legacy export broken

osu.Game/Beatmaps/BeatmapManager.cs

@@ -18,12 +18,15 @@ using osu.Framework.Platform;
 using osu.Game.Beatmaps.Formats;
 using osu.Game.Database;
 using osu.Game.Extensions;
+using osu.Game.IO;
 using osu.Game.IO.Archives;
 using osu.Game.Models;
 using osu.Game.Online.API;
 using osu.Game.Online.API.Requests.Responses;
 using osu.Game.Overlays.Notifications;
 using osu.Game.Rulesets;
+using osu.Game.Rulesets.Objects;
+using osu.Game.Rulesets.Objects.Types;
 using osu.Game.Skinning;
 using osu.Game.Utils;
 
@@ -400,6 +403,56 @@ namespace osu.Game.Beatmaps
 
         public Task Export(BeatmapSetInfo beatmap) => beatmapExporter.ExportAsync(beatmap.ToLive(Realm));
 
+        /// <summary>
+        /// Creates a copy of the <see cref="BeatmapSetInfo"/> and converts all beatmaps to legacy format, then exports it as a legacy package.
+        /// </summary>
+        /// <param name="beatmap"></param>
+        /// <returns></returns>
+        public Task ExportLegacy(BeatmapSetInfo beatmap)
+        {
+            var copy = beatmap.Clone(); // does the detach from realm
+
+            // convert all beatmaps to legacy format
+            foreach (var beatmapInfo in copy.Beatmaps)
+            {
+                // Convert beatmap
+                var file = beatmapInfo.File;
+
+                if (file == null)
+                    continue;
+
+                using var oldStream = new LineBufferedReader(ReadFile(file));
+                var beatmapContent = new LegacyBeatmapDecoder().Decode(oldStream);
+
+                foreach (var controlPoint in beatmapContent.ControlPointInfo.AllControlPoints)
+                    controlPoint.Time = Math.Floor(controlPoint.Time);
+
+                foreach (var hitObject in beatmapContent.HitObjects)
+                {
+                    hitObject.StartTime = Math.Floor(hitObject.StartTime);
+
+                    if (hitObject is IHasPath hasPath && BezierConverter.CountSegments(hasPath.Path.ControlPoints) > 1)
+                    {
+                        var newControlPoints = BezierConverter.ConvertToModernBezier(hasPath.Path.ControlPoints);
+                        hasPath.Path.ControlPoints.Clear();
+                        hasPath.Path.ControlPoints.AddRange(newControlPoints);
+                    }
+                }
+
+                using var newStream = new MemoryStream();
+                using var sw = new StreamWriter(newStream, Encoding.UTF8, 1024, true);
+                new LegacyBeatmapEncoder(beatmapContent, null).Encode(sw);
+                newStream.Seek(0, SeekOrigin.Begin);
+
+                beatmapInfo.MD5Hash = newStream.ComputeMD5Hash();
+                beatmapInfo.Hash = newStream.ComputeSHA2Hash();
+
+                AddFile(copy, newStream, file.Filename);
+            }
+
+            return beatmapExporter.ExportAsync(new RealmLiveUnmanaged<BeatmapSetInfo>(copy));
+        }
+
         private void updateHashAndMarkDirty(BeatmapSetInfo setInfo)
         {
             setInfo.Hash = beatmapImporter.ComputeHash(setInfo);

osu.Game/Beatmaps/BeatmapSetInfo.cs

@@ -90,6 +90,19 @@ namespace osu.Game.Beatmaps
             return ID == other.ID;
         }
 
+        public BeatmapSetInfo Clone()
+        {
+            var clone = (BeatmapSetInfo)this.Detach().MemberwiseClone();
+
+            for (int i = 0; i < clone.Beatmaps.Count; i++)
+                clone.Beatmaps[i] = clone.Beatmaps[i].Clone();
+
+            for (int i = 0; i < clone.Files.Count; i++)
+                clone.Files[i] = new RealmNamedFileUsage(clone.Files[i].File, clone.Files[i].Filename);
+
+            return clone;
+        }
+
         public override string ToString() => Metadata.GetDisplayString();
 
         public bool Equals(IBeatmapSetInfo? other) => other is BeatmapSetInfo b && Equals(b);

osu.Game/Database/ModelManager.cs

@@ -33,6 +33,8 @@ namespace osu.Game.Database
             Realm = realm;
         }
 
+        public Stream ReadFile(RealmNamedFileUsage file) => realmFileStore.Storage.GetStream(file.File.GetStoragePath());
+
         public void DeleteFile(TModel item, RealmNamedFileUsage file) =>
             performFileOperation(item, managed => DeleteFile(managed, managed.Files.First(f => f.Filename == file.Filename), managed.Realm));
 

osu.Game/Localisation/EditorStrings.cs

@@ -39,6 +39,11 @@ namespace osu.Game.Localisation
         /// </summary>
         public static LocalisableString ExportPackage => new TranslatableString(getKey(@"export_package"), @"Export package");
 
+        /// <summary>
+        /// "Export legacy package"
+        /// </summary>
+        public static LocalisableString ExportLegacyPackage => new TranslatableString(getKey(@"export_legacy_package"), @"Export legacy package");
+
         /// <summary>
         /// "Create new difficulty"
         /// </summary>

osu.Game/Rulesets/Objects/BezierConverter.cs

@@ -39,6 +39,13 @@ namespace osu.Game.Rulesets.Objects
                 new[] { new Vector2d(1, 0), new Vector2d(1, 1.2447058f), new Vector2d(-0.8526471f, 2.118367f), new Vector2d(-2.6211002f, 7.854936e-06f), new Vector2d(-0.8526448f, -2.118357f), new Vector2d(1, -1.2447058f), new Vector2d(1, 0) })
         };
 
+        /// <summary>
+        /// Counts the number of segments in a slider path.
+        /// </summary>
+        /// <param name="controlPoints">The control points of the path.</param>
+        /// <returns>The number of segments in a slider path.</returns>
+        public static int CountSegments(IList<PathControlPoint> controlPoints) => controlPoints.Where((t, i) => t.Type != null && i < controlPoints.Count - 1).Count();
+
         /// <summary>
         /// Converts a slider path to bezier control point positions compatible with the legacy osu! client.
         /// </summary>

osu.Game/Screens/Edit/Editor.cs

@@ -966,6 +966,7 @@ namespace osu.Game.Screens.Edit
         {
             new EditorMenuItem(WebCommonStrings.ButtonsSave, MenuItemType.Standard, () => Save()),
             new EditorMenuItem(EditorStrings.ExportPackage, MenuItemType.Standard, exportBeatmap) { Action = { Disabled = !RuntimeInfo.IsDesktop } },
+            new EditorMenuItem(EditorStrings.ExportLegacyPackage, MenuItemType.Standard, exportLegacyBeatmap) { Action = { Disabled = !RuntimeInfo.IsDesktop } },
             new EditorMenuItemSpacer(),
             createDifficultyCreationMenu(),
             createDifficultySwitchMenu(),
@@ -981,6 +982,12 @@ namespace osu.Game.Screens.Edit
             beatmapManager.Export(Beatmap.Value.BeatmapSetInfo);
         }
 
+        private void exportLegacyBeatmap()
+        {
+            Save();
+            beatmapManager.ExportLegacy(Beatmap.Value.BeatmapSetInfo);
+        }
+
         /// <summary>
         /// Beatmaps of the currently edited set, grouped by ruleset and ordered by difficulty.
         /// </summary>