Create placeholder classes instead of changing Children.

- Add MessagePlaceholder
- Use MessagePlacholder for when API is offline/user isn't a supporter
- Remove unnecessary placeholderFlow field
- Hook into API state changes

osu.Game/Screens/Select/Leaderboards/Leaderboard.cs

@@ -34,7 +34,6 @@ namespace osu.Game.Screens.Select.Leaderboards
 
         private readonly ScrollContainer scrollContainer;
         private readonly Container placeholderContainer;
-        private readonly FillFlowContainer placeholderFlow;
 
         private FillFlowContainer<LeaderboardScore> scrollFlow;
 
@@ -63,22 +62,7 @@ namespace osu.Game.Screens.Select.Leaderboards
 
                 if (!scores.Any())
                 {
-                    placeholderFlow.Children = new Drawable[]
+                    replacePlaceholder(new MessagePlaceholder(@"No records yet!"));
-                    {
-                        new SpriteIcon
-                        {
-                            Icon = FontAwesome.fa_exclamation_circle,
-                            Size = new Vector2(26),
-                            Margin = new MarginPadding { Right = 10 },
-                        },
-                        new OsuSpriteText
-                        {
-                            Text = @"No records yet!",
-                            TextSize = 22,
-                        },
-                    };
-
-                    placeholderContainer.FadeIn(fade_duration);
                     return;
                 }
 
@@ -135,17 +119,9 @@ namespace osu.Game.Screens.Select.Leaderboards
                 placeholderContainer = new Container
                 {
                     Alpha = 0,
-                    RelativeSizeAxes = Axes.Both,
+                    AutoSizeAxes = Axes.Both,
-                    Children = new Drawable[]
+                    Anchor = Anchor.Centre,
-                    {
+                    Origin = Anchor.Centre,
-                        placeholderFlow = new FillFlowContainer
-                        {
-                            Direction = FillDirection.Horizontal,
-                            Anchor = Anchor.Centre,
-                            Origin = Anchor.Centre,
-                            AutoSizeAxes = Axes.Both,
-                        },
-                    },
                 },
             };
         }
@@ -181,6 +157,9 @@ namespace osu.Game.Screens.Select.Leaderboards
 
             if (osuGame != null)
                 osuGame.Ruleset.ValueChanged += handleRulesetChange;
+
+            if (api != null)
+                api.OnStateChange += handleApiStateChange;
         }
 
         protected override void Dispose(bool isDisposing)
@@ -195,6 +174,23 @@ namespace osu.Game.Screens.Select.Leaderboards
 
         private void handleRulesetChange(RulesetInfo ruleset) => UpdateScores();
 
+        private void handleApiStateChange(APIState oldState, APIState newState)
+        {
+            if (Scope == LeaderboardScope.Local)
+                // No need to respond to API state change while current scope is local
+                return;
+
+            if (newState == APIState.Offline)
+            {
+                Scores = null;
+                replacePlaceholder(new MessagePlaceholder(@"Please login to view online leaderboards!"));
+                return;
+            }
+
+            if (newState == APIState.Online)
+                UpdateScores();
+        }
+
         protected virtual void UpdateScores()
         {
             if (!IsLoaded) return;
@@ -215,6 +211,20 @@ namespace osu.Game.Screens.Select.Leaderboards
                 return;
             }
 
+            if (!api.IsLoggedIn)
+            {
+                loading.Hide();
+                replacePlaceholder(new MessagePlaceholder(@"Please login to view online leaderboards!"));
+                return;
+            }
+
+            if (Scope != LeaderboardScope.Global && !api.LocalUser.Value.IsSupporter)
+            {
+                loading.Hide();
+                replacePlaceholder(new MessagePlaceholder(@"Please invest in a supporter tag to view this leaderboard!"));
+                return;
+            }
+
             getScoresRequest = new GetScoresRequest(Beatmap, osuGame?.Ruleset.Value ?? Beatmap.Ruleset, Scope);
             getScoresRequest.Success += r =>
             {
@@ -230,24 +240,21 @@ namespace osu.Game.Screens.Select.Leaderboards
             if (e is OperationCanceledException) return;
 
             Scores = null;
-            placeholderFlow.Children = new Drawable[]
+            replacePlaceholder(new RetrievalFailurePlaceholder
             {
-                new RetryButton
+                OnRetry = UpdateScores,
-                {
+            });
-                    Action = UpdateScores,
-                    Margin = new MarginPadding { Right = 10 },
-                },
-                new OsuSpriteText
-                {
-                    Anchor = Anchor.TopLeft,
-                    Text = @"Couldn't retrieve scores!",
-                    TextSize = 22,
-                },
-            };
-            placeholderContainer.FadeIn(fade_duration);
             Logger.Error(e, @"Couldn't fetch beatmap scores!");
         }
 
+        private void replacePlaceholder(Drawable placeholder)
+        {
+            placeholderContainer.FadeOutFromOne(fade_duration, Easing.OutQuint);
+            placeholderContainer.Clear(true);
+            placeholderContainer.Child = placeholder;
+            placeholderContainer.FadeInFromZero(fade_duration, Easing.OutQuint);
+        }
+
         protected override void Update()
         {
             base.Update();
@@ -277,6 +284,54 @@ namespace osu.Game.Screens.Select.Leaderboards
             }
         }
 
+        private class MessagePlaceholder : FillFlowContainer
+        {
+            public MessagePlaceholder(string message)
+            {
+                Direction = FillDirection.Horizontal;
+                AutoSizeAxes = Axes.Both;
+                Children = new Drawable[]
+                {
+                    new SpriteIcon
+                    {
+                        Icon = FontAwesome.fa_exclamation_circle,
+                        Size = new Vector2(26),
+                        Margin = new MarginPadding { Right = 10 },
+                    },
+                    new OsuSpriteText
+                    {
+                        Text = message,
+                        TextSize = 22,
+                    },
+                };
+            }
+        }
+
+        private class RetrievalFailurePlaceholder : FillFlowContainer
+        {
+            public Action OnRetry;
+
+            public RetrievalFailurePlaceholder()
+            {
+                Direction = FillDirection.Horizontal;
+                AutoSizeAxes = Axes.Both;
+                Children = new Drawable[]
+                {
+                    new RetryButton
+                    {
+                        Action = () => OnRetry?.Invoke(),
+                        Margin = new MarginPadding { Right = 10 },
+                    },
+                    new OsuSpriteText
+                    {
+                        Anchor = Anchor.TopLeft,
+                        Text = @"Couldn't retrieve scores!",
+                        TextSize = 22,
+                    },
+                };
+            }
+        }
+
         private class RetryButton : BeatSyncedContainer
         {
             private readonly SpriteIcon icon;