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CSourceSeeking::CheckCapabilities

  • 아티클
 
Microsoft DirectShow 9.0

CSourceSeeking::CheckCapabilities

The CheckCapabilities method queries whether the stream has specified seeking capabilities. This method implements the IMediaSeeking::CheckCapabilities method.

Syntax

  HRESULT CheckCapabilities(
    DWORD *pCapabilities
);

Parameters

pCapabilities

Pointer to a bitwise combination of one or more AM_SEEKING_SEEKING_CAPABILITIES attributes.

Return Value

Returns one of the HRESULT values listed in the following table.

Value Description
S_FALSE Not all of the capabilities in pCapabilities are present.
S_OK All capabilities in pCapabilities are present.
E_POINTER NULL pointer argument.

Remarks

As implemented, this method checks the value of *pCapabilities against the CSourceSeeking::m_dwSeekingCaps member variable. However, it does not set *pCapabilities equal to m_dwSeekingCaps, as described for the IMediaSeeking::CheckCapabilities method. Also, in the case where none of the specified capabilities are available, the method does not return E_FAIL. A more complete implementation would be as follows:

STDMETHODIMP CheckCapabilities(DWORD *pCapabilities)
{
    CheckPointer(pCapabilities, E_POINTER)
    DWORD dwCaps;
    HRESULT hr = GetCapabilities(&dwCaps);
    if (SUCCEEDED(hr))
    {
        dwCaps &= *pCapabilities;
        if (dwCaps)
        {
            hr =  (dwCaps == *pCapabilities ? S_OK : S_FALSE );
        }
        else 
        {
            hr = E_FAIL;
        }
        *pCapabilities = dwCaps;
    }
    else 
    {
        *pCapabilities = 0;
    }
    return hr;
}

Requirements

**  Header:** Declared in Ctlutil.h; include Streams.h.

**  Library:** Use Strmbase.lib (retail builds) or Strmbasd.lib (debug builds).

See Also