Step 3. Support QueryInterface
| Microsoft DirectShow 9.0 |
Step 3. Support QueryInterface
To expose the filter's new interfaces to clients, do the following:
Include the DECLARE_IUNKNOWN macro in the public declaration section of your filter:
public: DECLARE_IUNKNOWN;
Override CUnknown::NonDelegatingQueryInterface to check for the IIDs of the two interfaces:
STDMETHODIMP CGrayFilter::NonDelegatingQueryInterface(REFIID riid, void **ppv)
{
if (riid == IID_ISpecifyPropertyPages)
{
return GetInterface(
static_cast<ISpecifyPropertyPages*>(this),
ppv);
}
else if (riid == IID_ISaturation)
{
return GetInterface(static_cast<ISaturation*>(this), ppv);
}
else
{
// Call the parent class.
return CBaseFilter::NonDelegatingQueryInterface(riid, ppv);
// NOTE: This example assumes that the filter inherits directly
// from CBaseFilter. If your filter inherits from another class,
// call the NonDelegatingQueryInterface method of that class.
}
}
Next: Step 4. Create the Property Page.
See Also