Add support for creating new blank difficulties

osu.Game/Beatmaps/BeatmapManager.cs

@@ -73,7 +73,9 @@ namespace osu.Game.Beatmaps
             new BeatmapModelManager(realm, storage, onlineLookupQueue);
 
         /// <summary>
-        /// Create a new <see cref="WorkingBeatmap"/>.
+        /// Create a new beatmap set, backed by a <see cref="BeatmapSetInfo"/> model,
+        /// with a single difficulty which is backed by a <see cref="BeatmapInfo"/> model
+        /// and represented by the returned usable <see cref="WorkingBeatmap"/>.
         /// </summary>
         public WorkingBeatmap CreateNew(RulesetInfo ruleset, APIUser user)
         {
@@ -105,6 +107,34 @@ namespace osu.Game.Beatmaps
             return imported.PerformRead(s => GetWorkingBeatmap(s.Beatmaps.First()));
         }
 
+        /// <summary>
+        /// Add a new difficulty to the beatmap set represented by the provided <see cref="BeatmapSetInfo"/>.
+        /// The new difficulty will be backed by a <see cref="BeatmapInfo"/> model
+        /// and represented by the returned <see cref="WorkingBeatmap"/>.
+        /// </summary>
+        public WorkingBeatmap CreateNewBlankDifficulty(BeatmapSetInfo beatmapSetInfo, RulesetInfo rulesetInfo)
+        {
+            // 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 newBeatmap = new Beatmap
+            {
+                BeatmapInfo = new BeatmapInfo(rulesetInfo, new BeatmapDifficulty(), referenceBeatmap.Metadata.DeepClone())
+            };
+
+            foreach (var timingPoint in referenceBeatmap.Beatmap.ControlPointInfo.TimingPoints)
+                newBeatmap.ControlPointInfo.Add(timingPoint.Time, timingPoint.DeepClone());
+
+            var createdBeatmapInfo = beatmapModelManager.AddDifficultyToBeatmapSet(beatmapSetInfo, newBeatmap);
+            return GetWorkingBeatmap(createdBeatmapInfo);
+        }
+
+        // TODO: add back support for making a copy of another difficulty
+        // (likely via a separate `CopyDifficulty()` method).
+
         /// <summary>
         /// Delete a beatmap difficulty.
         /// </summary>

osu.Game/Beatmaps/BeatmapMetadata.cs

@@ -7,6 +7,7 @@ using Newtonsoft.Json;
 using osu.Framework.Testing;
 using osu.Game.Models;
 using osu.Game.Users;
+using osu.Game.Utils;
 using Realms;
 
 #nullable enable
@@ -16,7 +17,7 @@ namespace osu.Game.Beatmaps
     [ExcludeFromDynamicCompile]
     [Serializable]
     [MapTo("BeatmapMetadata")]
-    public class BeatmapMetadata : RealmObject, IBeatmapMetadataInfo
+    public class BeatmapMetadata : RealmObject, IBeatmapMetadataInfo, IDeepCloneable<BeatmapMetadata>
     {
         public string Title { get; set; } = string.Empty;
 
@@ -57,5 +58,18 @@ namespace osu.Game.Beatmaps
         IUser IBeatmapMetadataInfo.Author => Author;
 
         public override string ToString() => this.GetDisplayTitle();
+
+        public BeatmapMetadata DeepClone() => new BeatmapMetadata(Author.DeepClone())
+        {
+            Title = Title,
+            TitleUnicode = TitleUnicode,
+            Artist = Artist,
+            ArtistUnicode = ArtistUnicode,
+            Source = Source,
+            Tags = Tags,
+            PreviewTime = PreviewTime,
+            AudioFile = AudioFile,
+            BackgroundFile = BackgroundFile
+        };
     }
 }

osu.Game/Beatmaps/BeatmapModelManager.cs

@@ -49,7 +49,6 @@ namespace osu.Game.Beatmaps
         public virtual void Save(BeatmapInfo beatmapInfo, IBeatmap beatmapContent, ISkin? beatmapSkin = null)
         {
             var setInfo = beatmapInfo.BeatmapSet;
-
             Debug.Assert(setInfo != null);
 
             // Difficulty settings must be copied first due to the clone in `Beatmap<>.BeatmapInfo_Set`.
@@ -85,6 +84,24 @@ namespace osu.Game.Beatmaps
             WorkingBeatmapCache?.Invalidate(beatmapInfo);
         }
 
