From 32196c57af1b0b5a368a90af0d8ff09d1e88cf76 Mon Sep 17 00:00:00 2001
From: Drew DeVault <sir@cmpwn.com>
Date: Wed, 9 Nov 2016 00:17:48 -0500
Subject: [PATCH] Track the visible section in options

---
 osu.Game/Overlays/Options/OptionsSidebar.cs | 41 +++++++++++++++++----
 osu.Game/Overlays/OptionsOverlay.cs         | 36 +++++++++++++++---
 2 files changed, 64 insertions(+), 13 deletions(-)

diff --git a/osu.Game/Overlays/Options/OptionsSidebar.cs b/osu.Game/Overlays/Options/OptionsSidebar.cs
index 6f1cb4a48c..111aad5ecd 100644
--- a/osu.Game/Overlays/Options/OptionsSidebar.cs
+++ b/osu.Game/Overlays/Options/OptionsSidebar.cs
@@ -77,18 +77,36 @@ namespace osu.Game.Overlays.Options
             private TextAwesome drawableIcon;
             private SpriteText headerText;
             private Box backgroundBox;
+            private Box selectionIndicator;
             public Action Action;
 
-            public FontAwesome Icon
+            private OptionsSection section;
+            public OptionsSection Section
             {
-                get { return drawableIcon.Icon; }
-                set { drawableIcon.Icon = value; }
+                get
+                {
+                    return section;
+                }
+                set
+                {
+                    section = value;
+                    headerText.Text = value.Header;
+                    drawableIcon.Icon = value.Icon;
+                }
             }
-            
-            public string Header
+
+            private bool selected;
+            public bool Selected
             {
-                get { return headerText.Text; }
-                set { headerText.Text = value; }
+                get { return selected; }
+                set
+                {
+                    selected = value;
+                    if (selected)
+                        selectionIndicator.FadeIn(50);
+                    else
+                        selectionIndicator.FadeOut(50);
+                }
             }
 
             public SidebarButton()
@@ -122,6 +140,15 @@ namespace osu.Game.Overlays.Options
                         Position = new Vector2(default_width + 10, 0),
                         Anchor = Anchor.CentreLeft,
                         Origin = Anchor.CentreLeft,
+                    },
+                    selectionIndicator = new Box
+                    {
+                        Alpha = 0,
+                        RelativeSizeAxes = Axes.Y,
+                        Width = 5,
+                        Anchor = Anchor.CentreRight,
+                        Origin = Anchor.CentreRight,
+                        Colour = new Color4(233, 103, 161, 255)
                     }
                 };
             }
diff --git a/osu.Game/Overlays/OptionsOverlay.cs b/osu.Game/Overlays/OptionsOverlay.cs
index 2e00bef970..b72c2293c9 100644
--- a/osu.Game/Overlays/OptionsOverlay.cs
+++ b/osu.Game/Overlays/OptionsOverlay.cs
@@ -33,10 +33,12 @@ namespace osu.Game.Overlays
 
         private ScrollContainer scrollContainer;
         private OptionsSidebar sidebar;
+        private OptionsSidebar.SidebarButton[] sidebarButtons;
+        private OptionsSection[] sections;
 
         public OptionsOverlay()
         {
-            var sections = new OptionsSection[]
+            sections = new OptionsSection[]
             {
                 new GeneralSection(),
                 new GraphicsSection(),
@@ -67,6 +69,7 @@ namespace osu.Game.Overlays
                     RelativeSizeAxes = Axes.Y,
                     Width = width,
                     Margin = new MarginPadding { Left = sidebar_width },
+                    Scrolled = ScrollContainer_Scrolled,
                     Children = new[]
                     {
                         new FlowContainer
@@ -104,14 +107,15 @@ namespace osu.Game.Overlays
                 sidebar = new OptionsSidebar
                 {
                     Width = sidebar_width,
-                    Children = sections.Select(section =>
+                    Children = sidebarButtons = sections.Select(section =>
                         new OptionsSidebar.SidebarButton
                         {
-                            Icon = section.Icon,
-                            Header = section.Header,
-                            Action = () => scrollContainer.ScrollIntoView(section),
+                            Selected = sections[0] == section,
+                            Section = section,
+                            Action = () => scrollContainer.ScrollTo(
+                                scrollContainer.GetChildY(section) - scrollContainer.DrawSize.Y / 2),
                         }
-                    )
+                    ).ToArray()
                 }
             };
         }
@@ -123,6 +127,26 @@ namespace osu.Game.Overlays
             scrollContainer.Padding = new MarginPadding { Top = (game as OsuGame)?.Toolbar.DrawHeight ?? 0 };
         }
 
+        private void ScrollContainer_Scrolled(float value)
+        {
+            for (int i = sections.Length - 1; i >= 0; i--)
+            {
+                var section = sections[i];
+                float y = scrollContainer.GetChildY(section) - value;
+                if (y <= scrollContainer.DrawSize.Y / 2)
+                {
+                    var previous = sidebarButtons.SingleOrDefault(sb => sb.Selected);
+                    var next = sidebarButtons.SingleOrDefault(sb => sb.Section == section);
+                    if (next != null)
+                    {
+                        previous.Selected = false;
+                        next.Selected = true;
+                    }
+                    break;
+                }
+            }
+        }
+
         protected override bool OnMouseDown(InputState state, MouseDownEventArgs args) => true;
 
         protected override bool OnKeyDown(InputState state, KeyDownEventArgs args)