GetAsBitmap with subrect

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@42612 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/dcmemory.h

@@ -47,6 +47,8 @@ public:
 
 protected:
     void DoGetSize( int *width, int *height ) const;
+    virtual wxBitmap DoGetAsBitmap(const wxRect *subrect) const 
+    { return subrect == NULL ? GetSelectedBitmap() : GetSelectedBitmap().GetSubBitmap(*subrect); }
 
     DECLARE_DYNAMIC_CLASS(wxMemoryDC)
 };