--- a/Framework/Loaders/DicomStructureSetLoader.cpp	Wed May 29 13:44:55 2019 +0200
+++ b/Framework/Loaders/DicomStructureSetLoader.cpp	Wed May 29 16:15:04 2019 +0200
@@ -128,7 +128,7 @@
       std::set<std::string> instances;
       loader.content_->GetReferencedInstances(instances);
 
-      loader.countReferencedInstances_ = instances.size();
+      loader.countReferencedInstances_ = static_cast<unsigned int>(instances.size());
 
       for (std::set<std::string>::const_iterator
              it = instances.begin(); it != instances.end(); ++it)

--- a/Framework/Loaders/OrthancSeriesVolumeProgressiveLoader.cpp	Wed May 29 13:44:55 2019 +0200
+++ b/Framework/Loaders/OrthancSeriesVolumeProgressiveLoader.cpp	Wed May 29 16:15:04 2019 +0200
@@ -42,20 +42,22 @@
       DicomVolumeImageMPRSlicer::Slice(*that.volume_, plane),
       that_(that)
     {
-      if (GetProjection() == VolumeProjection_Axial)
+      if (IsValid())
       {
-        // For coronal and sagittal projections, we take the global
-        // revision of the volume because even if a single slice changes,
-        // this means the projection will yield a different result --> 
-        // we must increase the revision as soon as any slice changes 
-        SetRevision(that_.seriesGeometry_.GetSliceRevision(GetSliceIndex()));
-      }
+        if (GetProjection() == VolumeProjection_Axial)
+        {
+          // For coronal and sagittal projections, we take the global
+          // revision of the volume because even if a single slice changes,
+          // this means the projection will yield a different result --> 
+          // we must increase the revision as soon as any slice changes 
+          SetRevision(that_.seriesGeometry_.GetSliceRevision(GetSliceIndex()));
+        }
       
-      if (that_.strategy_.get() != NULL &&
-          IsValid() &&
-          GetProjection() == VolumeProjection_Axial)
-      {
-        that_.strategy_->SetCurrent(GetSliceIndex());
+        if (that_.strategy_.get() != NULL &&
+            GetProjection() == VolumeProjection_Axial)
+        {
+          that_.strategy_->SetCurrent(GetSliceIndex());
+        }
       }
     }
   };
@@ -264,7 +266,7 @@
         std::auto_ptr<GetOrthancImageCommand> tmp(new GetOrthancImageCommand);
         tmp->SetHttpHeader("Accept-Encoding", "gzip");
         tmp->SetHttpHeader("Accept", std::string(Orthanc::EnumerationToString(Orthanc::MimeType_Pam)));
-        tmp->SetInstanceUri(instance, slice.GetExpectedPixelFormat());          
+        tmp->SetInstanceUri(instance, slice.GetExpectedPixelFormat());
         tmp->SetExpectedPixelFormat(slice.GetExpectedPixelFormat());
         command.reset(tmp.release());
       }

--- a/Framework/Messages/MessageBroker.h	Wed May 29 13:44:55 2019 +0200
+++ b/Framework/Messages/MessageBroker.h	Wed May 29 16:15:04 2019 +0200
@@ -18,8 +18,9 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  **/
 
+#pragma once
 
-#pragma once
+#include "../StoneException.h"
 
 #include "boost/noncopyable.hpp"
 
@@ -40,6 +41,13 @@
     std::set<const IObserver*> activeObservers_;  // the list of observers that are currently alive (that have not been deleted)
 
   public:
+    MessageBroker()
+    {
+      static bool created = false;
+      ORTHANC_ASSERT(!created, "One broker to rule them all!");
+      created = true;
+    }
+
     void Register(const IObserver& observer)
     {
       activeObservers_.insert(&observer);

--- a/Framework/Oracle/OrthancRestApiCommand.h	Wed May 29 13:44:55 2019 +0200
+++ b/Framework/Oracle/OrthancRestApiCommand.h	Wed May 29 16:15:04 2019 +0200
@@ -95,6 +95,11 @@
 
     void SetBody(const Json::Value& json);
 
+    void SwapBody(std::string& body)
+    {
+      body_.swap(body);
+    }
+
     void SetHttpHeader(const std::string& key,
                        const std::string& value)
     {

--- a/Framework/Oracle/ThreadedOracle.cpp	Wed May 29 13:44:55 2019 +0200
+++ b/Framework/Oracle/ThreadedOracle.cpp	Wed May 29 16:15:04 2019 +0200
@@ -248,7 +248,7 @@
     client.SetTimeout(command.GetTimeout());
 
     CopyHttpHeaders(client, command.GetHttpHeaders());
-
+    
     std::string answer;
     Orthanc::HttpClient::HttpHeaders answerHeaders;
     client.ApplyAndThrowException(answer, answerHeaders);

--- a/Framework/Oracle/ThreadedOracle.h	Wed May 29 13:44:55 2019 +0200
+++ b/Framework/Oracle/ThreadedOracle.h	Wed May 29 16:15:04 2019 +0200
@@ -74,6 +74,7 @@
 
     virtual ~ThreadedOracle();
 
+    // The reference is not stored.
     void SetOrthancParameters(const Orthanc::WebServiceParameters& orthanc);
 
     void SetThreadsCount(unsigned int count);

--- a/Samples/Sdl/FusionMprSdl.cpp	Wed May 29 13:44:55 2019 +0200
+++ b/Samples/Sdl/FusionMprSdl.cpp	Wed May 29 16:15:04 2019 +0200
@@ -24,8 +24,6 @@
 
 #include "../../Framework/StoneInitialization.h"
 
-#include "../../Framework/Messages/IMessageEmitter.h"
-
 #include "../../Framework/Scene2D/CairoCompositor.h"
 #include "../../Framework/Scene2D/ColorTextureSceneLayer.h"
 #include "../../Framework/Scene2D/OpenGLCompositor.h"
@@ -50,7 +48,6 @@
 #include <boost/shared_ptr.hpp>
 #include <boost/weak_ptr.hpp>
 #include <boost/make_shared.hpp>
-#include <boost/thread.hpp>
 
