CEnumPins Class (Compact 2013)

3/26/2014

IEnumPins Interface

     CEnumPins Class

This class supports the IEnumPins enumeration interface by calling CBaseFilter methods. The CBaseFilter class supports the IBaseFilter::EnumPins method.

Each time one of this interface's methods is called, the CBaseFilter class checks to see if the pins that it enumerates have changed; it does this by calling CBaseFilter::GetPinVersion and matching the version the filter is keeping with the version that it stores during construction.

If a pin enumerator becomes stale, there is no mechanism for resynchronizing it with the filter. The user must release the interface and retrieve another one.

Because the enumeration operation is likely to fail if the pin version changes (indicating that the filter might have added or removed pins), all member functions in this class check the version by calling a private member function, which calls the owning filter's CBaseFilter::GetPinVersion member function.

These member functions then return VFW_E_ENUM_OUT_OF_SYNC if the version has changed. This should always work unless the filter has overridden CBaseFilter::GetPinVersion to do something unexpected.

All member functions in this class that return HRESULT and accept a pointer as a parameter return E_POINTER when passed a null pointer.

Member Functions

Member function	Description
CEnumPins	Constructs a CEnumPins object.

Implemented IUnknown Methods

Method	Description
AddRef	Increments the reference count.
QueryInterface	Returns pointers to supported interfaces.
Release	Decrements the reference count.

Implemented IEnumPins Methods

Method	Description
Clone	Creates a duplicate CEnumPins object with the same initial state.
Next	Returns the next pin after the current position.
Reset	Sets the current position back to the beginning.
Skip	Skips over one or more entries in the enumerator.

Requirements

Header	dshow.h, Streams.h
Library	ole32.lib, Ole32auth.lib, Strmbase.lib, Strmiids.lib, uuid.lib

See Also

Reference

DirectShow Classes