--- a/Applications/Samples/SingleFrameEditorApplication.h	Tue Feb 12 10:01:49 2019 +0100
+++ b/Applications/Samples/SingleFrameEditorApplication.h	Tue Feb 12 12:22:13 2019 +0100
@@ -33,6 +33,7 @@
 #include "../../Framework/Radiography/RadiographyWindowingTracker.h"
 #include "../../Framework/Radiography/RadiographySceneWriter.h"
 #include "../../Framework/Radiography/RadiographySceneReader.h"
+#include "../../Framework/Radiography/RadiographyMaskLayer.h"
 
 #include <Core/HttpClient.h>
 #include <Core/Images/FontRegistry.h>
@@ -470,7 +471,7 @@
         
         scene_.reset(new RadiographyScene(GetBroker()));
         //scene_->LoadDicomFrame(instance, frame, false); //.SetPan(200, 0);
-        scene_->LoadDicomFrame(context->GetOrthancApiClient(), "61f3143e-96f34791-ad6bbb8d-62559e75-45943e1b", 0, false, NULL);
+        RadiographyLayer& dicomLayer = scene_->LoadDicomFrame(context->GetOrthancApiClient(), "61f3143e-96f34791-ad6bbb8d-62559e75-45943e1b", 0, false, NULL);
 
 #if !defined(ORTHANC_ENABLE_WASM) || ORTHANC_ENABLE_WASM != 1
         Orthanc::HttpClient::ConfigureSsl(true, "/etc/ssl/certs/ca-certificates.crt");
@@ -478,6 +479,12 @@
         
         //scene_->LoadDicomWebFrame(context->GetWebService());
         
+        std::vector<MaskPoint> mask;
+        mask.push_back(MaskPoint(100, 100));
+        mask.push_back(MaskPoint(100, 1000));
+        mask.push_back(MaskPoint(1000, 1000));
+        scene_->LoadMask(mask, dynamic_cast<RadiographyDicomLayer&>(dicomLayer), 128.0f, NULL);
+
         {
           RadiographyLayer& layer = scene_->LoadText(fontRegistry_.GetFont(0), "Hello\nworld", NULL);
           layer.SetResizeable(true);

--- a/Framework/Radiography/RadiographyLayer.h	Tue Feb 12 10:01:49 2019 +0100
+++ b/Framework/Radiography/RadiographyLayer.h	Tue Feb 12 12:22:13 2019 +0100
@@ -276,5 +276,7 @@
 
     virtual bool GetRange(float& minValue,
                           float& maxValue) const = 0;
-  }; 
+
+    friend class RadiographyMaskLayer; // because it needs to GetTransform on the dicomLayer it relates to
+  };
 }

