--- a/OrthancStone/Resources/CMake/OrthancStoneConfiguration.cmake	Wed Oct 28 22:21:06 2020 +0100
+++ b/OrthancStone/Resources/CMake/OrthancStoneConfiguration.cmake	Thu Oct 29 17:01:29 2020 +0100
@@ -276,6 +276,8 @@
   ${ORTHANC_STONE_ROOT}/Scene2D/LookupTableStyleConfigurator.h
   ${ORTHANC_STONE_ROOT}/Scene2D/LookupTableTextureSceneLayer.cpp
   ${ORTHANC_STONE_ROOT}/Scene2D/LookupTableTextureSceneLayer.h
+  ${ORTHANC_STONE_ROOT}/Scene2D/MacroSceneLayer.cpp
+  ${ORTHANC_STONE_ROOT}/Scene2D/MacroSceneLayer.h
   ${ORTHANC_STONE_ROOT}/Scene2D/NullLayer.h
   ${ORTHANC_STONE_ROOT}/Scene2D/PanSceneTracker.cpp
   ${ORTHANC_STONE_ROOT}/Scene2D/PanSceneTracker.h

--- a/OrthancStone/Sources/Scene2D/ISceneLayer.h	Wed Oct 28 22:21:06 2020 +0100
+++ b/OrthancStone/Sources/Scene2D/ISceneLayer.h	Thu Oct 29 17:01:29 2020 +0100
@@ -40,7 +40,8 @@
       Type_Polyline,
       Type_Text,
       Type_FloatTexture,
-      Type_LookupTableTexture
+      Type_LookupTableTexture,
+      Type_Macro
     };
 
     virtual ~ISceneLayer()

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OrthancStone/Sources/Scene2D/MacroSceneLayer.cpp	Thu Oct 29 17:01:29 2020 +0100
@@ -0,0 +1,89 @@
+/**
+ * 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 Lesser 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program. If not, see
+ * <http://www.gnu.org/licenses/>.
+ **/
+
+
+#include "MacroSceneLayer.h"
+
+#include <OrthancException.h>
+
+namespace OrthancStone
+{
+  void MacroSceneLayer::Clear()
+  {
+    for (size_t i = 0; i < layers_.size(); i++)
+    {
+      assert(layers_[i] != NULL);
+      delete layers_[i];
+    }
+
+    layers_.clear();
+    BumpRevision();
+  }
+
+  
+  void MacroSceneLayer::AddLayer(ISceneLayer* layer)
+  {
+    if (layer == NULL)
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_NullPointer);
+    }
+    else
+    {
+      layers_.push_back(layer);
+      BumpRevision();
+    }
+  }
+
+  
+  ISceneLayer* MacroSceneLayer::Clone() const
+  {
+    std::unique_ptr<MacroSceneLayer> copy(new MacroSceneLayer);
+
+    copy->Reserve(layers_.size());
+
+    for (size_t i = 0; i < layers_.size(); i++)
+    {
+      assert(layers_[i] != NULL);
+      copy->layers_.push_back(layers_[i]->Clone());
+    }
+
+    return copy.release();
+  }
+  
+
+  bool MacroSceneLayer::GetBoundingBox(Extent2D& target) const
+  {
+    target.Reset();
+
+    for (size_t i = 0; i < layers_.size(); i++)
+    {
+      assert(layers_[i] != NULL);
+
+      Extent2D subextent;
+      if (layers_[i]->GetBoundingBox(subextent))
+      {
+        target.Union(subextent);
+      }
+    }
+
+    return true;
+  }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OrthancStone/Sources/Scene2D/MacroSceneLayer.h	Thu Oct 29 17:01:29 2020 +0100
@@ -0,0 +1,89 @@
+/**
+ * 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 Lesser 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program. If not, see
+ * <http://www.gnu.org/licenses/>.
+ **/
+
+
+#pragma once
+
+#include "ISceneLayer.h"
+
+#include <Compatibility.h>  // For ORTHANC_OVERRIDE
+
+#include <vector>
+
+namespace OrthancStone
+{
+  /**
+   * A "macro layer" is a group of sublayers that are handled as a
+   * whole.
+   **/
+  class MacroSceneLayer : public ISceneLayer
+  {
+  private:
+    std::vector<ISceneLayer*>  layers_;
+    uint64_t                   revision_;
+
+  protected:
+    void BumpRevision()
+    {
+      // this is *not* thread-safe!!!  => (SJO) no problem, Stone assumes mono-threading
+      revision_++;
+    }
+
+  public:
+    MacroSceneLayer() :
+      revision_(0)
+    {
+    }
+
+    virtual ~MacroSceneLayer()
+    {
+      Clear();
+    }
+
+    void Clear();      
+
+    void Reserve(size_t size)
+    {
+      layers_.reserve(size);
+    }
+
+    void AddLayer(ISceneLayer* layer);  // takes ownership
+
+    size_t GetSize() const
+    {
+      return layers_.size();
+    }
+
+    virtual ISceneLayer* Clone() const ORTHANC_OVERRIDE;
+
+    virtual Type GetType() const ORTHANC_OVERRIDE
+    {
+      return Type_Macro;
+    }
+
+    virtual bool GetBoundingBox(Extent2D& target) const ORTHANC_OVERRIDE;
+
+    virtual uint64_t GetRevision() const ORTHANC_OVERRIDE
+    {
+      return revision_;
+    }
+  };
+}