The filter pipeline supports the discard control. Filters can use this object, if they obtain it from IXpsDocumentProvider::GetXpsPart method. In some cases, processing this object might just include forwarding it to the next filter by using the IXpsDocumentConsumer::SendXpsUnknown method.
Filters can also create discard controls. To create a discard control, the filter must create an object that implements the IPartDiscardControl interface. Because the filter transfers ownership of the discard control when it sends it to the next filter, the filter must manage the lifetime of the discard control. If a filter creates a discard control, the filter DLL must not unload until the discard control has been released.
The IPartDiscardControl interface has these methods.
|IPartDiscardControl::GetDiscardProperties||The GetDiscardProperties method gets the properties of the discard control.|
|Header||filterpipeline.h (include Filterpipeline.h)|