--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Scene2D/Internals/CompositorHelper.cpp	Fri Apr 26 13:04:56 2019 +0200
@@ -0,0 +1,142 @@
+/**
+ * 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 "CompositorHelper.h"
+
+#include <Core/OrthancException.h>
+
+namespace OrthancStone
+{
+  namespace Internals
+  {
+    class CompositorHelper::Item : public boost::noncopyable
+    {
+    private:
+      std::auto_ptr<ILayerRenderer>  renderer_;
+      const ISceneLayer&             layer_;
+      uint64_t                       lastRevision_;
+
+    public:
+      Item(ILayerRenderer* renderer,     // Takes ownership
+           const ISceneLayer& layer) :
+        renderer_(renderer),
+        layer_(layer),
+        lastRevision_(layer.GetRevision())
+      {
+        if (renderer == NULL)
+        {
+          throw Orthanc::OrthancException(Orthanc::ErrorCode_NullPointer);
+        }
+      }
+
+      ILayerRenderer& GetRenderer() const
+      {
+        assert(renderer_.get() != NULL);
+        return *renderer_;
+      }
+
+      const ISceneLayer& GetLayer() const
+      {
+        return layer_;
+      }
+
+      uint64_t GetLastRevision() const
+      {
+        return lastRevision_;
+      }
+
+      void UpdateRenderer()
+      {
+        assert(renderer_.get() != NULL);
+        renderer_->Update(layer_);
+        lastRevision_ = layer_.GetRevision();
+      }
+    };
+
+
+    void CompositorHelper::Visit(const ISceneLayer& layer,
+                                 int depth)
+    {
+      Content::iterator found = content_.find(depth);
+
+      assert(found == content_.end() ||
+             found->second != NULL);
+
+      if (found == content_.end() ||
+          &found->second->GetLayer() != &layer)
+      {
+        // This is the first time this layer is rendered, or the layer
+        // is not the same as before
+        if (found != content_.end())
+        {
+          delete found->second;
+          content_.erase(found);
+        }
+
+        std::auto_ptr<ILayerRenderer> renderer(factory_.Create(layer));
+
+        if (renderer.get() != NULL)
+        {
+          renderer->Render(sceneTransform_);
+          content_[depth] = new Item(renderer.release(), layer);
+        }
+      }
+      else
+      {
+        // This layer has already been rendered
+        if (found->second->GetLastRevision() < layer.GetRevision())
+        {
+          found->second->UpdateRenderer();
+        }
+
+        found->second->GetRenderer().Render(sceneTransform_);
+      }
+
+      // Check invariants
+      assert(content_.find(depth) == content_.end() ||
+             (&content_[depth]->GetLayer() == &layer &&
+              content_[depth]->GetLastRevision() == layer.GetRevision()));
+    }
+
+
+    CompositorHelper::~CompositorHelper()
+    {
+      for (Content::iterator it = content_.begin(); it != content_.end(); ++it)
+      {
+        assert(it->second != NULL);
+        delete it->second;
+      }
+    }
+
+  
+    void CompositorHelper::Refresh(unsigned int canvasWidth,
+                                   unsigned int canvasHeight)
+    {
+      // Bring coordinate (0,0) to the center of the canvas
+      AffineTransform2D offset = AffineTransform2D::CreateOffset(
+        static_cast<double>(canvasWidth) / 2.0,
+        static_cast<double>(canvasHeight) / 2.0);
+
+      sceneTransform_ = AffineTransform2D::Combine(offset, scene_.GetSceneToCanvasTransform());
+      scene_.Apply(*this);
+    }
+  }
+}