reduce allocations in input handling

Pathoschild · Pathoschild · commit 3bb18fcdaf76 · 2026-02-01T18:17:24.000-05:00
This reuses the input builders instead of creating new ones each time we build input.
diff --git a/docs/release-notes.md b/docs/release-notes.md
@@ -3,6 +3,7 @@
 # Release notes
 ## Upcoming release
 * For players:
+  * Minor performance optimizations.
   * Fixed the Linux/macOS installer not saving the color scheme correctly in 4.5.0+.
   * Fixed typo in config UI text (thanks to QuentiumYT!).
   * Improved translations. Thanks to dewanggatrustha (updated Indonesian), QuentiumYT (updated French), and  Timur13240
diff --git a/src/SMAPI/Framework/Input/GamePadStateBuilder.cs b/src/SMAPI/Framework/Input/GamePadStateBuilder.cs
@@ -21,7 +21,7 @@ internal class GamePadStateBuilder : IInputStateBuilder<GamePadStateBuilder, Gam
     private GamePadState? State;
 
     /// <summary>The current button states.</summary>
-    private readonly Dictionary<SButton, ButtonState> ButtonStates;
+    private readonly Dictionary<SButton, ButtonState> ButtonStates = [];
 
     /// <summary>The left trigger value.</summary>
     private float LeftTrigger;
@@ -39,9 +39,8 @@ internal class GamePadStateBuilder : IInputStateBuilder<GamePadStateBuilder, Gam
     /*********
     ** Public methods
     *********/
-    /// <summary>Construct an instance.</summary>
-    /// <param name="state">The initial state.</param>
-    public GamePadStateBuilder(GamePadState state)
+    /// <inheritdoc />
+    public void Reset(GamePadState state)
     {
         this.State = state;
 
@@ -51,32 +50,39 @@ public GamePadStateBuilder(GamePadState state)
             GamePadButtons buttons = state.Buttons;
             GamePadTriggers triggers = state.Triggers;
             GamePadThumbSticks sticks = state.ThumbSticks;
-            this.ButtonStates = new Dictionary<SButton, ButtonState>
-            {
-                [SButton.DPadUp] = pad.Up,
-                [SButton.DPadDown] = pad.Down,
-                [SButton.DPadLeft] = pad.Left,
-                [SButton.DPadRight] = pad.Right,
-
-                [SButton.ControllerA] = buttons.A,
-                [SButton.ControllerB] = buttons.B,
-                [SButton.ControllerX] = buttons.X,
-                [SButton.ControllerY] = buttons.Y,
-                [SButton.LeftStick] = buttons.LeftStick,
-                [SButton.RightStick] = buttons.RightStick,
-                [SButton.LeftShoulder] = buttons.LeftShoulder,
-                [SButton.RightShoulder] = buttons.RightShoulder,
-                [SButton.ControllerBack] = buttons.Back,
-                [SButton.ControllerStart] = buttons.Start,
-                [SButton.BigButton] = buttons.BigButton
-            };
+
+            var states = this.ButtonStates;
+            states.Clear();
+            states[SButton.DPadUp] = pad.Up;
+            states[SButton.DPadDown] = pad.Down;
+            states[SButton.DPadLeft] = pad.Left;
+            states[SButton.DPadRight] = pad.Right;
+            states[SButton.ControllerA] = buttons.A;
+            states[SButton.ControllerB] = buttons.B;
+            states[SButton.ControllerX] = buttons.X;
+            states[SButton.ControllerY] = buttons.Y;
+            states[SButton.LeftStick] = buttons.LeftStick;
+            states[SButton.RightStick] = buttons.RightStick;
+            states[SButton.LeftShoulder] = buttons.LeftShoulder;
+            states[SButton.RightShoulder] = buttons.RightShoulder;
+            states[SButton.ControllerBack] = buttons.Back;
+            states[SButton.ControllerStart] = buttons.Start;
+            states[SButton.BigButton] = buttons.BigButton;
+
             this.LeftTrigger = triggers.Left;
             this.RightTrigger = triggers.Right;
             this.LeftStickPos = sticks.Left;
             this.RightStickPos = sticks.Right;
         }
         else
-            this.ButtonStates = [];
+        {
+            this.ButtonStates.Clear();
+
+            this.LeftTrigger = 0;
+            this.RightTrigger = 0;
+            this.LeftStickPos = Vector2.Zero;
+            this.RightStickPos = Vector2.Zero;
+        }
     }
 
     /// <inheritdoc />
diff --git a/src/SMAPI/Framework/Input/IInputStateBuilder.cs b/src/SMAPI/Framework/Input/IInputStateBuilder.cs
@@ -12,6 +12,10 @@ internal interface IInputStateBuilder<out THandler, TState>
     /*********
     ** Methods
     *********/
+    /// <summary>Reset the state.</summary>
+    /// <param name="state">The initial state before any overrides are applied.</param>
+    void Reset(TState state);
+
     /// <summary>Override the states for a set of buttons.</summary>
     /// <param name="overrides">The button state overrides.</param>
     THandler OverrideButtons(IDictionary<SButton, SButtonState> overrides);
diff --git a/src/SMAPI/Framework/Input/KeyboardStateBuilder.cs b/src/SMAPI/Framework/Input/KeyboardStateBuilder.cs
@@ -20,9 +20,8 @@ internal class KeyboardStateBuilder : IInputStateBuilder<KeyboardStateBuilder, K
     /*********
     ** Public methods
     *********/
-    /// <summary>Construct an instance.</summary>
-    /// <param name="state">The initial state.</param>
-    public KeyboardStateBuilder(KeyboardState state)
+    /// <inheritdoc />
+    public void Reset(KeyboardState state)
     {
         this.State = state;
 
diff --git a/src/SMAPI/Framework/Input/MouseStateBuilder.cs b/src/SMAPI/Framework/Input/MouseStateBuilder.cs
@@ -13,39 +13,38 @@ internal class MouseStateBuilder : IInputStateBuilder<MouseStateBuilder, MouseSt
     private MouseState? State;
 
