diff --git a/vtkm/rendering/Mapper.h b/vtkm/rendering/Mapper.h
index 66444d879..bcbba0f50 100644
--- a/vtkm/rendering/Mapper.h
+++ b/vtkm/rendering/Mapper.h
@@ -49,7 +49,7 @@ public:
   virtual void StartScene() = 0;
   virtual void EndScene() = 0;
   virtual void SetCanvas(vtkm::rendering::Canvas *canvas) = 0;
-  virtual vtkm::rendering::Canvas* GetCanvas() {return NULL;} //DRP fix this...
+  virtual vtkm::rendering::Canvas* GetCanvas() const = 0;
 
   virtual vtkm::rendering::Mapper *NewCopy() const = 0;
 
diff --git a/vtkm/rendering/MapperGL.cxx b/vtkm/rendering/MapperGL.cxx
index 09a3f9adb..2e226ca76 100644
--- a/vtkm/rendering/MapperGL.cxx
+++ b/vtkm/rendering/MapperGL.cxx
@@ -468,6 +468,12 @@ void MapperGL::SetCanvas(vtkm::rendering::Canvas *c)
   }
 }
 
+vtkm::rendering::Canvas *    
+MapperGL::GetCanvas() const
+{
+  return this->Canvas;
+}
+
 vtkm::rendering::Mapper *MapperGL::NewCopy() const
 {
   return new vtkm::rendering::MapperGL(*this);
diff --git a/vtkm/rendering/MapperGL.h b/vtkm/rendering/MapperGL.h
index ae051cd87..1cb99a0bf 100644
--- a/vtkm/rendering/MapperGL.h
+++ b/vtkm/rendering/MapperGL.h
@@ -48,7 +48,7 @@ public:
   void StartScene() VTKM_OVERRIDE;
   void EndScene() VTKM_OVERRIDE;
   void SetCanvas(vtkm::rendering::Canvas *canvas) VTKM_OVERRIDE;
-  virtual vtkm::rendering::Canvas* GetCanvas() {return this->Canvas;}
+  virtual vtkm::rendering::Canvas* GetCanvas() const VTKM_OVERRIDE;
 
   vtkm::rendering::Mapper *NewCopy() const VTKM_OVERRIDE;
 
diff --git a/vtkm/rendering/MapperRayTracer.cxx b/vtkm/rendering/MapperRayTracer.cxx
index 58c70cbe0..2459ac383 100644
--- a/vtkm/rendering/MapperRayTracer.cxx
+++ b/vtkm/rendering/MapperRayTracer.cxx
@@ -100,6 +100,12 @@ void MapperRayTracer::SetCanvas(vtkm::rendering::Canvas *canvas)
   }
 }
 
+vtkm::rendering::Canvas *
+MapperRayTracer::GetCanvas() const
+{
+  return this->Internals->Canvas;
+}
+
 struct MapperRayTracer::RenderFunctor
 {
   vtkm::rendering::MapperRayTracer *Self;
diff --git a/vtkm/rendering/MapperRayTracer.h b/vtkm/rendering/MapperRayTracer.h
index 87b7dd7f4..a61a547f9 100644
--- a/vtkm/rendering/MapperRayTracer.h
+++ b/vtkm/rendering/MapperRayTracer.h
@@ -37,6 +37,7 @@ public:
   ~MapperRayTracer();
 
   void SetCanvas(vtkm::rendering::Canvas *canvas) VTKM_OVERRIDE;
+  virtual vtkm::rendering::Canvas* GetCanvas() const VTKM_OVERRIDE;
 
   void RenderCells(const vtkm::cont::DynamicCellSet &cellset,
                    const vtkm::cont::CoordinateSystem &coords,
diff --git a/vtkm/rendering/MapperVolume.cxx b/vtkm/rendering/MapperVolume.cxx
index 4fbc37ccd..a47a5d2e1 100644
--- a/vtkm/rendering/MapperVolume.cxx
+++ b/vtkm/rendering/MapperVolume.cxx
@@ -106,6 +106,12 @@ void MapperVolume::SetCanvas(vtkm::rendering::Canvas *canvas)
   }
 }
 
+vtkm::rendering::Canvas *
+MapperVolume::GetCanvas() const
+{
+  return this->Internals->Canvas;
+}
+
 struct MapperVolume::RenderFunctor
 {
   vtkm::rendering::MapperVolume *Self;
diff --git a/vtkm/rendering/MapperVolume.h b/vtkm/rendering/MapperVolume.h
index 33cd441a2..07f0998e3 100644
--- a/vtkm/rendering/MapperVolume.h
+++ b/vtkm/rendering/MapperVolume.h
@@ -35,6 +35,7 @@ public:
   ~MapperVolume();
 
   void SetCanvas(vtkm::rendering::Canvas *canvas) VTKM_OVERRIDE;
+  virtual vtkm::rendering::Canvas* GetCanvas() const VTKM_OVERRIDE;  
 
   virtual void RenderCells(const vtkm::cont::DynamicCellSet &cellset,
                            const vtkm::cont::CoordinateSystem &coords,