add mouse scroll event (#310)

src/SMAPI/Events/IInputEvents.cs

@@ -13,5 +13,8 @@ namespace StardewModdingAPI.Events
 
         /// <summary>Raised after the player moves the in-game cursor.</summary>
         event EventHandler<InputCursorMovedArgsInput> CursorMoved;
+
+        /// <summary>Raised after the player scrolls the mouse wheel.</summary>
+        event EventHandler<InputMouseWheelScrolledEventArgs> MouseWheelScrolled;
     }
 }

src/SMAPI/Events/InputMouseWheelScrolledEventArgs.cs

@@ -0,0 +1,38 @@
+using System;
+
+namespace StardewModdingAPI.Events
+{
+    /// <summary>Event arguments when the player scrolls the mouse wheel.</summary>
+    public class InputMouseWheelScrolledEventArgs : EventArgs
+    {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>The cursor position.</summary>
+        public ICursorPosition Position { get; }
+
+        /// <summary>The old scroll value.</summary>
+        public int OldValue { get; }
+
+        /// <summary>The new scroll value.</summary>
+        public int NewValue { get; }
+
+        /// <summary>The amount by which the scroll value changed.</summary>
+        public int Delta => this.NewValue - this.OldValue;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="position">The cursor position.</param>
+        /// <param name="oldValue">The old scroll value.</param>
+        /// <param name="newValue">The new scroll value.</param>
+        public InputMouseWheelScrolledEventArgs(ICursorPosition position, int oldValue, int newValue)
+        {
+            this.Position = position;
+            this.OldValue = oldValue;
+            this.NewValue = newValue;
+        }
+    }
+}

src/SMAPI/Framework/Events/EventManager.cs

@@ -44,6 +44,9 @@ namespace StardewModdingAPI.Framework.Events
         /// <summary>Raised after the player moves the in-game cursor.</summary>
         public readonly ManagedEvent<InputCursorMovedArgsInput> Input_CursorMoved;
 
+        /// <summary>Raised after the player scrolls the mouse wheel.</summary>
+        public readonly ManagedEvent<InputMouseWheelScrolledEventArgs> Input_MouseWheelScrolled;
+
 
         /*********
         ** Events (old)
@@ -249,6 +252,7 @@ namespace StardewModdingAPI.Framework.Events
             this.Input_ButtonPressed = ManageEventOf<InputButtonPressedArgsInput>(nameof(IModEvents.Input), nameof(IInputEvents.ButtonPressed));
             this.Input_ButtonReleased = ManageEventOf<InputButtonReleasedArgsInput>(nameof(IModEvents.Input), nameof(IInputEvents.ButtonReleased));
             this.Input_CursorMoved = ManageEventOf<InputCursorMovedArgsInput>(nameof(IModEvents.Input), nameof(IInputEvents.CursorMoved));
+            this.Input_MouseWheelScrolled = ManageEventOf<InputMouseWheelScrolledEventArgs>(nameof(IModEvents.Input), nameof(IInputEvents.MouseWheelScrolled));
 
             this.World_BuildingListChanged = ManageEventOf<WorldBuildingListChangedEventArgs>(nameof(IModEvents.World), nameof(IWorldEvents.LocationListChanged));
             this.World_LargeTerrainFeatureListChanged = ManageEventOf<WorldLargeTerrainFeatureListChangedEventArgs>(nameof(IModEvents.World), nameof(IWorldEvents.LargeTerrainFeatureListChanged));

src/SMAPI/Framework/Events/ModInputEvents.cs

@@ -30,6 +30,13 @@ namespace StardewModdingAPI.Framework.Events
             remove => this.EventManager.Input_CursorMoved.Remove(value);
         }
 
+        /// <summary>Raised after the player scrolls the mouse wheel.</summary>
+        public event EventHandler<InputMouseWheelScrolledEventArgs> MouseWheelScrolled
+        {
+            add => this.EventManager.Input_MouseWheelScrolled.Add(value);
+            remove => this.EventManager.Input_MouseWheelScrolled.Remove(value);
+        }
+
 
         /*********
         ** Public methods

src/SMAPI/Framework/SGame.cs

@@ -103,6 +103,9 @@ namespace StardewModdingAPI.Framework
         /// <summary>Tracks changes to the cursor position.</summary>
         private readonly IValueWatcher<Point> CursorWatcher;
 
+        /// <summary>Tracks changes to the mouse wheel scroll.</summary>
+        private readonly IValueWatcher<int> MouseWheelScrollWatcher;
+
         /// <summary>The previous content locale.</summary>
         private LocalizedContentManager.LanguageCode? PreviousLocale;
 
@@ -172,6 +175,7 @@ namespace StardewModdingAPI.Framework
             // init watchers
             Game1.locations = new ObservableCollection<GameLocation>();
             this.CursorWatcher = WatcherFactory.ForEquatable(() => this.Input.MousePosition);
+            this.MouseWheelScrollWatcher = WatcherFactory.ForEquatable(() => this.Input.RealMouse.ScrollWheelValue);
             this.SaveIdWatcher = WatcherFactory.ForEquatable(() => Game1.hasLoadedGame ? Game1.uniqueIDForThisGame : 0);
             this.WindowSizeWatcher = WatcherFactory.ForEquatable(() => new Point(Game1.viewport.Width, Game1.viewport.Height));
             this.TimeWatcher = WatcherFactory.ForEquatable(() => Game1.timeOfDay);
@@ -180,6 +184,7 @@ namespace StardewModdingAPI.Framework
             this.Watchers.AddRange(new IWatcher[]
             {
                 this.CursorWatcher,
+                this.MouseWheelScrollWatcher,
                 this.SaveIdWatcher,
                 this.WindowSizeWatcher,
                 this.TimeWatcher,
@@ -468,6 +473,16 @@ namespace StardewModdingAPI.Framework
                         }
                         this.PreviousCursorPosition = cursor;
 
+                        // raise mouse wheel scrolled
+                        if (this.MouseWheelScrollWatcher.IsChanged)
+                        {
+                            int oldValue = this.MouseWheelScrollWatcher.PreviousValue;
+                            int newValue = this.MouseWheelScrollWatcher.CurrentValue;
+                            this.MouseWheelScrollWatcher.Reset();
+
+                            this.Events.Input_MouseWheelScrolled.Raise(new InputMouseWheelScrolledEventArgs(cursor, oldValue, newValue));
+                        }
+
                         // raise input button events
                         foreach (var pair in inputState.ActiveButtons)
                         {

src/SMAPI/StardewModdingAPI.csproj

@@ -85,6 +85,7 @@
     <Compile Include="..\..\build\GlobalAssemblyInfo.cs">
       <Link>Properties\GlobalAssemblyInfo.cs</Link>
     </Compile>
+    <Compile Include="Events\InputMouseWheelScrolledEventArgs.cs" />
     <Compile Include="Events\InputCursorMovedEventArgs.cs" />
     <Compile Include="Events\InputButtonReleasedEventArgs.cs" />
     <Compile Include="Events\InputButtonPressedEventArgs.cs" />