+        /// <summary>
+        /// Add a new difficulty to the beatmap set represented by the provided <see cref="BeatmapSetInfo"/>.
+        /// </summary>
+        public BeatmapInfo AddDifficultyToBeatmapSet(BeatmapSetInfo beatmapSetInfo, Beatmap beatmap)
+        {
+            return Realm.Run(realm =>
+            {
+                var beatmapInfo = beatmap.BeatmapInfo;
+
+                beatmapSetInfo.Beatmaps.Add(beatmapInfo);
+                beatmapInfo.BeatmapSet = beatmapSetInfo;
+
+                Save(beatmapInfo, beatmap);
+
+                return beatmapInfo.Detach();
+            });
+        }
+
         private static string getFilename(BeatmapInfo beatmapInfo)
         {
             var metadata = beatmapInfo.Metadata;
@@ -103,9 +120,9 @@ namespace osu.Game.Beatmaps
 
         public void Update(BeatmapSetInfo item)
         {
-            Realm.Write(realm =>
+            Realm.Write(r =>
             {
-                var existing = realm.Find<BeatmapSetInfo>(item.ID);
+                var existing = r.Find<BeatmapSetInfo>(item.ID);
                 item.CopyChangesToRealm(existing);
             });
         }

osu.Game/Database/RealmObjectExtensions.cs

@@ -58,7 +58,16 @@ namespace osu.Game.Database
                      if (existing != null)
                          copyChangesToRealm(beatmap, existing);
                      else
-                         d.Beatmaps.Add(beatmap);
+                     {
+                         var newBeatmap = new BeatmapInfo
+                         {
+                             ID = beatmap.ID,
+                             BeatmapSet = d,
+                             Ruleset = d.Realm.Find<RulesetInfo>(beatmap.Ruleset.ShortName)
+                         };
+                         d.Beatmaps.Add(newBeatmap);
+                         copyChangesToRealm(beatmap, newBeatmap);
+                     }
                  }
              });
 

osu.Game/Models/RealmUser.cs

@@ -2,12 +2,14 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using osu.Game.Database;
 using osu.Game.Users;
+using osu.Game.Utils;
 using Realms;
 
 namespace osu.Game.Models
 {
-    public class RealmUser : EmbeddedObject, IUser, IEquatable<RealmUser>
+    public class RealmUser : EmbeddedObject, IUser, IEquatable<RealmUser>, IDeepCloneable<RealmUser>
     {
         public int OnlineID { get; set; } = 1;
 
@@ -22,5 +24,7 @@ namespace osu.Game.Models
 
             return OnlineID == other.OnlineID && Username == other.Username;
         }
+
+        public RealmUser DeepClone() => (RealmUser)this.Detach().MemberwiseClone();
     }
 }

osu.Game/Screens/Edit/Editor.cs

@@ -822,11 +822,14 @@ namespace osu.Game.Screens.Edit
             var rulesetItems = new List<MenuItem>();
 
             foreach (var ruleset in rulesets.AvailableRulesets.OrderBy(ruleset => ruleset.OnlineID))
-                rulesetItems.Add(new EditorMenuItem(ruleset.Name));
+                rulesetItems.Add(new EditorMenuItem(ruleset.Name, MenuItemType.Standard, () => createNewDifficulty(ruleset)));
 
             return new EditorMenuItem("Create new difficulty") { Items = rulesetItems };
         }
 
+        private void createNewDifficulty(RulesetInfo rulesetInfo)
+            => loader?.ScheduleSwitchToNewDifficulty(editorBeatmap.BeatmapInfo.BeatmapSet, rulesetInfo, GetState());
+
         private EditorMenuItem createDifficultySwitchMenu()
         {
             var beatmapSet = playableBeatmap.BeatmapInfo.BeatmapSet;
@@ -850,7 +853,7 @@ namespace osu.Game.Screens.Edit
             return new EditorMenuItem("Change difficulty") { Items = difficultyItems };
         }
 
-        protected void SwitchToDifficulty(BeatmapInfo nextBeatmap) => loader?.ScheduleDifficultySwitch(nextBeatmap, GetState(nextBeatmap));
+        protected void SwitchToDifficulty(BeatmapInfo nextBeatmap) => loader?.ScheduleSwitchToExistingDifficulty(nextBeatmap, GetState(nextBeatmap));
 
         private void cancelExit()
         {

osu.Game/Screens/Edit/EditorLoader.cs

@@ -10,6 +10,7 @@ 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;
@@ -78,7 +79,13 @@ namespace osu.Game.Screens.Edit
             }
         }
 
-        public void ScheduleDifficultySwitch(BeatmapInfo nextBeatmap, EditorState editorState)
+        public void ScheduleSwitchToNewDifficulty(BeatmapSetInfo beatmapSetInfo, RulesetInfo rulesetInfo, EditorState editorState)
+            => scheduleDifficultySwitch(() => beatmapManager.CreateNewBlankDifficulty(beatmapSetInfo, rulesetInfo), editorState);
+
+        public void ScheduleSwitchToExistingDifficulty(BeatmapInfo beatmapInfo, EditorState editorState)
+            => scheduleDifficultySwitch(() => beatmapManager.GetWorkingBeatmap(beatmapInfo), editorState);
+
+        private void scheduleDifficultySwitch(Func<WorkingBeatmap> nextBeatmap, EditorState editorState)
         {
             scheduledDifficultySwitch?.Cancel();
             ValidForResume = true;
@@ -87,7 +94,7 @@ namespace osu.Game.Screens.Edit
 
             scheduledDifficultySwitch = Schedule(() =>
             {
-                Beatmap.Value = beatmapManager.GetWorkingBeatmap(nextBeatmap);
+                Beatmap.Value = nextBeatmap.Invoke();
                 state = editorState;
 
                 // This screen is a weird exception to the rule that nothing after song select changes the global beatmap.