From 0cb3926e1d090b7c336b16a5512f31f696d18661 Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Fri, 2 Oct 2020 15:44:32 +0900
Subject: [PATCH] Add event on EditorChangeHandler state change

---
 .../Editing/EditorChangeHandlerTest.cs        | 22 ++++++++++++++++++-
 osu.Game/Screens/Edit/EditorChangeHandler.cs  |  5 +++++
 osu.Game/Screens/Edit/IEditorChangeHandler.cs |  6 +++++
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/osu.Game.Tests/Editing/EditorChangeHandlerTest.cs b/osu.Game.Tests/Editing/EditorChangeHandlerTest.cs
index ff2c9fb1a9..b7a41ffd1c 100644
--- a/osu.Game.Tests/Editing/EditorChangeHandlerTest.cs
+++ b/osu.Game.Tests/Editing/EditorChangeHandlerTest.cs
@@ -12,6 +12,14 @@ namespace osu.Game.Tests.Editing
     [TestFixture]
     public class EditorChangeHandlerTest
     {
+        private int stateChangedFired;
+
+        [SetUp]
+        public void SetUp()
+        {
+            stateChangedFired = 0;
+        }
+
         [Test]
         public void TestSaveRestoreState()
         {
@@ -23,6 +31,8 @@ public void TestSaveRestoreState()
             addArbitraryChange(beatmap);
             handler.SaveState();
 
+            Assert.That(stateChangedFired, Is.EqualTo(1));
+
             Assert.That(handler.CanUndo.Value, Is.True);
             Assert.That(handler.CanRedo.Value, Is.False);
 
@@ -30,6 +40,8 @@ public void TestSaveRestoreState()
 
             Assert.That(handler.CanUndo.Value, Is.False);
             Assert.That(handler.CanRedo.Value, Is.True);
+
+            Assert.That(stateChangedFired, Is.EqualTo(2));
         }
 
         [Test]
@@ -45,6 +57,7 @@ public void TestSaveSameStateDoesNotSave()
 
             Assert.That(handler.CanUndo.Value, Is.True);
             Assert.That(handler.CanRedo.Value, Is.False);
+            Assert.That(stateChangedFired, Is.EqualTo(1));
 
             string hash = handler.CurrentStateHash;
 
@@ -52,6 +65,7 @@ public void TestSaveSameStateDoesNotSave()
             handler.SaveState();
 
             Assert.That(hash, Is.EqualTo(handler.CurrentStateHash));
+            Assert.That(stateChangedFired, Is.EqualTo(1));
 
             handler.RestoreState(-1);
 
@@ -60,6 +74,7 @@ public void TestSaveSameStateDoesNotSave()
             // we should only be able to restore once even though we saved twice.
             Assert.That(handler.CanUndo.Value, Is.False);
             Assert.That(handler.CanRedo.Value, Is.True);
+            Assert.That(stateChangedFired, Is.EqualTo(2));
         }
 
         [Test]
@@ -71,6 +86,8 @@ public void TestMaxStatesSaved()
 
             for (int i = 0; i < EditorChangeHandler.MAX_SAVED_STATES; i++)
             {
+                Assert.That(stateChangedFired, Is.EqualTo(i));
+
                 addArbitraryChange(beatmap);
                 handler.SaveState();
             }
@@ -114,7 +131,10 @@ public void TestMaxStatesExceeded()
         {
             var beatmap = new EditorBeatmap(new Beatmap());
 
-            return (new EditorChangeHandler(beatmap), beatmap);
+            var changeHandler = new EditorChangeHandler(beatmap);
+
+            changeHandler.OnStateChange += () => stateChangedFired++;
+            return (changeHandler, beatmap);
         }
 
         private void addArbitraryChange(EditorBeatmap beatmap)
diff --git a/osu.Game/Screens/Edit/EditorChangeHandler.cs b/osu.Game/Screens/Edit/EditorChangeHandler.cs
index 617c436ee0..616d0608c0 100644
--- a/osu.Game/Screens/Edit/EditorChangeHandler.cs
+++ b/osu.Game/Screens/Edit/EditorChangeHandler.cs
@@ -21,6 +21,8 @@ public class EditorChangeHandler : IEditorChangeHandler
         public readonly Bindable<bool> CanUndo = new Bindable<bool>();
         public readonly Bindable<bool> CanRedo = new Bindable<bool>();
 
+        public event Action OnStateChange;
+
         private readonly LegacyEditorBeatmapPatcher patcher;
         private readonly List<byte[]> savedStates = new List<byte[]>();
 
@@ -109,6 +111,8 @@ public void SaveState()
                 savedStates.Add(newState);
 
                 currentState = savedStates.Count - 1;
+
+                OnStateChange?.Invoke();
                 updateBindables();
             }
         }
@@ -136,6 +140,7 @@ public void RestoreState(int direction)
 
             isRestoring = false;
 
+            OnStateChange?.Invoke();
             updateBindables();
         }
 
diff --git a/osu.Game/Screens/Edit/IEditorChangeHandler.cs b/osu.Game/Screens/Edit/IEditorChangeHandler.cs
index c1328252d4..a23a956e14 100644
--- a/osu.Game/Screens/Edit/IEditorChangeHandler.cs
+++ b/osu.Game/Screens/Edit/IEditorChangeHandler.cs
@@ -1,6 +1,7 @@
 // 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.Game.Rulesets.Objects;
 
 namespace osu.Game.Screens.Edit
@@ -10,6 +11,11 @@ namespace osu.Game.Screens.Edit
     /// </summary>
     public interface IEditorChangeHandler
     {
+        /// <summary>
+        /// Fired whenever a state change occurs.
+        /// </summary>
+        public event Action OnStateChange;
+
         /// <summary>
         /// Begins a bulk state change event. <see cref="EndChange"/> should be invoked soon after.
         /// </summary>