 #include <stdio.h>
 #include "../../Framework/Oracle/GetOrthancWebViewerJpegCommand.h"
@@ -65,76 +62,6 @@
 
 namespace OrthancStone
 {
-
-  class NativeApplicationContext : public IMessageEmitter
-  {
-  private:
-    boost::shared_mutex  mutex_;
-    MessageBroker        broker_;
-    IObservable          oracleObservable_;
-
-  public:
-    NativeApplicationContext() :
-      oracleObservable_(broker_)
-    {
-    }
-
-
-    virtual void EmitMessage(const IObserver& observer,
-      const IMessage& message) ORTHANC_OVERRIDE
-    {
-      try
-      {
-        boost::unique_lock<boost::shared_mutex>  lock(mutex_);
-        oracleObservable_.EmitMessage(observer, message);
-      }
-      catch (Orthanc::OrthancException& e)
-      {
-        LOG(ERROR) << "Exception while emitting a message: " << e.What();
-      }
-    }
-
-
-    class ReaderLock : public boost::noncopyable
-    {
-    private:
-      NativeApplicationContext& that_;
-      boost::shared_lock<boost::shared_mutex>  lock_;
-
-    public:
-      ReaderLock(NativeApplicationContext& that) :
-        that_(that),
-        lock_(that.mutex_)
-      {
-      }
-    };
-
-
-    class WriterLock : public boost::noncopyable
-    {
-    private:
-      NativeApplicationContext& that_;
-      boost::unique_lock<boost::shared_mutex>  lock_;
-
-    public:
-      WriterLock(NativeApplicationContext& that) :
-        that_(that),
-        lock_(that.mutex_)
-      {
-      }
-
-      MessageBroker& GetBroker()
-      {
-        return that_.broker_;
-      }
-
-      IObservable& GetOracleObservable()
-      {
-        return that_.oracleObservable_;
-      }
-    };
-  };
-
   const char* FusionMprMeasureToolToString(size_t i)
   {
     static const char* descs[] = {
@@ -474,10 +401,31 @@
   }
 
 
-  FusionMprSdlApp::FusionMprSdlApp(MessageBroker& broker) : IObserver(broker)
+  FusionMprSdlApp::FusionMprSdlApp(MessageBroker& broker)
+    : IObserver(broker)
+    , broker_(broker)
+    , oracleObservable_(broker)
+    , oracle_(*this)
     , currentTool_(FusionMprGuiTool_Rotate)
   {
-    controller_ = boost::shared_ptr<ViewportController>(new ViewportController(broker));
+    //oracleObservable.RegisterObserverCallback
+    //(new Callable
+    //  <FusionMprSdlApp, SleepOracleCommand::TimeoutMessage>(*this, &FusionMprSdlApp::Handle));
+
+    //oracleObservable.RegisterObserverCallback
+    //(new Callable
+    //  <Toto, GetOrthancImageCommand::SuccessMessage>(*this, &FusionMprSdlApp::Handle));
+
+    //oracleObservable.RegisterObserverCallback
+    //(new Callable
+    //  <FusionMprSdlApp, GetOrthancWebViewerJpegCommand::SuccessMessage>(*this, &ToFusionMprSdlAppto::Handle));
+
+    oracleObservable_.RegisterObserverCallback
+    (new Callable
+      <FusionMprSdlApp, OracleCommandExceptionMessage>(*this, &FusionMprSdlApp::Handle));
+    
+    controller_ = boost::shared_ptr<ViewportController>(
+      new ViewportController(broker_));
 
     controller_->RegisterObserverCallback(
       new Callable<FusionMprSdlApp, ViewportController::SceneTransformChanged>
@@ -653,18 +601,11 @@
 
 
     //////// from loader
-
-        // from main
-    NativeApplicationContext context;
-    ThreadedOracle oracle(context);
-
-
-
     {
       Orthanc::WebServiceParameters p;
       //p.SetUrl("http://localhost:8043/");
       p.SetCredentials("orthanc", "orthanc");
-      oracle.SetOrthancParameters(p);
+      oracle_.SetOrthancParameters(p);
     }
 
     //////// from Run
@@ -678,38 +619,16 @@
     boost::shared_ptr<DicomStructureSetLoader>  rtstructLoader;
 
     {
-      NativeApplicationContext::WriterLock lock(context);
-      //toto.reset(new Toto(oracle, lock.GetOracleObservable()));
-      oracle_ = &oracle;
-      IObservable* oracleObservable = &lock.GetOracleObservable();
-
-
-      //oracleObservable->RegisterObserverCallback
-      //(new Callable
-      //  <FusionMprSdlApp, SleepOracleCommand::TimeoutMessage>(*this, &FusionMprSdlApp::Handle));
-
-
-      //oracleObservable->RegisterObserverCallback
-      //(new Callable
-      //  <Toto, GetOrthancImageCommand::SuccessMessage>(*this, &FusionMprSdlApp::Handle));
-
-      //oracleObservable->RegisterObserverCallback
-      //(new Callable
-      //  <FusionMprSdlApp, GetOrthancWebViewerJpegCommand::SuccessMessage>(*this, &ToFusionMprSdlAppto::Handle));
-
-      oracleObservable->RegisterObserverCallback
-      (new Callable
-        <FusionMprSdlApp, OracleCommandExceptionMessage>(*this, &FusionMprSdlApp::Handle));
-      
-
-      ctLoader.reset(new OrthancSeriesVolumeProgressiveLoader(ct, oracle, lock.GetOracleObservable()));
-      doseLoader.reset(new OrthancMultiframeVolumeLoader(dose, oracle, lock.GetOracleObservable()));
-      rtstructLoader.reset(new DicomStructureSetLoader(oracle, lock.GetOracleObservable()));
+      ctLoader.reset(new OrthancSeriesVolumeProgressiveLoader(ct, oracle_, oracleObservable_));
+      doseLoader.reset(new OrthancMultiframeVolumeLoader(dose, oracle_, oracleObservable_));
+      rtstructLoader.reset(new DicomStructureSetLoader(oracle_, oracleObservable_));
     }
 
-
     //toto->SetReferenceLoader(*ctLoader);
-    doseLoader->RegisterObserverCallback
+    //doseLoader->RegisterObserverCallback
+    //(new Callable
+    //  <FusionMprSdlApp, DicomVolumeImage::GeometryReadyMessage>(*this, &FusionMprSdlApp::Handle));
+    ctLoader->RegisterObserverCallback
     (new Callable
       <FusionMprSdlApp, DicomVolumeImage::GeometryReadyMessage>(*this, &FusionMprSdlApp::Handle));
 
@@ -725,10 +644,10 @@
 
     this->SetStructureSet(2, rtstructLoader);
 
-#if 0
+#if 1
     // BGO data
     ctLoader->LoadSeries("a04ecf01-79b2fc33-58239f7e-ad9db983-28e81afa");  // CT
-    doseLoader->LoadInstance("830a69ff-8e4b5ee3-b7f966c8-bccc20fb-d322dceb");  // RT-DOSE
+    //doseLoader->LoadInstance("830a69ff-8e4b5ee3-b7f966c8-bccc20fb-d322dceb");  // RT-DOSE
     //rtstructLoader->LoadInstance("54460695-ba3885ee-ddf61ac0-f028e31d-a6e474d9");  // RT-STRUCT
 #else
     //ctLoader->LoadSeries("cb3ea4d1-d08f3856-ad7b6314-74d88d77-60b05618");  // CT
@@ -741,7 +660,7 @@
     rtstructLoader->LoadInstance("54460695-ba3885ee-ddf61ac0-f028e31d-a6e474d9");  // RT-STRUCT
 #endif
 
