Preload song select instances in multiplayer / playlists

Off the back of some very old feedback:
https://www.reddit.com/r/osugame/comments/1dga6m5/comment/l8ot8qy/

Maybe resolves some of ppy#21952, too
(definitely not all of it, state is still lost even with this).

Mirrors the setup `MainMenu` does. It's not really possible to just keep
one instance around since `ScreenStack` protests when trying to push an
already-loaded screen.

osu.Game/Screens/OnlinePlay/Multiplayer/Match/MultiplayerMatchSettingsOverlay.cs

@@ -11,7 +11,6 @@
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Shapes;
-using osu.Framework.Screens;
 using osu.Game.Graphics;
 using osu.Game.Graphics.Containers;
 using osu.Game.Graphics.Sprites;
@@ -277,11 +276,7 @@ private void load(OverlayColourProvider colourProvider, OsuColour colours)
  RelativeSizeAxes = Axes.X,
  Height = 40,
  Text = "Select beatmap",
- Action = () =>
- {
- if (matchSubScreen.IsCurrentScreen())
- matchSubScreen.Push(new MultiplayerMatchSongSelect(matchSubScreen.Room));
- }
+ Action = () => matchSubScreen.OpenSongSelection()
  }
  }
  }

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerMatchSongSelect.cs

@@ -25,7 +25,6 @@ public partial class MultiplayerMatchSongSelect : OnlinePlaySongSelect
  private OngoingOperationTracker operationTracker { get; set; } = null!;
 
  private readonly IBindable<bool> operationInProgress = new Bindable<bool>();
- private readonly PlaylistItem? itemToEdit;
 
  private LoadingLayer loadingLayer = null!;
  private IDisposable? selectionOperation;
@@ -34,11 +33,9 @@ public partial class MultiplayerMatchSongSelect : OnlinePlaySongSelect
  /// Construct a new instance of multiplayer song select.
  /// </summary>
  /// <param name="room">The room.</param>
- /// <param name="itemToEdit">The item to be edited. May be null, in which case a new item will be added to the playlist.</param>
- public MultiplayerMatchSongSelect(Room room, PlaylistItem? itemToEdit = null)
- : base(room, itemToEdit)
+ public MultiplayerMatchSongSelect(Room room)
+ : base(room)
  {
- this.itemToEdit = itemToEdit;
  }
 
  [BackgroundDependencyLoader]
@@ -79,15 +76,15 @@ protected override bool SelectItem(PlaylistItem item)
 
  var multiplayerItem = new MultiplayerPlaylistItem
  {
- ID = itemToEdit?.ID ?? 0,
+ ID = PlaylistItem?.ID ?? 0,
  BeatmapID = item.Beatmap.OnlineID,
  BeatmapChecksum = item.Beatmap.MD5Hash,
  RulesetID = item.RulesetID,
  RequiredMods = item.RequiredMods.ToArray(),
  AllowedMods = item.AllowedMods.ToArray()
  };
 
- Task task = itemToEdit != null ? client.EditPlaylistItem(multiplayerItem) : client.AddPlaylistItem(multiplayerItem);
+ Task task = PlaylistItem != null ? client.EditPlaylistItem(multiplayerItem) : client.AddPlaylistItem(multiplayerItem);
 
  task.FireAndForget(onSuccess: () =>
  {

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerMatchSubScreen.cs

@@ -6,6 +6,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
+using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
@@ -51,6 +52,7 @@ public partial class MultiplayerMatchSubScreen : RoomSubScreen, IHandlePresentBe
  private OsuGame game { get; set; }
 
  private AddItemButton addItemButton;
+ private MultiplayerMatchSongSelect songSelect;
 
  public MultiplayerMatchSubScreen(Room room)
  : base(room)
@@ -59,6 +61,28 @@ public MultiplayerMatchSubScreen(Room room)
  Activity.Value = new UserActivity.InLobby(room);
  }
 
+ [BackgroundDependencyLoader]
+ private void load()
+ {
+ preloadSongSelect();
+ }
+
+ private void preloadSongSelect()
+ {
+ LoadComponentAsync(songSelect = new MultiplayerMatchSongSelect(Room));
+ }
+
+ private MultiplayerMatchSongSelect consumeSongSelect([CanBeNull] PlaylistItem initialItem = null)
+ {
+ var s = songSelect;
+ Debug.Assert(s != null);
+
+ songSelect = null;
+
+ s.PlaylistItem = initialItem;
+ return s;
+ }
+
  protected override void LoadComplete()
  {
  base.LoadComplete();
@@ -225,7 +249,7 @@ internal void OpenSongSelection(PlaylistItem itemToEdit = null)
  if (!this.IsCurrentScreen())
  return;
 
- this.Push(new MultiplayerMatchSongSelect(Room, itemToEdit));
+ this.Push(consumeSongSelect(itemToEdit));
  }
 
  protected override Drawable CreateFooter() => new MultiplayerMatchFooter();
@@ -244,6 +268,12 @@ protected override void UpdateMods()
  Mods.Value = client.LocalUser.Mods.Select(m => m.ToMod(rulesetInstance)).Concat(SelectedItem.Value.RequiredMods.Select(m => m.ToMod(rulesetInstance))).ToList();
  }
 
