Add wxDataViewEvent::InitData() helper

Reuse it from both the generic and macOS versions to avoid doing the
same thing in both of them.

include/wx/dataview.h

@@ -936,6 +936,9 @@ public:
     // insertion of items, this is the proposed child index for the insertion.
     void SetProposedDropIndex(int index) { m_proposedDropIndex = index; }
     int GetProposedDropIndex() const { return m_proposedDropIndex;}
+
+    // Internal, only used by wxWidgets itself.
+    void InitData(wxDataObjectComposite* obj, wxDataFormat format);
 #endif // wxUSE_DRAG_AND_DROP
 
     virtual wxEvent *Clone() const wxOVERRIDE { return new wxDataViewEvent(*this); }

src/common/datavcmn.cpp

@@ -1805,6 +1805,18 @@ void wxDataViewEvent::Init(wxDataViewCtrlBase* dvc,
     SetEventObject(dvc);
 }
 
+#if wxUSE_DRAG_AND_DROP
+
+void wxDataViewEvent::InitData(wxDataObjectComposite* obj, wxDataFormat format)
+{
+    SetDataFormat(format);
+
+    SetDataObject(obj->GetObject(format));
+    SetDataSize(obj->GetDataSize(format));
+}
+
+#endif // wxUSE_DRAG_AND_DROP
+
 #if wxUSE_SPINCTRL
 
 // -------------------------------------

src/generic/datavgen.cpp

@@ -2391,9 +2391,7 @@ wxDragResult wxDataViewMainWindow::OnData(wxDataFormat format, wxCoord x, wxCoor
 
     wxDataViewEvent event(wxEVT_DATAVIEW_ITEM_DROP, m_owner, dropItemInfo.m_item);
     event.SetProposedDropIndex(dropItemInfo.m_proposedDropIndex);
-    event.SetDataFormat( format );
+    event.InitData(obj, format);
-    event.SetDataSize(obj->GetDataSize(format));
-    event.SetDataObject(obj->GetObject(format));
     event.SetDropEffect( def );
     if ( !m_owner->HandleWindowEvent( event ) || !event.IsAllowed() )
         return wxDragNone;

src/osx/cocoa/dataview.mm

@@ -729,20 +729,22 @@ outlineView:(NSOutlineView*)outlineView
     // Create event
     wxDataViewEvent event(eventType, dvc, wxDataViewItemFromItem(item));
 
-    // Retrieve data info if user released mouse buttton (drop occured)
+    // Retrieve the data itself if user released mouse button (drop occurred)
     if (eventType == wxEVT_DATAVIEW_ITEM_DROP)
     {
         if (!dt->GetData())
             return NSDragOperationNone;
 
         wxDataObjectComposite *obj = static_cast<wxDataObjectComposite*>(dt->GetDataObject());
-        event.SetDataSize(obj->GetDataSize(format));
+        event.InitData(obj, format);
-        event.SetDataObject(obj->GetObject(format));
+    }
+    else // Otherwise set just the data format
+    {
+        event.SetDataFormat(format);
     }
 
     // Setup other event properties
     event.SetProposedDropIndex(index);
-    event.SetDataFormat(format);
     if (index == -1)
     {
         event.SetDropEffect(wxDragCopy);