Update C# wrapper with visual C# compatible version (#126)

- Custom serializer to fix utf-8 strings in C#

examples/button-clicker/Assets/DiscordController.cs

@@ -11,7 +11,7 @@ public class DiscordJoinRequestEvent : UnityEngine.Events.UnityEvent<DiscordRpc.
 
 public class DiscordController : MonoBehaviour
 {
-    public DiscordRpc.RichPresence presence;
+    public DiscordRpc.RichPresence presence = new DiscordRpc.RichPresence();
     public string applicationId;
     public string optionalSteamId;
     public int callbackCalls;
@@ -33,7 +33,7 @@ public class DiscordController : MonoBehaviour
 
         presence.details = string.Format("Button clicked {0} times", clickCounter);
 
-        DiscordRpc.UpdatePresence(ref presence);
+        DiscordRpc.UpdatePresence(presence);
     }
 
     public void RequestRespondYes()

examples/button-clicker/Assets/DiscordRpc.cs

@@ -1,4 +1,7 @@
-using System.Runtime.InteropServices;
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Text;
 
 public class DiscordRpc
 {
@@ -30,27 +33,27 @@ public class DiscordRpc
         public RequestCallback requestCallback;
     }
 
-    [System.Serializable]
+    [Serializable, StructLayout(LayoutKind.Sequential)]
-    public struct RichPresence
+    public struct RichPresenceStruct
     {
-        public string state; /* max 128 bytes */
+        public IntPtr state; /* max 128 bytes */
-        public string details; /* max 128 bytes */
+        public IntPtr details; /* max 128 bytes */
         public long startTimestamp;
         public long endTimestamp;
-        public string largeImageKey; /* max 32 bytes */
+        public IntPtr largeImageKey; /* max 32 bytes */
-        public string largeImageText; /* max 128 bytes */
+        public IntPtr largeImageText; /* max 128 bytes */
-        public string smallImageKey; /* max 32 bytes */
+        public IntPtr smallImageKey; /* max 32 bytes */
-        public string smallImageText; /* max 128 bytes */
+        public IntPtr smallImageText; /* max 128 bytes */
-        public string partyId; /* max 128 bytes */
+        public IntPtr partyId; /* max 128 bytes */
         public int partySize;
         public int partyMax;
-        public string matchSecret; /* max 128 bytes */
+        public IntPtr matchSecret; /* max 128 bytes */
-        public string joinSecret; /* max 128 bytes */
+        public IntPtr joinSecret; /* max 128 bytes */
-        public string spectateSecret; /* max 128 bytes */
+        public IntPtr spectateSecret; /* max 128 bytes */
         public bool instance;
     }
 
-    [System.Serializable]
+    [Serializable]
     public struct JoinRequest
     {
         public string userId;
@@ -76,12 +79,139 @@ public class DiscordRpc
     public static extern void RunCallbacks();
 
     [DllImport("discord-rpc", EntryPoint = "Discord_UpdatePresence", CallingConvention = CallingConvention.Cdecl)]
-    public static extern void UpdatePresence(ref RichPresence presence);
+    private static extern void UpdatePresenceNative(ref RichPresenceStruct presence);
 
     [DllImport("discord-rpc", EntryPoint = "Discord_ClearPresence", CallingConvention = CallingConvention.Cdecl)]
     public static extern void ClearPresence();
 
     [DllImport("discord-rpc", EntryPoint = "Discord_Respond", CallingConvention = CallingConvention.Cdecl)]
     public static extern void Respond(string userId, Reply reply);
+
+    public static void UpdatePresence(RichPresence presence)
+    {
+        var presencestruct = presence.GetStruct();
+        UpdatePresenceNative(ref presencestruct);
+        presence.FreeMem();
     }
 
