Added Achivement.GetIconAsync() (waits for load if not loaded)

Facepunch.Steamworks.Test/UserStatsTest.cs

@@ -13,7 +13,7 @@ namespace Steamworks
     public class UserStatsTest
 	{
 		[TestMethod]
-        public void AchievementList()
+        public async Task AchievementList()
         {
 			foreach ( var a in SteamUserStats.Achievements )
 			{
@@ -24,7 +24,7 @@ public void AchievementList()
 				Console.WriteLine( $"	a.Description: {a.Description}" );
 				Console.WriteLine( $"	a.GlobalUnlocked:	{a.GlobalUnlocked}" );
 
-				var icon = a.GetIcon();
+				var icon = await a.GetIconAsync();
 
 				Console.WriteLine( $"	a.Icon:	{icon}" );
 			}			

Facepunch.Steamworks/SteamUserStats.cs

@@ -43,8 +43,16 @@ internal static void InstallEvents()
 			UserStatsStored_t.Install( x => OnUserStatsStored?.Invoke( x.Result ) );
 			UserAchievementStored_t.Install( x => OnAchievementProgress?.Invoke( x.AchievementName, (int) x.CurProgress, (int)x.MaxProgress ) );
 			UserStatsUnloaded_t.Install( x => OnUserStatsUnloaded?.Invoke( x.SteamIDUser ) );
+			UserAchievementIconFetched_t.Install( x => OnAchievementIconFetched( x.AchievementName, x.IconHandle ) );
+
 		}
 
+
+		/// <summary>
+		/// called when the achivement icon is loaded
+		/// </summary>
+		internal static event Action<string, int> OnAchievementIconFetched;
+
 		/// <summary>
 		/// called when the latests stats and achievements have been received
 		///	from the server

Facepunch.Steamworks/SteamUtils.cs

@@ -99,6 +99,8 @@ public static bool GetImageSize( int image, out uint width, out uint height )
 		/// </summary>
 		public static Data.Image? GetImage( int image )
 		{
+			if ( image == 0 ) return null;
+
 			var i = new Data.Image();
 
 			if ( !GetImageSize( image, out i.Width, out i.Height ) )

Facepunch.Steamworks/Structs/Achievement.cs

@@ -55,13 +55,57 @@ public DateTime? UnlockTime
 		}
 
 		/// <summary>
-		/// Gets the icon of the achievement
+		/// Gets the icon of the achievement. This can return a null image even though the image exists if the image
+		/// hasn't been downloaded by Steam yet. You can use GetIconAsync if you want to wait for the image to be downloaded.
 		/// </summary>
 		public Image? GetIcon()
 		{
 			return SteamUtils.GetImage( SteamUserStats.Internal.GetAchievementIcon( Value ) );
 		}
 
+
+		/// <summary>
+		/// Gets the icon of the achievement, waits for it to load if we have to
+		/// </summary>
+		public async Task<Image?> GetIconAsync( int timeout = 5000 )
+		{
+			var i = SteamUserStats.Internal.GetAchievementIcon( Value );
+			if ( i != 0 ) return SteamUtils.GetImage( i );
+
+			var ident = Identifier;
+			bool gotCallback = false;
+
+			Action<string, int> f = ( x, icon ) =>
+			{
+				if ( x != ident ) return;
+				i = icon;
+				gotCallback = true;
+			};
+
+			try
+			{
+				SteamUserStats.OnAchievementIconFetched += f;
+
+				int waited = 0;
+				while ( !gotCallback )
+				{
+					await Task.Delay( 10 );
+					waited += 10;
+
+					// Time out after x milliseconds
+					if ( waited > timeout )
+						return null;
+				}
+
+				if ( i == 0 ) return null;
+				return SteamUtils.GetImage( i );
+			}
+			finally
+			{
+				SteamUserStats.OnAchievementIconFetched -= f;
+			}
+		}
+
 		/// <summary>
 		/// Returns the fraction (0-1) of users who have unlocked the specified achievement, or -1 if no data available.
 		/// </summary>