Add `World.FurnitureListChanged` event

Create a new event available to SMAPI mods to track furniture changes. To facilitate the event, a `FurnitureListChangedEventArgs` class is added as well.

Fixes #778

5 files changed, 25 insertions, 1 deletions

diff --git a/src/SMAPI/Framework/Events/EventManager.cs b/src/SMAPI/Framework/Events/EventManager.cs
index f4abfffe..dfc289ed 100644
--- a/src/SMAPI/Framework/Events/EventManager.cs
+++ b/src/SMAPI/Framework/Events/EventManager.cs
@@ -162,6 +162,9 @@ namespace StardewModdingAPI.Framework.Events
         /// <summary>Raised after terrain features (like floors and trees) are added or removed in a location.</summary>
         public readonly ManagedEvent<TerrainFeatureListChangedEventArgs> TerrainFeatureListChanged;
 
+        /// <summary>Raised after furniture are added or removed in a location.</summary>
+        public readonly ManagedEvent<FurnitureListChangedEventArgs> FurnitureListChanged;
+
         /****
         ** Specialized
         ****/
@@ -238,6 +241,7 @@ namespace StardewModdingAPI.Framework.Events
             this.ObjectListChanged = ManageEventOf<ObjectListChangedEventArgs>(nameof(IModEvents.World), nameof(IWorldEvents.ObjectListChanged));
             this.ChestInventoryChanged = ManageEventOf<ChestInventoryChangedEventArgs>(nameof(IModEvents.World), nameof(IWorldEvents.ChestInventoryChanged));
             this.TerrainFeatureListChanged = ManageEventOf<TerrainFeatureListChangedEventArgs>(nameof(IModEvents.World), nameof(IWorldEvents.TerrainFeatureListChanged));
+            this.FurnitureListChanged = ManageEventOf<FurnitureListChangedEventArgs>(nameof(IModEvents.World), nameof(IWorldEvents.FurnitureListChanged));
 
             this.LoadStageChanged = ManageEventOf<LoadStageChangedEventArgs>(nameof(IModEvents.Specialized), nameof(ISpecializedEvents.LoadStageChanged));
             this.UnvalidatedUpdateTicking = ManageEventOf<UnvalidatedUpdateTickingEventArgs>(nameof(IModEvents.Specialized), nameof(ISpecializedEvents.UnvalidatedUpdateTicking), isPerformanceCritical: true);
diff --git a/src/SMAPI/Framework/Events/ModWorldEvents.cs b/src/SMAPI/Framework/Events/ModWorldEvents.cs
index 21b1b664..f4c40abc 100644
--- a/src/SMAPI/Framework/Events/ModWorldEvents.cs
+++ b/src/SMAPI/Framework/Events/ModWorldEvents.cs
@@ -65,6 +65,13 @@ namespace StardewModdingAPI.Framework.Events
             remove => this.EventManager.TerrainFeatureListChanged.Remove(value);
         }
 
+        /// <summary>Raised after furniture are added or removed in a location.</summary>
+        public event EventHandler<FurnitureListChangedEventArgs> FurnitureListChanged
+        {
+            add => this.EventManager.FurnitureListChanged.Add(value, this.Mod);
+            remove => this.EventManager.FurnitureListChanged.Remove(value);
+        }
+
 
         /*********
         ** Public methods
diff --git a/src/SMAPI/Framework/SCore.cs b/src/SMAPI/Framework/SCore.cs
index 8b2c7544..bf88798b 100644
--- a/src/SMAPI/Framework/SCore.cs
+++ b/src/SMAPI/Framework/SCore.cs
@@ -914,6 +914,10 @@ namespace StardewModdingAPI.Framework
                                 // terrain features changed
                                 if (locState.TerrainFeatures.IsChanged)
                                     events.TerrainFeatureListChanged.Raise(new TerrainFeatureListChangedEventArgs(location, locState.TerrainFeatures.Added, locState.TerrainFeatures.Removed));
+
+                                // furniture changed
+                                if (locState.Furniture.IsChanged)
+                                    events.FurnitureListChanged.Raise(new FurnitureListChangedEventArgs(location, locState.Furniture.Added, locState.Furniture.Removed));
                             }
                         }
 
