cr);
+      }
+    }
+  }
+}