VarjoNativeInterface.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using VRCFaceTracking;

namespace VRCFTVarjoModule
{
    class VarjoNativeInterface : VarjoInterface
    {
        private IntPtr _session;

        public override bool Initialize()
        {
            if (!VarjoAvailable())
            {
                Logger.Error("Varjo headset isn't detected");
                return false;
            }
            LoadLibrary();
            _session = varjo_SessionInit();
            if (_session == IntPtr.Zero)
            {
                return false;
            }
            if (!varjo_IsGazeAllowed(_session))
            {
                Logger.Error("Gaze tracking is not allowed! Please enable it in the Varjo Base!");
                return false;
            }
            varjo_GazeInit(_session);
            varjo_SyncProperties(_session);
            return true;
        }

        public override void Teardown()
        {
            //no need to tear down anything right?
        }

        public override void Update()
        {
            if (_session == IntPtr.Zero)
                return;

            // Get's GazeData and EyeMeasurements from the Varjo SDK
            // Return value states whether or not the request was successful (true = has Data; false = Error occured)
            bool hasData = varjo_GetGazeData(_session, out gazeData, out eyeMeasurements);

            if (!hasData)
                Logger.Msg("Error while getting Gaze Data");
        }
        public override string GetName()
        {
            return "native DLL";
        }

        private bool LoadLibrary()
        {
            IEnumerable<string> dllPaths = ExtractAssemblies(new string[] { "Varjo.VarjoLib.dll" });
            var path = dllPaths.First();
            if (path == null)
            {
                Logger.Error(string.Concat("Couldn't extract the library ", path));
                return false;
            }
            if (LoadLibrary(path) == IntPtr.Zero)
            {
                Logger.Error(string.Concat("Unable to load library ", path));
                return false;
            }
            Logger.Msg(string.Concat("Loaded library ", path));
            return true;
        }


        // I can't ask nicely to add my DLL into the dependency list so I had to steal code from the main repo :(
        private static IEnumerable<string> ExtractAssemblies(IEnumerable<string> resourceNames)
        {
            var extractedPaths = new List<string>();

            var dirName = Path.Combine(Utils.PersistentDataDirectory, "StockLibs");
            if (!Directory.Exists(dirName))
                Directory.CreateDirectory(dirName);

            foreach (var dll in resourceNames)
            {
                var dllPath = Path.Combine(dirName, GetAssemblyNameFromPath(dll));

                using (var stm = Assembly.GetAssembly(typeof(VarjoNativeInterface)).GetManifestResourceStream("VRCFTVarjoModule.TrackingLibs." + dll))
                {
                    try
                    {
                        using (Stream outFile = File.Create(dllPath))
                        {
                            const int sz = 4096;
                            var buf = new byte[sz];
                            while (true)
                            {
                                if (stm == null) continue;
                                var nRead = stm.Read(buf, 0, sz);
                                if (nRead < 1)
                                    break;
                                outFile.Write(buf, 0, nRead);
                            }
                        }

                        extractedPaths.Add(dllPath);
                    }
                    catch (Exception e)
                    {
                        Logger.Error($"Failed to get DLL: " + e.Message);
                    }
                }
            }
            return extractedPaths;
        }

        private static string GetAssemblyNameFromPath(string path)
        {
            var splitPath = path.Split('.').ToList();
            splitPath.Reverse();
            return splitPath[1] + ".dll";
        }

        [DllImport("kernel32", CharSet = CharSet.Unicode, ExactSpelling = false, SetLastError = true)]
        private static extern IntPtr LoadLibrary(string lpFileName);

        [DllImport("VarjoLib", CharSet = CharSet.Auto)]
        private static extern bool varjo_IsAvailable();

        [DllImport("VarjoLib", CharSet = CharSet.Auto)]
        private static extern IntPtr varjo_SessionInit();

        [DllImport("VarjoLib", CharSet = CharSet.Auto)]
        private static extern void varjo_SessionShutDown(IntPtr session);

        [DllImport("VarjoLib", CharSet = CharSet.Auto)]
        private static extern void varjo_GazeInit(IntPtr session);

        [DllImport("VarjoLib", CharSet = CharSet.Auto)]
        private static extern int varjo_GetError(IntPtr session);

        [DllImport("VarjoLib", CharSet = CharSet.Auto)]
        private static extern string varjo_GetErrorDesc(int errorCode);

        [DllImport("VarjoLib", CharSet = CharSet.Auto)]
        private static extern bool varjo_IsGazeAllowed(IntPtr session);

        [DllImport("VarjoLib", CharSet = CharSet.Auto)]
        private static extern bool varjo_IsGazeCalibrated(IntPtr session);

        [DllImport("VarjoLib", CharSet = CharSet.Auto)]
        private static extern GazeData varjo_GetGaze(IntPtr session);

        [DllImport("VarjoLib", CharSet = CharSet.Auto)]
        private static extern bool varjo_GetGazeData(IntPtr session, out GazeData gaze, out EyeMeasurements eyeMeasurements);

        [DllImport("VarjoLib", CharSet = CharSet.Auto)]
        private static extern void varjo_RequestGazeCalibration(IntPtr session);

        [DllImport("VarjoLib", CharSet = CharSet.Auto)]
        private static extern bool varjo_GetPropertyBool(IntPtr session, int propertyKey);

        [DllImport("VarjoLib", CharSet = CharSet.Auto)]
        private static extern int varjo_GetPropertyInt(IntPtr session, int propertyKey);

        [DllImport("VarjoLib", CharSet = CharSet.Auto)]
        private static extern void varjo_SyncProperties(IntPtr session);

    }
}