Add flow for copying existing difficulty content

osu.Game/Beatmaps/BeatmapManager.cs

@@ -20,6 +20,7 @@ using osu.Game.Online.API;
 using osu.Game.Online.API.Requests.Responses;
 using osu.Game.Overlays.Notifications;
 using osu.Game.Rulesets;
+using osu.Game.Screens.Edit;
 using osu.Game.Skinning;
 using osu.Game.Stores;
 
@@ -112,29 +113,36 @@ namespace osu.Game.Beatmaps
         /// The new difficulty will be backed by a <see cref="BeatmapInfo"/> model
         /// and represented by the returned <see cref="WorkingBeatmap"/>.
         /// </summary>
-        public virtual WorkingBeatmap CreateNewBlankDifficulty(BeatmapSetInfo beatmapSetInfo, RulesetInfo rulesetInfo)
+        public virtual WorkingBeatmap CreateNewBlankDifficulty(NewDifficultyCreationParameters creationParameters)
         {
-            // fetch one of the existing difficulties to copy timing points and metadata from,
-            // so that the user doesn't have to fill all of that out again.
-            // this silently assumes that all difficulties have the same timing points and metadata,
-            // but cases where this isn't true seem rather rare / pathological.
-            var referenceBeatmap = GetWorkingBeatmap(beatmapSetInfo.Beatmaps.First());
+            var referenceBeatmap = creationParameters.ReferenceBeatmap;
+            var targetBeatmapSet = creationParameters.BeatmapSet;
 
-            var newBeatmapInfo = new BeatmapInfo(rulesetInfo, new BeatmapDifficulty(), referenceBeatmap.Metadata.DeepClone());
+            var newBeatmapInfo = new BeatmapInfo(creationParameters.Ruleset, new BeatmapDifficulty(), referenceBeatmap.Metadata.DeepClone());
 
             // populate circular beatmap set info <-> beatmap info references manually.
             // several places like `BeatmapModelManager.Save()` or `GetWorkingBeatmap()`
             // rely on them being freely traversable in both directions for correct operation.
-            beatmapSetInfo.Beatmaps.Add(newBeatmapInfo);
-            newBeatmapInfo.BeatmapSet = beatmapSetInfo;
+            targetBeatmapSet.Beatmaps.Add(newBeatmapInfo);
+            newBeatmapInfo.BeatmapSet = targetBeatmapSet;
 
-            var newBeatmap = new Beatmap { BeatmapInfo = newBeatmapInfo };
-            foreach (var timingPoint in referenceBeatmap.Beatmap.ControlPointInfo.TimingPoints)
+            IBeatmap newBeatmap;
+
+            if (creationParameters.ClearAllObjects)
+            {
+                newBeatmap = new Beatmap { BeatmapInfo = newBeatmapInfo };
+                foreach (var timingPoint in referenceBeatmap.ControlPointInfo.TimingPoints)
                     newBeatmap.ControlPointInfo.Add(timingPoint.Time, timingPoint.DeepClone());
+            }
+            else
+            {
+                newBeatmap = referenceBeatmap.Clone();
+                newBeatmap.BeatmapInfo = newBeatmapInfo;
+            }
 
             beatmapModelManager.Save(newBeatmapInfo, newBeatmap);
 
-            workingBeatmapCache.Invalidate(beatmapSetInfo);
+            workingBeatmapCache.Invalidate(targetBeatmapSet);
             return GetWorkingBeatmap(newBeatmap.BeatmapInfo);
         }
 

osu.Game/Screens/Edit/CreateNewDifficultyDialog.cs

@@ -0,0 +1,45 @@
+// 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 osu.Framework.Graphics.Sprites;
+using osu.Game.Overlays.Dialog;
+
+namespace osu.Game.Screens.Edit
+{
+    public class CreateNewDifficultyDialog : PopupDialog
+    {
+        /// <summary>
+        /// Delegate used to create new difficulties.
+        /// A value of <see langword="true"/> in the <c>clearAllObjects</c> parameter
+        /// indicates that the new difficulty should have its hitobjects cleared;
+        /// otherwise, the new difficulty should be an exact copy of an existing one.
+        /// </summary>
+        public delegate void CreateNewDifficulty(bool clearAllObjects);
+
+        public CreateNewDifficultyDialog(CreateNewDifficulty createNewDifficulty)
+        {
+            HeaderText = "Would you like to clear all objects?";
+
+            Icon = FontAwesome.Regular.Clone;
+
+            Buttons = new PopupDialogButton[]
+            {
+                new PopupDialogOkButton
+                {
+                    Text = "Yeah, let's start from scratch!",
+                    Action = () => createNewDifficulty.Invoke(true)
+                },
+                new PopupDialogCancelButton
+                {
+                    Text = "No, create an exact copy of this difficulty",
+                    Action = () => createNewDifficulty.Invoke(false)
+                },
+                new PopupDialogCancelButton
+                {
+                    Text = "I changed my mind, I want to keep editing this difficulty",
+                    Action = () => { }
+                }
+            };
+        }
+    }
+}

