8 files changed, 119 insertions, 64 deletions
diff --git a/src/StardewModdingAPI/Framework/Content/AssetData.cs b/src/StardewModdingAPI/Framework/Content/AssetData.cs
new file mode 100644
index 00000000..1ab9eebd
--- /dev/null
+++ b/src/StardewModdingAPI/Framework/Content/AssetData.cs
@@ -0,0 +1,44 @@
+using System;
+
+namespace StardewModdingAPI.Framework.Content
+{
+    /// <summary>Base implementation for a content helper which encapsulates access and changes to content being read from a data file.</summary>
+    /// <typeparam name="TValue">The interface value type.</typeparam>
+    internal class AssetData<TValue> : AssetInfo, IAssetData<TValue>
+    {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>The content data being read.</summary>
+        public TValue Data { get; protected set; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="locale">The content's locale code, if the content is localised.</param>
+        /// <param name="assetName">The normalised asset name being read.</param>
+        /// <param name="data">The content data being read.</param>
+        /// <param name="getNormalisedPath">Normalises an asset key to match the cache key.</param>
+        public AssetData(string locale, string assetName, TValue data, Func<string, string> getNormalisedPath)
+            : base(locale, assetName, data.GetType(), getNormalisedPath)
+        {
+            this.Data = data;
+        }
+
+        /// <summary>Replace the entire content value with the given value. This is generally not recommended, since it may break compatibility with other mods or different versions of the game.</summary>
+        /// <param name="value">The new content value.</param>
+        /// <exception cref="ArgumentNullException">The <paramref name="value"/> is null.</exception>
+        /// <exception cref="InvalidCastException">The <paramref name="value"/>'s type is not compatible with the loaded asset's type.</exception>
+        public void ReplaceWith(TValue value)
+        {
+            if (value == null)
+                throw new ArgumentNullException(nameof(value), "Can't set a loaded asset to a null value.");
+            if (!this.DataType.IsInstanceOfType(value))
+                throw new InvalidCastException($"Can't replace loaded asset of type {this.GetFriendlyTypeName(this.DataType)} with value of type {this.GetFriendlyTypeName(value.GetType())}. The new type must be compatible to prevent game errors.");
+
+            this.Data = value;
+        }
+    }
+}
diff --git a/src/StardewModdingAPI/Framework/Content/ContentEventHelperForDictionary.cs b/src/StardewModdingAPI/Framework/Content/AssetDataForDictionary.cs
index 26f059e4..e9b29b12 100644
--- a/src/StardewModdingAPI/Framework/Content/ContentEventHelperForDictionary.cs
+++ b/src/StardewModdingAPI/Framework/Content/AssetDataForDictionary.cs
@@ -5,7 +5,7 @@ using System.Linq;
 namespace StardewModdingAPI.Framework.Content
 {
     /// <summary>Encapsulates access and changes to dictionary content being read from a data file.</summary>
-    internal class ContentEventHelperForDictionary<TKey, TValue> : ContentEventData<IDictionary<TKey, TValue>>, IContentEventHelperForDictionary<TKey, TValue>
+    internal class AssetDataForDictionary<TKey, TValue> : AssetData<IDictionary<TKey, TValue>>, IAssetDataForDictionary<TKey, TValue>
     {
         /*********
         ** Public methods
@@ -15,7 +15,7 @@ namespace StardewModdingAPI.Framework.Content
         /// <param name="assetName">The normalised asset name being read.</param>
         /// <param name="data">The content data being read.</param>
         /// <param name="getNormalisedPath">Normalises an asset key to match the cache key.</param>
-        public ContentEventHelperForDictionary(string locale, string assetName, IDictionary<TKey, TValue> data, Func<string, string> getNormalisedPath)
+        public AssetDataForDictionary(string locale, string assetName, IDictionary<TKey, TValue> data, Func<string, string> getNormalisedPath)
             : base(locale, assetName, data, getNormalisedPath) { }
 
