Important:
This is retired content. This content is outdated and is no longer being maintained. It is provided as a courtesy for individuals who are still using these technologies. This content may contain URLs that were valid when originally published, but now link to sites or pages that no longer exist.
4/8/2010

An application can use the RegistryNotifyWindowfunction to register a custom Windows message that detects changes in the Bluetoothregistry value located under the HKEY_LOCAL_MACHINE\System\State\Hardwarekey. When the state of the Bluetooth radio changes, the specified Window is notified through the custom message. The pConditionparameter points to the NOTIFICATIONCONDITIONstructure that stores the the registration criteria.

To stop receiving notifications through messages, call the RegistryCloseNotificationfunction and pass the handle returned by RegistryNotifyWindowas a parameter.

The following code example shows how to register for notifications using RegistryNotifyWindow.

Note:
Error handling has been omitted in this topic for clarity.
Copy Code 
HRESULT RegisterBluetoothWindowsMessage(HWND hDlg)
{
  #define SN_BLUETOOTHPOWERBSTATE_ROOT	HKEY_LOCAL_MACHINE
  #define SN_BLUETOOTHPOWERBSTATE_PATH   
TEXT("System\\State\\Hardware")
  #define SN_BLUETOOTHPOWERBSTATE_VALUE   TEXT("Bluetooth")
  #define SN_BLUETOOTHPOWERBSTATE_BITMASK 3

  HRESULT  hr		= NULL;
  NOTIFICATIONCONDITION  nc;
  HREGNOTIFY  g_hNotify_Windows = NULL;   // Handles to
notifications through Windows message

  nc.ctComparisonType	= REG_CT_ANYCHANGE;
  nc.dwMask			= SN_BLUETOOTHPOWERBSTATE_BITMASK;
  nc.TargetValue.dw	= 0;

   hr = RegistryNotifyWindow(
		SN_BLUETOOTHPOWERBSTATE_ROOT,
		SN_BLUETOOTHPOWERBSTATE_PATH,
		SN_BLUETOOTHPOWERBSTATE_VALUE,
		hDlg, 
		WM_CHANGE_BLUETOOTH,  // This notification uses a custom
window message.
		0,
		&nc,
		&g_hNotify_Windows
		);

  if (FAILED(hr))
  {
	//perform error handling;
	return hr;
  }
  return S_OK;
}

See Also