-    oracle.Start();
+    oracle_.Start();
 
 //// END from loader
 
@@ -818,7 +737,7 @@
      * as in (*).
      **/
 
-    oracle.Stop();
+    oracle_.Stop();
     //// END from loader
   }
 
@@ -861,7 +780,7 @@
 
   try
   {
-    MessageBroker broker;
+    OrthancStone::MessageBroker broker;
     boost::shared_ptr<FusionMprSdlApp> app(new FusionMprSdlApp(broker));
     g_app = app;
     app->PrepareScene();

--- a/Samples/Sdl/FusionMprSdl.h	Wed May 29 13:44:55 2019 +0200
+++ b/Samples/Sdl/FusionMprSdl.h	Wed May 29 16:15:04 2019 +0200
@@ -19,12 +19,17 @@
  **/
 
 #include "../../Framework/Messages/IObserver.h"
+#include "../../Framework/Messages/IMessageEmitter.h"
+#include "../../Framework/Oracle/OracleCommandExceptionMessage.h"
 #include "../../Framework/Scene2DViewport/ViewportController.h"
+#include "../../Framework/Volumes/DicomVolumeImage.h"
+#include "../../Framework/Oracle/ThreadedOracle.h"
 
 #include <boost/enable_shared_from_this.hpp>
+#include <boost/thread.hpp>
+#include <boost/noncopyable.hpp>
+
 #include <SDL.h>
-#include "../../Framework/Volumes/DicomVolumeImage.h"
-#include "../../Framework/Oracle/OracleCommandExceptionMessage.h"
 
 namespace OrthancStone
 {
@@ -33,8 +38,11 @@
   class ILayerStyleConfigurator;
   class DicomStructureSetLoader;
   class IOracle;
+  class ThreadedOracle;
   class VolumeSceneLayerSource;
+  class NativeFusionMprApplicationContext;
 
+   
   enum FusionMprGuiTool
   {
     FusionMprGuiTool_Rotate = 0,
@@ -54,12 +62,18 @@
 
   class Scene2D;
 
+  /**
+  This application subclasses IMessageEmitter to use a mutex before forwarding Oracle messages (that
+  can be sent from multiple threads)
+  */
   class FusionMprSdlApp : public IObserver
     , public boost::enable_shared_from_this<FusionMprSdlApp>
+    , public IMessageEmitter
   {
   public:
     // 12 because.
     FusionMprSdlApp(MessageBroker& broker);
+
     void PrepareScene();
     void Run();
     void SetInfoDisplayMessage(std::string key, std::string value);
@@ -77,7 +91,31 @@
     void OnSceneTransformChanged(
       const ViewportController::SceneTransformChanged& message);
 
+
+    virtual void EmitMessage(const IObserver& observer,
+      const IMessage& message) ORTHANC_OVERRIDE
+    {
+      try
+      {
+        boost::unique_lock<boost::shared_mutex>  lock(mutex_);
+        oracleObservable_.EmitMessage(observer, message);
+      }
+      catch (Orthanc::OrthancException& e)
+      {
+        LOG(ERROR) << "Exception while emitting a message: " << e.What();
+        throw;
+      }
+    }
+    
   private:
+#if 1
+    // if threaded (not wasm)
+    MessageBroker& broker_;
+    IObservable oracleObservable_;
+    ThreadedOracle oracle_;
+    boost::shared_mutex mutex_; // to serialize messages from the ThreadedOracle
+#endif
+
     void SelectNextTool();
 
     /**
@@ -132,7 +170,7 @@
 
   private:
     CoordinateSystem3D  plane_;
-    IOracle* oracle_ = nullptr;
+
     boost::shared_ptr<VolumeSceneLayerSource>  source1_, source2_, source3_;
 
     std::auto_ptr<OpenGLCompositor> compositor_;

--- a/Samples/Sdl/Loader.cpp	Wed May 29 13:44:55 2019 +0200
+++ b/Samples/Sdl/Loader.cpp	Wed May 29 16:15:04 2019 +0200
@@ -166,9 +166,9 @@
   {
     printf("Geometry ready\n");
     
-    //plane_ = message.GetOrigin().GetGeometry().GetSagittalGeometry();
+    plane_ = message.GetOrigin().GetGeometry().GetSagittalGeometry();
     //plane_ = message.GetOrigin().GetGeometry().GetAxialGeometry();
-    plane_ = message.GetOrigin().GetGeometry().GetCoronalGeometry();
+    //plane_ = message.GetOrigin().GetGeometry().GetCoronalGeometry();
     plane_.SetOrigin(message.GetOrigin().GetGeometry().GetCoordinates(0.5f, 0.5f, 0.5f));
 
     Refresh();
@@ -302,6 +302,8 @@
 void Run(OrthancStone::NativeApplicationContext& context,
          OrthancStone::ThreadedOracle& oracle)
 {
+  // the oracle has been supplied with the context (as an IEmitter) upon
+  // creation
   boost::shared_ptr<OrthancStone::DicomVolumeImage>  ct(new OrthancStone::DicomVolumeImage);
   boost::shared_ptr<OrthancStone::DicomVolumeImage>  dose(new OrthancStone::DicomVolumeImage);
 
@@ -314,6 +316,11 @@
   {
     OrthancStone::NativeApplicationContext::WriterLock lock(context);
     toto.reset(new Toto(oracle, lock.GetOracleObservable()));
+
+    // the oracle is used to schedule commands
+    // the oracleObservable is used by the loaders to:
+    // - request the broker (lifetime mgmt)
+    // - register the loader callbacks (called indirectly by the oracle)
     ctLoader.reset(new OrthancStone::OrthancSeriesVolumeProgressiveLoader(ct, oracle, lock.GetOracleObservable()));
     doseLoader.reset(new OrthancStone::OrthancMultiframeVolumeLoader(dose, oracle, lock.GetOracleObservable()));
     rtstructLoader.reset(new OrthancStone::DicomStructureSetLoader(oracle, lock.GetOracleObservable()));

