Platform SDK: DirectX |
This topic pertains only to applications written in C++.
Because universal serial bus (USB) devices can be added to and removed from the system without rebooting, you might want your application to be able to respond to a new configuration of input devices. For example, you might allow a new player to join a game in progress by plugging in another controller.
To receive a message when a device is changed, you must first register for notification, as in the following code example:
PVOID hNotifyDevNode; void RegisterForDevChange(HWND hDlg, PVOID *hNotifyDevNode) { DEV_BROADCAST_DEVICEINTERFACE *pFilterData = (DEV_BROADCAST_DEVICEINTERFACE*) _alloca(sizeof(DEV_BROADCAST_DEVICEINTERFACE)); ASSERT (pFilterData); ZeroMemory(pFilterData, sizeof(DEV_BROADCAST_DEVICEINTERFACE)); pFilterData->dbcc_size = sizeof(DEV_BROADCAST_DEVICEINTERFACE); pFilterData->dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE; pFilterData->dbcc_classguid = GUID_CLASS_INPUT; *hNotifyDevNode = RegisterDeviceNotification(hDlg, pFilterData, DEVICE_NOTIFY_WINDOW_HANDLE); }
Then, in your main window procedure, check for messages announcing that a device has been attached, is about to be removed, or has been removed, as follows:
MyWindowProc(HWND hWnd, UINT nMsg, WPARAM wParam, LPARAM lParam) { switch (nMsg) { case WM_DEVICECHANGE: { switch (wParam) { case DBT_DEVICEARRIVAL: // Handle device arrival break; case DBT_DEVICEQUERYREMOVE: // Handle device removal request break; case DBT_DEVICEREMOVECOMPLETE: // Handle device removal break; } } . . . } }
In response to a DBT_DEVICEARRIVAL event, obtain the instance GUID of the device by using IDirectInput7::FindDevice, and pass this value to IDirectInput7::CreateDeviceEx.
For more information, see Device Management in the the Platform SDK.