--- a/Applications/Samples/SingleFrameEditorApplication.h	Wed Feb 13 14:14:42 2019 +0100
+++ b/Applications/Samples/SingleFrameEditorApplication.h	Thu Feb 14 10:18:02 2019 +0100
@@ -24,6 +24,7 @@
 #include "SampleApplicationBase.h"
 
 #include "../../Framework/Radiography/RadiographyLayerCropTracker.h"
+#include "../../Framework/Radiography/RadiographyLayerMaskTracker.h"
 #include "../../Framework/Radiography/RadiographyLayerMoveTracker.h"
 #include "../../Framework/Radiography/RadiographyLayerResizeTracker.h"
 #include "../../Framework/Radiography/RadiographyLayerRotateTracker.h"
@@ -134,16 +135,9 @@
 
             return NULL;
           }
-          else if (tool_ == Tool_Mask)
-          {
-//            maskLayer_
-//                case Tool_Mask:
-//                  return new RadiographyLayerMaskTracker
-//                      (undoRedoStack_, widget.GetScene(), view, selected, x, y, corner);
-            return NULL;
-          }
           else if (tool_ == Tool_Crop ||
-                   tool_ == Tool_Resize)
+                   tool_ == Tool_Resize ||
+                   tool_ == Tool_Mask)
           {
             RadiographyScene::LayerAccessor accessor(widget.GetScene(), selected);
             
@@ -156,6 +150,9 @@
                 return new RadiographyLayerCropTracker
                     (undoRedoStack_, widget.GetScene(), view, selected, controlPoint);
 
+              case Tool_Mask:
+                return new RadiographyLayerMaskTracker
+                    (undoRedoStack_, widget.GetScene(), view, selected, controlPoint);
 
               case Tool_Resize:
                 return new RadiographyLayerResizeTracker

--- a/Framework/Radiography/RadiographyLayer.cpp	Wed Feb 13 14:14:42 2019 +0100
+++ b/Framework/Radiography/RadiographyLayer.cpp	Thu Feb 14 10:18:02 2019 +0100
@@ -305,47 +305,41 @@
 
   size_t RadiographyLayer::GetControlPointCount() const {return 4;}
 
-  void RadiographyLayer::GetControlPointInternal(ControlPoint& controlPoint,
-                                                 size_t index) const
+  void RadiographyLayer::GetControlPoint(ControlPoint& cpScene /* out in scene coordinates */,
+                                         size_t index) const
   {
     unsigned int cropX, cropY, cropWidth, cropHeight;
     GetCrop(cropX, cropY, cropWidth, cropHeight);
 
+    ControlPoint cp;
     switch (index)
     {
     case ControlPoint_TopLeftCorner:
-      controlPoint = ControlPoint(cropX, cropY, ControlPoint_TopLeftCorner);
+      cp = ControlPoint(cropX, cropY, ControlPoint_TopLeftCorner);
       break;
 
     case ControlPoint_TopRightCorner:
-      controlPoint = ControlPoint(cropX + cropWidth, cropY, ControlPoint_TopRightCorner);
+      cp = ControlPoint(cropX + cropWidth, cropY, ControlPoint_TopRightCorner);
       break;
 
     case ControlPoint_BottomLeftCorner:
-      controlPoint = ControlPoint(cropX, cropY + cropHeight, ControlPoint_BottomLeftCorner);
+      cp = ControlPoint(cropX, cropY + cropHeight, ControlPoint_BottomLeftCorner);
       break;
 
     case ControlPoint_BottomRightCorner:
-      controlPoint = ControlPoint(cropX + cropWidth, cropY + cropHeight, ControlPoint_BottomRightCorner);
+      cp = ControlPoint(cropX + cropWidth, cropY + cropHeight, ControlPoint_BottomRightCorner);
       break;
 
     default:
       throw Orthanc::OrthancException(Orthanc::ErrorCode_ParameterOutOfRange);
     }
 
+    // transforms image coordinates into scene coordinates
+    GetTransform().Apply(cp.x, cp.y);
+    cpScene = cp;
   }
 
