Merge pull request #16716 from peppy/carousel-less-invalidations

Refactor carousel drawables to reduce invalidations

osu.Game/Screens/Select/BeatmapCarousel.cs

@@ -894,10 +894,8 @@ 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 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));
+            // 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);
         }
 
         private enum PendingScrollOperation

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

@@ -21,8 +21,6 @@ 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;
@@ -37,17 +35,14 @@ public CarouselHeader()
             RelativeSizeAxes = Axes.X;
             Height = DrawableCarouselItem.MAX_HEIGHT;
 
-            InternalChild = BorderContainer = new Container
+            Masking = true;
+            CornerRadius = corner_radius;
+            BorderColour = new Color4(221, 255, 255, 255);
+
+            InternalChildren = new Drawable[]
             {
-                RelativeSizeAxes = Axes.Both,
-                Masking = true,
-                CornerRadius = corner_radius,
-                BorderColour = new Color4(221, 255, 255, 255),
-                Children = new Drawable[]
-                {
-                    Content,
-                    hoverLayer = new HoverLayer()
-                }
+                Content,
+                hoverLayer = new HoverLayer()
             };
         }
 
@@ -66,21 +61,21 @@ private void updateState(ValueChangedEvent<CarouselItemState> state)
                 case CarouselItemState.NotSelected:
                     hoverLayer.InsetForBorder = false;
 
-                    BorderContainer.BorderThickness = 0;
-                    BorderContainer.EdgeEffect = new EdgeEffectParameters
+                    BorderThickness = 0;
+                    EdgeEffect = new EdgeEffectParameters
                     {
                         Type = EdgeEffectType.Shadow,
                         Offset = new Vector2(1),
                         Radius = 10,
-                        Colour = Color4.Black.Opacity(100),
+                        Colour = Color4.Black.Opacity(0.5f),
                     };
                     break;
 
                 case CarouselItemState.Selected:
                     hoverLayer.InsetForBorder = true;
 
-                    BorderContainer.BorderThickness = border_thickness;
-                    BorderContainer.EdgeEffect = new EdgeEffectParameters
+                    BorderThickness = border_thickness;
+                    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 = height + CAROUSEL_BEATMAP_SPACING;
+        public const float HEIGHT = header_height + CAROUSEL_BEATMAP_SPACING;
 
-        private const float height = MAX_HEIGHT * 0.6f;
+        private const float header_height = MAX_HEIGHT * 0.6f;
 
         private readonly BeatmapInfo beatmapInfo;
 
@@ -67,16 +67,18 @@ 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

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

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

@@ -60,44 +60,38 @@ public CarouselItem Item
             }
         }
 
-        protected DrawableCarouselItem()
+        protected DrawableCarouselItem(float headerHeight = MAX_HEIGHT)
         {
             RelativeSizeAxes = Axes.X;
 
-            Alpha = 0;
-
             InternalChildren = new Drawable[]
             {
                 MovementContainer = new Container
                 {
                     RelativeSizeAxes = Axes.Both,
                     Children = new Drawable[]
                     {
-                        Header = new CarouselHeader(),
+                        Header = new CarouselHeader
+                        {
+                            Height = headerHeight,
+                        },
                         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)
@@ -121,29 +115,56 @@ 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);
 
-            switch (Item.State.Value)
+            if (lastAppliedState != Item.State.Value)
             {
-                case CarouselItemState.NotSelected:
-                    Deselected();
-                    break;
+                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.Selected:
-                    Selected();
-                    break;
+                switch (lastAppliedState)
+                {
+                    case CarouselItemState.NotSelected:
+                        Deselected();
+                        break;
+
+                    case CarouselItemState.Selected:
+                        Selected();
+                        break;
+                }
             }
 
             if (!Item.Visible)
-                this.FadeOut(300, Easing.OutQuint);
+                Hide();
             else
-                this.FadeIn(250);
+                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);
         }
 
         protected virtual void Selected()