ISpNotifySource::SetNotifyCallbackFunction (SAPI 5.3)

Speech API 5.3
Microsoft Speech API 5.3


ISpNotifySource::SetNotifyCallbackFunction sets up this instance to send notifications using a standard C-style callback function.

HRESULT SetNotifyCallbackFunction(
   SPNOTIFYCALLBACK   *pfnCallback,
   WPARAM              wParam,
   LPARAM              lParam


[in] The notification callback function to be used.
[in] Constant WPARAM value that will be passed to the pfnCallback function when it is called.
[in] Constant LPARAM value that will be passed to the pfnCallback function when it is called.

Return values

S_OKFunction completed successfully.
E_INVALIDARGCallback function is invalid.
FAILED (hr)Appropriate error message.


It is the responsibility of the client code to control the lifetime of a notification. To remove an installed notify callback, call ISpEventSource::SetNotifySink (NULL). The final release of an object that supports ISpEventSource will automatically remove an installed notify callback.

The SAPI implementation uses a hidden window to call back the client on the same thread that was used to initialize the event source. Notification callbacks are the result of processing a window message. When this notification mechanism is used:

  1. The SPNOTIFYCALLBACK method will always be called on the thread that initialized the event source or notify translator object.
  2. The thread must have a window message pump.

The SPNOTIFYCALLBACK function is declared as follows:

    typedef void __stdcall SPNOTIFYCALLBACK(WPARAM wParam, LPARAM lParam);