--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OrthancStone/Sources/Scene2D/Internals/CompositorHelper.cpp	Tue Jul 07 16:21:02 2020 +0200
@@ -0,0 +1,177 @@
+/**
+ * Stone of Orthanc
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2020 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 <OrthancException.h>
+
+namespace OrthancStone
+{
+  namespace Internals
+  {
+    class CompositorHelper::Item : public boost::noncopyable
+    {
+    private:
+      std::unique_ptr<ILayerRenderer>  renderer_;
+      const ISceneLayer&             layer_;
+      uint64_t                       layerIdentifier_;
+      uint64_t                       lastRevision_;
+
+    public:
+      Item(ILayerRenderer* renderer,     // Takes ownership
+           const ISceneLayer& layer,
+           uint64_t layerIdentifier) :
+        renderer_(renderer),
+        layer_(layer),
+        layerIdentifier_(layerIdentifier),
+        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 GetLayerIdentifier() const
+      {
+        return layerIdentifier_;
+      }
+
+      uint64_t GetLastRevision() const
+      {
+        return lastRevision_;
+      }
+
+      void UpdateRenderer()
+      {
+        assert(renderer_.get() != NULL);
+        renderer_->Update(layer_);
+        lastRevision_ = layer_.GetRevision();
+      }
+    };
+
+
+    void CompositorHelper::Visit(const Scene2D& scene,
+                                 const ISceneLayer& layer,
+                                 uint64_t layerIdentifier,
+                                 int depth)
+    {
+      // "Visit()" is only applied to layers existing in the scene
+      assert(scene.HasLayer(depth)); 
+
+      Content::iterator found = content_.find(depth);
+
+      assert(found == content_.end() ||
+             found->second != NULL);
+
+      if (found == content_.end() ||
+          found->second->GetLayerIdentifier() != layerIdentifier)
+      {
+        // 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);
+        }
+
+        // the returned renderer can be NULL in case of an unknown layer
+        // or a NullLayer
+        std::unique_ptr<ILayerRenderer> renderer(factory_.Create(layer));
+
+        if (renderer.get() != NULL)
+        {
+          renderer->Render(sceneTransform_, canvasWidth_, canvasHeight_);
+          content_[depth] = new Item(renderer.release(), layer, layerIdentifier);
+        }
+      }
+      else
+      {
+        // This layer has already been rendered
+        assert(found->second->GetLastRevision() <= layer.GetRevision());
+
+        if (found->second->GetLastRevision() < layer.GetRevision())
+        {
+          found->second->UpdateRenderer();
+        }
+
+        found->second->GetRenderer().Render(sceneTransform_, canvasWidth_, canvasHeight_);
+      }
+
+      // Check invariants
+      assert(content_.find(depth) == content_.end() ||
+             (content_[depth]->GetLayerIdentifier() == layerIdentifier &&
+              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(const Scene2D& scene,
+                                   unsigned int canvasWidth,
+                                   unsigned int canvasHeight)
+    {
+      /**
+       * Safeguard mechanism to enforce the fact that the same scene
+       * is always used with the compositor. Note that the safeguard
+       * is not 100% bullet-proof, as a new scene might reuse the same
+       * address as a previous scene.
+       **/
+      if (lastScene_ != NULL &&
+          lastScene_ != &scene)
+      {
+        throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls,
+                                        "ICompositor::ResetScene() should have been called");
+      }
+
+      lastScene_ = &scene;
+
+      // 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());
+      canvasWidth_ = canvasWidth;
+      canvasHeight_ = canvasHeight;
+      scene.Apply(*this);
+    }
+  }
+}