--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Scene2DViewport/IFlexiblePointerTracker.h	Wed May 15 16:56:17 2019 +0200
@@ -0,0 +1,81 @@
+/**
+ * Stone of Orthanc
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2019 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/>.
+ **/
+
+
+#pragma once
+
+#include "PointerTypes.h"
+
+#include <Framework/Scene2D/PointerEvent.h>
+
+namespace OrthancStone
+{
+  /**
+  This interface represents a flexible mouse tracker that can respond to 
+  several events and is not automatically deleted upon mouse up or when touch
+  interaction is suspended : for instance, a stateful tracker with a two-step 
+  interaction like: click & drag --> mouse up --> drag --> mouse click 
+  (for instance, for an angle measuring tracker or an ellipse tracker)
+  */
+  class IFlexiblePointerTracker : public boost::noncopyable
+  {
+  public:
+    virtual ~IFlexiblePointerTracker() {}
+
+    /**
+    This method will be repeatedly called during user interaction
+    */
+    virtual void PointerMove(const PointerEvent& event) = 0;
+
+    /**
+    This method will be called when a touch/pointer is removed (mouse up, 
+    pen lift, finger removed...)
+    */
+    virtual void PointerUp(const PointerEvent& event) = 0;
+
+    /**
+    This method will be called when a touch/pointer is added (mouse down, 
+    pen or finger press)
+    */
+    virtual void PointerDown(const PointerEvent& event) = 0;
+
+    /**
+    This method will be repeatedly called by the tracker owner (for instance,
+    the application) to check whether the tracker must keep on receiving 
+    interaction or if its job is done and it should be deleted.
+    */
+    virtual bool IsActive() const = 0;
+
+    /**
+    This will be called if the tracker needs to be dismissed without committing
+    its changes to the underlying model. If the model has been modified during
+    tracker lifetime, it must be restored to its initial value
+    */
+    virtual void Cancel() = 0;
+  };
+
+
+  /**
+  This factory adopts the supplied simple tracker and creates a flexible 
+  tracker wrapper around it.
+  */
+  FlexiblePointerTrackerPtr CreateSimpleTrackerAdapter(PointerTrackerPtr);
+}
+