How to send MIDI to own virtual output port with Android MIDI Package?

Question

I am creating a Java Android app which uses the Android MIDI Package: https://developer.android.com/reference/android/media/midi/package-summary#extend_midideviceservice

The app needs to deploy its own virtual midi input and output port. So far the input side is working nicely. I can deploy the output port, its visible in other apps but I don't know how send to the output port and can't find proper documentation on that.

Does anyone have good documentation/example on opening and using the self-deployed output port?

My device_info.xml:

<devices>
    <device
        manufacturer="anyManufacturer"
        product="Virtual"
        name="myApp Virtual Inport">
        <input-port name="input" />
    </device>
    <device
        manufacturer="anyManufacturer"
        product="Virtual"
        name="myApp Virtual Outport">
        <output-port name="output" />
    </device>
</devices>

Answer 1

My own solution:

XML:

<devices>
    <device
        manufacturer="anyManufacturer"
        product="Virtual"
        name="myApp Virtual Port">
        <input-port name="input" />
        <output-port name="output" />
    </device>
</devices>

Then in the service call getOutputPortReceivers() to get the output port. https://developer.android.com/reference/android/media/midi/MidiDeviceService#getOutputPortReceivers()

then you can use send() on that MidiReceiver.

public class MIDIConnectDeviceService extends MidiDeviceService {
    private MidiReceiver mInputReceiver = new MyReceiver();
    private static MidiReceiver mOutputReceiver; 

    @Override
    public void onCreate() {
        super.onCreate();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
    }

    @Override
    // Declare the receivers associated with your input ports.
    public MidiReceiver[] onGetInputPortReceivers() {
        return new MidiReceiver[] { mInputReceiver };
    }    

    public static void send(byte[] msg, int offset, int count, long timestamp) throws IOException {
        if (mOutputReceiver != null){
            mOutputReceiver.send(msg, offset, count, timestamp);
        }
    }

    class MyReceiver extends MidiReceiver {
        @Override
        public void onSend(byte[] data, int offset, int count,
                           long timestamp) throws IOException {

        }
    }

    @Override
    public void onDeviceStatusChanged(MidiDeviceStatus status) {
        MidiReceiver[] midiReceivers = getOutputPortReceivers();
        mOutputReceiver = midiReceivers[0];
    }
}