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

2 files changed, 47 insertions, 0 deletions

diff --git a/src/SMAPI/Events/FurnitureListChangedEventArgs.cs b/src/SMAPI/Events/FurnitureListChangedEventArgs.cs
new file mode 100644
index 00000000..04fcf9ff
--- /dev/null
+++ b/src/SMAPI/Events/FurnitureListChangedEventArgs.cs
@@ -0,0 +1,44 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using StardewValley;
+using StardewValley.Objects;
+
+namespace StardewModdingAPI.Events
+{
+    /// <summary>Event arguments for a <see cref="IWorldEvents.FurnitureListChanged"/> event.</summary>
+    public class FurnitureListChangedEventArgs : EventArgs
+    {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>The location which changed.</summary>
+        public GameLocation Location { get; }
+
+        /// <summary>The furniture added to the location.</summary>
+        public IEnumerable<Furniture> Added { get; }
+
+        /// <summary>The furniture removed from the location.</summary>
+        public IEnumerable<Furniture> Removed { get; }
+
+        /// <summary>Whether this is the location containing the local player.</summary>
+        public bool IsCurrentLocation => object.ReferenceEquals(this.Location, Game1.player?.currentLocation);
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="location">The location which changed.</param>
+        /// <param name="added">The furniture added to the location.</param>
+        /// <param name="removed">The furniture removed from the location.</param>
+        internal FurnitureListChangedEventArgs(GameLocation location, IEnumerable<Furniture> added, IEnumerable<Furniture> removed)
+        {
+            this.Location = location;
+            this.Added = added.ToArray();
+            this.Removed = removed.ToArray();
+        }
+    }
+}
diff --git a/src/SMAPI/Events/IWorldEvents.cs b/src/SMAPI/Events/IWorldEvents.cs
index 9569a57b..c023e1f0 100644
--- a/src/SMAPI/Events/IWorldEvents.cs
+++ b/src/SMAPI/Events/IWorldEvents.cs
@@ -28,5 +28,8 @@ namespace StardewModdingAPI.Events
 
         /// <summary>Raised after terrain features (like floors and trees) are added or removed in a location.</summary>
         event EventHandler<TerrainFeatureListChangedEventArgs> TerrainFeatureListChanged;
+
+        /// <summary>Raised after furniture are added or removed in a location.</summary>
+        event EventHandler<FurnitureListChangedEventArgs> FurnitureListChanged;
     }
 }