--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OrthancStone/Sources/Scene2D/RotateSceneTracker.cpp	Tue Jul 07 16:21:02 2020 +0200
@@ -0,0 +1,73 @@
+/**
+ * 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 Affero 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
+ * Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+#include "RotateSceneTracker.h"
+#include "../Scene2DViewport/ViewportController.h"
+
+namespace OrthancStone
+{
+  RotateSceneTracker::RotateSceneTracker(boost::shared_ptr<IViewport> viewport,
+                                         const PointerEvent& event)
+    : OneGesturePointerTracker(viewport)
+    , click_(event.GetMainPosition())
+    , aligner_(viewport, click_)
+    , isFirst_(true)
+  {
+    std::unique_ptr<IViewport::ILock> lock(viewport_->Lock());
+    originalSceneToCanvas_ = lock->GetController().GetSceneToCanvasTransform();
+
+  }
+
+  void RotateSceneTracker::PointerMove(const PointerEvent& event)
+  {
+    ScenePoint2D p = event.GetMainPosition();
+    double dx = p.GetX() - click_.GetX();
+    double dy = p.GetY() - click_.GetY();
+
+    if (std::abs(dx) > 5.0 ||
+        std::abs(dy) > 5.0)
+    {
+      double a = atan2(dy, dx);
+
+      if (isFirst_)
+      {
+        referenceAngle_ = a;
+        isFirst_ = false;
+      }
+
+      std::unique_ptr<IViewport::ILock> lock(viewport_->Lock());
+
+      lock->GetController().SetSceneToCanvasTransform(
+        AffineTransform2D::Combine(
+          AffineTransform2D::CreateRotation(a - referenceAngle_),
+          originalSceneToCanvas_));
+      aligner_.Apply();
+      lock->Invalidate();
+    }
+  }
+
+  void RotateSceneTracker::Cancel()
+  {
+    // See remark above
+    std::unique_ptr<IViewport::ILock> lock(viewport_->Lock());
+    lock->GetController().SetSceneToCanvasTransform(originalSceneToCanvas_);
+    lock->Invalidate();
+  }
+}