-
-
-  void RadiographyLayer::GetControlPoint(ControlPoint& controlPoint /* out */,
-                                         size_t index) const
-  {
-    GetControlPointInternal(controlPoint, index);
-    GetTransform().Apply(controlPoint.x, controlPoint.y);
-  }
-
-
-  bool RadiographyLayer::LookupControlPoint(ControlPoint& controlPoint /* out */,
+  bool RadiographyLayer::LookupControlPoint(ControlPoint& cpScene /* out */,
                                             double x,
                                             double y,
                                             double zoom,
@@ -362,7 +356,7 @@
 
       if (d <= threshold)
       {
-        controlPoint = cp;
+        cpScene = cp;
         return true;
       }
     }

--- a/Framework/Radiography/RadiographyLayer.h	Wed Feb 13 14:14:42 2019 +0100
+++ b/Framework/Radiography/RadiographyLayer.h	Thu Feb 14 10:18:02 2019 +0100
@@ -178,9 +178,6 @@
       prefferedPhotometricDisplayMode_ = prefferedPhotometricDisplayMode;
     }
 
-    virtual void GetControlPointInternal(ControlPoint& controlPoint,
-                                         size_t index) const;
-
   private:
     void UpdateTransform();
 
@@ -260,10 +257,10 @@
 
     Extent2D GetExtent() const;
 
-    bool GetPixel(unsigned int& imageX,
-                  unsigned int& imageY,
-                  double sceneX,
-                  double sceneY) const;
+    virtual bool GetPixel(unsigned int& imageX,
+                          unsigned int& imageY,
+                          double sceneX,
+                          double sceneY) const;
 
     void SetPixelSpacing(double x,
                          double y);
@@ -271,12 +268,12 @@
     void GetCenter(double& centerX,
                    double& centerY) const;
 
-    void GetControlPoint(ControlPoint& controlPoint,
-                         size_t index) const;
+    virtual void GetControlPoint(ControlPoint& cpScene /* out in scene coordinates */,
+                                 size_t index) const;
 
     virtual size_t GetControlPointCount() const;
 
-    bool LookupControlPoint(ControlPoint& controlPoint /* out */,
+    bool LookupControlPoint(ControlPoint& cpScene /* out */,
                             double x,
                             double y,
                             double zoom,