     /// <summary>The current button states.</summary>
-    private readonly IDictionary<SButton, ButtonState> ButtonStates;
+    private readonly Dictionary<SButton, ButtonState> ButtonStates = [];
 
     /// <summary>The mouse wheel scroll value.</summary>
-    private readonly int ScrollWheelValue;
+    private int ScrollWheelValue;
 
 
     /*********
     ** Accessors
     *********/
     /// <summary>The X cursor position.</summary>
-    public int X { get; }
+    public int X { get; private set; }
 
     /// <summary>The Y cursor position.</summary>
-    public int Y { get; }
+    public int Y { get; private set; }
 
 
     /*********
     ** Public methods
     *********/
-    /// <summary>Construct an instance.</summary>
-    /// <param name="state">The initial state.</param>
-    public MouseStateBuilder(MouseState state)
+    /// <inheritdoc />
+    public void Reset(MouseState state)
     {
         this.State = state;
 
-        this.ButtonStates = new Dictionary<SButton, ButtonState>
-        {
-            [SButton.MouseLeft] = state.LeftButton,
-            [SButton.MouseMiddle] = state.MiddleButton,
-            [SButton.MouseRight] = state.RightButton,
-            [SButton.MouseX1] = state.XButton1,
-            [SButton.MouseX2] = state.XButton2
-        };
+        var states = this.ButtonStates;
+        states.Clear();
+        states[SButton.MouseLeft] = state.LeftButton;
+        states[SButton.MouseMiddle] = state.MiddleButton;
+        states[SButton.MouseRight] = state.RightButton;
+        states[SButton.MouseX1] = state.XButton1;
+        states[SButton.MouseX2] = state.XButton2;
+
         this.X = state.X;
         this.Y = state.Y;
         this.ScrollWheelValue = state.ScrollWheelValue;
diff --git a/src/SMAPI/Framework/Input/SInputState.cs b/src/SMAPI/Framework/Input/SInputState.cs
@@ -29,6 +29,15 @@ internal sealed class SInputState : InputState
     /// <summary>Whether there are new overrides in <see cref="CustomPressedKeys"/> or <see cref="CustomReleasedKeys"/> that haven't been applied to the previous state.</summary>
     private bool HasNewOverrides;
 
+    /// <summary>The builder which reads the game pad state and applies overrides.</summary>
+    private readonly GamePadStateBuilder ControllerStateBuilder = new();
+
+    /// <summary>The builder which reads the keyboard state and applies overrides.</summary>
+    private readonly KeyboardStateBuilder KeyboardStateBuilder = new();
+
+    /// <summary>The builder which reads the mouse state and applies overrides.</summary>
+    private readonly MouseStateBuilder MouseStateBuilder = new();
+
 
     /*********
     ** Accessors
@@ -68,10 +77,15 @@ public void TrueUpdate()
         {
             float zoomMultiplier = (1f / Game1.options.zoomLevel);
 
+            // get builders
+            GamePadStateBuilder controller = this.ControllerStateBuilder;
+            KeyboardStateBuilder keyboard = this.KeyboardStateBuilder;
+            MouseStateBuilder mouse = this.MouseStateBuilder;
+
             // get real values
-            var controller = new GamePadStateBuilder(base.GetGamePadState());
-            var keyboard = new KeyboardStateBuilder(base.GetKeyboardState());
-            var mouse = new MouseStateBuilder(base.GetMouseState());
+            controller.Reset(base.GetGamePadState());
+            keyboard.Reset(base.GetKeyboardState());
+            mouse.Reset(base.GetMouseState());
             Vector2 cursorAbsolutePos = new((mouse.X * zoomMultiplier) + Game1.viewport.X, (mouse.Y * zoomMultiplier) + Game1.viewport.Y);
             Vector2? playerTilePos = Context.IsPlayerFree ? Game1.player.Tile : null;
             HashSet<SButton> reallyDown = new(this.GetPressedButtons(keyboard, mouse, controller));
@@ -159,9 +173,13 @@ public void ApplyOverrides()
     {
         if (this.HasNewOverrides)
         {
-            var controller = new GamePadStateBuilder(this.ControllerState);
-            var keyboard = new KeyboardStateBuilder(this.KeyboardState);
-            var mouse = new MouseStateBuilder(this.MouseState);
+            GamePadStateBuilder controller = this.ControllerStateBuilder;
+            KeyboardStateBuilder keyboard = this.KeyboardStateBuilder;
+            MouseStateBuilder mouse = this.MouseStateBuilder;
+
+            controller.Reset(this.ControllerState);
+            keyboard.Reset(this.KeyboardState);
+            mouse.Reset(this.MouseState);
 
             if (this.ApplyOverrides(pressed: this.CustomPressedKeys, released: this.CustomReleasedKeys, controller, keyboard, mouse))
             {
