/**
* Registers a callback to receive notifications when MIDI devices are added and removed.
*
+ * The {@link DeviceCallback#onDeviceStatusChanged} method will be called immediately
+ * for any devices that have open ports. This allows applications to know which input
+ * ports are already in use and, therefore, unavailable.
+ *
+ * Applications should call {@link #getDevices} before registering the callback
+ * to get a list of devices already added.
+ *
* @param callback a {@link DeviceCallback} for MIDI device notifications
* @param handler The {@link android.os.Handler Handler} that will be used for delivering the
* device notifications. If handler is null, then the thread used for the
Client client = getClient(token);
if (client == null) return;
client.addListener(listener);
+ // Let listener know whether any ports are already busy.
+ updateStickyDeviceStatus(client.mUid, listener);
}
@Override
client.removeListener(listener);
}
+ // Inform listener of the status of all known devices.
+ private void updateStickyDeviceStatus(int uid, IMidiDeviceListener listener) {
+ synchronized (mDevicesByInfo) {
+ for (Device device : mDevicesByInfo.values()) {
+ // ignore private devices that our client cannot access
+ if (device.isUidAllowed(uid)) {
+ try {
+ MidiDeviceStatus status = device.getDeviceStatus();
+ if (status != null) {
+ listener.onDeviceStatusChanged(status);
+ }
+ } catch (RemoteException e) {
+ Log.e(TAG, "remote exception", e);
+ }
+ }
+ }
+ }
+ }
+
private static final MidiDeviceInfo[] EMPTY_DEVICE_INFO_ARRAY = new MidiDeviceInfo[0];
public MidiDeviceInfo[] getDevices() {