add internal context for more robust draw loop detection (#257)

src/StardewModdingAPI/Constants.cs

@@ -20,10 +20,10 @@ namespace StardewModdingAPI
         ** Properties
         *********/
         /// <summary>The directory path containing the current save's data (if a save is loaded).</summary>
-        private static string RawSavePath => Constants.IsSaveLoaded ? Path.Combine(Constants.SavesPath, Constants.GetSaveFolderName()) : null;
+        private static string RawSavePath => Context.IsSaveLoaded ? Path.Combine(Constants.SavesPath, Constants.GetSaveFolderName()) : null;
 
         /// <summary>Whether the directory containing the current save's data exists on disk.</summary>
-        private static bool SavePathReady => Constants.IsSaveLoaded && Directory.Exists(Constants.RawSavePath);
+        private static bool SavePathReady => Context.IsSaveLoaded && Directory.Exists(Constants.RawSavePath);
 
 
         /*********
@@ -54,7 +54,7 @@ namespace StardewModdingAPI
         public static string SavesPath { get; } = Path.Combine(Constants.DataPath, "Saves");
 
         /// <summary>The directory name containing the current save's data (if a save is loaded and the directory exists).</summary>
-        public static string SaveFolderName => Constants.IsSaveLoaded ? Constants.GetSaveFolderName() : "";
+        public static string SaveFolderName => Context.IsSaveLoaded ? Constants.GetSaveFolderName() : "";
 
         /// <summary>The directory path containing the current save's data (if a save is loaded and the directory exists).</summary>
         public static string CurrentSavePath => Constants.SavePathReady ? Path.Combine(Constants.SavesPath, Constants.GetSaveFolderName()) : "";
@@ -74,9 +74,6 @@ namespace StardewModdingAPI
         /// <summary>The full path to the folder containing mods.</summary>
         internal static string ModPath { get; } = Path.Combine(Constants.ExecutionPath, "Mods");
 
-        /// <summary>Whether a player save has been loaded.</summary>
-        internal static bool IsSaveLoaded => Game1.hasLoadedGame && !string.IsNullOrEmpty(Game1.player.name);
-
         /// <summary>The game's current semantic version.</summary>
         internal static ISemanticVersion GameVersion { get; } = Constants.GetGameVersion();
 

src/StardewModdingAPI/Context.cs

@@ -0,0 +1,17 @@
+using StardewValley;
+
+namespace StardewModdingAPI
+{
+    /// <summary>Provides information about the current game state.</summary>
+    internal static class Context
+    {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>Whether a player save has been loaded.</summary>
+        public static bool IsSaveLoaded => Game1.hasLoadedGame && !string.IsNullOrEmpty(Game1.player.name);
+
+        /// <summary>Whether the game is currently running the draw loop.</summary>
+        public static bool IsInDrawLoop { get; set; }
+    }
+}

src/StardewModdingAPI/Framework/ContentHelper.cs

@@ -141,9 +141,11 @@ namespace StardewModdingAPI.Framework
         /// <remarks>Based on <a href="https://gist.github.com/Layoric/6255384">code by Layoric</a>.</remarks>
         private Texture2D PremultiplyTransparency(Texture2D texture)
         {
-            if (Game1.graphics.GraphicsDevice.GetRenderTargets().Any()) // TODO: use a more robust check to detect if the game is drawing
+            // validate
+            if (Context.IsInDrawLoop)
                 throw new NotSupportedException("Can't load a PNG file while the game is drawing to the screen. Make sure you load content outside the draw loop.");
 
+            // process texture
             using (RenderTarget2D renderTarget = new RenderTarget2D(Game1.graphics.GraphicsDevice, texture.Width, texture.Height))
             using (SpriteBatch spriteBatch = new SpriteBatch(Game1.graphics.GraphicsDevice))
             {

src/StardewModdingAPI/Framework/SGame.cs

@@ -287,6 +287,7 @@ namespace StardewModdingAPI.Framework
         [SuppressMessage("ReSharper", "RedundantTypeArgumentsOfMethod", Justification = "copied from game code as-is")]
         protected override void Draw(GameTime gameTime)
         {
+            Context.IsInDrawLoop = true;
             try
             {
                 if (Game1.debugMode)
@@ -938,6 +939,7 @@ namespace StardewModdingAPI.Framework
             {
                 this.Monitor.Log($"An error occured in the overridden draw loop: {ex.GetLogSummary()}", LogLevel.Error);
             }
+            Context.IsInDrawLoop = false;
         }
 
         /****
@@ -1081,7 +1083,7 @@ namespace StardewModdingAPI.Framework
             }
 
             // save loaded event
-            if (Constants.IsSaveLoaded && !SaveGame.IsProcessing/*still loading save*/ && this.AfterLoadTimer >= 0)
+            if (Context.IsSaveLoaded && !SaveGame.IsProcessing/*still loading save*/ && this.AfterLoadTimer >= 0)
             {
                 if (this.AfterLoadTimer == 0)
                 {

src/StardewModdingAPI/Mod.cs

@@ -65,7 +65,7 @@ namespace StardewModdingAPI
             {
                 Mod.DeprecationManager.Warn($"{nameof(Mod)}.{nameof(Mod.PerSaveConfigPath)}", "1.0", DeprecationLevel.Info);
                 Mod.DeprecationManager.MarkWarned($"{nameof(Mod)}.{nameof(Mod.PerSaveConfigFolder)}", "1.0"); // avoid redundant warnings
-                return Constants.IsSaveLoaded ? Path.Combine(this.PerSaveConfigFolder, $"{Constants.SaveFolderName}.json") : "";
+                return Context.IsSaveLoaded ? Path.Combine(this.PerSaveConfigFolder, $"{Constants.SaveFolderName}.json") : "";
             }
         }
 

src/StardewModdingAPI/StardewModdingAPI.csproj

@@ -152,6 +152,7 @@
     <Compile Include="Framework\Content\ContentEventHelper.cs" />
     <Compile Include="Framework\Content\ContentEventHelperForDictionary.cs" />
     <Compile Include="Framework\Content\ContentEventHelperForImage.cs" />
+    <Compile Include="Context.cs" />
     <Compile Include="Framework\Logging\ConsoleInterceptionManager.cs" />
     <Compile Include="Framework\Logging\InterceptingTextWriter.cs" />
     <Compile Include="Framework\CommandHelper.cs" />