Revert "Merge pull request #16716 from peppy/carousel-less-invalidati…

…ons"

This reverts commit 8d13e05, reversing
changes made to 95582a9.

osu.Game/Screens/Select/BeatmapCarousel.cs

@@ -925,8 +925,10 @@ private void updateItem(DrawableCarouselItem item, DrawableCarouselItem parent =
             // child items (difficulties) are still visible.
             item.Header.X = offsetX(dist, visibleHalfHeight) - (parent?.X ?? 0);
 
-            // We are applying alpha to the header here such that we can layer alpha transformations on top.
-            item.Header.Alpha = Math.Clamp(1.75f - 1.5f * dist, 0, 1);
+            // We are applying a multiplicative alpha (which is internally done by nesting an
+            // additional container and setting that container's alpha) such that we can
+            // layer alpha transformations on top.
+            item.SetMultiplicativeAlpha(Math.Clamp(1.75f - 1.5f * dist, 0, 1));
         }
 
         private enum PendingScrollOperation

osu.Game/Screens/Select/Carousel/CarouselHeader.cs

@@ -21,6 +21,8 @@ namespace osu.Game.Screens.Select.Carousel
 {
     public class CarouselHeader : Container
     {
+        public Container BorderContainer;
+
         public readonly Bindable<CarouselItemState> State = new Bindable<CarouselItemState>(CarouselItemState.NotSelected);
 
         private readonly HoverLayer hoverLayer;
@@ -35,14 +37,17 @@ public CarouselHeader()
             RelativeSizeAxes = Axes.X;
             Height = DrawableCarouselItem.MAX_HEIGHT;
 
-            Masking = true;
-            CornerRadius = corner_radius;
-            BorderColour = new Color4(221, 255, 255, 255);
-
-            InternalChildren = new Drawable[]
+            InternalChild = BorderContainer = new Container
             {
-                Content,
-                hoverLayer = new HoverLayer()
+                RelativeSizeAxes = Axes.Both,
+                Masking = true,
+                CornerRadius = corner_radius,
+                BorderColour = new Color4(221, 255, 255, 255),
+                Children = new Drawable[]
+                {
+                    Content,
+                    hoverLayer = new HoverLayer()
+                }
             };
         }
 
@@ -61,21 +66,21 @@ private void updateState(ValueChangedEvent<CarouselItemState> state)
                 case CarouselItemState.NotSelected:
                     hoverLayer.InsetForBorder = false;
 
-                    BorderThickness = 0;
-                    EdgeEffect = new EdgeEffectParameters
+                    BorderContainer.BorderThickness = 0;
+                    BorderContainer.EdgeEffect = new EdgeEffectParameters
                     {
                         Type = EdgeEffectType.Shadow,
                         Offset = new Vector2(1),
                         Radius = 10,
-                        Colour = Color4.Black.Opacity(0.5f),
+                        Colour = Color4.Black.Opacity(100),
                     };
                     break;
 
                 case CarouselItemState.Selected:
                     hoverLayer.InsetForBorder = true;
 
-                    BorderThickness = border_thickness;
-                    EdgeEffect = new EdgeEffectParameters
+                    BorderContainer.BorderThickness = border_thickness;
+                    BorderContainer.EdgeEffect = new EdgeEffectParameters
                     {
                         Type = EdgeEffectType.Glow,
                         Colour = new Color4(130, 204, 255, 150),

osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmap.cs

@@ -36,9 +36,9 @@ public class DrawableCarouselBeatmap : DrawableCarouselItem, IHasContextMenu
         /// <summary>
         /// The height of a carousel beatmap, including vertical spacing.
         /// </summary>
-        public const float HEIGHT = header_height + CAROUSEL_BEATMAP_SPACING;
+        public const float HEIGHT = height + CAROUSEL_BEATMAP_SPACING;
 
-        private const float header_height = MAX_HEIGHT * 0.6f;
+        private const float height = MAX_HEIGHT * 0.6f;
 
         private readonly BeatmapInfo beatmapInfo;
 
@@ -67,18 +67,16 @@ public class DrawableCarouselBeatmap : DrawableCarouselItem, IHasContextMenu
         private CancellationTokenSource starDifficultyCancellationSource;
 
         public DrawableCarouselBeatmap(CarouselBeatmap panel)
-            : base(header_height)
         {
             beatmapInfo = panel.BeatmapInfo;
             Item = panel;
-
-            // Difficulty panels should start hidden for a better initial effect.
-            Hide();
         }
 
