From 18295a9b97cc84d7f87a3c39d5f6b7897007ebc4 Mon Sep 17 00:00:00 2001
From: Huo Yaoyuan <huoyaoyuan@hotmail.com>
Date: Sun, 25 Jun 2017 10:06:54 +0800
Subject: [PATCH] Handle scrolling in SectionsContainer.

---
 .../Graphics/Containers/SectionsContainer.cs  | 23 ++++++++++++++-----
 osu.Game/Overlays/SettingsOverlay.cs          |  3 +--
 osu.Game/Overlays/UserProfileOverlay.cs       |  3 +--
 3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/osu.Game/Graphics/Containers/SectionsContainer.cs b/osu.Game/Graphics/Containers/SectionsContainer.cs
index 63cc6f1a85..8221c5d3a6 100644
--- a/osu.Game/Graphics/Containers/SectionsContainer.cs
+++ b/osu.Game/Graphics/Containers/SectionsContainer.cs
@@ -16,7 +16,7 @@ namespace osu.Game.Graphics.Containers
         where T : Drawable
     {
         private Drawable expandableHeader, fixedHeader, footer, headerBackground;
-        public readonly ScrollContainer ScrollContainer;
+        private readonly ScrollContainer scrollContainer;
         private readonly Container headerBackgroundContainer;
         private readonly FlowContainer<T> scrollContentContainer;
 
@@ -62,13 +62,13 @@ namespace osu.Game.Graphics.Containers
                 if (value == footer) return;
 
                 if (footer != null)
-                    ScrollContainer.Remove(footer);
+                    scrollContainer.Remove(footer);
                 footer = value;
                 if (value == null) return;
 
                 footer.Anchor |= Anchor.y2;
                 footer.Origin |= Anchor.y2;
-                ScrollContainer.Add(footer);
+                scrollContainer.Add(footer);
                 lastKnownScroll = float.NaN;
             }
         }
@@ -122,10 +122,11 @@ namespace osu.Game.Graphics.Containers
 
         public SectionsContainer()
         {
-            AddInternal(ScrollContainer = new ScrollContainer()
+            AddInternal(scrollContainer = new ScrollContainer()
             {
                 RelativeSizeAxes = Axes.Both,
                 Masking = true,
+                ScrollbarVisible = false,
                 Children = new Drawable[] { scrollContentContainer = CreateScrollContentContainer() },
                 Depth = float.MaxValue
             });
@@ -137,6 +138,15 @@ namespace osu.Game.Graphics.Containers
             originalSectionsMargin = scrollContentContainer.Margin;
         }
 
+        public void ScrollToTop(T section)
+        {
+            float pos = scrollContainer.GetChildPosInContent(section);
+            float current = scrollContainer.Current;
+            float scrollOffset = FixedHeader?.LayoutSize.Y ?? 0;
+            if (section == Children.First() && current < pos - scrollOffset) return;
+            scrollContainer.ScrollTo(pos - scrollOffset);
+        }
+
         private float lastKnownScroll;
         protected override void UpdateAfterChildren()
         {
@@ -151,7 +161,7 @@ namespace osu.Game.Graphics.Containers
                 updateSectionsMargin();
             }
 
-            float currentScroll = Math.Max(0, ScrollContainer.Current);
+            float currentScroll = Math.Max(0, scrollContainer.Current);
             if (currentScroll != lastKnownScroll)
             {
                 lastKnownScroll = currentScroll;
@@ -169,10 +179,11 @@ namespace osu.Game.Graphics.Containers
 
                 T bestMatch = null;
                 float minDiff = float.MaxValue;
+                float scrollOffset = FixedHeader?.LayoutSize.Y ?? 0;
 
                 foreach (var section in Children)
                 {
-                    float diff = Math.Abs(ScrollContainer.GetChildPosInContent(section) - currentScroll);
+                    float diff = Math.Abs(scrollContainer.GetChildPosInContent(section) - currentScroll - scrollOffset);
                     if (diff < minDiff)
                     {
                         minDiff = diff;
diff --git a/osu.Game/Overlays/SettingsOverlay.cs b/osu.Game/Overlays/SettingsOverlay.cs
index 267489fc79..2734aa642d 100644
--- a/osu.Game/Overlays/SettingsOverlay.cs
+++ b/osu.Game/Overlays/SettingsOverlay.cs
@@ -93,7 +93,7 @@ namespace osu.Game.Overlays
                         new SidebarButton
                         {
                             Section = section,
-                            Action = sectionsContainer.ScrollContainer.ScrollIntoView,
+                            Action = sectionsContainer.ScrollToTop
                         }
                     ).ToArray()
                 }
@@ -162,7 +162,6 @@ namespace osu.Game.Overlays
 
             public SettingsSectionsContainer()
             {
-                ScrollContainer.ScrollbarVisible = false;
                 HeaderBackground = new Box
                 {
                     Colour = Color4.Black,
diff --git a/osu.Game/Overlays/UserProfileOverlay.cs b/osu.Game/Overlays/UserProfileOverlay.cs
index fc6a050d3e..1cc11bc4e9 100644
--- a/osu.Game/Overlays/UserProfileOverlay.cs
+++ b/osu.Game/Overlays/UserProfileOverlay.cs
@@ -112,7 +112,6 @@ namespace osu.Game.Overlays
                     RelativeSizeAxes = Axes.Both
                 }
             };
-            sectionsContainer.ScrollContainer.ScrollbarVisible = false;
             Add(sectionsContainer);
             sectionsContainer.SelectedSection.ValueChanged += s =>
             {
@@ -135,7 +134,7 @@ namespace osu.Game.Overlays
                 if (lastSection != s)
                 {
                     lastSection = s;
-                    sectionsContainer.ScrollContainer.ScrollIntoView(lastSection);
+                    sectionsContainer.ScrollToTop(lastSection);
                 }
             };