Added overload of Leaderboard.FetchScores that takes a callback

Facepunch.Steamworks.Test/Client/Leaderboard.cs

@@ -51,6 +51,53 @@ namespace Facepunch.Steamworks.Test
             }
         }
 
+        [TestMethod]
+        public void GetLeaderboardCallback()
+        {
+            using ( var client = new Steamworks.Client( 252490 ) )
+            {
+                var board = client.GetLeaderboard( "TestLeaderboard", Steamworks.Client.LeaderboardSortMethod.Ascending, Steamworks.Client.LeaderboardDisplayType.Numeric );
+
+                while ( !board.IsValid )
+                {
+                    Thread.Sleep( 10 );
+                    client.Update();
+                }
+
+                Assert.IsTrue( board.IsValid );
+                Assert.IsFalse( board.IsError );
+                Assert.IsNotNull( board.Name );
+
+                Console.WriteLine( $"Board name is \"{board.Name}\"" );
+                Console.WriteLine( $"Board has \"{board.TotalEntries}\" entries" );
+
+                board.AddScore( true, 86275309, 7, 8, 9 );
+
+                var done = false;
+
+                board.FetchScores( Steamworks.Leaderboard.RequestType.Global, 0, 20, ( success, results ) =>
+                {
+                    Assert.IsTrue( success );
+
+                    foreach ( var entry in board.Results )
+                    {
+                        Console.WriteLine( $"{entry.GlobalRank}: {entry.SteamId} ({entry.Name}) with {entry.Score}" );
+
+                        if ( entry.SubScores != null )
+                            Console.WriteLine( " - " + string.Join( ";", entry.SubScores.Select( x => x.ToString() ).ToArray() ) );
+                    }
+
+                    done = true;
+                } );
+
+                while ( !done )
+                {
+                    Thread.Sleep( 10 );
+                    client.Update();
+                }
+            }
+        }
+
         [TestMethod]
         public void AddScores()
         {

Facepunch.Steamworks/Client/Leaderboard.cs

@@ -125,6 +125,55 @@ namespace Facepunch.Steamworks
             return true;
         }
 
+        private unsafe void ReadScores( LeaderboardScoresDownloaded_t result, List<Entry> dest )
+        {
+            for ( var i = 0; i < result.CEntryCount; i++ )
+                fixed ( int* ptr = subEntriesBuffer )
+                {
+                    var entry = new LeaderboardEntry_t();
+                    if ( client.native.userstats.GetDownloadedLeaderboardEntry( result.SteamLeaderboardEntries, i, ref entry, (IntPtr) ptr, subEntriesBuffer.Length ) )
+                        dest.Add( new Entry
+                        {
+                            GlobalRank = entry.GlobalRank,
+                            Score = entry.Score,
+                            SteamId = entry.SteamIDUser,
+                            SubScores = entry.CDetails == 0 ? null : subEntriesBuffer.Take( entry.CDetails ).ToArray(),
+                            Name = client.Friends.GetName( entry.SteamIDUser )
+                        } );
+                }
+        }
+
+        [ThreadStatic] private static List<Entry> _sEntryBuffer;
+
+        public delegate void FetchScoresCallback( bool success, Entry[] results );
+
+        /// <summary>
+        ///     Fetch a subset of scores. The scores are passed to <paramref name="callback"/>.
+        /// </summary>
+        /// <returns>Returns true if we have started the query</returns>
+        public bool FetchScores( RequestType RequestType, int start, int end, FetchScoresCallback callback )
+        {
+            if ( !IsValid ) return false;
+
+            client.native.userstats.DownloadLeaderboardEntries( BoardId, (LeaderboardDataRequest) RequestType, start, end, ( result, error ) =>
+            {
+                if ( error )
+                {
+                    callback( false, null );
+                }
+                else
+                {
+                    if ( _sEntryBuffer == null ) _sEntryBuffer = new List<Entry>();
+                    else _sEntryBuffer.Clear();
+
+                    ReadScores( result, _sEntryBuffer );
+                    callback( true, _sEntryBuffer.ToArray() );
+                }
+            } );
+
+            return true;
+        }
+
         private unsafe void OnScores( LeaderboardScoresDownloaded_t result, bool error )
         {
             IsQuerying = false;
@@ -135,21 +184,7 @@ namespace Facepunch.Steamworks
                 return;
 
             var list = new List<Entry>();
-
+            ReadScores( result, list );
-            for ( var i = 0; i < result.CEntryCount; i++ )
-                fixed ( int* ptr = subEntriesBuffer )
-                {
-                    var entry = new LeaderboardEntry_t();
-                    if ( client.native.userstats.GetDownloadedLeaderboardEntry( result.SteamLeaderboardEntries, i, ref entry, (IntPtr) ptr, subEntriesBuffer.Length ) )
-                        list.Add( new Entry
-                        {
-                            GlobalRank = entry.GlobalRank,
-                            Score = entry.Score,
-                            SteamId = entry.SteamIDUser,
-                            SubScores = entry.CDetails == 0 ? null : subEntriesBuffer.Take( entry.CDetails ).ToArray(),
-                            Name = client.Friends.GetName( entry.SteamIDUser )
-                        } );
-                }
 
             Results = list.ToArray();
         }