         [BackgroundDependencyLoader(true)]
         private void load(BeatmapManager manager, SongSelect songSelect)
         {
+            Header.Height = height;
+
             if (songSelect != null)
             {
                 startRequested = b => songSelect.FinaliseSelection(b);

osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmapSet.cs

@@ -122,10 +122,12 @@ protected override void UpdateItem()
                 },
             };
 
-            background.DelayedLoadComplete += d => d.FadeInFromZero(750, Easing.OutQuint);
-            mainFlow.DelayedLoadComplete += d => d.FadeInFromZero(500, Easing.OutQuint);
+            background.DelayedLoadComplete += fadeContentIn;
+            mainFlow.DelayedLoadComplete += fadeContentIn;
         }
 
+        private void fadeContentIn(Drawable d) => d.FadeInFromZero(750, Easing.OutQuint);
+
         protected override void Deselected()
         {
             base.Deselected();

osu.Game/Screens/Select/Carousel/DrawableCarouselItem.cs

@@ -60,38 +60,44 @@ public CarouselItem Item
             }
         }
 
-        protected DrawableCarouselItem(float headerHeight = MAX_HEIGHT)
+        protected DrawableCarouselItem()
         {
             RelativeSizeAxes = Axes.X;
 
+            Alpha = 0;
+
             InternalChildren = new Drawable[]
             {
                 MovementContainer = new Container
                 {
                     RelativeSizeAxes = Axes.Both,
                     Children = new Drawable[]
                     {
-                        Header = new CarouselHeader
-                        {
-                            Height = headerHeight,
-                        },
+                        Header = new CarouselHeader(),
                         Content = new Container
                         {
                             RelativeSizeAxes = Axes.Both,
-                            Y = headerHeight,
                         }
                     }
                 },
             };
         }
 
+        public void SetMultiplicativeAlpha(float alpha) => Header.BorderContainer.Alpha = alpha;
+
         protected override void LoadComplete()
         {
             base.LoadComplete();
 
             UpdateItem();
         }
 
+        protected override void Update()
+        {
+            base.Update();
+            Content.Y = Header.Height;
+        }
+
         protected virtual void UpdateItem()
         {
             if (item == null)
@@ -115,56 +121,29 @@ protected virtual void UpdateItem()
 
         private void onStateChange(ValueChangedEvent<bool> _) => Scheduler.AddOnce(ApplyState);
 
-        private CarouselItemState? lastAppliedState;
-
         protected virtual void ApplyState()
         {
+            // Use the fact that we know the precise height of the item from the model to avoid the need for AutoSize overhead.
+            // Additionally, AutoSize doesn't work well due to content starting off-screen and being masked away.
+            Height = Item.TotalHeight;
+
             Debug.Assert(Item != null);
 
-            if (lastAppliedState != Item.State.Value)
+            switch (Item.State.Value)
             {
-                lastAppliedState = Item.State.Value;
-
-                // Use the fact that we know the precise height of the item from the model to avoid the need for AutoSize overhead.
-                // Additionally, AutoSize doesn't work well due to content starting off-screen and being masked away.
-                Height = Item.TotalHeight;
+                case CarouselItemState.NotSelected:
+                    Deselected();
+                    break;
 
-                switch (lastAppliedState)
-                {
-                    case CarouselItemState.NotSelected:
-                        Deselected();
-                        break;
-
-                    case CarouselItemState.Selected:
-                        Selected();
-                        break;
-                }
+                case CarouselItemState.Selected:
+                    Selected();
+                    break;
             }
 
             if (!Item.Visible)
-                Hide();
+                this.FadeOut(300, Easing.OutQuint);
             else
-                Show();
-        }
-
-        private bool isVisible = true;
-
-        public override void Show()
-        {
-            if (isVisible)
-                return;
-
-            isVisible = true;
-            this.FadeIn(250);
-        }
-
-        public override void Hide()
-        {
-            if (!isVisible)
-                return;
-
-            isVisible = false;
-            this.FadeOut(300, Easing.OutQuint);
+                this.FadeIn(250);
         }
 
         protected virtual void Selected()