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Radiography/RadiographyLayerMaskTracker.cpp	Thu Feb 14 10:18:02 2019 +0100
@@ -0,0 +1,140 @@
+/**
+ * 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/>.
+ **/
+
+
+#include "RadiographyLayerMaskTracker.h"
+#include "RadiographyMaskLayer.h"
+
+#include "RadiographySceneCommand.h"
+
+#include <Core/OrthancException.h>
+
+namespace OrthancStone
+{
+  class RadiographyLayerMaskTracker::UndoRedoCommand : public RadiographySceneCommand
+  {
+  private:
+    ControlPoint sourceSceneCp_;
+    ControlPoint targetSceneCp_;
+
+  protected:
+    virtual void UndoInternal(RadiographyLayer& layer) const
+    {
+      RadiographyMaskLayer* maskLayer = dynamic_cast<RadiographyMaskLayer*>(&layer);
+      if (maskLayer == NULL)
+      {
+        throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
+      }
+      unsigned int ix, iy; // image coordinates
+      if (maskLayer->GetPixel(ix, iy, sourceSceneCp_.x, sourceSceneCp_.y))
+      {
+        maskLayer->SetCorner(MaskPoint(ix, iy), sourceSceneCp_.index);
+      }
+    }
+
+    virtual void RedoInternal(RadiographyLayer& layer) const
+    {
+      RadiographyMaskLayer* maskLayer = dynamic_cast<RadiographyMaskLayer*>(&layer);
+      if (maskLayer == NULL)
+      {
+        throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
+      }
+      unsigned int ix, iy; // image coordinates
+      if (maskLayer->GetPixel(ix, iy, targetSceneCp_.x, targetSceneCp_.y))
+      {
+        maskLayer->SetCorner(MaskPoint(ix, iy), targetSceneCp_.index);
+      }
+    }
+
+  public:
+    UndoRedoCommand(const RadiographyLayerMaskTracker& tracker) :
+      RadiographySceneCommand(tracker.accessor_),
+      sourceSceneCp_(tracker.startSceneCp_),
+      targetSceneCp_(tracker.endSceneCp_)
+    {
+      RadiographyMaskLayer* maskLayer = dynamic_cast<RadiographyMaskLayer*>(&(tracker.accessor_.GetLayer()));
+      if (maskLayer == NULL)
+      {
+        throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
+      }
+      unsigned int ix, iy; // image coordinates
+      if (maskLayer->GetPixel(ix, iy, targetSceneCp_.x, targetSceneCp_.y))
+      {
+        maskLayer->SetCorner(MaskPoint(ix, iy), targetSceneCp_.index);
+      }
+    }
+  };
+
+
+  RadiographyLayerMaskTracker::RadiographyLayerMaskTracker(UndoRedoStack& undoRedoStack,
+                                                           RadiographyScene& scene,
+                                                           const ViewportGeometry& view,
+                                                           size_t layer,
+                                                           const ControlPoint& startSceneControlPoint) :
+    undoRedoStack_(undoRedoStack),
+    accessor_(scene, layer),
+    startSceneCp_(startSceneControlPoint),
+    endSceneCp_(startSceneControlPoint)
+  {
+  }
+
+
+  void RadiographyLayerMaskTracker::Render(CairoContext& context,
+                                           double zoom)
+  {
+    throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
+  }
+
+
+  void RadiographyLayerMaskTracker::MouseUp()
+  {
+    if (accessor_.IsValid() && startSceneCp_.x != endSceneCp_.x && startSceneCp_.y != endSceneCp_.y)
+    {
+      undoRedoStack_.Add(new UndoRedoCommand(*this));
+    }
+  }
+
+  
+  void RadiographyLayerMaskTracker::MouseMove(int displayX,
+                                              int displayY,
+                                              double sceneX,
+                                              double sceneY,
+                                              const std::vector<Touch>& displayTouches,
+                                              const std::vector<Touch>& sceneTouches)
+  {
+    if (accessor_.IsValid())
+    {
+      unsigned int ix, iy; // image coordinates
+
+      RadiographyLayer& layer = accessor_.GetLayer();
+      if (layer.GetPixel(ix, iy, sceneX, sceneY))
+      {
+        endSceneCp_ = ControlPoint(sceneX, sceneY, startSceneCp_.index);
+
+        RadiographyMaskLayer* maskLayer = dynamic_cast<RadiographyMaskLayer*>(&layer);
+        if (maskLayer == NULL)
+        {
+          throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
+        }
+        maskLayer->SetCorner(MaskPoint(ix, iy), startSceneCp_.index);
+      }
+    }
+  }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Radiography/RadiographyLayerMaskTracker.h	Thu Feb 14 10:18:02 2019 +0100
@@ -0,0 +1,65 @@
+/**
+ * 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 "../Toolbox/UndoRedoStack.h"
+#include "../Toolbox/ViewportGeometry.h"
+#include "../Widgets/IWorldSceneMouseTracker.h"
+#include "RadiographyScene.h"
+
+namespace OrthancStone
+{
+  class RadiographyLayerMaskTracker : public IWorldSceneMouseTracker
+  {
+  private:
+    class UndoRedoCommand;
+
+    UndoRedoStack&                   undoRedoStack_;
+    RadiographyScene::LayerAccessor  accessor_;
+    ControlPoint                     startSceneCp_;
+    ControlPoint                     endSceneCp_;
+
+  public:
+    RadiographyLayerMaskTracker(UndoRedoStack& undoRedoStack,
+                                RadiographyScene& scene,
+                                const ViewportGeometry& view,
+                                size_t layer,
+                                const ControlPoint& startSceneControlPoint);
+
+    virtual bool HasRender() const
+    {
+      return false;
+    }
+
+    virtual void Render(CairoContext& context,
+                        double zoom);
+
+    virtual void MouseUp();
+
+    virtual void MouseMove(int displayX,
+                           int displayY,
+                           double sceneX,
+                           double sceneY,
+                           const std::vector<Touch>& displayTouches,
+                           const std::vector<Touch>& sceneTouches);
+  };
+}

--- a/Framework/Radiography/RadiographyMaskLayer.cpp	Wed Feb 13 14:14:42 2019 +0100
+++ b/Framework/Radiography/RadiographyMaskLayer.cpp	Thu Feb 14 10:18:02 2019 +0100
@@ -42,6 +42,15 @@
     return dicomLayer_.GetTransformInverse();
   }
 
