--- a/Framework/Scene2D/CairoCompositor.cpp	Sat Apr 27 10:56:25 2019 +0200
+++ b/Framework/Scene2D/CairoCompositor.cpp	Sat Apr 27 12:38:25 2019 +0200
@@ -82,7 +82,7 @@
   }
 
 
-  CairoCompositor::CairoCompositor(Scene2D& scene,
+  CairoCompositor::CairoCompositor(const Scene2D& scene,
                                    unsigned int canvasWidth,
                                    unsigned int canvasHeight) :
     helper_(scene, *this)

--- a/Framework/Scene2D/CairoCompositor.h	Sat Apr 27 10:56:25 2019 +0200
+++ b/Framework/Scene2D/CairoCompositor.h	Sat Apr 27 12:38:25 2019 +0200
@@ -57,7 +57,7 @@
     virtual Internals::CompositorHelper::ILayerRenderer* Create(const ISceneLayer& layer);
 
   public:
-    CairoCompositor(Scene2D& scene,
+    CairoCompositor(const Scene2D& scene,
                     unsigned int canvasWidth,
                     unsigned int canvasHeight);
     

--- a/Framework/Scene2D/Internals/CompositorHelper.h	Sat Apr 27 10:56:25 2019 +0200
+++ b/Framework/Scene2D/Internals/CompositorHelper.h	Sat Apr 27 12:38:25 2019 +0200
@@ -58,7 +58,7 @@
 
       typedef std::map<int, Item*>  Content;
 
-      Scene2D&           scene_;
+      const Scene2D&     scene_;
       IRendererFactory&  factory_;
       Content            content_;
       AffineTransform2D  sceneTransform_;
@@ -68,7 +68,7 @@
                          int depth);
 
     public:
-      CompositorHelper(Scene2D& scene,
+      CompositorHelper(const Scene2D& scene,
                        IRendererFactory& factory) :
         scene_(scene),
         factory_(factory)

--- a/Framework/Scene2D/OpenGLCompositor.cpp	Sat Apr 27 10:56:25 2019 +0200
+++ b/Framework/Scene2D/OpenGLCompositor.cpp	Sat Apr 27 12:38:25 2019 +0200
@@ -119,7 +119,7 @@
 
 
   OpenGLCompositor::OpenGLCompositor(OpenGL::IOpenGLContext& context,
-                                     Scene2D& scene) :
+                                     const Scene2D& scene) :
     context_(context),
     helper_(scene, *this),
     colorTextureProgram_(context),

--- a/Framework/Scene2D/OpenGLCompositor.h	Sat Apr 27 10:56:25 2019 +0200
+++ b/Framework/Scene2D/OpenGLCompositor.h	Sat Apr 27 12:38:25 2019 +0200
@@ -52,7 +52,7 @@
 
   public:
     OpenGLCompositor(OpenGL::IOpenGLContext& context,
-                     Scene2D& scene);
+                     const Scene2D& scene);
 
     ~OpenGLCompositor();
 

--- a/Framework/Scene2D/Scene2D.cpp	Sat Apr 27 10:56:25 2019 +0200
+++ b/Framework/Scene2D/Scene2D.cpp	Sat Apr 27 12:38:25 2019 +0200
@@ -87,7 +87,7 @@
   }
 
   
-  void Scene2D::Apply(IVisitor& visitor)
+  void Scene2D::Apply(IVisitor& visitor) const
   {
     for (Content::const_iterator it = content_.begin(); 
          it != content_.end(); ++it)

--- a/Framework/Scene2D/Scene2D.h	Sat Apr 27 10:56:25 2019 +0200
+++ b/Framework/Scene2D/Scene2D.h	Sat Apr 27 12:38:25 2019 +0200
@@ -69,7 +69,7 @@
 
     void DeleteLayer(int depth);
 
-    void Apply(IVisitor& visitor);
+    void Apply(IVisitor& visitor) const;
 
     const AffineTransform2D& GetSceneToCanvasTransform() const
     {

--- a/Resources/CMake/OrthancStoneConfiguration.cmake	Sat Apr 27 10:56:25 2019 +0200
+++ b/Resources/CMake/OrthancStoneConfiguration.cmake	Sat Apr 27 12:38:25 2019 +0200
@@ -107,6 +107,13 @@
 
 
 if (ENABLE_OPENGL)
+  include(FindOpenGL)
+  if (NOT OPENGL_FOUND)
+    message(FATAL_ERROR "Cannot find OpenGL on your system")
+  endif()
+
+  link_libraries(${OPENGL_LIBRARIES})
+
   add_definitions(
     -DGL_GLEXT_PROTOTYPES=1
     -DORTHANC_ENABLE_OPENGL=1