         /// <summary>Add or replace an entry in the dictionary.</summary>
diff --git a/src/StardewModdingAPI/Framework/Content/ContentEventHelperForImage.cs b/src/StardewModdingAPI/Framework/Content/AssetDataForImage.cs
index da30590b..45c5588b 100644
--- a/src/StardewModdingAPI/Framework/Content/ContentEventHelperForImage.cs
+++ b/src/StardewModdingAPI/Framework/Content/AssetDataForImage.cs
@@ -5,7 +5,7 @@ using Microsoft.Xna.Framework.Graphics;
 namespace StardewModdingAPI.Framework.Content
 {
     /// <summary>Encapsulates access and changes to dictionary content being read from a data file.</summary>
-    internal class ContentEventHelperForImage : ContentEventData<Texture2D>, IContentEventHelperForImage
+    internal class AssetDataForImage : AssetData<Texture2D>, IAssetDataForImage
     {
         /*********
         ** Public methods
@@ -15,7 +15,7 @@ namespace StardewModdingAPI.Framework.Content
         /// <param name="assetName">The normalised asset name being read.</param>
         /// <param name="data">The content data being read.</param>
         /// <param name="getNormalisedPath">Normalises an asset key to match the cache key.</param>
-        public ContentEventHelperForImage(string locale, string assetName, Texture2D data, Func<string, string> getNormalisedPath)
+        public AssetDataForImage(string locale, string assetName, Texture2D data, Func<string, string> getNormalisedPath)
             : base(locale, assetName, data, getNormalisedPath) { }
 
         /// <summary>Overwrite part of the image.</summary>
diff --git a/src/StardewModdingAPI/Framework/Content/ContentEventHelper.cs b/src/StardewModdingAPI/Framework/Content/AssetDataForObject.cs
index 9bf1ea17..af2f54ae 100644
--- a/src/StardewModdingAPI/Framework/Content/ContentEventHelper.cs
+++ b/src/StardewModdingAPI/Framework/Content/AssetDataForObject.cs
@@ -5,7 +5,7 @@ using Microsoft.Xna.Framework.Graphics;
 namespace StardewModdingAPI.Framework.Content
 {
     /// <summary>Encapsulates access and changes to content being read from a data file.</summary>
-    internal class ContentEventHelper : ContentEventData<object>, IContentEventHelper
+    internal class AssetDataForObject : AssetData<object>, IAssetData
     {
         /*********
         ** Public methods
@@ -15,23 +15,23 @@ namespace StardewModdingAPI.Framework.Content
         /// <param name="assetName">The normalised asset name being read.</param>
         /// <param name="data">The content data being read.</param>
         /// <param name="getNormalisedPath">Normalises an asset key to match the cache key.</param>
-        public ContentEventHelper(string locale, string assetName, object data, Func<string, string> getNormalisedPath)
+        public AssetDataForObject(string locale, string assetName, object data, Func<string, string> getNormalisedPath)
             : base(locale, assetName, data, getNormalisedPath) { }
 
         /// <summary>Get a helper to manipulate the data as a dictionary.</summary>
         /// <typeparam name="TKey">The expected dictionary key.</typeparam>
         /// <typeparam name="TValue">The expected dictionary balue.</typeparam>
         /// <exception cref="InvalidOperationException">The content being read isn't a dictionary.</exception>
-        public IContentEventHelperForDictionary<TKey, TValue> AsDictionary<TKey, TValue>()
+        public IAssetDataForDictionary<TKey, TValue> AsDictionary<TKey, TValue>()
         {
-            return new ContentEventHelperForDictionary<TKey, TValue>(this.Locale, this.AssetName, this.GetData<IDictionary<TKey, TValue>>(), this.GetNormalisedPath);
+            return new AssetDataForDictionary<TKey, TValue>(this.Locale, this.AssetName, this.GetData<IDictionary<TKey, TValue>>(), this.GetNormalisedPath);
         }
 
         /// <summary>Get a helper to manipulate the data as an image.</summary>
         /// <exception cref="InvalidOperationException">The content being read isn't an image.</exception>
-        public IContentEventHelperForImage AsImage()
+        public IAssetDataForImage AsImage()
         {
-            return new ContentEventHelperForImage(this.Locale, this.AssetName, this.GetData<Texture2D>(), this.GetNormalisedPath);
+            return new AssetDataForImage(this.Locale, this.AssetName, this.GetData<Texture2D>(), this.GetNormalisedPath);
         }
 
