CAsyncMonikerFile::OnDataAvailable

Статья
10/16/2008

An asynchronous moniker calls OnDataAvailable to provide data to the client as it becomes available, during asynchronous bind operations.

virtual void OnDataAvailable( 
   DWORD dwSize, 
   DWORD bscfFlag  
);

Параметры

dwSize
The cumulative amount (in bytes) of data available since the beginning of the binding. Can be zero, indicating that the amount of data is not relevant to the operation, or that no specific amount became available.
bscfFlag
A BSCF enumeration value. Can be one or more of the following values:
- BSCF_FIRSTDATANOTIFICATION Identifies the first call to OnDataAvailable for a given bind operation.
- BSCF_INTERMEDIATEDATANOTIFICATION Identifies an intermediary call to OnDataAvailable for a bind operation.
- BSCF_LASTDATANOTIFICATION Identifies the last call to OnDataAvailable for a bind operation.

Заметки

The default implementation of this function does nothing. See the following example for a sample implementation.

Пример

void CMyMoniker::OnDataAvailable(DWORD dwSize, DWORD bscfFlag)
{
   if ((bscfFlag & BSCF_FIRSTDATANOTIFICATION) != 0)
   {
      m_dwReadBefore = 0;
      m_strText.Empty();
   }

   DWORD dwArriving = dwSize - m_dwReadBefore;

   if (dwArriving > 0)
   {
      int nLen = m_strText.GetLength();
      ASSERT((DWORD)nLen == m_dwReadBefore);
      LPTSTR psz = m_strText.GetBuffer(nLen + dwArriving);
      Read(psz + nLen, dwArriving);
      m_strText.ReleaseBuffer(nLen + dwArriving);
      m_dwReadBefore = dwSize;
   }
}