Add Hold to Walk mod for osu!catch

osu.Game.Rulesets.Catch/CatchRuleset.cs

@@ -150,6 +150,7 @@ namespace osu.Game.Rulesets.Catch
                         new CatchModFloatingFruits(),
                         new CatchModMuted(),
                         new CatchModNoScope(),
+                        new CatchModHoldToWalk(),
                     };
 
                 case ModType.System:

osu.Game.Rulesets.Catch/Mods/CatchModHoldToWalk.cs

@@ -0,0 +1,80 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Sprites;
+using osu.Framework.Input.Bindings;
+using osu.Framework.Input.Events;
+using osu.Framework.Localisation;
+using osu.Game.Rulesets.Catch.Objects;
+using osu.Game.Rulesets.Catch.UI;
+using osu.Game.Rulesets.Mods;
+using osu.Game.Rulesets.UI;
+using osu.Game.Screens.Play;
+using osuTK;
+
+namespace osu.Game.Rulesets.Catch.Mods
+{
+    public partial class CatchModHoldToWalk : Mod, IApplicableToDrawableRuleset<CatchHitObject>, IApplicableToPlayer
+    {
+        public override string Name => "Hold to Walk";
+        public override string Acronym => "HW";
+        public override LocalisableString Description => "Hold the Dash key to walk!";
+        public override double ScoreMultiplier => 1;
+        public override IconUsage? Icon => FontAwesome.Solid.Running;
+        public override Type[] IncompatibleMods => new[] { typeof(ModAutoplay), typeof(ModRelax) };
+
+        private DrawableCatchRuleset drawableRuleset = null!;
+
+        public void ApplyToDrawableRuleset(DrawableRuleset<CatchHitObject> drawableRuleset)
+        {
+            this.drawableRuleset = (DrawableCatchRuleset)drawableRuleset;
+        }
+
+        public void ApplyToPlayer(Player player)
+        {
+            if (!drawableRuleset.HasReplayLoaded.Value)
+            {
+                var catchPlayfield = (CatchPlayfield)drawableRuleset.Playfield;
+                catchPlayfield.Catcher.Dashing = true;
+                catchPlayfield.CatcherArea.Add(new InvertDashInputHelper(catchPlayfield.CatcherArea));
+            }
+        }
+
+        private partial class InvertDashInputHelper : Drawable, IKeyBindingHandler<CatchAction>
+        {
+            private readonly CatcherArea catcherArea;
+
+            public override bool ReceivePositionalInputAt(Vector2 screenSpacePos) => true;
+
+            public InvertDashInputHelper(CatcherArea catcherArea)
+            {
+                this.catcherArea = catcherArea;
+
+                RelativeSizeAxes = Axes.Both;
+            }
+
+            public bool OnPressed(KeyBindingPressEvent<CatchAction> e)
+            {
+                switch (e.Action)
+                {
+                    case CatchAction.MoveLeft or CatchAction.MoveRight:
+                        break;
+
+                    case CatchAction.Dash:
+                        catcherArea.Catcher.Dashing = false;
+                        return true;
+                }
+
+                return false;
+            }
+
+            public void OnReleased(KeyBindingReleaseEvent<CatchAction> e)
+            {
+                if (e.Action == CatchAction.Dash)
+                    catcherArea.Catcher.Dashing = true;
+            }
+        }
+    }
+}