         /// <summary>Get the data as a given type.</summary>
diff --git a/src/StardewModdingAPI/Framework/Content/ContentEventData.cs b/src/StardewModdingAPI/Framework/Content/AssetInfo.cs
index 1a1779d4..08bc3a03 100644
--- a/src/StardewModdingAPI/Framework/Content/ContentEventData.cs
+++ b/src/StardewModdingAPI/Framework/Content/AssetInfo.cs
@@ -4,9 +4,7 @@ using Microsoft.Xna.Framework.Graphics;
 
 namespace StardewModdingAPI.Framework.Content
 {
-    /// <summary>Base implementation for a content helper which encapsulates access and changes to content being read from a data file.</summary>
-    /// <typeparam name="TValue">The interface value type.</typeparam>
-    internal class ContentEventData<TValue> : EventArgs, IContentEventData<TValue>
+    internal class AssetInfo : IAssetInfo
     {
         /*********
         ** Properties
@@ -24,9 +22,6 @@ namespace StardewModdingAPI.Framework.Content
         /// <summary>The normalised asset name being read. The format may change between platforms; see <see cref="IsAssetName"/> to compare with a known path.</summary>
         public string AssetName { get; }
 
-        /// <summary>The content data being read.</summary>
-        public TValue Data { get; protected set; }
-
         /// <summary>The content data type.</summary>
         public Type DataType { get; }
 
@@ -37,23 +32,13 @@ namespace StardewModdingAPI.Framework.Content
         /// <summary>Construct an instance.</summary>
         /// <param name="locale">The content's locale code, if the content is localised.</param>
         /// <param name="assetName">The normalised asset name being read.</param>
-        /// <param name="data">The content data being read.</param>
-        /// <param name="getNormalisedPath">Normalises an asset key to match the cache key.</param>
-        public ContentEventData(string locale, string assetName, TValue data, Func<string, string> getNormalisedPath)
-            : this(locale, assetName, data, data.GetType(), getNormalisedPath) { }
-
-        /// <summary>Construct an instance.</summary>
-        /// <param name="locale">The content's locale code, if the content is localised.</param>
-        /// <param name="assetName">The normalised asset name being read.</param>
-        /// <param name="data">The content data being read.</param>
-        /// <param name="dataType">The content data type being read.</param>
+        /// <param name="type">The content type being read.</param>
         /// <param name="getNormalisedPath">Normalises an asset key to match the cache key.</param>
-        public ContentEventData(string locale, string assetName, TValue data, Type dataType, Func<string, string> getNormalisedPath)
+        public AssetInfo(string locale, string assetName, Type type, Func<string, string> getNormalisedPath)
         {
             this.Locale = locale;
             this.AssetName = assetName;
-            this.Data = data;
-            this.DataType = dataType;
+            this.DataType = type;
             this.GetNormalisedPath = getNormalisedPath;
         }
 
@@ -65,20 +50,6 @@ namespace StardewModdingAPI.Framework.Content
             return this.AssetName.Equals(path, StringComparison.InvariantCultureIgnoreCase);
         }
 
-        /// <summary>Replace the entire content value with the given value. This is generally not recommended, since it may break compatibility with other mods or different versions of the game.</summary>
-        /// <param name="value">The new content value.</param>
-        /// <exception cref="ArgumentNullException">The <paramref name="value"/> is null.</exception>
-        /// <exception cref="InvalidCastException">The <paramref name="value"/>'s type is not compatible with the loaded asset's type.</exception>
-        public void ReplaceWith(TValue value)
-        {
-            if (value == null)
-                throw new ArgumentNullException(nameof(value), "Can't set a loaded asset to a null value.");
-            if (!this.DataType.IsInstanceOfType(value))
-                throw new InvalidCastException($"Can't replace loaded asset of type {this.GetFriendlyTypeName(this.DataType)} with value of type {this.GetFriendlyTypeName(value.GetType())}. The new type must be compatible to prevent game errors.");
-
-            this.Data = value;
-        }
-
 