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Samples/WebAssembly/BasicMPR.cpp	Wed May 29 16:15:04 2019 +0200
@@ -0,0 +1,880 @@
+/**
+ * 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 <emscripten.h>
+#include <emscripten/fetch.h>
+#include <emscripten/html5.h>
+
+#include "../../Framework/Loaders/OrthancSeriesVolumeProgressiveLoader.h"
+#include "../../Framework/OpenGL/WebAssemblyOpenGLContext.h"
+#include "../../Framework/Scene2D/GrayscaleStyleConfigurator.h"
+#include "../../Framework/Scene2D/OpenGLCompositor.h"
+#include "../../Framework/Scene2D/PanSceneTracker.h"
+#include "../../Framework/Scene2D/RotateSceneTracker.h"
+#include "../../Framework/Scene2D/ZoomSceneTracker.h"
+#include "../../Framework/Scene2DViewport/IFlexiblePointerTracker.h"
+#include "../../Framework/Scene2DViewport/ViewportController.h"
+#include "../../Framework/StoneInitialization.h"
+#include "../../Framework/Volumes/VolumeSceneLayerSource.h"
+
+#include <Core/OrthancException.h>
+#include <Core/Toolbox.h>
+
+
+static const unsigned int FONT_SIZE = 32;
+
+
+namespace OrthancStone
+{
+  class WebAssemblyViewport : public boost::noncopyable
+  {
+  private:
+    // the construction order is important because compositor_
+    // will hold a reference to the scene that belong to the 
+    // controller_ object
+    OpenGL::WebAssemblyOpenGLContext       context_;
+    boost::shared_ptr<ViewportController>  controller_;
+    OpenGLCompositor                       compositor_;
+
+    void SetupEvents(const std::string& canvas);
+
+  public:
+    WebAssemblyViewport(MessageBroker& broker,
+                        const std::string& canvas) :
+      context_(canvas),
+      controller_(new ViewportController(broker)),
+      compositor_(context_, *controller_->GetScene())
+    {
+      compositor_.SetFont(0, Orthanc::EmbeddedResources::UBUNTU_FONT, 
+                          FONT_SIZE, Orthanc::Encoding_Latin1);
+      SetupEvents(canvas);
+    }
+
+    Scene2D& GetScene()
+    {
+      return *controller_->GetScene();
+    }
+
+    const boost::shared_ptr<ViewportController>& GetController()
+    {
+      return controller_;
+    }
+
+    void UpdateSize()
+    {
+      context_.UpdateSize();
+      compositor_.UpdateSize();
+      Refresh();
+    }
+
+    void Refresh()
+    {
+      compositor_.Refresh();
+    }
+
+    const std::string& GetCanvasIdentifier() const
+    {
+      return context_.GetCanvasIdentifier();
+    }
+
+    ScenePoint2D GetPixelCenterCoordinates(int x, int y) const
+    {
+      return compositor_.GetPixelCenterCoordinates(x, y);
+    }
+
+    unsigned int GetCanvasWidth() const
+    {
+      return context_.GetCanvasWidth();
+    }
+
+    unsigned int GetCanvasHeight() const
+    {
+      return context_.GetCanvasHeight();
+    }
+  };
+
+  class ActiveTracker : public boost::noncopyable
+  {
+  private:
+    boost::shared_ptr<IFlexiblePointerTracker> tracker_;
+    std::string                             canvasIdentifier_;
+    bool                                    insideCanvas_;
+    
+  public:
+    ActiveTracker(const boost::shared_ptr<IFlexiblePointerTracker>& tracker,
+                  const WebAssemblyViewport& viewport) :
+      tracker_(tracker),
+      canvasIdentifier_(viewport.GetCanvasIdentifier()),
+      insideCanvas_(true)
+    {
+      if (tracker_.get() == NULL)
+      {
+        throw Orthanc::OrthancException(Orthanc::ErrorCode_NullPointer);
+      }
+    }
+
+    bool IsAlive() const
+    {
+      return tracker_->IsAlive();
+    }
+
+    void PointerMove(const PointerEvent& event)
+    {
+      tracker_->PointerMove(event);
+    }
+
+    void PointerUp(const PointerEvent& event)
+    {
+      tracker_->PointerUp(event);
+    }
+  };
+}
+
+static OrthancStone::PointerEvent* ConvertMouseEvent(
+  const EmscriptenMouseEvent&        source,
+  OrthancStone::WebAssemblyViewport& viewport)
+{
+  std::auto_ptr<OrthancStone::PointerEvent> target(
+    new OrthancStone::PointerEvent);
+
+  target->AddPosition(viewport.GetPixelCenterCoordinates(
+    source.targetX, source.targetY));
+  target->SetAltModifier(source.altKey);
+  target->SetControlModifier(source.ctrlKey);
+  target->SetShiftModifier(source.shiftKey);
+
+  return target.release();
+}
+
+std::auto_ptr<OrthancStone::ActiveTracker> tracker_;
+
+EM_BOOL OnMouseEvent(int eventType, 
+                     const EmscriptenMouseEvent *mouseEvent, 
+                     void *userData)
+{
+  if (mouseEvent != NULL &&
+      userData != NULL)
+  {
+    OrthancStone::WebAssemblyViewport& viewport = 
+      *reinterpret_cast<OrthancStone::WebAssemblyViewport*>(userData);
+
+    switch (eventType)
+    {
+      case EMSCRIPTEN_EVENT_CLICK:
+      {
+        static unsigned int count = 0;
+        char buf[64];
+        sprintf(buf, "click %d", count++);
+
+        std::auto_ptr<OrthancStone::TextSceneLayer> layer(new OrthancStone::TextSceneLayer);
+        layer->SetText(buf);
+        viewport.GetScene().SetLayer(100, layer.release());
+        viewport.Refresh();
+        break;
+      }
+
+      case EMSCRIPTEN_EVENT_MOUSEDOWN:
+      {
+        boost::shared_ptr<OrthancStone::IFlexiblePointerTracker> t;
+
+        {
+          std::auto_ptr<OrthancStone::PointerEvent> event(
+            ConvertMouseEvent(*mouseEvent, viewport));
+
+          switch (mouseEvent->button)
+          {
+            case 0:  // Left button
+              emscripten_console_log("Creating RotateSceneTracker");
+              t.reset(new OrthancStone::RotateSceneTracker(
+                viewport.GetController(), *event));
+              break;
+
+            case 1:  // Middle button
+              emscripten_console_log("Creating PanSceneTracker");
+              LOG(INFO) << "Creating PanSceneTracker" ;
+              t.reset(new OrthancStone::PanSceneTracker(
+                viewport.GetController(), *event));
+              break;
+
+            case 2:  // Right button
+              emscripten_console_log("Creating ZoomSceneTracker");
+              t.reset(new OrthancStone::ZoomSceneTracker(
+                viewport.GetController(), *event, viewport.GetCanvasWidth()));
+              break;
+
+            default:
+              break;
+          }
+        }
+
+        if (t.get() != NULL)
+        {
+          tracker_.reset(
+            new OrthancStone::ActiveTracker(t, viewport));
+          viewport.Refresh();
+        }
+
+        break;
+      }
+
+      case EMSCRIPTEN_EVENT_MOUSEMOVE:
+        if (tracker_.get() != NULL)
+        {
+          std::auto_ptr<OrthancStone::PointerEvent> event(
+            ConvertMouseEvent(*mouseEvent, viewport));
+          tracker_->PointerMove(*event);
+          viewport.Refresh();
+        }
+        break;
+
+      case EMSCRIPTEN_EVENT_MOUSEUP:
+        if (tracker_.get() != NULL)
+        {
+          std::auto_ptr<OrthancStone::PointerEvent> event(
+            ConvertMouseEvent(*mouseEvent, viewport));
+          tracker_->PointerUp(*event);
+          viewport.Refresh();
+          if (!tracker_->IsAlive())
+            tracker_.reset();
+        }
+        break;
+
+      default:
+        break;
+    }
+  }
+
+  return true;
+}
+
+
+void OrthancStone::WebAssemblyViewport::SetupEvents(const std::string& canvas)
+{
+  emscripten_set_mousedown_callback(canvas.c_str(), this, false, OnMouseEvent);
+  emscripten_set_mousemove_callback(canvas.c_str(), this, false, OnMouseEvent);
+  emscripten_set_mouseup_callback(canvas.c_str(), this, false, OnMouseEvent);
+}
+
+
+
+
+namespace OrthancStone
+{
+  class VolumeSlicerViewport : public IObserver
+  {
+  private:
+    OrthancStone::WebAssemblyViewport      viewport_;
+    std::auto_ptr<VolumeSceneLayerSource>  source_;
+    VolumeProjection                       projection_;
+    std::vector<CoordinateSystem3D>        planes_;
+    size_t                                 currentPlane_;
+
+    void Handle(const DicomVolumeImage::GeometryReadyMessage& message)
+    {
+      LOG(INFO) << "Geometry is available";
+
+      const VolumeImageGeometry& geometry = message.GetOrigin().GetGeometry();
+
+      const unsigned int depth = geometry.GetProjectionDepth(projection_);
+      currentPlane_ = depth / 2;
+      
+      planes_.resize(depth);
+
+      for (unsigned int z = 0; z < depth; z++)
+      {
+        planes_[z] = geometry.GetProjectionSlice(projection_, z);
+      }
+    }
+    
+  public:
+    VolumeSlicerViewport(MessageBroker& broker,
+                         const std::string& canvas,
+                         VolumeProjection projection) :
+      IObserver(broker),
+      viewport_(broker, canvas),
+      projection_(projection),
+      currentPlane_(0)
+    {
+    }
+
+    void UpdateSize()
+    {
+      viewport_.UpdateSize();