+ public override void OnResuming(ScreenTransitionEvent e)
+ {
+ base.OnResuming(e);
+ preloadSongSelect();
+ }
+
  [Resolved(canBeNull: true)]
  private IDialogOverlay dialogOverlay { get; set; }
 

osu.Game/Screens/OnlinePlay/OnlinePlaySongSelect.cs

@@ -35,6 +35,12 @@ public abstract partial class OnlinePlaySongSelect : SongSelect, IOnlinePlaySubS
  [Resolved(typeof(Room), nameof(Room.Playlist))]
  protected BindableList<PlaylistItem> Playlist { get; private set; } = null!;
 
+ /// <summary>
+ /// An optional initial <see cref="PlaylistItem"/> to use for the initial beatmap/ruleset/mods.
+ /// If <see langword="null"/>, the last <see cref="PlaylistItem"/> in the room will be used.
+ /// </summary>
+ public PlaylistItem? PlaylistItem { get; set; }
+
  [Resolved]
  private RulesetStore rulesets { get; set; } = null!;
 
@@ -46,21 +52,19 @@ public abstract partial class OnlinePlaySongSelect : SongSelect, IOnlinePlaySubS
  protected readonly Bindable<IReadOnlyList<Mod>> FreeMods = new Bindable<IReadOnlyList<Mod>>(Array.Empty<Mod>());
 
  private readonly Room room;
- private readonly PlaylistItem? initialItem;
  private readonly FreeModSelectOverlay freeModSelectOverlay;
 
+ private PlaylistItem? initialItem => PlaylistItem ?? room.Playlist.LastOrDefault();
+
  private IDisposable? freeModSelectOverlayRegistration;
 
  /// <summary>
  /// Creates a new <see cref="OnlinePlaySongSelect"/>.
  /// </summary>
  /// <param name="room">The room.</param>
- /// <param name="initialItem">An optional initial <see cref="PlaylistItem"/> to use for the initial beatmap/ruleset/mods.
- /// If <c>null</c>, the last <see cref="PlaylistItem"/> in the room will be used.</param>
- protected OnlinePlaySongSelect(Room room, PlaylistItem? initialItem = null)
+ protected OnlinePlaySongSelect(Room room)
  {
  this.room = room;
- this.initialItem = initialItem ?? room.Playlist.LastOrDefault();
 
  Padding = new MarginPadding { Horizontal = HORIZONTAL_OVERFLOW_PADDING };
 
@@ -82,6 +86,13 @@ protected override void LoadComplete()
  {
  base.LoadComplete();
 
+ freeModSelectOverlayRegistration = OverlayManager?.RegisterBlockingOverlay(freeModSelectOverlay);
+ }
+
+ public override void OnEntering(ScreenTransitionEvent e)
+ {
+ base.OnEntering(e);
+
  if (initialItem != null)
  {
  // Prefer using a local databased beatmap lookup since OnlineId may be -1 for an invalid beatmap selection.
@@ -115,8 +126,6 @@ protected override void LoadComplete()
 
  Mods.BindValueChanged(onModsChanged);
  Ruleset.BindValueChanged(onRulesetChanged);
-
- freeModSelectOverlayRegistration = OverlayManager?.RegisterBlockingOverlay(freeModSelectOverlay);
  }
 
  private void onModsChanged(ValueChangedEvent<IReadOnlyList<Mod>> mods)

osu.Game/Screens/OnlinePlay/Playlists/PlaylistsRoomSubScreen.cs

@@ -35,6 +35,7 @@ public partial class PlaylistsRoomSubScreen : RoomSubScreen
 
  private MatchLeaderboard leaderboard;
  private SelectionPollingComponent selectionPollingComponent;
+ private PlaylistsSongSelect songSelect;
 
  private FillFlowContainer progressSection;
 
@@ -52,6 +53,22 @@ private void load([CanBeNull] IdleTracker idleTracker)
  isIdle.BindTo(idleTracker.IsIdle);
 
  AddInternal(selectionPollingComponent = new SelectionPollingComponent(Room));
+ preloadSongSelect();
+ }
+
+ private void preloadSongSelect()
+ {
+ if (songSelect == null)
+ LoadComponentAsync(songSelect = new PlaylistsSongSelect(Room));
+ }
+
+ private PlaylistsSongSelect consumeSongSelect()
+ {
+ var s = songSelect;
+ Debug.Assert(s != null);
+
+ songSelect = null;
+ return s;
  }
 
  protected override void LoadComplete()
@@ -234,7 +251,7 @@ protected override void LoadComplete()
  EditPlaylist = () =>
  {
  if (this.IsCurrentScreen())
- this.Push(new PlaylistsSongSelect(Room));
+ this.Push(consumeSongSelect());
  },
  };
 
@@ -248,5 +265,12 @@ private void updatePollingRate()
  {
  Exited = () => leaderboard.RefetchScores()
  });
+
+ public override void OnResuming(ScreenTransitionEvent e)
+ {
+ base.OnResuming(e);
+
+ preloadSongSelect();
+ }
  }
 }