+  bool RadiographyMaskLayer::GetPixel(unsigned int& imageX,
+                        unsigned int& imageY,
+                        double sceneX,
+                        double sceneY) const
+  {
+    return dicomLayer_.GetPixel(imageX, imageY, sceneX, sceneY);
+  }
+
+
   void ComputeMaskExtent(unsigned int& left, unsigned int& right, unsigned int& top, unsigned int& bottom, const std::vector<MaskPoint>& corners)
   {
     left = std::numeric_limits<unsigned int>::max();
@@ -59,6 +68,15 @@
     }
   }
 
+  void RadiographyMaskLayer::SetCorner(const MaskPoint& corner, size_t index)
+  {
+    if (index < corners_.size())
+      corners_[index] = corner;
+    else
+      corners_.push_back(corner);
+    invalidated_ = true;
+  }
+
   void RadiographyMaskLayer::SetCorners(const std::vector<MaskPoint>& corners)
   {
     corners_ = corners;
@@ -161,8 +179,8 @@
 
         for (i = 0; i < cpSize; i++)
         {
-          if ((cpy[i] <= y && cpy[j] >=  y)
-              ||  (cpy[j] <= y && cpy[i] >= y))
+          if ((cpy[i] < y && cpy[j] >=  y)
+              ||  (cpy[j] < y && cpy[i] >= y))
           {
             nodeX[nodes++]= (int)(cpx[i] + (y - cpy[i])/(cpy[j] - cpy[i]) *(cpx[j] - cpx[i]));
           }

--- a/Framework/Radiography/RadiographyMaskLayer.h	Wed Feb 13 14:14:42 2019 +0100
+++ b/Framework/Radiography/RadiographyMaskLayer.h	Thu Feb 14 10:18:02 2019 +0100
@@ -60,6 +60,7 @@
     }
 
     void SetCorners(const std::vector<MaskPoint>& corners);
+    void SetCorner(const MaskPoint& corner, size_t index);
 
     virtual void Render(Orthanc::ImageAccessor& buffer,
                         const AffineTransform2D& viewTransform,
@@ -70,10 +71,14 @@
       return corners_.size();
     }
 
-    virtual void GetControlPointInternal(ControlPoint& controlPoint,
+    virtual void GetControlPoint(ControlPoint& cpScene,
                                          size_t index) const
     {
-      controlPoint = ControlPoint(corners_[index].x, corners_[index].y, index);
+      ControlPoint cp(corners_[index].x, corners_[index].y, index);
+
+      // transforms image coordinates into scene coordinates
+      GetTransform().Apply(cp.x, cp.y);
+      cpScene = cp;
     }
 
     virtual bool GetDefaultWindowing(float& center,
@@ -102,6 +107,11 @@
 
     }
 
+    virtual bool GetPixel(unsigned int& imageX,
+                          unsigned int& imageY,
+                          double sceneX,
+                          double sceneY) const;
+
   protected:
     virtual const AffineTransform2D& GetTransform() const;
 

--- a/Resources/CMake/OrthancStoneConfiguration.cmake	Wed Feb 13 14:14:42 2019 +0100
+++ b/Resources/CMake/OrthancStoneConfiguration.cmake	Thu Feb 14 10:18:02 2019 +0100
@@ -258,6 +258,7 @@
   ${ORTHANC_STONE_ROOT}/Framework/Radiography/RadiographyDicomLayer.cpp
   ${ORTHANC_STONE_ROOT}/Framework/Radiography/RadiographyLayer.cpp
   ${ORTHANC_STONE_ROOT}/Framework/Radiography/RadiographyLayerCropTracker.cpp
+  ${ORTHANC_STONE_ROOT}/Framework/Radiography/RadiographyLayerMaskTracker.cpp
   ${ORTHANC_STONE_ROOT}/Framework/Radiography/RadiographyLayerMoveTracker.cpp
   ${ORTHANC_STONE_ROOT}/Framework/Radiography/RadiographyLayerResizeTracker.cpp
   ${ORTHANC_STONE_ROOT}/Framework/Radiography/RadiographyLayerRotateTracker.cpp