         /*********
         ** Protected methods
diff --git a/src/StardewModdingAPI/Framework/ContentHelper.cs b/src/StardewModdingAPI/Framework/ContentHelper.cs
index 7fd5e803..f4b541e9 100644
--- a/src/StardewModdingAPI/Framework/ContentHelper.cs
+++ b/src/StardewModdingAPI/Framework/ContentHelper.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Linq;
@@ -33,6 +34,13 @@ namespace StardewModdingAPI.Framework
 
 
         /*********
+        ** Accessors
+        *********/
+        /// <summary>Editors which change content assets after they're loaded.</summary>
+        internal IList<IAssetEditor> AssetEditors { get; } = new List<IAssetEditor>();
+
+
+        /*********
         ** Public methods
         *********/
         /// <summary>Construct an instance.</summary>
diff --git a/src/StardewModdingAPI/Framework/SContentManager.cs b/src/StardewModdingAPI/Framework/SContentManager.cs
index acd3e108..38457862 100644
--- a/src/StardewModdingAPI/Framework/SContentManager.cs
+++ b/src/StardewModdingAPI/Framework/SContentManager.cs
@@ -3,11 +3,9 @@ using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
 using System.Linq;
-using System.Threading;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Content;
 using StardewModdingAPI.AssemblyRewriters;
-using StardewModdingAPI.Events;
 using StardewModdingAPI.Framework.Content;
 using StardewModdingAPI.Framework.Reflection;
 using StardewValley;
@@ -42,6 +40,9 @@ namespace StardewModdingAPI.Framework
         /*********
         ** Accessors
         *********/
+        /// <summary>Implementations which change assets after they're loaded.</summary>
+        internal IDictionary<IModMetadata, IList<IAssetEditor>> Editors { get; } = new Dictionary<IModMetadata, IList<IAssetEditor>>();
+
         /// <summary>The absolute path to the <see cref="ContentManager.RootDirectory"/>.</summary>
         public string FullRootDirectory => Path.Combine(Constants.ExecutionPath, this.RootDirectory);
 
@@ -52,13 +53,6 @@ namespace StardewModdingAPI.Framework
         /// <summary>Construct an instance.</summary>
         /// <param name="serviceProvider">The service provider to use to locate services.</param>
         /// <param name="rootDirectory">The root directory to search for content.</param>
-        /// <param name="monitor">Encapsulates monitoring and logging.</param>
-        public SContentManager(IServiceProvider serviceProvider, string rootDirectory, IMonitor monitor)
-            : this(serviceProvider, rootDirectory, Thread.CurrentThread.CurrentUICulture, null, monitor) { }
-
-        /// <summary>Construct an instance.</summary>
-        /// <param name="serviceProvider">The service provider to use to locate services.</param>
-        /// <param name="rootDirectory">The root directory to search for content.</param>
         /// <param name="currentCulture">The current culture for which to localise content.</param>
         /// <param name="languageCodeOverride">The current language code for which to localise content.</param>
         /// <param name="monitor">Encapsulates monitoring and logging.</param>
@@ -66,8 +60,8 @@ namespace StardewModdingAPI.Framework
             : base(serviceProvider, rootDirectory, currentCulture, languageCodeOverride)
         {
             // initialise
-            this.Monitor = monitor;
             IReflectionHelper reflection = new ReflectionHelper();
+            this.Monitor = monitor;
 
             // get underlying fields for interception
             this.Cache = reflection.GetPrivateField<Dictionary<string, object>>(this, "loadedAssets").GetValue();
@@ -125,14 +119,20 @@ namespace StardewModdingAPI.Framework
             if (this.IsNormalisedKeyLoaded(assetName))
                 return base.Load<T>(assetName);
 
-            // load data
-            T data = base.Load<T>(assetName);
-
             // let mods intercept content
-            IContentEventHelper helper = new ContentEventHelper(cacheLocale, assetName, data, this.NormaliseAssetName);
-            ContentEvents.InvokeAfterAssetLoaded(this.Monitor, helper);
-            this.Cache[assetName] = helper.Data;
-            return (T)helper.Data;
+            IAssetInfo info = new AssetInfo(cacheLocale, assetName, typeof(T), this.NormaliseAssetName);
+            Lazy<IAssetData> data = new Lazy<IAssetData>(() => new AssetDataForObject(info.Locale, info.AssetName, base.Load<T>(assetName), this.NormaliseAssetName));
+            if (this.TryOverrideAssetLoad(info, data, out T result))
+            {
+                if (result == null)
+                    throw new InvalidCastException($"Can't override asset '{assetName}' with a null value.");
+
+                this.Cache[assetName] = result;
+                return result;
+            }
+
+            // fallback to default behavior
+            return base.Load<T>(assetName);
         }
 