osu.Game/Screens/Edit/Editor.cs

@@ -841,7 +841,25 @@ namespace osu.Game.Screens.Edit
         }
 
         protected void CreateNewDifficulty(RulesetInfo rulesetInfo)
-            => loader?.ScheduleSwitchToNewDifficulty(editorBeatmap.BeatmapInfo.BeatmapSet, rulesetInfo, GetState());
+        {
+            if (!rulesetInfo.Equals(editorBeatmap.BeatmapInfo.Ruleset))
+            {
+                switchToNewDifficulty(rulesetInfo, true);
+                return;
+            }
+
+            dialogOverlay.Push(new CreateNewDifficultyDialog(clearAllObjects => switchToNewDifficulty(rulesetInfo, clearAllObjects)));
+        }
+
+        private void switchToNewDifficulty(RulesetInfo rulesetInfo, bool clearAllObjects)
+            => loader?.ScheduleSwitchToNewDifficulty(new NewDifficultyCreationParameters
+            {
+                BeatmapSet = editorBeatmap.BeatmapInfo.BeatmapSet,
+                Ruleset = rulesetInfo,
+                ReferenceBeatmap = playableBeatmap,
+                ClearAllObjects = clearAllObjects,
+                EditorState = GetState()
+            });
 
         private EditorMenuItem createDifficultySwitchMenu()
         {

osu.Game/Screens/Edit/EditorLoader.cs

@@ -11,7 +11,6 @@ using osu.Framework.Screens;
 using osu.Framework.Threading;
 using osu.Game.Beatmaps;
 using osu.Game.Graphics.UserInterface;
-using osu.Game.Rulesets;
 using osu.Game.Rulesets.Mods;
 using osu.Game.Screens.Menu;
 using osu.Game.Screens.Play;
@@ -80,12 +79,12 @@ namespace osu.Game.Screens.Edit
             }
         }
 
-        public void ScheduleSwitchToNewDifficulty(BeatmapSetInfo beatmapSetInfo, RulesetInfo rulesetInfo, EditorState editorState)
+        public void ScheduleSwitchToNewDifficulty(NewDifficultyCreationParameters creationParameters)
             => scheduleDifficultySwitch(() =>
             {
                 try
                 {
-                    return beatmapManager.CreateNewBlankDifficulty(beatmapSetInfo, rulesetInfo);
+                    return beatmapManager.CreateNewBlankDifficulty(creationParameters);
                 }
                 catch (Exception ex)
                 {
@@ -94,7 +93,7 @@ namespace osu.Game.Screens.Edit
                     Logger.Error(ex, ex.Message);
                     return Beatmap.Value;
                 }
-            }, editorState);
+            }, creationParameters.EditorState);
 
         public void ScheduleSwitchToExistingDifficulty(BeatmapInfo beatmapInfo, EditorState editorState)
             => scheduleDifficultySwitch(() => beatmapManager.GetWorkingBeatmap(beatmapInfo), editorState);

osu.Game/Screens/Edit/NewDifficultyCreationParameters.cs

@@ -0,0 +1,36 @@
+// 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 osu.Game.Beatmaps;
+using osu.Game.Rulesets;
+
+namespace osu.Game.Screens.Edit
+{
+    public class NewDifficultyCreationParameters
+    {
+        /// <summary>
+        /// The <see cref="BeatmapSetInfo"/> that should contain the newly-created difficulty.
+        /// </summary>
+        public BeatmapSetInfo BeatmapSet { get; set; }
+
+        /// <summary>
+        /// The <see cref="RulesetInfo"/> that the new difficulty should be playable for.
+        /// </summary>
+        public RulesetInfo Ruleset { get; set; }
+
+        /// <summary>
+        /// A reference <see cref="IBeatmap"/> upon which the new difficulty should be based.
+        /// </summary>
+        public IBeatmap ReferenceBeatmap { get; set; }
+
+        /// <summary>
+        /// Whether all objects should be cleared from the new difficulty.
+        /// </summary>
+        public bool ClearAllObjects { get; set; }
+
+        /// <summary>
+        /// The saved state of the previous <see cref="Editor"/> which should be restored upon opening the newly-created difficulty.
+        /// </summary>
+        public EditorState EditorState { get; set; }
+    }
+}

osu.Game/Tests/Visual/EditorTestScene.cs

@@ -136,7 +136,7 @@ namespace osu.Game.Tests.Visual
                 return new TestWorkingBeatmapCache(this, audioManager, resources, storage, defaultBeatmap, host);
             }
 
-            public override WorkingBeatmap CreateNewBlankDifficulty(BeatmapSetInfo beatmapSetInfo, RulesetInfo rulesetInfo)
+            public override WorkingBeatmap CreateNewBlankDifficulty(NewDifficultyCreationParameters creationParameters)
             {
                 // don't actually care about properly creating a difficulty for this context.
                 return TestBeatmap;