+    }
+
+    void SetSlicer(int layerDepth,
+                   const boost::shared_ptr<IVolumeSlicer>& slicer,
+                   IObservable& loader,
+                   ILayerStyleConfigurator* configurator)
+    {
+      if (source_.get() != NULL)
+      {
+        throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls,
+                                        "Only one slicer can be registered");
+      }
+      
+      loader.RegisterObserverCallback(
+        new Callable<VolumeSlicerViewport, DicomVolumeImage::GeometryReadyMessage>
+        (*this, &VolumeSlicerViewport::Handle));
+
+      source_.reset(new VolumeSceneLayerSource(viewport_.GetScene(), layerDepth, slicer));
+
+      if (configurator != NULL)
+      {
+        source_->SetConfigurator(configurator);
+      }
+    }    
+
+    void Refresh()
+    {
+      if (source_.get() != NULL &&
+          currentPlane_ < planes_.size())
+      {
+        source_->Update(planes_[currentPlane_]);
+      }
+    }
+  };
+
+
+
+
+  class WebAssemblyOracle :
+    public IOracle,
+    public IObservable
+  {
+  private:
+    typedef std::map<std::string, std::string>  HttpHeaders;
+    
+    class FetchContext : public boost::noncopyable
+    {
+    private:
+      class Emitter : public IMessageEmitter
+      {
+      private:
+        WebAssemblyOracle&  oracle_;
+
+      public:
+        Emitter(WebAssemblyOracle&  oracle) :
+          oracle_(oracle)
+        {
+        }
+
+        virtual void EmitMessage(const IObserver& receiver,
+                                 const IMessage& message)
+        {
+          oracle_.EmitMessage(receiver, message);
+        }
+      };
+
+      Emitter                        emitter_;
+      const IObserver&               receiver_;
+      std::auto_ptr<IOracleCommand>  command_;
+      std::string                    expectedContentType_;
+
+    public:
+      FetchContext(WebAssemblyOracle& oracle,
+                   const IObserver& receiver,
+                   IOracleCommand* command,
+                   const std::string& expectedContentType) :
+        emitter_(oracle),
+        receiver_(receiver),
+        command_(command),
+        expectedContentType_(expectedContentType)
+      {
+        if (command == NULL)
+        {
+          throw Orthanc::OrthancException(Orthanc::ErrorCode_NullPointer);
+        }
+      }
+
+      const std::string& GetExpectedContentType() const
+      {
+        return expectedContentType_;
+      }
+
+      void EmitMessage(const IMessage& message)
+      {
+        emitter_.EmitMessage(receiver_, message);
+      }
+
+      IMessageEmitter& GetEmitter()
+      {
+        return emitter_;
+      }
+
+      const IObserver& GetReceiver() const
+      {
+        return receiver_;
+      }
+
+      IOracleCommand& GetCommand() const
+      {
+        return *command_;
+      }
+
+      template <typename T>
+      const T& GetTypedCommand() const
+      {
+        return dynamic_cast<T&>(*command_);
+      }
+    };
+    
+    static void FetchSucceeded(emscripten_fetch_t *fetch)
+    {
+      /**
+       * Firstly, make a local copy of the fetched information, and
+       * free data associated with the fetch.
+       **/
+      
+      std::auto_ptr<FetchContext> context(reinterpret_cast<FetchContext*>(fetch->userData));
+
+      std::string answer;
+      if (fetch->numBytes > 0)
+      {
+        answer.assign(fetch->data, fetch->numBytes);
+      }
+
+      /**
+       * TODO - HACK - As of emscripten-1.38.31, the fetch API does
+       * not contain a way to retrieve the HTTP headers of the
+       * answer. We make the assumption that the "Content-Type" header
+       * of the response is the same as the "Accept" header of the
+       * query. This should be fixed in future versions of emscripten.
+       * https://github.com/emscripten-core/emscripten/pull/8486
+       **/
+
+      HttpHeaders headers;
+      if (!context->GetExpectedContentType().empty())
+      {
+        headers["Content-Type"] = context->GetExpectedContentType();
+      }
+      
+      
+      emscripten_fetch_close(fetch);
+
+
+      /**
+       * Secondly, use the retrieved data.
+       **/
+
+      try
+      {
+        if (context.get() == NULL)
+        {
+          throw Orthanc::OrthancException(Orthanc::ErrorCode_NullPointer);
+        }
+        else
+        {
+          switch (context->GetCommand().GetType())
+          {
+            case IOracleCommand::Type_OrthancRestApi:
+            {
+              OrthancRestApiCommand::SuccessMessage message
+                (context->GetTypedCommand<OrthancRestApiCommand>(), headers, answer);
+              context->EmitMessage(message);
+              break;
+            }
+            
+            case IOracleCommand::Type_GetOrthancImage:
+            {
+              context->GetTypedCommand<GetOrthancImageCommand>().ProcessHttpAnswer
+                (context->GetEmitter(), context->GetReceiver(), answer, headers);
+              break;
+            }
+          
+            case IOracleCommand::Type_GetOrthancWebViewerJpeg:
+            {
+              context->GetTypedCommand<GetOrthancWebViewerJpegCommand>().ProcessHttpAnswer
+                (context->GetEmitter(), context->GetReceiver(), answer);
+              break;
+            }
+          
+            default:
+              LOG(ERROR) << "Command type not implemented by the WebAssembly Oracle: "
+                         << context->GetCommand().GetType();
+          }
+        }
+      }
+      catch (Orthanc::OrthancException& e)
+      {
+        LOG(ERROR) << "Error while processing a fetch answer in the oracle: " << e.What();
+      }
+    }
+
+    static void FetchFailed(emscripten_fetch_t *fetch)
+    {
+      std::auto_ptr<FetchContext> context(reinterpret_cast<FetchContext*>(fetch->userData));
+      
+      LOG(ERROR) << "Fetching " << fetch->url << " failed, HTTP failure status code: " << fetch->status;
+
+      /**
+       * TODO - The following code leads to an infinite recursion, at
+       * least with Firefox running on incognito mode => WHY?
+       **/      
+      //emscripten_fetch_close(fetch); // Also free data on failure.
+    }
+
+
+    class FetchCommand : public boost::noncopyable
+    {
+    private:
+      WebAssemblyOracle&             oracle_;
+      const IObserver&               receiver_;
+      std::auto_ptr<IOracleCommand>  command_;
+      Orthanc::HttpMethod            method_;
+      std::string                    uri_;
+      std::string                    body_;
+      HttpHeaders                    headers_;
+      unsigned int                   timeout_;
+      std::string                    expectedContentType_;
+
+    public:
+      FetchCommand(WebAssemblyOracle& oracle,
+                   const IObserver& receiver,
+                   IOracleCommand* command) :
+        oracle_(oracle),
+        receiver_(receiver),
+        command_(command),
+        method_(Orthanc::HttpMethod_Get),
+        timeout_(0)
+      {
+        if (command == NULL)
+        {
+          throw Orthanc::OrthancException(Orthanc::ErrorCode_NullPointer);
+        }
+      }
+
+      void SetMethod(Orthanc::HttpMethod method)
+      {
+        method_ = method;
+      }
+
+      void SetUri(const std::string& uri)
+      {
+        uri_ = uri;
+      }
+
+      void SetBody(std::string& body /* will be swapped */)
+      {
+        body_.swap(body);
+      }
+
+      void SetHttpHeaders(const HttpHeaders& headers)
+      {
+        headers_ = headers;
+      }
+
+      void SetTimeout(unsigned int timeout)
+      {
+        timeout_ = timeout;
+      }
+
+      void Execute()
+      {
+        if (command_.get() == NULL)
+        {
+          // Cannot call Execute() twice
+          throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls);          
+        }
+
+        emscripten_fetch_attr_t attr;
+        emscripten_fetch_attr_init(&attr);
+
+        const char* method;
+      
+        switch (method_)
+        {
+          case Orthanc::HttpMethod_Get:
+            method = "GET";
+            break;
+
+          case Orthanc::HttpMethod_Post:
+            method = "POST";
+            break;
+
+          case Orthanc::HttpMethod_Delete:
+            method = "DELETE";
+            break;
+
+          case Orthanc::HttpMethod_Put:
+            method = "PUT";
+            break;
+
+          default:
+            throw Orthanc::OrthancException(Orthanc::ErrorCode_NotImplemented);
+        }
+
+        strcpy(attr.requestMethod, method);
+
+        attr.attributes = EMSCRIPTEN_FETCH_LOAD_TO_MEMORY;
+        attr.onsuccess = FetchSucceeded;
+        attr.onerror = FetchFailed;
+        attr.timeoutMSecs = timeout_ * 1000;