diff --git a/src/SMAPI/Framework/StateTracking/LocationTracker.cs b/src/SMAPI/Framework/StateTracking/LocationTracker.cs
index 519fe8f4..6d3a62bb 100644
--- a/src/SMAPI/Framework/StateTracking/LocationTracker.cs
+++ b/src/SMAPI/Framework/StateTracking/LocationTracker.cs
@@ -48,6 +48,9 @@ namespace StardewModdingAPI.Framework.StateTracking
         /// <summary>Tracks added or removed terrain features.</summary>
         public IDictionaryWatcher<Vector2, TerrainFeature> TerrainFeaturesWatcher { get; }
 
+        /// <summary>Tracks added or removed furniture.</summary>
+        public ICollectionWatcher<Furniture> FurnitureWatcher { get; }
+
         /// <summary>Tracks items added or removed to chests.</summary>
         public IDictionary<Vector2, ChestTracker> ChestWatchers { get; } = new Dictionary<Vector2, ChestTracker>();
 
@@ -68,6 +71,7 @@ namespace StardewModdingAPI.Framework.StateTracking
             this.NpcsWatcher = WatcherFactory.ForNetCollection(location.characters);
             this.ObjectsWatcher = WatcherFactory.ForNetDictionary(location.netObjects);
             this.TerrainFeaturesWatcher = WatcherFactory.ForNetDictionary(location.terrainFeatures);
+            this.FurnitureWatcher = WatcherFactory.ForNetCollection(location.furniture);
 
             this.Watchers.AddRange(new IWatcher[]
             {
@@ -76,7 +80,8 @@ namespace StardewModdingAPI.Framework.StateTracking
                 this.LargeTerrainFeaturesWatcher,
                 this.NpcsWatcher,
                 this.ObjectsWatcher,
-                this.TerrainFeaturesWatcher
+                this.TerrainFeaturesWatcher,
+                this.FurnitureWatcher
             });
 
             this.UpdateChestWatcherList(added: location.Objects.Pairs, removed: new KeyValuePair<Vector2, SObject>[0]);
diff --git a/src/SMAPI/Framework/StateTracking/Snapshots/LocationSnapshot.cs b/src/SMAPI/Framework/StateTracking/Snapshots/LocationSnapshot.cs
index 6ae52fd0..6c9cc4f5 100644
--- a/src/SMAPI/Framework/StateTracking/Snapshots/LocationSnapshot.cs
+++ b/src/SMAPI/Framework/StateTracking/Snapshots/LocationSnapshot.cs
@@ -34,6 +34,9 @@ namespace StardewModdingAPI.Framework.StateTracking.Snapshots
         /// <summary>Tracks added or removed terrain features.</summary>
         public SnapshotListDiff<KeyValuePair<Vector2, TerrainFeature>> TerrainFeatures { get; } = new SnapshotListDiff<KeyValuePair<Vector2, TerrainFeature>>();
 
+        /// <summary>Tracks added or removed furniture.</summary>
+        public SnapshotListDiff<Furniture> Furniture { get; } = new SnapshotListDiff<Furniture>();
+
         /// <summary>Tracks changed chest inventories.</summary>
         public IDictionary<Chest, SnapshotItemListDiff> ChestItems { get; } = new Dictionary<Chest, SnapshotItemListDiff>();
 
@@ -59,6 +62,7 @@ namespace StardewModdingAPI.Framework.StateTracking.Snapshots
             this.Npcs.Update(watcher.NpcsWatcher);
             this.Objects.Update(watcher.ObjectsWatcher);
             this.TerrainFeatures.Update(watcher.TerrainFeaturesWatcher);
+            this.Furniture.Update(watcher.FurnitureWatcher);
 
             // chest inventories
             this.ChestItems.Clear();