Rename AllowBackButton to AllowUserExit and rewrite visibility flow structure

Co-authored-by: Dean Herbert <pe@ppy.sh>

osu.Game/OsuGame.cs

@@ -175,6 +175,11 @@ namespace osu.Game
         /// </summary>
         public readonly IBindable<OverlayActivation> OverlayActivationMode = new Bindable<OverlayActivation>();
 
+        /// <summary>
+        /// Whether the back button is currently displayed.
+        /// </summary>
+        public readonly IBindable<bool> BackButtonVisibility = new Bindable<bool>();
+
         IBindable<LocalUserPlayingState> ILocalUserPlayInfo.PlayingState => playingState;
 
         private readonly Bindable<LocalUserPlayingState> playingState = new Bindable<LocalUserPlayingState>();
@@ -1019,7 +1024,7 @@ namespace osu.Game
                                             if (!(ScreenStack.CurrentScreen is IOsuScreen currentScreen))
                                                 return;
 
-                                            if (!((Drawable)currentScreen).IsLoaded || (currentScreen.AllowBackButton && !currentScreen.OnBackButton()))
+                                            if (!((Drawable)currentScreen).IsLoaded || (currentScreen.AllowUserExit && !currentScreen.OnBackButton()))
                                                 ScreenStack.Exit();
                                         }
                                     },
@@ -1189,6 +1194,14 @@ namespace osu.Game
                 if (mode.NewValue != OverlayActivation.All) CloseAllOverlays();
             };
 
+            BackButtonVisibility.ValueChanged += visible =>
+            {
+                if (visible.NewValue)
+                    BackButton.Show();
+                else
+                    BackButton.Hide();
+            };
+
             // Importantly, this should be run after binding PostNotification to the import handlers so they can present the import after game startup.
             handleStartupImport();
         }
@@ -1581,20 +1594,14 @@ namespace osu.Game
 
             if (current is IOsuScreen currentOsuScreen)
             {
-                if (currentOsuScreen.AllowBackButton)
+                BackButtonVisibility.UnbindFrom(currentOsuScreen.BackButtonVisibility);
-                    BackButton.State.UnbindFrom(currentOsuScreen.BackButtonState);
-
                 OverlayActivationMode.UnbindFrom(currentOsuScreen.OverlayActivationMode);
                 API.Activity.UnbindFrom(currentOsuScreen.Activity);
             }
 
             if (newScreen is IOsuScreen newOsuScreen)
             {
-                if (newOsuScreen.AllowBackButton)
+                BackButtonVisibility.BindTo(newOsuScreen.BackButtonVisibility);
-                    ((IBindable<Visibility>)BackButton.State).BindTo(newOsuScreen.BackButtonState);
-                else
-                    BackButton.Hide();
-
                 OverlayActivationMode.BindTo(newOsuScreen.OverlayActivationMode);
                 API.Activity.BindTo(newOsuScreen.Activity);
 

osu.Game/Overlays/Settings/Sections/Maintenance/MigrationRunScreen.cs

@@ -26,7 +26,7 @@ namespace osu.Game.Overlays.Settings.Sections.Maintenance
         [Resolved(canBeNull: true)]
         private OsuGame game { get; set; }
 
-        public override bool AllowBackButton => false;
+        public override bool AllowUserExit => false;
 
         public override bool AllowExternalScreenChange => false;
 

osu.Game/Screens/Edit/Editor.cs

@@ -80,7 +80,7 @@ namespace osu.Game.Screens.Edit
 
         public override float BackgroundParallaxAmount => 0.1f;
 
-        public override bool AllowBackButton => false;
+        public override bool AllowUserExit => false;
 
         public override bool HideOverlaysOnEnter => true;
 

osu.Game/Screens/Edit/EditorLoader.cs

@@ -36,7 +36,7 @@ namespace osu.Game.Screens.Edit
 
         public override float BackgroundParallaxAmount => 0.1f;
 
-        public override bool AllowBackButton => false;
+        public override bool AllowUserExit => false;
 
         public override bool HideOverlaysOnEnter => true;
 

osu.Game/Screens/IOsuScreen.cs

@@ -3,10 +3,8 @@
 
 using System.Collections.Generic;
 using osu.Framework.Bindables;
-using osu.Framework.Graphics.Containers;
 using osu.Framework.Screens;
 using osu.Game.Beatmaps;
-using osu.Game.Graphics.UserInterface;
 using osu.Game.Input.Bindings;
 using osu.Game.Overlays;
 using osu.Game.Rulesets;
@@ -24,15 +22,20 @@ namespace osu.Game.Screens
         bool DisallowExternalBeatmapRulesetChanges { get; }
 
         /// <summary>
-        /// Whether the user can exit this <see cref="IOsuScreen"/> by pressing the back button.
+        /// Whether the user can exit this <see cref="IOsuScreen"/>.
         /// </summary>
-        bool AllowBackButton { get; }
+        /// <remarks>
+        /// When overriden to <c>false</c>,
+        /// the user is blocked from exiting the screen via the <see cref="GlobalAction.Back"/> action,
+        /// and the back button is hidden from this screen by the initial state of <see cref="BackButtonVisibility"/> being set to hidden.
+        /// </remarks>
+        bool AllowUserExit { get; }
 
         /// <summary>
         /// Whether a footer (and a back button) should be displayed underneath the screen.
         /// </summary>
         /// <remarks>
-        /// Temporarily, the back button is shown regardless of whether <see cref="AllowBackButton"/> is true.
+        /// Temporarily, the back button is shown regardless of whether <see cref="AllowUserExit"/> is true.
         /// </remarks>
         bool ShowFooter { get; }
 
