IPrintAsyncNotifyCallback::OnEventNotify method (prnasnot.h)

Alerts a listener that a notification is available on a specified channel. This method is called by the print system.

Syntax

HRESULT OnEventNotify(
  [in] IPrintAsyncNotifyChannel    *pChannel,
  [in] IPrintAsyncNotifyDataObject *pData
);

Parameters

[in] pChannel

A pointer to the channel used by the sender and the listener.

[in] pData

A pointer to the object that contains the notification data and its size and type.

Return value

The return values are COM error codes. Because this function might complete the operation successfully yet return an HRESULT other than S_OK you should use the SUCCEEDED or FAILED macro to determine the success of the call. To get the specific HRESULT that was returned by the function, use the HRESULT_CODE macro.

See PrintAsyncNotifyError for other possible return values.

For more information about COM error codes, see Error Handling.

The following code example shows how these macros can be used to evaluate the return value.

if (SUCCEEDED(hr)){
  // Call was successful 
}

if (FAILED(hr)) {
  // Call failed 
}

if (FAILED(hr)) {
  // Call failed, check HRESULT value returned
  switch (HRESULT_CODE(hr)){
    case INTERNAL_NOTIFICATION_QUEUE_IS_FULL:
      // Some action 
      break;
    default:
      // Default action 
      break;
  }
} else {
  // Call succeeded 
}

Remarks

To deliver a notification, the print spooler will call the OnEventNotify method of the IPrintAsyncNotifyCallback object provided by the listening application at the time it registered for notifications. For unidirectional notifications, pChannel is NULL. For bidirectional channels, pChannel points to an IPrintAsyncNotifyChannel to be used by a listening application to send a notification in response. The listener will do this by calling the SendNotification method of the IPrintAsyncNotifyChannel.

Requirements

See also

Asynchronous Printing Notification Interfaces

Error Handling

IPrintAsyncNotifyCallback

Printing