+
+        std::vector<const char*> headers;
+        headers.reserve(2 * headers_.size() + 1);
+
+        std::string expectedContentType;
+        
+        for (HttpHeaders::const_iterator it = headers_.begin(); it != headers_.end(); ++it)
+        {
+          std::string key;
+          Orthanc::Toolbox::ToLowerCase(key, it->first);
+          
+          if (key == "accept")
+          {
+            expectedContentType = it->second;
+          }
+
+          if (key != "accept-encoding")  // Web browsers forbid the modification of this HTTP header
+          {
+            headers.push_back(it->first.c_str());
+            headers.push_back(it->second.c_str());
+          }
+        }
+        
+        headers.push_back(NULL);  // Termination of the array of HTTP headers
+
+        attr.requestHeaders = &headers[0];
+
+        if (!body_.empty())
+        {
+          attr.requestDataSize = body_.size();
+          attr.requestData = body_.c_str();
+        }
+
+        // Must be the last call to prevent memory leak on error
+        attr.userData = new FetchContext(oracle_, receiver_, command_.release(), expectedContentType);
+        emscripten_fetch(&attr, uri_.c_str());
+      }        
+    };
+    
+    
+    void Execute(const IObserver& receiver,
+                 OrthancRestApiCommand* command)
+    {
+      FetchCommand fetch(*this, receiver, command);
+
+      fetch.SetMethod(command->GetMethod());
+      fetch.SetUri(command->GetUri());
+      fetch.SetHttpHeaders(command->GetHttpHeaders());
+      fetch.SetTimeout(command->GetTimeout());
+      
+      if (command->GetMethod() == Orthanc::HttpMethod_Put ||
+          command->GetMethod() == Orthanc::HttpMethod_Put)
+      {
+        std::string body;
+        command->SwapBody(body);
+        fetch.SetBody(body);
+      }
+      
+      fetch.Execute();
+    }
+    
+    
+    void Execute(const IObserver& receiver,
+                 GetOrthancImageCommand* command)
+    {
+      FetchCommand fetch(*this, receiver, command);
+
+      fetch.SetUri(command->GetUri());
+      fetch.SetHttpHeaders(command->GetHttpHeaders());
+      fetch.SetTimeout(command->GetTimeout());
+      
+      fetch.Execute();
+    }
+    
+    
+    void Execute(const IObserver& receiver,
+                 GetOrthancWebViewerJpegCommand* command)
+    {
+      FetchCommand fetch(*this, receiver, command);
+
+      fetch.SetUri(command->GetUri());
+      fetch.SetHttpHeaders(command->GetHttpHeaders());
+      fetch.SetTimeout(command->GetTimeout());
+      
+      fetch.Execute();
+    }
+
+    
+  public:
+    WebAssemblyOracle(MessageBroker& broker) :
+      IObservable(broker)
+    {
+    }
+    
+    virtual void Schedule(const IObserver& receiver,
+                          IOracleCommand* command)
+    {
+      std::auto_ptr<IOracleCommand> protection(command);
+
+      if (command == NULL)
+      {
+        throw Orthanc::OrthancException(Orthanc::ErrorCode_NullPointer);
+      }
+
+      switch (command->GetType())
+      {
+        case IOracleCommand::Type_OrthancRestApi:
+          Execute(receiver, dynamic_cast<OrthancRestApiCommand*>(protection.release()));
+          break;
+        
+        case IOracleCommand::Type_GetOrthancImage:
+          Execute(receiver, dynamic_cast<GetOrthancImageCommand*>(protection.release()));
+          break;
+
+        case IOracleCommand::Type_GetOrthancWebViewerJpeg:
+          Execute(receiver, dynamic_cast<GetOrthancWebViewerJpegCommand*>(protection.release()));
+          break;          
+            
+        default:
+          LOG(ERROR) << "Command type not implemented by the WebAssembly Oracle: " << command->GetType();
+      }
+    }
+
+    virtual void Start()
+    {
+    }
+
+    virtual void Stop()
+    {
+    }
+  };
+}
+
+
+
+
+boost::shared_ptr<OrthancStone::DicomVolumeImage>  ct_(new OrthancStone::DicomVolumeImage);
+
+boost::shared_ptr<OrthancStone::OrthancSeriesVolumeProgressiveLoader>  loader_;
+
+std::auto_ptr<OrthancStone::VolumeSlicerViewport>  viewport1_;
+std::auto_ptr<OrthancStone::VolumeSlicerViewport>  viewport2_;
+std::auto_ptr<OrthancStone::VolumeSlicerViewport>  viewport3_;
+
+OrthancStone::MessageBroker  broker_;
+OrthancStone::WebAssemblyOracle  oracle_(broker_);
+
+
+EM_BOOL OnWindowResize(int eventType, const EmscriptenUiEvent *uiEvent, void *userData)
+{
+  try
+  {
+    if (viewport1_.get() != NULL)
+    {
+      viewport1_->UpdateSize();
+    }
+  
+    if (viewport2_.get() != NULL)
+    {
+      viewport2_->UpdateSize();
+    }
+  
+    if (viewport3_.get() != NULL)
+    {
+      viewport3_->UpdateSize();
+    }
+  }
+  catch (Orthanc::OrthancException& e)
+  {
+    LOG(ERROR) << "Exception while updating canvas size: " << e.What();
+  }
+  
+  return true;
+}
+
+
+
+
+EM_BOOL OnAnimationFrame(double time, void *userData)
+{
+  try
+  {
+    if (viewport1_.get() != NULL)
+    {
+      viewport1_->Refresh();
+    }
+  
+    if (viewport2_.get() != NULL)
+    {
+      viewport2_->Refresh();
+    }
+  
+    if (viewport3_.get() != NULL)
+    {
+      viewport3_->Refresh();
+    }
+
+    return true;
+  }
+  catch (Orthanc::OrthancException& e)
+  {
+    LOG(ERROR) << "Exception in the animation loop, stopping now: " << e.What();
+    return false;
+  }  
+}
+
+
+extern "C"
+{
+  int main(int argc, char const *argv[]) 
+  {
+    OrthancStone::StoneInitialize();
+    Orthanc::Logging::EnableInfoLevel(true);
+    // Orthanc::Logging::EnableTraceLevel(true);
+    EM_ASM(window.dispatchEvent(new CustomEvent("WebAssemblyLoaded")););
+  }
+
+  EMSCRIPTEN_KEEPALIVE
+  void Initialize()
+  {
+    try
+    {
+      loader_.reset(new OrthancStone::OrthancSeriesVolumeProgressiveLoader(ct_, oracle_, oracle_));
+    
+      viewport1_.reset(new OrthancStone::VolumeSlicerViewport(broker_, "mycanvas1", OrthancStone::VolumeProjection_Axial));
+      viewport1_->SetSlicer(0, loader_, *loader_, new OrthancStone::GrayscaleStyleConfigurator);
+      viewport1_->UpdateSize();
+
+      viewport2_.reset(new OrthancStone::VolumeSlicerViewport(broker_, "mycanvas2", OrthancStone::VolumeProjection_Coronal));
+      viewport2_->SetSlicer(0, loader_, *loader_, new OrthancStone::GrayscaleStyleConfigurator);
+      viewport2_->UpdateSize();
+
+      viewport3_.reset(new OrthancStone::VolumeSlicerViewport(broker_, "mycanvas3", OrthancStone::VolumeProjection_Sagittal));
+      viewport3_->SetSlicer(0, loader_, *loader_, new OrthancStone::GrayscaleStyleConfigurator);
+      viewport3_->UpdateSize();
+
+      emscripten_set_resize_callback("#window", NULL, false, OnWindowResize);
+    
+      emscripten_request_animation_frame_loop(OnAnimationFrame, NULL);
+
+      oracle_.Start();
+      loader_->LoadSeries("a04ecf01-79b2fc33-58239f7e-ad9db983-28e81afa");
+    }
+    catch (Orthanc::OrthancException& e)
+    {
+      LOG(ERROR) << "Exception during Initialize(): " << e.What();
+    }
+  }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Samples/WebAssembly/BasicMPR.html	Wed May 29 16:15:04 2019 +0200
@@ -0,0 +1,69 @@
+<!doctype html>
+<html lang="en-us">
+  <head>
+    <meta charset="utf-8">
+    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
+
+    <!-- Disable pinch zoom on mobile devices -->
+    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
+    <meta name="HandheldFriendly" content="true" />
+    
+    
+    <title>Stone of Orthanc</title>
+
+    <style>
+      html, body {
+      width: 100%;
+      height: 100%;
+      margin: 0px;
+      border: 0;
+      overflow: hidden; /*  Disable scrollbars */
+      display: block;  /* No floating content on sides */
+      }
+
+      #mycanvas1 {
+      position:absolute;
+      left:0%;
+      top:0%;
+      background-color: red;
+      width: 50%;
+      height: 100%;
+      }
+
+      #mycanvas2 {
+      position:absolute;
+      left:50%;
+      top:0%;
+      background-color: green;
+      width: 50%;
+      height: 50%;
+      }
+
+      #mycanvas3 {
+      position:absolute;
+      left:50%;
+      top:50%;
+      background-color: blue;
+      width: 50%;
+      height: 50%;
+      }
+    </style>
+  </head>
+  <body>
+    <canvas id="mycanvas1" oncontextmenu="return false;"></canvas>
+    <canvas id="mycanvas2" oncontextmenu="return false;"></canvas>
+    <canvas id="mycanvas3" oncontextmenu="return false;"></canvas>
+
+    <script type="text/javascript">
+      if (!('WebAssembly' in window)) {
+      alert('Sorry, your browser does not support WebAssembly :(');
+      } else {
+      window.addEventListener('WebAssemblyLoaded', function() {
+      Module.ccall('Initialize', null, null, null);
+      });
+      }
+    </script>
+
+    <script type="text/javascript" async src="BasicMPR.js"></script>
+  </body>
+</html>

