GPv3: Add wrapper class for DrawingReference

Adds a simple C++ wrapper so we don't have to use
`MEM_dupallocN`, `MEM_freeN` etc.

source/blender/blenkernel/BKE_grease_pencil.hh

@@ -110,6 +110,13 @@ class Drawing : public ::GreasePencilDrawing {
   bool has_users() const;
 };
 
+class DrawingReference : public ::GreasePencilDrawingReference {
+ public:
+  DrawingReference();
+  DrawingReference(const DrawingReference &other);
+  ~DrawingReference();
+};
+
 class LayerGroup;
 class Layer;
 
@@ -705,6 +712,16 @@ inline const blender::bke::greasepencil::Drawing &GreasePencilDrawing::wrap() co
   return *reinterpret_cast<const blender::bke::greasepencil::Drawing *>(this);
 }
 
+inline blender::bke::greasepencil::DrawingReference &GreasePencilDrawingReference::wrap()
+{
+  return *reinterpret_cast<blender::bke::greasepencil::DrawingReference *>(this);
+}
+inline const blender::bke::greasepencil::DrawingReference &GreasePencilDrawingReference::wrap()
+    const
+{
+  return *reinterpret_cast<const blender::bke::greasepencil::DrawingReference *>(this);
+}
+
 inline GreasePencilFrame GreasePencilFrame::null()
 {
   return GreasePencilFrame{-1, 0, 0};

source/blender/blenkernel/intern/grease_pencil.cc

@@ -113,7 +113,7 @@ static void grease_pencil_copy_data(Main * /*bmain*/,
         const GreasePencilDrawingReference *src_drawing_reference =
             reinterpret_cast<const GreasePencilDrawingReference *>(src_drawing_base);
         grease_pencil_dst->drawing_array[i] = reinterpret_cast<GreasePencilDrawingBase *>(
-            MEM_dupallocN(src_drawing_reference));
+            MEM_new<bke::greasepencil::DrawingReference>(__func__, src_drawing_reference->wrap()));
         break;
       }
     }
@@ -432,6 +432,24 @@ void Drawing::tag_topology_changed()
   this->tag_positions_changed();
 }
 
+DrawingReference::DrawingReference()
+{
+  this->base.type = GP_DRAWING_REFERENCE;
+  this->base.flag = 0;
+
+  this->id_reference = nullptr;
+}
+
+DrawingReference::DrawingReference(const DrawingReference &other)
+{
+  this->base.type = GP_DRAWING_REFERENCE;
+  this->base.flag = other.base.flag;
+
+  this->id_reference = other.id_reference;
+}
+
+DrawingReference::~DrawingReference() {}
+
 const Drawing *get_eval_grease_pencil_layer_drawing(const GreasePencil &grease_pencil,
                                                     const int layer_index)
 {
@@ -1643,7 +1661,7 @@ static void remove_drawings_unchecked(GreasePencil &grease_pencil,
       case GP_DRAWING_REFERENCE: {
         GreasePencilDrawingReference *drawing_reference_to_remove =
             reinterpret_cast<GreasePencilDrawingReference *>(drawing_base_to_remove);
-        MEM_freeN(drawing_reference_to_remove);
+        MEM_delete(&drawing_reference_to_remove->wrap());
         break;
       }
     }
@@ -2518,7 +2536,7 @@ static void free_drawing_array(GreasePencil &grease_pencil)
       case GP_DRAWING_REFERENCE: {
         GreasePencilDrawingReference *drawing_reference =
             reinterpret_cast<GreasePencilDrawingReference *>(drawing_base);
-        MEM_freeN(drawing_reference);
+        MEM_delete(&drawing_reference->wrap());
         break;
       }
     }

source/blender/makesdna/DNA_grease_pencil_types.h

@@ -28,6 +28,7 @@ class GreasePencilDrawingRuntime;
 namespace greasepencil {
 class DrawingRuntime;
 class Drawing;
+class DrawingReference;
 class TreeNode;
 class Layer;
 class LayerRuntime;
@@ -120,6 +121,10 @@ typedef struct GreasePencilDrawingReference {
    * See the note in `GreasePencilLayer->frames()` for a detailed explanation of this.
    */
   struct GreasePencil *id_reference;
+#ifdef __cplusplus
+  blender::bke::greasepencil::DrawingReference &wrap();
+  const blender::bke::greasepencil::DrawingReference &wrap() const;
+#endif
 } GreasePencilDrawingReference;
 
 /**