Called by the framework to retrieve data in the specified format when the specified storage medium is a file.
Nonzero if successful; otherwise 0.
The specified format is one previously placed in the COleDataSource object using the DelayRenderData member function for delayed rendering. The default implementation of this function simply returns FALSE.
This is an advanced overridable. Override this function to supply your data in the requested format and medium. Depending on your data, you might want to override one of the other versions of this function instead. If you want to handle multiple storage media, override OnRenderData. If your data is in a file, or is of variable size, override OnRenderFileData. For more information on delayed rendering as handled by MFC, see the article Data Objects and Data Sources: Manipulation.