--- a/Samples/WebAssembly/BasicScene.cpp	Wed May 29 13:44:55 2019 +0200
+++ b/Samples/WebAssembly/BasicScene.cpp	Wed May 29 16:15:04 2019 +0200
@@ -113,14 +113,14 @@
     chain.push_back(ScenePoint2D(0 - 0.5, 2 - 0.5));
     chain.push_back(ScenePoint2D(2 - 0.5, 2 - 0.5));
     chain.push_back(ScenePoint2D(2 - 0.5, 0 - 0.5));
-    layer->AddChain(chain, true);
+    layer->AddChain(chain, true, 255, 0, 0);
 
     chain.clear();
     chain.push_back(ScenePoint2D(-5, -5));
     chain.push_back(ScenePoint2D(5, -5));
     chain.push_back(ScenePoint2D(5, 5));
     chain.push_back(ScenePoint2D(-5, 5));
-    layer->AddChain(chain, true);
+    layer->AddChain(chain, true, 0, 255, 0);
 
     double dy = 1.01;
     chain.clear();
@@ -128,9 +128,8 @@
     chain.push_back(ScenePoint2D(4, -4 + dy));
     chain.push_back(ScenePoint2D(-4, -4 + 2.0 * dy));
     chain.push_back(ScenePoint2D(4, 2));
-    layer->AddChain(chain, false);
+    layer->AddChain(chain, false, 0, 0, 255);
 