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Samples/Sdl/BasicScene.cpp	Sat Apr 27 12:38:25 2019 +0200
@@ -0,0 +1,322 @@
+/**
+ * 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/>.
+ **/
+
+
+// From Stone
+#include "../../Applications/Sdl/SdlOpenGLWindow.h"
+#include "../../Framework/Scene2D/CairoCompositor.h"
+#include "../../Framework/Scene2D/OpenGLCompositor.h"
+#include "../../Framework/Scene2D/Scene2D.h"
+#include "../../Framework/Scene2D/PanSceneTracker.h"
+#include "../../Framework/Scene2D/RotateSceneTracker.h"
+#include "../../Framework/Scene2D/ZoomSceneTracker.h"
+#include "../../Framework/Scene2D/ColorTextureSceneLayer.h"
+
+// From Orthanc framework
+#include <Core/Logging.h>
+#include <Core/OrthancException.h>
+#include <Core/Images/Image.h>
+#include <Core/Images/ImageProcessing.h>
+#include <Core/Images/PngWriter.h>
+
+#include <SDL.h>
+#include <stdio.h>
+
+static const unsigned int FONT_SIZE = 64;
+
+
+void PrepareScene(OrthancStone::Scene2D& scene)
+{
+  using namespace OrthancStone;
+
+  // Texture of 2x2 size
+  {
+    Orthanc::Image i(Orthanc::PixelFormat_RGB24, 2, 2, false);
+    
+    uint8_t *p = reinterpret_cast<uint8_t*>(i.GetRow(0));
+    p[0] = 255;
+    p[1] = 0;
+    p[2] = 0;
+
+    p[3] = 0;
+    p[4] = 255;
+    p[5] = 0;
+
+    p = reinterpret_cast<uint8_t*>(i.GetRow(1));
+    p[0] = 0;
+    p[1] = 0;
+    p[2] = 255;
+
+    p[3] = 255;
+    p[4] = 0;
+    p[5] = 0;
+
+    scene.SetLayer(12, new ColorTextureSceneLayer(i));
+
+    std::auto_ptr<ColorTextureSceneLayer> l(new ColorTextureSceneLayer(i));
+    l->SetOrigin(-3, 2);
+    l->SetPixelSpacing(1.5, 1);
+    l->SetAngle(20.0 / 180.0 * M_PI);
+    scene.SetLayer(14, l.release());
+  }
+
+  // Texture of 1x1 size
+  {
+    Orthanc::Image i(Orthanc::PixelFormat_RGB24, 1, 1, false);
+    
+    uint8_t *p = reinterpret_cast<uint8_t*>(i.GetRow(0));
+    p[0] = 255;
+    p[1] = 0;
+    p[2] = 0;
+
+    std::auto_ptr<ColorTextureSceneLayer> l(new ColorTextureSceneLayer(i));
+    l->SetOrigin(-2, 1);
+    l->SetAngle(20.0 / 180.0 * M_PI);
+    scene.SetLayer(13, l.release());
+  }
+
+  // Some lines
+  {
+    std::auto_ptr<PolylineSceneLayer> layer(new PolylineSceneLayer);
+
+    layer->SetThickness(1);
+
+    PolylineSceneLayer::Chain chain;
+    chain.push_back(ScenePoint2D(0 - 0.5, 0 - 0.5));
+    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);
+
+    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);
+
+    double dy = 1.01;
+    chain.clear();
+    chain.push_back(ScenePoint2D(-4, -4));
+    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->SetColor(0,255, 255);
+    scene.SetLayer(50, layer.release());
+  }
+
+  // Some text
+  scene.SetLayer(170, new TextSceneLayer(0, 0, "Hello", 0, BitmapAnchor_Center, 20));
+}
+
+
+void TakeScreenshot(const std::string& target,
+                    const OrthancStone::Scene2D& scene,
+                    unsigned int canvasWidth,
+                    unsigned int canvasHeight)
+{
+  // Take a screenshot, then save it as PNG file
+  OrthancStone::CairoCompositor compositor(scene, canvasWidth, canvasHeight);
+  compositor.SetFont(0, Orthanc::EmbeddedResources::UBUNTU_FONT, FONT_SIZE, Orthanc::Encoding_Latin1);
+  compositor.Refresh();
+
+  Orthanc::ImageAccessor canvas;
+  compositor.GetCanvas().GetReadOnlyAccessor(canvas);
+
+  Orthanc::Image png(Orthanc::PixelFormat_RGB24, canvas.GetWidth(), canvas.GetHeight(), false);
+  Orthanc::ImageProcessing::Convert(png, canvas);
+        
+  Orthanc::PngWriter writer;
