Fix hit error meters not updating visual state when hidden

It is an expectation of users that when the HUD is shown after a period
of being hidden, it will visually reflect the state based on recent
judgements.

To achieve this, I've added `AlwaysPresent` and moved the transform
application to the meter level, rather than at a child level. If this is
seen as a bad direction, `AlwaysPresent` can be applied to the drawable
children and the transforms can be moved back.

Also of note, `ColourHitErrorMeter` is pretty weird. The flow class
could potentially be removed and reduce `AlwaysPresent` usage by one.
Can do that refactor as part of this PR if preferred.

Closes #18624.

osu.Game/Screens/Play/HUD/HitErrorMeters/BarHitErrorMeter.cs

@@ -400,6 +400,9 @@ namespace osu.Game.Screens.Play.HUD.HitErrorMeters
         {
             const int arrow_move_duration = 800;
 
+            const int judgement_fade_in_duration = 100;
+            const int judgement_fade_out_duration = 5000;
+
             if (!judgement.IsHit || judgement.HitObject.HitWindows?.WindowFor(HitResult.Miss) == 0)
                 return;
 
@@ -420,12 +423,26 @@ namespace osu.Game.Screens.Play.HUD.HitErrorMeters
                 }
             }
 
-            judgementsContainer.Add(new JudgementLine
+            var judgementLine = new JudgementLine
             {
                 JudgementLineThickness = { BindTarget = JudgementLineThickness },
                 Y = getRelativeJudgementPosition(judgement.TimeOffset),
                 Colour = GetColourForHitResult(judgement.Type),
-            });
+                Alpha = 0,
+                Width = 0,
+            };
+
+            judgementsContainer.Add(judgementLine);
+
+            // Importantly, transforms should be applied in this method rather than constructed drawables
+            // to ensure that they are applied even when the `HitErrorMeter` is hidden (see `AlwaysPresent` usage).
+            judgementLine
+                .FadeTo(0.6f, judgement_fade_in_duration, Easing.OutQuint)
+                .ResizeWidthTo(1, judgement_fade_in_duration, Easing.OutQuint)
+                .Then()
+                .FadeOut(judgement_fade_out_duration)
+                .ResizeWidthTo(0, judgement_fade_out_duration, Easing.InQuint)
+                .Expire();
 
             arrow.MoveToY(
                 getRelativeJudgementPosition(floatingAverage = floatingAverage * 0.9 + judgement.TimeOffset * 0.1)
@@ -456,23 +473,9 @@ namespace osu.Game.Screens.Play.HUD.HitErrorMeters
 
             protected override void LoadComplete()
             {
-                const int judgement_fade_in_duration = 100;
-                const int judgement_fade_out_duration = 5000;
-
                 base.LoadComplete();
 
-                Alpha = 0;
-                Width = 0;
-
                 JudgementLineThickness.BindValueChanged(thickness => Height = thickness.NewValue, true);
-
-                this
-                    .FadeTo(0.6f, judgement_fade_in_duration, Easing.OutQuint)
-                    .ResizeWidthTo(1, judgement_fade_in_duration, Easing.OutQuint)
-                    .Then()
-                    .FadeOut(judgement_fade_out_duration)
-                    .ResizeWidthTo(0, judgement_fade_out_duration, Easing.InQuint)
-                    .Expire();
             }
         }
 

osu.Game/Screens/Play/HUD/HitErrorMeters/ColourHitErrorMeter.cs

@@ -51,47 +51,37 @@ namespace osu.Game.Screens.Play.HUD.HitErrorMeters
                 Direction = FillDirection.Vertical;
                 LayoutDuration = animation_duration;
                 LayoutEasing = Easing.OutQuint;
+                AlwaysPresent = true;
             }
 
             public void Push(Color4 colour)
             {
-                Add(new HitErrorCircle(colour, drawable_judgement_size));
+                var hitErrorCircle = new HitErrorCircle(colour);
+
+                Add(hitErrorCircle);
+
+                hitErrorCircle.FadeInFromZero(animation_duration, Easing.OutQuint);
+                hitErrorCircle.MoveToY(-drawable_judgement_size);
+                hitErrorCircle.MoveToY(0, animation_duration, Easing.OutQuint);
 
                 if (Children.Count > MAX_DISPLAYED_JUDGEMENTS)
                     Children.FirstOrDefault(c => !c.IsRemoved)?.Remove();
             }
         }
 
-        internal class HitErrorCircle : Container
+        internal class HitErrorCircle : Circle
         {
             public bool IsRemoved { get; private set; }
 
-            private readonly Circle circle;
+            public HitErrorCircle(Color4 colour)
-
-            public HitErrorCircle(Color4 colour, int size)
             {
-                Size = new Vector2(size);
+                Colour = colour;
-                Child = circle = new Circle
+                Size = new Vector2(drawable_judgement_size);
-                {
-                    RelativeSizeAxes = Axes.Both,
-                    Alpha = 0,
-                    Colour = colour
-                };
-            }
-
-            protected override void LoadComplete()
-            {
-                base.LoadComplete();
-
-                circle.FadeInFromZero(animation_duration, Easing.OutQuint);
-                circle.MoveToY(-DrawSize.Y);
-                circle.MoveToY(0, animation_duration, Easing.OutQuint);
             }
 
             public void Remove()
             {
                 IsRemoved = true;
-
                 this.FadeOut(animation_duration, Easing.OutQuint).Expire();
             }
         }

osu.Game/Screens/Play/HUD/HitErrorMeters/HitErrorMeter.cs

@@ -37,6 +37,8 @@ namespace osu.Game.Screens.Play.HUD.HitErrorMeters
         {
             base.LoadComplete();
 
+            AlwaysPresent = true;
+
             if (gameplayClockContainer != null)
                 gameplayClockContainer.OnSeek += Clear;