-    layer->SetColor(0,255, 255);
     scene->SetLayer(50, layer.release());
   }
 

--- a/Samples/WebAssembly/CMakeLists.txt	Wed May 29 13:44:55 2019 +0200
+++ b/Samples/WebAssembly/CMakeLists.txt	Wed May 29 16:15:04 2019 +0200
@@ -13,6 +13,7 @@
 set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -s ERROR_ON_UNDEFINED_SYMBOLS=1")
 set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -s ALLOW_MEMORY_GROWTH=1")
 set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -s ASSERTIONS=1 -s DISABLE_EXCEPTION_CATCHING=0")
+#set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -s EXIT_RUNTIME=1")
 
 
 #####################################################################
@@ -68,20 +69,40 @@
   ${ORTHANC_STONE_SOURCES}
   )
 
-add_executable(BasicScene
-  BasicScene.cpp
-  )
+
+if (OFF)
+  add_executable(BasicScene
+    BasicScene.cpp
+    )
+
+  target_link_libraries(BasicScene OrthancStone)
+
+  install(
+    TARGETS BasicScene
+    RUNTIME DESTINATION ${CMAKE_INSTALL_PREFIX}
+    )
+endif()
 
-target_link_libraries(BasicScene OrthancStone)
+
+if (ON)
+  add_executable(BasicMPR
+    BasicMPR.cpp
+    )
 
-install(
-  TARGETS BasicScene
-  RUNTIME DESTINATION ${CMAKE_INSTALL_PREFIX}
-  )
+  target_link_libraries(BasicMPR OrthancStone)
+
+  install(
+    TARGETS BasicMPR
+    RUNTIME DESTINATION ${CMAKE_INSTALL_PREFIX}
+    )
+endif()
+  
 
 install(
   FILES
+  ${CMAKE_CURRENT_BINARY_DIR}/BasicMPR.wasm
   ${CMAKE_CURRENT_BINARY_DIR}/BasicScene.wasm
+  ${CMAKE_SOURCE_DIR}/BasicMPR.html
   ${CMAKE_SOURCE_DIR}/BasicScene.html
   ${CMAKE_SOURCE_DIR}/Configuration.json
   ${CMAKE_SOURCE_DIR}/index.html

--- a/Samples/WebAssembly/NOTES.txt	Wed May 29 13:44:55 2019 +0200
+++ b/Samples/WebAssembly/NOTES.txt	Wed May 29 16:15:04 2019 +0200
@@ -1,7 +1,7 @@
 $ source ~/Downloads/emsdk/emsdk_env.sh
 $ cmake -G Ninja -DCMAKE_TOOLCHAIN_FILE=${EMSCRIPTEN}/cmake/Modules/Platform/Emscripten.cmake -DCMAKE_BUILD_TYPE=Release -DALLOW_DOWNLOADS=ON .. -DCMAKE_INSTALL_PREFIX=/tmp/stone
 $ ninja install
-$ sudo docker run -p 4242:4242 -p 8042:8042 --rm -v /tmp/stone:/root/stone:ro jodogne/orthanc-plugins:1.5.6 /root/stone/Configuration.json --verbose
+$ docker run -p 4242:4242 -p 8042:8042 --rm -v /tmp/stone:/root/stone:ro -v /tmp/stone-db/:/var/lib/orthanc/db/ jodogne/orthanc-plugins:1.5.6 /root/stone/Configuration.json --verbose
 
 notes BGO :
 source ~/apps/emsdk/emsdk_env.sh
@@ -11,4 +11,4 @@
 cmake -G Ninja -DCMAKE_TOOLCHAIN_FILE=${EMSCRIPTEN}/cmake/Modules/Platform/Emscripten.cmake -DCMAKE_BUILD_TYPE=Release -DALLOW_DOWNLOADS=ON .. -DCMAKE_INSTALL_PREFIX=/mnt/c/osi/dev/orthanc-stone/Samples/WebAssembly/installDir
 ninja install
 
-docker run -p 4242:4242 -p 8042:8042 --rm -v "C:/osi/dev/orthanc-stone/Samples/WebAssembly/installDir:/root/stone:ro" jodogne/orthanc-plugins:1.5.6 /root/stone/Configuration.json --verbose
\ No newline at end of file
+docker run -p 4242:4242 -p 8042:8042 --rm -v "C:/osi/dev/orthanc-stone/Samples/WebAssembly/installDir:/root/stone:ro" jodogne/orthanc-plugins:1.5.6 /root/stone/Configuration.json --verbose

--- a/Samples/WebAssembly/index.html	Wed May 29 13:44:55 2019 +0200
+++ b/Samples/WebAssembly/index.html	Wed May 29 16:15:04 2019 +0200
@@ -10,6 +10,7 @@
     <h1>Available samples</h1>
     <ul>
       <li><a href="BasicScene.html">Basic scene</a></li>
+      <li><a href="BasicMPR.html">Basic MPR display</a></li>
     </ul>
   </body>
 </html>