+    public class RichPresence
+    {
+        private RichPresenceStruct _presence;
+        private readonly List<IntPtr> _buffers = new List<IntPtr>(10);
+
+        public string state; /* max 128 bytes */
+        public string details; /* max 128 bytes */
+        public long startTimestamp;
+        public long endTimestamp;
+        public string largeImageKey; /* max 32 bytes */
+        public string largeImageText; /* max 128 bytes */
+        public string smallImageKey; /* max 32 bytes */
+        public string smallImageText; /* max 128 bytes */
+        public string partyId; /* max 128 bytes */
+        public int partySize;
+        public int partyMax;
+        public string matchSecret; /* max 128 bytes */
+        public string joinSecret; /* max 128 bytes */
+        public string spectateSecret; /* max 128 bytes */
+        public bool instance;
+
+        /// <summary>
+        /// Get the <see cref="RichPresenceStruct"/> reprensentation of this instance
+        /// </summary>
+        /// <returns><see cref="RichPresenceStruct"/> reprensentation of this instance</returns>
+        internal RichPresenceStruct GetStruct()
+        {
+            if (_buffers.Count > 0)
+            {
+                FreeMem();
+            }
+
+            _presence.state = StrToPtr(state, 128);
+            _presence.details = StrToPtr(details, 128);
+            _presence.startTimestamp = startTimestamp;
+            _presence.endTimestamp = endTimestamp;
+            _presence.largeImageKey = StrToPtr(largeImageKey, 32);
+            _presence.largeImageText = StrToPtr(largeImageText, 128);
+            _presence.smallImageKey = StrToPtr(smallImageKey, 32);
+            _presence.smallImageText = StrToPtr(smallImageText, 128);
+            _presence.partyId = StrToPtr(partyId, 128);
+            _presence.partySize = partySize;
+            _presence.partyMax = partyMax;
+            _presence.matchSecret = StrToPtr(matchSecret, 128);
+            _presence.joinSecret = StrToPtr(joinSecret, 128);
+            _presence.spectateSecret = StrToPtr(spectateSecret, 128);
+            _presence.instance = instance;
+
+            return _presence;
+        }
+
+        /// <summary>
+        /// Returns a pointer to a representation of the given string with a size of maxbytes
+        /// </summary>
+        /// <param name="input">String to convert</param>
+        /// <param name="maxbytes">Max number of bytes to use</param>
+        /// <returns>Pointer to the UTF-8 representation of <see cref="input"/></returns>
+        private IntPtr StrToPtr(string input, int maxbytes)
+        {
+            if (string.IsNullOrEmpty(input)) return IntPtr.Zero;
+            var convstr = StrClampBytes(input, maxbytes);
+            var convbytecnt = Encoding.UTF8.GetByteCount(convstr);
+            var buffer = Marshal.AllocHGlobal(convbytecnt);
+            _buffers.Add(buffer);
+            Marshal.Copy(Encoding.UTF8.GetBytes(convstr), 0, buffer, convbytecnt);
+            return buffer;
+        }
+
+        /// <summary>
+        /// Convert string to UTF-8 and add null termination
+        /// </summary>
+        /// <param name="toconv">string to convert</param>
+        /// <returns>UTF-8 representation of <see cref="toconv"/> with added null termination</returns>
+        private static string StrToUtf8NullTerm(string toconv)
+        {
+            var str = toconv.Trim();
+            var bytes = Encoding.Default.GetBytes(str);
+            if (bytes.Length > 0 && bytes[bytes.Length - 1] != 0)
+            {
+                str += "\0\0";
+            }
+            return Encoding.UTF8.GetString(Encoding.UTF8.GetBytes(str));
+        }
+
+        /// <summary>
+        /// Clamp the string to the given byte length preserving null termination
+        /// </summary>
+        /// <param name="toclamp">string to clamp</param>
+        /// <param name="maxbytes">max bytes the resulting string should have (including null termination)</param>
+        /// <returns>null terminated string with a byte length less or equal to <see cref="maxbytes"/></returns>
+        private static string StrClampBytes(string toclamp, int maxbytes)
+        {
+            var str = StrToUtf8NullTerm(toclamp);
+            var strbytes = Encoding.UTF8.GetBytes(str);
+
+            if (strbytes.Length <= maxbytes)
+            {
+                return str;
+            }
+
+            var newstrbytes = new byte[] { };
+            Array.Copy(strbytes, 0, newstrbytes, 0, maxbytes - 1);
+            newstrbytes[newstrbytes.Length - 1] = 0;
+            newstrbytes[newstrbytes.Length - 2] = 0;
+
+            return Encoding.UTF8.GetString(newstrbytes);
+        }
+
+        /// <summary>
+        /// Free the allocated memory for conversion to <see cref="RichPresenceStruct"/>
+        /// </summary>
+        internal void FreeMem()
+        {
+            for (var i = _buffers.Count - 1; i >= 0; i--)
+            {
+                Marshal.FreeHGlobal(_buffers[i]);
+                _buffers.RemoveAt(i);
+            }
+        }
+    }
+}