Merge branch 'dvc-multi-format-dnd'

Accept multiple data formats via drag-and-drop in wxDataViewCtrl.

See #2478, #2616.

include/wx/dataview.h

@@ -760,8 +760,21 @@ public:
 #if wxUSE_DRAG_AND_DROP
     virtual bool EnableDragSource(const wxDataFormat& WXUNUSED(format))
         { return false; }
-    virtual bool EnableDropTarget(const wxDataFormat& WXUNUSED(format))
-        { return false; }
+
+    bool EnableDropTargets(const wxVector<wxDataFormat>& formats)
+        { return DoEnableDropTarget(formats); }
+
+    bool EnableDropTarget(const wxDataFormat& format)
+    {
+        wxVector<wxDataFormat> formats;
+        if (format.GetType() != wxDF_INVALID)
+        {
+            formats.push_back(format);
+        }
+
+        return DoEnableDropTarget(formats);
+    }
+
 #endif // wxUSE_DRAG_AND_DROP
 
     // define control visual attributes
@@ -792,6 +805,17 @@ protected:
     virtual void DoSetExpanderColumn() = 0 ;
     virtual void DoSetIndent() = 0;
 
+#if wxUSE_DRAG_AND_DROP
+    // Helper function which can be used by DoEnableDropTarget() implementations
+    // in the derived classes: return a composite data object supporting the
+    // given formats or null if the vector is empty.
+    static wxDataObjectComposite*
+    CreateDataObject(const wxVector<wxDataFormat>& formats);
+
+    virtual bool DoEnableDropTarget(const wxVector<wxDataFormat>& WXUNUSED(formats))
+        { return false; }
+#endif // wxUSE_DRAG_AND_DROP
+
     // Just expand this item assuming it is already shown, i.e. its parent has
     // been already expanded using ExpandAncestors().
     //
@@ -912,6 +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); }
@@ -945,6 +972,7 @@ protected:
 #if wxUSE_DRAG_AND_DROP
     wxDataObject       *m_dataObject;
 
+    wxMemoryBuffer      m_dataBuf;
     wxDataFormat        m_dataFormat;
     void*               m_dataBuffer;
     size_t              m_dataSize;