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Radiography/RadiographyMaskLayer.cpp	Tue Feb 12 12:22:13 2019 +0100
@@ -0,0 +1,247 @@
+/**
+ * Stone of Orthanc
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2018 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 "RadiographyMaskLayer.h"
+#include "RadiographyDicomLayer.h"
+
+#include "RadiographyScene.h"
+#include "Core/Images/Image.h"
+#include "Core/Images/ImageProcessing.h"
+#include <Core/OrthancException.h>
+
+namespace OrthancStone
+{
+
+  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();
+    right = std::numeric_limits<unsigned int>::min();
+    top = std::numeric_limits<unsigned int>::max();
+    bottom = std::numeric_limits<unsigned int>::min();
+
+    for (size_t i = 0; i < corners.size(); i++)
+    {
+      const MaskPoint& p = corners[i];
+      left = std::min(p.x, left);
+      right = std::max(p.x, right);
+      bottom = std::max(p.y, bottom);
+      top = std::min(p.y, top);
+    }
+  }
+
+  void RadiographyMaskLayer::SetCorners(const std::vector<MaskPoint>& corners)
+  {
+    corners_ = corners;
+    invalidated_ = true;
+  }
+
+  void RadiographyMaskLayer::Render(Orthanc::ImageAccessor& buffer,
+                      const AffineTransform2D& viewTransform,
+                      ImageInterpolation interpolation) const
+  {
+    if (dicomLayer_.GetWidth() == 0) // nothing to do if the DICOM layer is not displayed (or not loaded)
+      return;
+
+    if (invalidated_)
+    {
+      mask_.reset(new Orthanc::Image(Orthanc::PixelFormat_Grayscale8, dicomLayer_.GetWidth(), dicomLayer_.GetHeight(), false));
+
+      DrawMask();
+
+//      for (unsigned int i = 0; i < 100; i++)
+//      {
+//        for (unsigned int j = 0; j < 50; j++)
+//        {
+//          if ((i + j) % 2 == 1)
+//          {
+//            Orthanc::ImageAccessor region;
+//            mask_->GetRegion(region, i* 20, j * 20, 20, 20);
+//            Orthanc::ImageProcessing::Set(region, 255);
+//          }
+//        }
+//      }
+      invalidated_ = false;
+    }
+
+    {// rendering
+      if (buffer.GetFormat() != Orthanc::PixelFormat_Float32)
+      {
+        throw Orthanc::OrthancException(Orthanc::ErrorCode_IncompatibleImageFormat);
+      }
+
+      unsigned int cropX, cropY, cropWidth, cropHeight;
+      dicomLayer_.GetCrop(cropX, cropY, cropWidth, cropHeight);
+
+      const AffineTransform2D t = AffineTransform2D::Combine(
+            viewTransform, dicomLayer_.GetTransform(),
+            AffineTransform2D::CreateOffset(cropX, cropY));
+
+      Orthanc::ImageAccessor cropped;
+      mask_->GetRegion(cropped, cropX, cropY, cropWidth, cropHeight);
+
+      Orthanc::Image tmp(Orthanc::PixelFormat_Grayscale8, buffer.GetWidth(), buffer.GetHeight(), false);
+
+      t.Apply(tmp, cropped, interpolation, true /* clear */);
+
+      // Blit
+      const unsigned int width = buffer.GetWidth();
+      const unsigned int height = buffer.GetHeight();
+
+      for (unsigned int y = 0; y < height; y++)
+      {
+        float *q = reinterpret_cast<float*>(buffer.GetRow(y));
+        const uint8_t *p = reinterpret_cast<uint8_t*>(tmp.GetRow(y));
+
+        for (unsigned int x = 0; x < width; x++, p++, q++)
+        {
+          if (*p == 0)
+            *q = foreground_;
+          // else keep the underlying pixel value
+        }
+      }
+
+    }
+  }
+
+  // from https://www.geeksforgeeks.org/how-to-check-if-a-given-point-lies-inside-a-polygon/
+  // Given three colinear points p, q, r, the function checks if
+  // point q lies on line segment 'pr'
+  bool onSegment(const MaskPoint& p, const MaskPoint& q, const MaskPoint& r)
+  {
+      if (q.x <= std::max(p.x, r.x) && q.x >= std::min(p.x, r.x) &&
+              q.y <= std::max(p.y, r.y) && q.y >= std::min(p.y, r.y))
+          return true;
+      return false;
+  }
+
+  // To find orientation of ordered triplet (p, q, r).
+  // The function returns following values
+  // 0 --> p, q and r are colinear
+  // 1 --> Clockwise
+  // 2 --> Counterclockwise
+  int orientation(const MaskPoint& p, const MaskPoint& q, const MaskPoint& r)
+  {
+      int val = (q.y - p.y) * (r.x - q.x) -
+                (q.x - p.x) * (r.y - q.y);
+
+      if (val == 0) return 0;  // colinear
+      return (val > 0)? 1: 2; // clock or counterclock wise
+  }
+
+  // The function that returns true if line segment 'p1q1'
+  // and 'p2q2' intersect.
+  bool doIntersect(const MaskPoint& p1, const MaskPoint& q1, const MaskPoint& p2, const MaskPoint& q2)
+  {
+      // Find the four orientations needed for general and
+      // special cases
+      int o1 = orientation(p1, q1, p2);
+      int o2 = orientation(p1, q1, q2);
+      int o3 = orientation(p2, q2, p1);
+      int o4 = orientation(p2, q2, q1);
+
