split wxPrintPreviewBase::RenderPage() into helper methods in the same way its done on the trunk

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@54404 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/prntbase.h

@@ -575,6 +575,10 @@ protected:
 private:
     void Init(wxPrintout *printout, wxPrintout *printoutForPrinting);
 
+    // helpers for RenderPage():
+    bool RenderPageIntoDC(wxDC& dc, int pageNum);
+    bool RenderPageIntoBitmap(wxBitmap& bmp, int pageNum);
+
     DECLARE_NO_COPY_CLASS(wxPrintPreviewBase)
     DECLARE_CLASS(wxPrintPreviewBase)
 };