From 6ab29a62d04b66130928cdb463b7b48424025fb5 Mon Sep 17 00:00:00 2001
From: ekrctb <ekrctb@gmail.com>
Date: Tue, 11 Oct 2022 14:23:17 +0900
Subject: [PATCH] Anchor drag box on time (catch, mania)

Not done for taiko because I cannot figure out how it should work with the overlapping scroll algorithm.
---
 .../Edit/CatchBlueprintContainer.cs           |  3 +
 .../Edit/ManiaBlueprintContainer.cs           |  3 +
 .../Compose/Components/ScrollingDragBox.cs    | 63 +++++++++++++++++++
 3 files changed, 69 insertions(+)
 create mode 100644 osu.Game/Screens/Edit/Compose/Components/ScrollingDragBox.cs

diff --git a/osu.Game.Rulesets.Catch/Edit/CatchBlueprintContainer.cs b/osu.Game.Rulesets.Catch/Edit/CatchBlueprintContainer.cs
index 58f493b4b8..20d432d62e 100644
--- a/osu.Game.Rulesets.Catch/Edit/CatchBlueprintContainer.cs
+++ b/osu.Game.Rulesets.Catch/Edit/CatchBlueprintContainer.cs
@@ -5,6 +5,7 @@
 
 using osu.Game.Rulesets.Catch.Edit.Blueprints;
 using osu.Game.Rulesets.Catch.Objects;
+using osu.Game.Rulesets.Catch.UI;
 using osu.Game.Rulesets.Edit;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Screens.Edit.Compose.Components;
@@ -36,5 +37,7 @@ namespace osu.Game.Rulesets.Catch.Edit
 
             return base.CreateHitObjectBlueprintFor(hitObject);
         }
+
+        protected sealed override DragBox CreateDragBox() => new ScrollingDragBox((CatchPlayfield)Composer.Playfield);
     }
 }
diff --git a/osu.Game.Rulesets.Mania/Edit/ManiaBlueprintContainer.cs b/osu.Game.Rulesets.Mania/Edit/ManiaBlueprintContainer.cs
index ad75afff8e..c3fad1e22b 100644
--- a/osu.Game.Rulesets.Mania/Edit/ManiaBlueprintContainer.cs
+++ b/osu.Game.Rulesets.Mania/Edit/ManiaBlueprintContainer.cs
@@ -6,6 +6,7 @@
 using osu.Game.Rulesets.Edit;
 using osu.Game.Rulesets.Mania.Edit.Blueprints;
 using osu.Game.Rulesets.Mania.Objects;
+using osu.Game.Rulesets.Mania.UI;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Screens.Edit.Compose.Components;
 
@@ -33,5 +34,7 @@ namespace osu.Game.Rulesets.Mania.Edit
         }
 
         protected override SelectionHandler<HitObject> CreateSelectionHandler() => new ManiaSelectionHandler();
+
+        protected sealed override DragBox CreateDragBox() => new ScrollingDragBox((ManiaPlayfield)Composer.Playfield);
     }
 }
diff --git a/osu.Game/Screens/Edit/Compose/Components/ScrollingDragBox.cs b/osu.Game/Screens/Edit/Compose/Components/ScrollingDragBox.cs
new file mode 100644
index 0000000000..2d2c88247b
--- /dev/null
+++ b/osu.Game/Screens/Edit/Compose/Components/ScrollingDragBox.cs
@@ -0,0 +1,63 @@
+// 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.Input.Events;
+using osu.Game.Rulesets.UI.Scrolling;
+
+namespace osu.Game.Screens.Edit.Compose.Components
+{
+    /// <summary>
+    /// A <see cref="DragBox"/> that scrolls along with the scrolling playfield.
+    /// </summary>
+    public class ScrollingDragBox : DragBox
+    {
+        public double MinTime { get; private set; }
+
+        public double MaxTime { get; private set; }
+
+        private double? startTime;
+
+        private readonly ScrollingPlayfield playfield;
+
+        public ScrollingDragBox(ScrollingPlayfield playfield)
+        {
+            this.playfield = playfield;
+        }
+
+        public override void HandleDrag(MouseButtonEvent e)
+        {
+            base.HandleDrag(e);
+
+            startTime ??= playfield.TimeAtScreenSpacePosition(e.ScreenSpaceMouseDownPosition);
+            double endTime = playfield.TimeAtScreenSpacePosition(e.ScreenSpaceMousePosition);
+
+            MinTime = Math.Min(startTime.Value, endTime);
+            MaxTime = Math.Max(startTime.Value, endTime);
+
+            var startPos = ToLocalSpace(playfield.ScreenSpacePositionAtTime(startTime.Value));
+            var endPos = ToLocalSpace(playfield.ScreenSpacePositionAtTime(endTime));
+
+            switch (playfield.ScrollingInfo.Direction.Value)
+            {
+                case ScrollingDirection.Up:
+                case ScrollingDirection.Down:
+                    Box.Y = Math.Min(startPos.Y, endPos.Y);
+                    Box.Height = Math.Max(startPos.Y, endPos.Y) - Box.Y;
+                    break;
+
+                case ScrollingDirection.Left:
+                case ScrollingDirection.Right:
+                    Box.X = Math.Min(startPos.X, endPos.X);
+                    Box.Width = Math.Max(startPos.X, endPos.X) - Box.X;
+                    break;
+            }
+        }
+
+        public override void Hide()
+        {
+            base.Hide();
+            startTime = null;
+        }
+    }
+}