+  writer.WriteToFile(target, png);
+}
+
+
+void HandleApplicationEvent(OrthancStone::Scene2D& scene,
+                            const SDL_Event& event,
+                            std::auto_ptr<OrthancStone::IPointerTracker>& activeTracker,
+                            unsigned int windowWidth,
+                            unsigned int windowHeight)
+{
+  if (event.type == SDL_MOUSEBUTTONDOWN)
+  {
+    OrthancStone::PointerEvent e;
+    e.AddIntegerPosition(event.button.x, event.button.y);
+
+    switch (event.button.button)
+    {
+      case SDL_BUTTON_MIDDLE:
+        activeTracker.reset(new OrthancStone::PanSceneTracker(scene, e));
+        break;
+
+      case SDL_BUTTON_RIGHT:
+        activeTracker.reset(new OrthancStone::ZoomSceneTracker
+                            (scene, e, windowWidth, windowHeight));
+        break;
+
+      case SDL_BUTTON_LEFT:
+        activeTracker.reset(new OrthancStone::RotateSceneTracker
+                            (scene, e, windowWidth, windowHeight));
+        break;
+
+      default:
+        break;
+    }
+  }
+  else if (event.type == SDL_KEYDOWN &&
+           event.key.repeat == 0 /* Ignore key bounce */)
+  {
+    switch (event.key.keysym.sym)
+    {
+      case SDLK_s:
+        scene.FitContent(windowWidth, windowHeight);
+        break;
+              
+      case SDLK_c:
+        TakeScreenshot("screenshot.png", scene, windowWidth, windowHeight);
+        break;
+              
+      default:
+        break;
+    }
+  }
+}
+
+
+static void GLAPIENTRY
+OpenGLMessageCallback(GLenum source,
+                      GLenum type,
+                      GLuint id,
+                      GLenum severity,
+                      GLsizei length,
+                      const GLchar* message,
+                      const void* userParam )
+{
+  if (severity != GL_DEBUG_SEVERITY_NOTIFICATION)
+  {
+    fprintf(stderr, "GL CALLBACK: %s type = 0x%x, severity = 0x%x, message = %s\n",
+            ( type == GL_DEBUG_TYPE_ERROR ? "** GL ERROR **" : "" ),
+            type, severity, message );
+  }
+}
+
+
+void Run(OrthancStone::Scene2D& scene)
+{
+  OrthancStone::SdlOpenGLWindow window("Hello", 1024, 768);
+  scene.FitContent(window.GetCanvasWidth(), window.GetCanvasHeight());
+
+  glEnable(GL_DEBUG_OUTPUT);
+  glDebugMessageCallback(OpenGLMessageCallback, 0 );
+
+  OrthancStone::OpenGLCompositor compositor(window, scene);
+  compositor.SetFont(0, Orthanc::EmbeddedResources::UBUNTU_FONT, 
+                     FONT_SIZE, Orthanc::Encoding_Latin1);
+
+  std::auto_ptr<OrthancStone::IPointerTracker>  tracker;
+
+  bool stop = false;
+  while (!stop)
+  {
+    compositor.Refresh();
+
+    SDL_Event event;
+    while (!stop &&
+           SDL_PollEvent(&event))
+    {
+      if (event.type == SDL_QUIT)
+      {
+        stop = true;
+        break;
+      }
+      else if (event.type == SDL_MOUSEMOTION)
+      {
+        if (tracker.get() != NULL)
+        {
+          OrthancStone::PointerEvent e;
+          e.AddIntegerPosition(event.button.x, event.button.y);
+          tracker->Update(e);
+        }
+      }
+      else if (event.type == SDL_MOUSEBUTTONUP)
+      {
+        if (tracker.get() != NULL)
+        {
+          tracker->Release();
+          tracker.reset(NULL);
+        }
+      }
+      else if (event.type == SDL_WINDOWEVENT &&
+               event.window.event == SDL_WINDOWEVENT_SIZE_CHANGED)
+      {
+        tracker.reset(NULL);
+        compositor.UpdateSize();
+      }
+      else if (event.type == SDL_KEYDOWN &&
