put Bar into its own file and let it only add a background if BackgroundColour is changed

osu.Game/Graphics/UserInterface/Bar.cs

@@ -0,0 +1,134 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using OpenTK;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Colour;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Sprites;
+using System;
+
+namespace osu.Game.Graphics.UserInterface
+{
+    public class Bar : Container
+    {
+        private Box background;
+        private readonly Box bar;
+
+        private const int resize_duration = 250;
+
+        private const EasingTypes easing = EasingTypes.InOutCubic;
+
+        private float length;
+        public float Length
+        {
+            get
+            {
+                return length;
+            }
+            set
+            {
+                length = MathHelper.Clamp(value, 0, 1);
+                updateBarLength();
+            }
+        }
+
+        public SRGBColour BackgroundColour
+        {
+            get
+            {
+                return background?.Colour ?? default(SRGBColour);
+            }
+            set
+            {
+                if (background == null)
+                    Add(background = new Box
+                    {
+                        RelativeSizeAxes = Axes.Both,
+                        Depth = 1,
+                    });
+                background.Colour = value;
+            }
+        }
+
+        public SRGBColour BarColour
+        {
+            get
+            {
+                return bar.Colour;
+            }
+            set
+            {
+                bar.Colour = value;
+            }
+        }
+
+        private BarDirection direction = BarDirection.LeftToRight;
+        public BarDirection Direction
+        {
+            get
+            {
+                return direction;
+            }
+            set
+            {
+                direction = value;
+                updateBarLength();
+            }
+        }
+
+        public Bar()
+        {
+            Children = new[]
+            {
+                bar = new Box
+                {
+                    RelativeSizeAxes = Axes.Both,
+                }
+            };
+        }
+
+        private void updateBarLength()
+        {
+            switch (direction)
+            {
+                case BarDirection.LeftToRight:
+                case BarDirection.RightToLeft:
+                    bar.ResizeTo(new Vector2(length, 1), resize_duration, easing);
+                    break;
+
+                case BarDirection.TopToBottom:
+                case BarDirection.BottomToTop:
+                    bar.ResizeTo(new Vector2(1, length), resize_duration, easing);
+                    break;
+            }
+
+            switch (direction)
+            {
+                case BarDirection.LeftToRight:
+                case BarDirection.TopToBottom:
+                    bar.Anchor = Anchor.TopLeft;
+                    bar.Origin = Anchor.TopLeft;
+                    break;
+
+                case BarDirection.RightToLeft:
+                case BarDirection.BottomToTop:
+                    bar.Anchor = Anchor.BottomRight;
+                    bar.Origin = Anchor.BottomRight;
+                    break;
+            }
+        }
+    }
+
+    [Flags]
+    public enum BarDirection
+    {
+        LeftToRight = 1 << 0,
+        RightToLeft = 1 << 1,
+        TopToBottom = 1 << 2,
+        BottomToTop = 1 << 3,
+
+        Vertical = TopToBottom | BottomToTop,
+        Horizontal = LeftToRight | RightToLeft,
+    }
+}

osu.Game/Graphics/UserInterface/BarGraph.cs

@@ -4,10 +4,7 @@
 using OpenTK;
 using OpenTK.Graphics;
 using osu.Framework.Graphics;
-using osu.Framework.Graphics.Colour;
 using osu.Framework.Graphics.Containers;
-using osu.Framework.Graphics.Sprites;
-using System;
 using System.Collections.Generic;
 using System.Linq;
 
@@ -53,129 +50,8 @@ namespace osu.Game.Graphics.UserInterface
                             Size = (direction & BarDirection.Horizontal) > 0 ? new Vector2(1, 1.0f / values.Count) : new Vector2(1.0f / values.Count, 1),
                             Length = values[i] / values.Max(),
                             Direction = Direction,
-                            BackgroundColour = new Color4(0, 0, 0, 0),
                         });
             }
         }
     }
-
-    public class Bar : Container
-    {
-        private readonly Box background;
-        private readonly Box bar;
-
-        private const int resize_duration = 250;
-
-        private const EasingTypes easing = EasingTypes.InOutCubic;
-
-        private float length;
-        public float Length
-        {
-            get
-            {
-                return length;
-            }
-            set
-            {
-                length = MathHelper.Clamp(value, 0, 1);
-                updateBarLength();
-            }
-        }
-
-        public SRGBColour BackgroundColour
-        {
-            get
-            {
-                return background.Colour;
-            }
-            set
-            {
-                background.Colour = value;
-            }
-        }
-
-        public SRGBColour BarColour
-        {
-            get
-            {
-                return bar.Colour;
-            }
-            set
-            {
-                bar.Colour = value;
-            }
-        }
-
-        private BarDirection direction = BarDirection.LeftToRight;
-        public BarDirection Direction
-        {
-            get
-            {
-                return direction;
-            }
-            set
-            {
-                direction = value;
-                updateBarLength();
-            }
-        }
-
-        public Bar()
-        {
-            Children = new[]
-            {
-                background = new Box
-                {
-                    RelativeSizeAxes = Axes.Both,
-                },
-                bar = new Box
-                {
-                    RelativeSizeAxes = Axes.Both,
-                }
-            };
-        }
-
-        private void updateBarLength()
-        {
-            switch (direction)
-            {
-                case BarDirection.LeftToRight:
-                case BarDirection.RightToLeft:
-                    bar.ResizeTo(new Vector2(length, 1), resize_duration, easing);
-                    break;
-
-                case BarDirection.TopToBottom:
-                case BarDirection.BottomToTop:
-                    bar.ResizeTo(new Vector2(1, length), resize_duration, easing);
-                    break;
-            }
-
-            switch (direction)
-            {
-                case BarDirection.LeftToRight:
-                case BarDirection.TopToBottom:
-                    bar.Anchor = Anchor.TopLeft;
-                    bar.Origin = Anchor.TopLeft;
-                    break;
-
-                case BarDirection.RightToLeft:
-                case BarDirection.BottomToTop:
-                    bar.Anchor = Anchor.BottomRight;
-                    bar.Origin = Anchor.BottomRight;
-                    break;
-            }
-        }
-    }
-
-    [Flags]
-    public enum BarDirection
-    {
-        LeftToRight = 1 << 0,
-        RightToLeft = 1 << 1,
-        TopToBottom = 1 << 2,
-        BottomToTop = 1 << 3,
-
-        Vertical = TopToBottom | BottomToTop,
-        Horizontal = LeftToRight | RightToLeft,
-    }
 }

osu.Game/Screens/Select/BeatmapDetailArea.cs

@@ -56,7 +56,6 @@ namespace osu.Game.Screens.Select
                             case BeatmapDetailTab.Details:
                                 Details.Show();
                                 Leaderboard.Hide();
-                                updateDetails();
                                 break;
 
                             default:
@@ -66,6 +65,7 @@ namespace osu.Game.Screens.Select
                                 break;
                         }
                         currentTab = tab;
+                        updateDetails();
                     },
                 },
                 content = new Container

osu.Game/osu.Game.csproj

@@ -87,6 +87,7 @@
     <Compile Include="Graphics\Sprites\OsuSpriteText.cs" />
     <Compile Include="Graphics\Transforms\TransformAccent.cs" />
     <Compile Include="Graphics\UserInterface\BackButton.cs" />
+    <Compile Include="Graphics\UserInterface\Bar.cs" />
     <Compile Include="Graphics\UserInterface\FocusedTextBox.cs" />
     <Compile Include="Graphics\UserInterface\Nub.cs" />
     <Compile Include="Graphics\UserInterface\OsuMenu.cs" />