RushMidi.Library/MidiInputDevice.cs

using System;
using System.Collections.Concurrent;
using System.Threading;
using static RushMidiLibrary.MidiApiWindows;

namespace RushMidiLibrary {
    public class MidiInputDevice : MidiDevice {
        private MidiApiWindows.MidiInProc _inputCallback;
        private UIntPtr _deviceId;
        private MidiApiWindows.HMIDIIN _deviceHandle;
        private Thread _messageProcessingThread;
        private bool _messageProcessingThreadExitRequest = false;

        readonly BlockingCollection<Message> _messageQueue = new BlockingCollection<Message>();

        private struct Message {
            public MidiApiWindows.HMIDIIN hMidiIn;
            public MidiApiWindows.MidiInMessage wMsg;
            public UIntPtr dwInstance;
            public UIntPtr dwParam1;
            public UIntPtr dwParam2;
        }

        public MidiInputDevice(UIntPtr deviceId, MidiApiWindows.MIDIINCAPS caps) {
            _deviceId = deviceId;
        }

        public static MidiInputDevice[] Enumerate() {
            var devs = MidiApiWindows.midiInGetNumDevs();
            MidiInputDevice[] result = new MidiInputDevice[devs];
            for (uint deviceId = 0; deviceId < devs; deviceId++) {
                MidiApiWindows.MIDIINCAPS caps;
                MidiApiWindows.midiInGetDevCaps((UIntPtr)deviceId, out caps);
                result[deviceId] = new MidiInputDevice((UIntPtr)deviceId, caps);
            }
            return result;
        }

        public void Open() {
            _inputCallback = this.InputCallback;

            BeginMessageProcessing();
            try {
                CheckMMResult(MidiApiWindows.midiInOpen(out _deviceHandle, _deviceId, _inputCallback, (UIntPtr)0));
            }
            catch (Exception) {
                EndMessageProcessing();
                throw;
            }

        }

        public void Start() {
            CheckMMResult(MidiApiWindows.midiInStart(_deviceHandle));
        }

        private void InputCallback(MidiApiWindows.HMIDIIN hMidiIn, MidiApiWindows.MidiInMessage wMsg, UIntPtr dwInstance, UIntPtr dwParam1, UIntPtr dwParam2) {
            Message message = new Message();
            message.hMidiIn = hMidiIn;
            message.wMsg = wMsg;
            message.dwInstance = dwInstance;
            message.dwParam1 = dwParam1;
            message.dwParam2 = dwParam2;
            _messageQueue.Add(message);
        }


        private void BeginMessageProcessing() {
            _messageProcessingThreadExitRequest = false;
            _messageProcessingThread = new Thread(MessageProcessingThreadHandler);
            _messageProcessingThread.Start();
        }

        private void MessageProcessingThreadHandler() {
            while (!_messageProcessingThreadExitRequest) {
                Message message;
                if (_messageQueue.TryTake(out message, 100)) {
                    HandleMessage(message);
                }
            }
        }

        private void EndMessageProcessing() {
            _messageProcessingThreadExitRequest = true;
            _messageProcessingThread.Join();
        }

        private void HandleMessage(Message message) {

            switch (message.wMsg) {
                case MidiInMessage.MIM_DATA:
                    HandleMessageData(new MidiShortMessage(message.dwParam1, message.dwParam2));
                    break;
                case MidiInMessage.MIM_LONGDATA:
                    HandleMessageLongData(message.dwParam1, message.dwParam2);
                    break;
                default:
                    break;
            }
        }

        private void HandleMessageData(MidiShortMessage message) {
            if (message.IsNoteOn) {
                MidiChannel channel;
                int noteId;
                int velocity;
                uint timestamp;
                message.GetNoteOn(out channel, out noteId, out velocity, out timestamp);

                var note = new MidiNote(noteId);

                Console.WriteLine($"Received short message NoteOn: Name={note.Name} Octave={note.OctaveName} Channel={channel.ToString()}, NoteId={noteId}, Velocity={velocity}, Timestapm={timestamp}");

            } else if (message.IsNoteOff) {
                MidiChannel channel;
                int noteId;
                int velocity;
                uint timestamp;
                message.GetNoteOff(out channel, out noteId, out velocity, out timestamp);

                var note = new MidiNote(noteId);

                Console.WriteLine($"Received short message NoteOff: Name={note.Name} Octave={note.OctaveName} Channel={channel.ToString()}, NoteId={noteId}, Velocity={velocity}, Timestapm={timestamp}");

            } else {
                Console.WriteLine($"Received short message");
            }

        }

        private void HandleMessageLongData(UIntPtr dwParam1, UIntPtr dwParam2) {
            Console.WriteLine($"Received long message");
        }
    }
}