From f8047d6ab6d96bf9c7b87fcf50b93e2b084da2b5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bart=C5=82omiej=20Dach?= <dach.bartlomiej@gmail.com>
Date: Sun, 23 Jul 2023 19:48:39 +0200
Subject: [PATCH] Migrate skin element rotation handling to
 `SelectionRotationHandler`

---
 .../SkinEditor/SkinSelectionHandler.cs        | 29 +-----
 .../SkinSelectionRotationHandler.cs           | 94 +++++++++++++++++++
 2 files changed, 98 insertions(+), 25 deletions(-)
 create mode 100644 osu.Game/Overlays/SkinEditor/SkinSelectionRotationHandler.cs

diff --git a/osu.Game/Overlays/SkinEditor/SkinSelectionHandler.cs b/osu.Game/Overlays/SkinEditor/SkinSelectionHandler.cs
index 4a1ddd9d69..bee973bea0 100644
--- a/osu.Game/Overlays/SkinEditor/SkinSelectionHandler.cs
+++ b/osu.Game/Overlays/SkinEditor/SkinSelectionHandler.cs
@@ -26,31 +26,11 @@ namespace osu.Game.Overlays.SkinEditor
         [Resolved]
         private SkinEditor skinEditor { get; set; } = null!;
 
-        public override bool HandleRotation(float angle)
+        public override SelectionRotationHandler CreateRotationHandler() => new SkinSelectionRotationHandler(ChangeHandler)
         {
-            if (SelectedBlueprints.Count == 1)
-            {
-                // for single items, rotate around the origin rather than the selection centre.
-                ((Drawable)SelectedBlueprints.First().Item).Rotation += angle;
-            }
-            else
-            {
-                var selectionQuad = getSelectionQuad();
-
-                foreach (var b in SelectedBlueprints)
-                {
-                    var drawableItem = (Drawable)b.Item;
-
-                    var rotatedPosition = GeometryUtils.RotatePointAroundOrigin(b.ScreenSpaceSelectionPoint, selectionQuad.Centre, angle);
-                    updateDrawablePosition(drawableItem, rotatedPosition);
-
-                    drawableItem.Rotation += angle;
-                }
-            }
-
-            // this isn't always the case but let's be lenient for now.
-            return true;
-        }
+            SelectedItems = { BindTarget = SelectedItems },
+            UpdatePosition = updateDrawablePosition
+        };
 
         public override bool HandleScale(Vector2 scale, Anchor anchor)
         {
@@ -172,7 +152,6 @@ namespace osu.Game.Overlays.SkinEditor
         {
             base.OnSelectionChanged();
 
-            SelectionBox.CanRotate = true;
             SelectionBox.CanScaleX = true;
             SelectionBox.CanScaleY = true;
             SelectionBox.CanFlipX = true;
diff --git a/osu.Game/Overlays/SkinEditor/SkinSelectionRotationHandler.cs b/osu.Game/Overlays/SkinEditor/SkinSelectionRotationHandler.cs
new file mode 100644
index 0000000000..e60e2b1e12
--- /dev/null
+++ b/osu.Game/Overlays/SkinEditor/SkinSelectionRotationHandler.cs
@@ -0,0 +1,94 @@
+// 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 System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Game.Screens.Edit;
+using osu.Game.Screens.Edit.Compose.Components;
+using osu.Game.Skinning;
+using osu.Game.Utils;
+using osuTK;
+
+namespace osu.Game.Overlays.SkinEditor
+{
+    public class SkinSelectionRotationHandler : SelectionRotationHandler
+    {
+        private readonly IEditorChangeHandler? changeHandler;
+
+        public BindableList<ISerialisableDrawable> SelectedItems { get; } = new BindableList<ISerialisableDrawable>();
+        public Action<Drawable, Vector2> UpdatePosition { get; init; } = null!;
+
+        public SkinSelectionRotationHandler(IEditorChangeHandler? changeHandler)
+        {
+            this.changeHandler = changeHandler;
+
+            SelectedItems.CollectionChanged += (_, __) => updateState();
+        }
+
+        private void updateState()
+        {
+            CanRotate.Value = SelectedItems.Count > 0;
+        }
+
+        private Drawable[]? objectsInRotation;
+
+        private Vector2? defaultOrigin;
+        private Dictionary<Drawable, float>? originalRotations;
+        private Dictionary<Drawable, Vector2>? originalPositions;
+
+        public override void Begin()
+        {
+            if (objectsInRotation != null)
+                throw new InvalidOperationException($"Cannot {nameof(Begin)} a rotate operation while another is in progress!");
+
+            changeHandler?.BeginChange();
+
+            objectsInRotation = SelectedItems.Cast<Drawable>().ToArray();
+            originalRotations = objectsInRotation.ToDictionary(d => d, d => d.Rotation);
+            originalPositions = objectsInRotation.ToDictionary(d => d, d => d.ToScreenSpace(d.OriginPosition));
+            defaultOrigin = GeometryUtils.GetSurroundingQuad(objectsInRotation.SelectMany(d => d.ScreenSpaceDrawQuad.GetVertices().ToArray())).Centre;
+        }
+
+        public override void Update(float rotation, Vector2? origin = null)
+        {
+            if (objectsInRotation == null)
+                throw new InvalidOperationException($"Cannot {nameof(Update)} a rotate operation without calling {nameof(Begin)} first!");
+
+            Debug.Assert(originalRotations != null && originalPositions != null && defaultOrigin != null);
+
+            if (objectsInRotation.Length == 1 && origin == null)
+            {
+                // for single items, rotate around the origin rather than the selection centre by default.
+                objectsInRotation[0].Rotation = originalRotations.Single().Value + rotation;
+                return;
+            }
+
+            var actualOrigin = origin ?? defaultOrigin.Value;
+
+            foreach (var drawableItem in objectsInRotation)
+            {
+                var rotatedPosition = GeometryUtils.RotatePointAroundOrigin(originalPositions[drawableItem], actualOrigin, rotation);
+                UpdatePosition(drawableItem, rotatedPosition);
+
+                drawableItem.Rotation = originalRotations[drawableItem] + rotation;
+            }
+        }
+
+        public override void Commit()
+        {
+            if (objectsInRotation == null)
+                throw new InvalidOperationException($"Cannot {nameof(Commit)} a rotate operation without calling {nameof(Begin)} first!");
+
+            changeHandler?.EndChange();
+
+            objectsInRotation = null;
+            originalPositions = null;
+            originalRotations = null;
+            defaultOrigin = null;
+        }
+    }
+}