--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Scene2D/CompositorHelper.h	Fri Apr 19 17:57:58 2019 +0200
@@ -0,0 +1,81 @@
+/**
+ * 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 "Scene2D.h"
+
+namespace OrthancStone
+{
+  class CompositorHelper : protected Scene2D::IVisitor
+  {
+  public:
+    class ILayerRenderer : public boost::noncopyable
+    {
+    public:
+      virtual ~ILayerRenderer()
+      {
+      }
+
+      virtual void Render(const AffineTransform2D& transform) = 0;
+
+      // "Update()" is only called if the type of the layer has not changed
+      virtual void Update(const ISceneLayer& layer) = 0;
+    };
+
+    class IRendererFactory : public boost::noncopyable
+    {
+    public:
+      virtual ~IRendererFactory()
+      {
+      }
+
+      virtual ILayerRenderer* Create(const ISceneLayer& layer) = 0;
+    };
+
+  private:
+    class Item;
+
+    typedef std::map<int, Item*>  Content;
+
+    Scene2D&           scene_;
+    IRendererFactory&  factory_;
+    Content            content_;
+    AffineTransform2D  sceneTransform_;
+
+  protected:
+    virtual void Visit(const ISceneLayer& layer,
+                       int depth);
+
+  public:
+    CompositorHelper(Scene2D& scene,
+                     IRendererFactory& factory) :
+      scene_(scene),
+      factory_(factory)
+    {
+    }
+
+    ~CompositorHelper();
+
+    void Refresh(unsigned int canvasWidth,
+                 unsigned int canvasHeight);
+  };
+}