+      // General case
+      if (o1 != o2 && o3 != o4)
+          return true;
+
+      // Special Cases
+      // p1, q1 and p2 are colinear and p2 lies on segment p1q1
+      if (o1 == 0 && onSegment(p1, p2, q1)) return true;
+
+      // p1, q1 and p2 are colinear and q2 lies on segment p1q1
+      if (o2 == 0 && onSegment(p1, q2, q1)) return true;
+
+      // p2, q2 and p1 are colinear and p1 lies on segment p2q2
+      if (o3 == 0 && onSegment(p2, p1, q2)) return true;
+
+       // p2, q2 and q1 are colinear and q1 lies on segment p2q2
+      if (o4 == 0 && onSegment(p2, q1, q2)) return true;
+
+      return false; // Doesn't fall in any of the above cases
+  }
+
+  // Define Infinite (Using INT_MAX caused overflow problems)
+  #define MASK_INF 1000000
+
+  // Returns true if the point p lies inside the polygon[] with n vertices
+  bool isInside(const std::vector<MaskPoint>& polygon, const MaskPoint& p)
+  {
+      // There must be at least 3 vertices in polygon[]
+      if (polygon.size() < 3)  return false;
+
+      // Create a point for line segment from p to infinite
+      MaskPoint extreme = {MASK_INF, p.y};
+
+      // Count intersections of the above line with sides of polygon
+      int count = 0, i = 0;
+      do
+      {
+          int next = (i+1) % polygon.size();
+
+          // Check if the line segment from 'p' to 'extreme' intersects
+          // with the line segment from 'polygon[i]' to 'polygon[next]'
+          if (doIntersect(polygon[i], polygon[next], p, extreme))
+          {
+              // If the point 'p' is colinear with line segment 'i-next',
+              // then check if it lies on segment. If it lies, return true,
+              // otherwise false
+              if (orientation(polygon[i], p, polygon[next]) == 0)
+                 return onSegment(polygon[i], p, polygon[next]);
+
+              count++;
+          }
+          i = next;
+      } while (i != 0);
+
+      // Return true if count is odd, false otherwise
+      return count&1;  // Same as (count%2 == 1)
+  }
+
+
+  void RadiographyMaskLayer::DrawMask() const
+  {
+    unsigned int left;
+    unsigned int right;
+    unsigned int top;
+    unsigned int bottom;
+
+    ComputeMaskExtent(left, right, top, bottom, corners_);
+
+    Orthanc::ImageProcessing::Set(*mask_, 0);
+
+    MaskPoint p(left, top);
+    for (p.y = top; p.y <= bottom; p.y++)
+    {
+      unsigned char* q = reinterpret_cast<unsigned char*>(mask_->GetRow(p.y));
+      for (p.x = left; p.x <= right; p.x++, q++)
+      {
+        if (isInside(corners_, p))
+        {
+          *q = 255;
+        }
+      }
+    }
+
+//    Orthanc::ImageAccessor region;
+//    mask_->GetRegion(region, 100, 100, 1000, 1000);
+//    Orthanc::ImageProcessing::Set(region, 255);
+  }
+
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Radiography/RadiographyMaskLayer.h	Tue Feb 12 12:22:13 2019 +0100
@@ -0,0 +1,97 @@
+/**
+ * Stone of Orthanc
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2018 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 "RadiographyLayer.h"
+#include "Core/Images/Image.h"
+
+namespace OrthancStone
+{
+  class RadiographyScene;
+  class RadiographyDicomLayer;
+
+  struct MaskPoint
+  {
+    unsigned int x;
+    unsigned int y;
+
+    MaskPoint(unsigned int x, unsigned int y)
+      : x(x),
+        y(y)
+    {}
+  };
+
+  class RadiographyMaskLayer : public RadiographyLayer
+  {
+  private:
+    std::vector<MaskPoint>            corners_;
+    const RadiographyDicomLayer&      dicomLayer_;
+    mutable bool                      invalidated_;
+    float                             foreground_;
+
+    mutable std::auto_ptr<Orthanc::ImageAccessor>  mask_;
+  public:
+    RadiographyMaskLayer(const RadiographyScene& scene, const RadiographyDicomLayer& dicomLayer,
+                         float foreground) :
+      RadiographyLayer(),
+      dicomLayer_(dicomLayer),
+      invalidated_(true),
+      foreground_(foreground)
+    {
+    }
+
+    void SetCorners(const std::vector<MaskPoint>& corners);
+
+    virtual void Render(Orthanc::ImageAccessor& buffer,
+                        const AffineTransform2D& viewTransform,
+                        ImageInterpolation interpolation) const;
+
+    virtual bool GetDefaultWindowing(float& center,
+                                     float& width) const
+    {
+      return false;
+    }
+
+    virtual bool GetRange(float& minValue,
+                          float& maxValue) const
+    {
+      minValue = 0;
+      maxValue = 0;
+
+      if (foreground_ < 0)
+      {
+        minValue = foreground_;
+      }
+
+      if (foreground_ > 0)
+      {
+        maxValue = foreground_;
+      }
+
+      return true;
+
+    }
+
+  private:
+    void DrawMask() const;
+  };
+}