+               event.key.repeat == 0 /* Ignore key bounce */)
+      {
+        switch (event.key.keysym.sym)
+        {
+          case SDLK_f:
+            window.GetWindow().ToggleMaximize();
+            break;
+              
+          case SDLK_q:
+            stop = true;
+            break;
+
+          default:
+            HandleApplicationEvent(scene, event, tracker, window.GetCanvasWidth(), window.GetCanvasHeight());
+            break;
+        }
+      }
+      else
+      {
+        HandleApplicationEvent(scene, event, tracker, window.GetCanvasWidth(), window.GetCanvasHeight());
+      }
+    }
+
+    SDL_Delay(1);
+  }
+}
+
+
+int main()
+{
+  Orthanc::Logging::Initialize();
+  OrthancStone::SdlWindow::GlobalInitialize();
+
+  try
+  {
+    OrthancStone::Scene2D scene;
+    PrepareScene(scene);
+    Run(scene);
+  }
+  catch (Orthanc::OrthancException& e)
+  {
+    LOG(ERROR) << "EXCEPTION: " << e.What();
+  }
+
+  OrthancStone::SdlWindow::GlobalFinalize();
+  Orthanc::Logging::Finalize();
+
+  return 0;
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Samples/Sdl/CMakeLists.txt	Sat Apr 27 12:38:25 2019 +0200
@@ -0,0 +1,65 @@
+cmake_minimum_required(VERSION 2.8.3)
+
+
+#####################################################################
+## Configuration of the Orthanc framework
+#####################################################################
+
+# This CMake file defines the "ORTHANC_STONE_VERSION" macro, so it
+# must be the first inclusion
+include(${CMAKE_SOURCE_DIR}/../../Resources/CMake/Version.cmake)
+
+if (ORTHANC_STONE_VERSION STREQUAL "mainline")
+  set(ORTHANC_FRAMEWORK_VERSION "mainline")
+  set(ORTHANC_FRAMEWORK_DEFAULT_SOURCE "hg")
+else()
+  set(ORTHANC_FRAMEWORK_VERSION "1.5.7")
+  set(ORTHANC_FRAMEWORK_DEFAULT_SOURCE "web")
+endif()
+
+set(ORTHANC_FRAMEWORK_SOURCE "${ORTHANC_FRAMEWORK_DEFAULT_SOURCE}" CACHE STRING "Source of the Orthanc source code (can be \"hg\", \"archive\", \"web\" or \"path\")")
+set(ORTHANC_FRAMEWORK_ARCHIVE "" CACHE STRING "Path to the Orthanc archive, if ORTHANC_FRAMEWORK_SOURCE is \"archive\"")
+set(ORTHANC_FRAMEWORK_ROOT "" CACHE STRING "Path to the Orthanc source directory, if ORTHANC_FRAMEWORK_SOURCE is \"path\"")
+
+
+#####################################################################
+## Configuration of the Stone framework
+#####################################################################
+
+include(${CMAKE_SOURCE_DIR}/../../Resources/CMake/OrthancStoneParameters.cmake)
+include(${ORTHANC_ROOT}/Resources/CMake/DownloadPackage.cmake)
+
+DownloadPackage(
+  "a24b8136b8f3bb93f166baf97d9328de"
+  "http://orthanc.osimis.io/ThirdPartyDownloads/ubuntu-font-family-0.83.zip"
+  "${CMAKE_BINARY_DIR}/ubuntu-font-family-0.83")
+
+set(ORTHANC_STONE_APPLICATION_RESOURCES
+  UBUNTU_FONT  ${CMAKE_BINARY_DIR}/ubuntu-font-family-0.83/Ubuntu-R.ttf
+  )
+
+SET(ENABLE_GOOGLE_TEST OFF)
+SET(ENABLE_LOCALE ON)
+SET(ENABLE_SDL ON)
+SET(ENABLE_WEB_CLIENT ON)
+SET(ORTHANC_SANDBOXED OFF)
+LIST(APPEND ORTHANC_BOOST_COMPONENTS program_options)
+
+include(${CMAKE_SOURCE_DIR}/../../Resources/CMake/OrthancStoneConfiguration.cmake)
+
+include_directories(${ORTHANC_STONE_ROOT})
+
+
+#####################################################################
+## Build the samples
+#####################################################################
+
+add_library(OrthancStone STATIC
+  ${ORTHANC_STONE_SOURCES}
+  )
+
+add_executable(BasicScene
+  BasicScene.cpp
+  )
+
+target_link_libraries(BasicScene OrthancStone)