@@ -63,13 +66,9 @@ namespace osu.Game.Screens
         IBindable<OverlayActivation> OverlayActivationMode { get; }
 
         /// <summary>
-        /// Controls the visibility state of <see cref="BackButton"/> to better work with screen-specific transitions (i.e. quick restart in player).
+        /// Whether the back button should be displayed in this screen.
-        /// The back button can still be triggered by the <see cref="GlobalAction.Back"/> action even while hidden.
         /// </summary>
-        /// <remarks>
+        IBindable<bool> BackButtonVisibility { get; }
-        /// This is ignored when <see cref="AllowBackButton"/> is set to false.
-        /// </remarks>
-        IBindable<Visibility> BackButtonState { get; }
 
         /// <summary>
         /// The current <see cref="UserActivity"/> for this screen.

osu.Game/Screens/Menu/MainMenu.cs

@@ -48,7 +48,7 @@ namespace osu.Game.Screens.Menu
 
         public override bool HideOverlaysOnEnter => Buttons == null || Buttons.State == ButtonSystemState.Initial;
 
-        public override bool AllowBackButton => false;
+        public override bool AllowUserExit => false;
 
         public override bool AllowExternalScreenChange => true;
 

osu.Game/Screens/OnlinePlay/OnlinePlayScreen.cs

@@ -180,7 +180,7 @@ namespace osu.Game.Screens.OnlinePlay
             if (!(screenStack.CurrentScreen is IOnlinePlaySubScreen onlineSubScreen))
                 return false;
 
-            if (((Drawable)onlineSubScreen).IsLoaded && onlineSubScreen.AllowBackButton && onlineSubScreen.OnBackButton())
+            if (((Drawable)onlineSubScreen).IsLoaded && onlineSubScreen.AllowUserExit && onlineSubScreen.OnBackButton())
                 return true;
 
             if (screenStack.CurrentScreen != null && !(screenStack.CurrentScreen is LoungeSubScreen))

osu.Game/Screens/OsuScreen.cs

@@ -11,7 +11,6 @@ using osu.Framework.Audio;
 using osu.Framework.Audio.Sample;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
-using osu.Framework.Graphics.Containers;
 using osu.Framework.Screens;
 using osu.Game.Beatmaps;
 using osu.Game.Overlays;
@@ -38,7 +37,7 @@ namespace osu.Game.Screens
 
         public string Description => Title;
 
-        public virtual bool AllowBackButton => true;
+        public virtual bool AllowUserExit => true;
 
         public virtual bool ShowFooter => false;
 
@@ -57,9 +56,14 @@ namespace osu.Game.Screens
 
         IBindable<OverlayActivation> IOsuScreen.OverlayActivationMode => OverlayActivationMode;
 
-        public readonly Bindable<Visibility> BackButtonState = new Bindable<Visibility>(Visibility.Visible);
+        /// <summary>
+        /// The initial visibility state of the back button when this screen is entered for the first time.
+        /// </summary>
+        protected virtual bool InitialBackButtonVisibility => AllowUserExit;
 
-        IBindable<Visibility> IOsuScreen.BackButtonState => BackButtonState;
+        public readonly Bindable<bool> BackButtonVisibility;
+
+        IBindable<bool> IOsuScreen.BackButtonVisibility => BackButtonVisibility;
 
         public virtual bool CursorVisible => true;
 
@@ -159,6 +163,7 @@ namespace osu.Game.Screens
             Origin = Anchor.Centre;
 
             OverlayActivationMode = new Bindable<OverlayActivation>(InitialOverlayActivationMode);
+            BackButtonVisibility = new Bindable<bool>(InitialBackButtonVisibility);
         }
 
         [BackgroundDependencyLoader(true)]

osu.Game/Screens/Play/Player.cs

@@ -57,7 +57,7 @@ namespace osu.Game.Screens.Play
         /// </summary>
         public event Action OnGameplayStarted;
 
-        public override bool AllowBackButton => false; // handled by HoldForMenuButton
+        public override bool AllowUserExit => false; // handled by HoldForMenuButton
 
         protected override bool PlayExitSound => !isRestarting;
 

osu.Game/Screens/Play/PlayerLoader.cs

@@ -478,7 +478,7 @@ namespace osu.Game.Screens.Play
 
             if (quickRestart)
             {
-                BackButtonState.Value = Visibility.Hidden;
+                BackButtonVisibility.Value = false;
 
                 // A quick restart starts by triggering a fade to black
                 AddInternal(quickRestartBlackLayer = new Box
@@ -499,7 +499,7 @@ namespace osu.Game.Screens.Play
                     .ScaleTo(1)
                     .FadeInFromZero(500, Easing.OutQuint);
 
-                this.Delay(quick_restart_initial_delay).Schedule(() => BackButtonState.Value = Visibility.Visible);
+                this.Delay(quick_restart_initial_delay).Schedule(() => BackButtonVisibility.Value = true);
             }
             else
             {

osu.Game/Screens/StartupScreen.cs

@@ -10,7 +10,7 @@ namespace osu.Game.Screens
     /// </summary>
     public abstract partial class StartupScreen : OsuScreen
     {
-        public override bool AllowBackButton => false;
+        public override bool AllowUserExit => false;
 
         public override bool HideOverlaysOnEnter => true;