--- a/Framework/Radiography/RadiographyScene.cpp	Tue Feb 12 10:01:49 2019 +0100
+++ b/Framework/Radiography/RadiographyScene.cpp	Tue Feb 12 12:22:13 2019 +0100
@@ -24,6 +24,7 @@
 #include "RadiographyAlphaLayer.h"
 #include "RadiographyDicomLayer.h"
 #include "RadiographyTextLayer.h"
+#include "RadiographyMaskLayer.h"
 #include "../Toolbox/DicomFrameConverter.h"
 
 #include <Core/Images/Image.h>
@@ -292,6 +293,22 @@
     return LoadAlphaBitmap(block.release(), geometry);
   }
 
+  RadiographyLayer& RadiographyScene::LoadMask(const std::vector<MaskPoint>& corners,
+                                               const RadiographyDicomLayer& dicomLayer,
+                                               float foreground,
+                                               RadiographyLayer::Geometry* geometry)
+  {
+    std::auto_ptr<RadiographyMaskLayer>  mask(new RadiographyMaskLayer(*this, dicomLayer, foreground));
+    mask->SetCorners(corners);
+    if (geometry != NULL)
+    {
+      mask->SetGeometry(*geometry);
+    }
+
+    return RegisterLayer(mask.release());
+  }
+
+
   RadiographyLayer& RadiographyScene::LoadAlphaBitmap(Orthanc::ImageAccessor* bitmap, RadiographyLayer::Geometry *geometry)
   {
     std::auto_ptr<RadiographyAlphaLayer>  alpha(new RadiographyAlphaLayer(*this));

--- a/Framework/Radiography/RadiographyScene.h	Tue Feb 12 10:01:49 2019 +0100
+++ b/Framework/Radiography/RadiographyScene.h	Tue Feb 12 12:22:13 2019 +0100
@@ -27,6 +27,9 @@
 
 namespace OrthancStone
 {
+  struct MaskPoint;
+  class RadiographyDicomLayer;
+
   class RadiographyScene :
       public IObserver,
       public IObservable
@@ -150,6 +153,11 @@
                                     unsigned int height,
                                     RadiographyLayer::Geometry* geometry);
 
+    RadiographyLayer& LoadMask(const std::vector<MaskPoint>& corners,
+                               const RadiographyDicomLayer& dicomLayer,
+                               float foreground,
+                               RadiographyLayer::Geometry* geometry);
+
     RadiographyLayer& LoadAlphaBitmap(Orthanc::ImageAccessor* bitmap,  // takes ownership
                                       RadiographyLayer::Geometry* geometry);
 

--- a/Resources/CMake/OrthancStoneConfiguration.cmake	Tue Feb 12 10:01:49 2019 +0100
+++ b/Resources/CMake/OrthancStoneConfiguration.cmake	Tue Feb 12 12:22:13 2019 +0100
@@ -261,6 +261,7 @@
   ${ORTHANC_STONE_ROOT}/Framework/Radiography/RadiographyLayerMoveTracker.cpp
   ${ORTHANC_STONE_ROOT}/Framework/Radiography/RadiographyLayerResizeTracker.cpp
   ${ORTHANC_STONE_ROOT}/Framework/Radiography/RadiographyLayerRotateTracker.cpp
+  ${ORTHANC_STONE_ROOT}/Framework/Radiography/RadiographyMaskLayer.cpp
   ${ORTHANC_STONE_ROOT}/Framework/Radiography/RadiographyScene.cpp
   ${ORTHANC_STONE_ROOT}/Framework/Radiography/RadiographySceneCommand.cpp
   ${ORTHANC_STONE_ROOT}/Framework/Radiography/RadiographySceneReader.cpp