Using DirectInput to receive signal after plugging in joystick

Question

I have a C++ program that enumerates all the input devices (using direct input) at the start of the program. If the program is started, and then I plug in another controller, this controller won't be recognized until the program is restarted. Anyone know of an event I can use that will cause my program to enumerate all of the devices after a new one is plugged in?

Answer 1

This article discusses how to detect game pad changes. First of all, you can handle the WM_DEVICECHANGE message and check wParam for DBT_DEVICEARRIVAL or DBT_DEVICEREMOVECOMPLETE. It seems that in order to receive these as WPARAMs, though, you need to call RegisterDeviceNotification first.

The article's example of how to do this is as follows:

DEV_BROADCAST_DEVICEINTERFACE notificationFilter;
ZeroMemory(&notificationFilter, sizeof(notificationFilter));
 
notificationFilter.dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE;
notificationFilter.dbcc_size = sizeof(notificationFilter);
 
HDEVNOTIFY hDevNotify;
hDevNotify = RegisterDeviceNotification(m_hWnd, &notificationFilter,
   DEVICE_NOTIFY_WINDOW_HANDLE |
   DEVICE_NOTIFY_ALL_INTERFACE_CLASSES);
 
if(hDevNotify == NULL) {
   // do some error handling
}

The only other thing to watch out for is that the minimum supported OS for this is XP, so you need to put in the appropriate #define for that before including the Windows headers.

Depending on what you want to do, you might not even have to call this function first. Instead, you can just check DBT_DEVNODES_CHANGED to not differentiate between a device being plugged or unplugged. That could save some code if you don't care.