--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Scene2DViewport/OneGesturePointerTracker.h	Sun May 19 16:26:17 2019 +0200
@@ -0,0 +1,54 @@
+/**
+ * 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 "IFlexiblePointerTracker.h"
+
+namespace OrthancStone
+{
+  /**
+  This base is class allows to write simple trackers that deal with single 
+  drag gestures. It is *not* suitables for multi-state trackers where various
+  mouse operations need to be handled.
+
+  In order to write such a tracker:
+  - subclass this class
+  - you may store the initial click/touch position in the constructor
+  - implement PointerMove to react to pointer/touch events
+  - implement Cancel to restore the state at initial tracker creation time
+  */
+  class OneGesturePointerTracker : public IFlexiblePointerTracker
+  {
+  public:
+    OneGesturePointerTracker(ViewportControllerWPtr controllerW);
+    virtual void PointerUp(const PointerEvent& event) ORTHANC_OVERRIDE;
+    virtual void PointerDown(const PointerEvent& event) ORTHANC_OVERRIDE;
+    virtual bool IsAlive() const ORTHANC_OVERRIDE;
+  
+  protected:
+    ViewportControllerPtr  GetController();
+
+  private:
+    ViewportControllerWPtr controllerW_;
+    bool                   alive_;
+  };
+}
+