         /// <summary>Inject an asset into the cache.</summary>
@@ -171,5 +171,35 @@ namespace StardewModdingAPI.Framework
                 ? locale
                 : null;
         }
+
+        /// <summary>Try to override an asset being loaded.</summary>
+        /// <typeparam name="T">The asset type.</typeparam>
+        /// <param name="info">The asset metadata.</param>
+        /// <param name="data">The loaded asset data.</param>
+        /// <param name="result">The asset to use instead.</param>
+        /// <returns>Returns whether the asset should be overridden by <paramref name="result"/>.</returns>
+        private bool TryOverrideAssetLoad<T>(IAssetInfo info, Lazy<IAssetData> data, out T result)
+        {
+            bool edited = false;
+
+            // apply editors
+            foreach (var modEditors in this.Editors)
+            {
+                IModMetadata mod = modEditors.Key;
+                foreach (IAssetEditor editor in modEditors.Value)
+                {
+                    if (!editor.CanEdit<T>(info))
+                        continue;
+
+                    this.Monitor.Log($"{mod.DisplayName} intercepted {info.AssetName}.", LogLevel.Trace);
+                    editor.Edit<T>(data.Value);
+                    edited = true;
+                }
+            }
+
+            // return result
+            result = edited ? (T)data.Value.Data : default(T);
+            return edited;
+        }
     }
 }
diff --git a/src/StardewModdingAPI/Framework/SGame.cs b/src/StardewModdingAPI/Framework/SGame.cs
index 602a522b..e4c2a233 100644
--- a/src/StardewModdingAPI/Framework/SGame.cs
+++ b/src/StardewModdingAPI/Framework/SGame.cs
@@ -4,6 +4,7 @@ using System.Collections.Generic;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
+using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
@@ -29,6 +30,9 @@ namespace StardewModdingAPI.Framework
         /****
         ** SMAPI state
         ****/
+        /// <summary>Encapsulates monitoring and logging.</summary>
+        private readonly IMonitor Monitor;
+
         /// <summary>The maximum number of consecutive attempts SMAPI should make to recover from a draw error.</summary>
         private readonly Countdown DrawCrashTimer = new Countdown(60); // 60 ticks = roughly one second
 
@@ -48,8 +52,6 @@ namespace StardewModdingAPI.Framework
         /// <summary>Whether the game's zoom level is at 100% (i.e. nothing should be scaled).</summary>
         public bool ZoomLevelIsOne => Game1.options.zoomLevel.Equals(1.0f);
 
-        /// <summary>Encapsulates monitoring and logging.</summary>
-        private readonly IMonitor Monitor;
 
         /****
         ** Game state
@@ -189,7 +191,7 @@ namespace StardewModdingAPI.Framework
             //   2. Since Game1.content isn't initialised yet, and we need one main instance to
             //      support custom map tilesheets, detect when Game1.content is being initialised
             //      and use the same instance.
-            this.Content = new SContentManager(this.Content.ServiceProvider, this.Content.RootDirectory, this.Monitor);
+            this.Content = new SContentManager(this.Content.ServiceProvider, this.Content.RootDirectory, Thread.CurrentThread.CurrentUICulture, null, this.Monitor);
         }
 
         /****
@@ -206,7 +208,7 @@ namespace StardewModdingAPI.Framework
                 return mainContentManager;
 
             // build new instance
-            return new SContentManager(this.Content.ServiceProvider, this.Content.RootDirectory, this.Monitor);
+            return new SContentManager(this.Content.ServiceProvider, this.Content.RootDirectory, Thread.CurrentThread.CurrentUICulture, null, this.Monitor);
         }
 
         /// <summary>The method called when the game is updating its state. This happens roughly 60 times per second.</summary>