mirror of https://github.com/ppy/osu
286 lines
9.5 KiB
C#
286 lines
9.5 KiB
C#
// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
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// See the LICENCE file in the repository root for full licence text.
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#nullable disable
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using System;
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using System.Diagnostics;
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using System.Linq;
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using JetBrains.Annotations;
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using osu.Framework.Allocation;
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using osu.Framework.Bindables;
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using osu.Framework.Graphics;
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using osu.Framework.Graphics.Containers;
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using osu.Framework.Layout;
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using osu.Framework.Utils;
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namespace osu.Game.Graphics.Containers
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{
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/// <summary>
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/// A container that can scroll to each section inside it.
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/// </summary>
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[Cached]
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public class SectionsContainer<T> : Container<T>
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where T : Drawable
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{
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public Bindable<T> SelectedSection { get; } = new Bindable<T>();
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private T lastClickedSection;
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public Drawable ExpandableHeader
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{
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get => expandableHeader;
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set
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{
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if (value == expandableHeader) return;
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if (expandableHeader != null)
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RemoveInternal(expandableHeader, false);
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expandableHeader = value;
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if (value == null) return;
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AddInternal(expandableHeader);
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lastKnownScroll = null;
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}
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}
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public Drawable FixedHeader
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{
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get => fixedHeader;
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set
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{
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if (value == fixedHeader) return;
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fixedHeader?.Expire();
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fixedHeader = value;
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if (value == null) return;
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AddInternal(fixedHeader);
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lastKnownScroll = null;
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}
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}
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public Drawable Footer
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{
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get => footer;
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set
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{
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if (value == footer) return;
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if (footer != null)
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scrollContainer.Remove(footer, false);
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footer = value;
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if (value == null) return;
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footer.Anchor |= Anchor.y2;
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footer.Origin |= Anchor.y2;
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scrollContainer.Add(footer);
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lastKnownScroll = null;
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}
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}
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public Drawable HeaderBackground
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{
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get => headerBackground;
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set
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{
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if (value == headerBackground) return;
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headerBackgroundContainer.Clear();
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headerBackground = value;
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if (value == null) return;
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headerBackgroundContainer.Add(headerBackground);
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lastKnownScroll = null;
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}
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}
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protected override Container<T> Content => scrollContentContainer;
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private readonly UserTrackingScrollContainer scrollContainer;
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private readonly Container headerBackgroundContainer;
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private readonly MarginPadding originalSectionsMargin;
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private Drawable expandableHeader, fixedHeader, footer, headerBackground;
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private FlowContainer<T> scrollContentContainer;
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private float? headerHeight, footerHeight;
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private float? lastKnownScroll;
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/// <summary>
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/// The percentage of the container to consider the centre-point for deciding the active section (and scrolling to a requested section).
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/// </summary>
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private const float scroll_y_centre = 0.1f;
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public SectionsContainer()
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{
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AddRangeInternal(new Drawable[]
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{
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scrollContainer = CreateScrollContainer().With(s =>
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{
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s.RelativeSizeAxes = Axes.Both;
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s.Masking = true;
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s.ScrollbarVisible = false;
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s.Child = scrollContentContainer = CreateScrollContentContainer();
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}),
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headerBackgroundContainer = new Container
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{
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RelativeSizeAxes = Axes.X
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}
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});
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originalSectionsMargin = scrollContentContainer.Margin;
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}
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public override void Add(T drawable)
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{
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base.Add(drawable);
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Debug.Assert(drawable != null);
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lastKnownScroll = null;
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headerHeight = null;
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footerHeight = null;
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}
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public void ScrollTo(Drawable target)
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{
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lastKnownScroll = null;
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// implementation similar to ScrollIntoView but a bit more nuanced.
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float top = scrollContainer.GetChildPosInContent(target);
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float bottomScrollExtent = scrollContainer.ScrollableExtent;
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float scrollTarget = top - scrollContainer.DisplayableContent * scroll_y_centre;
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if (scrollTarget > bottomScrollExtent)
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scrollContainer.ScrollToEnd();
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else
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scrollContainer.ScrollTo(scrollTarget);
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if (target is T section)
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lastClickedSection = section;
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}
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public void ScrollToTop() => scrollContainer.ScrollTo(0);
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[NotNull]
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protected virtual UserTrackingScrollContainer CreateScrollContainer() => new UserTrackingScrollContainer();
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[NotNull]
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protected virtual FlowContainer<T> CreateScrollContentContainer() =>
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new FillFlowContainer<T>
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{
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Direction = FillDirection.Vertical,
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AutoSizeAxes = Axes.Y,
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RelativeSizeAxes = Axes.X,
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};
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protected override bool OnInvalidate(Invalidation invalidation, InvalidationSource source)
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{
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bool result = base.OnInvalidate(invalidation, source);
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if (source == InvalidationSource.Child && (invalidation & Invalidation.DrawSize) != 0)
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{
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InvalidateScrollPosition();
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result = true;
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}
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return result;
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}
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protected void InvalidateScrollPosition()
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{
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lastKnownScroll = null;
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lastClickedSection = null;
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}
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protected override void UpdateAfterChildren()
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{
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base.UpdateAfterChildren();
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float fixedHeaderSize = FixedHeader?.LayoutSize.Y ?? 0;
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float expandableHeaderSize = ExpandableHeader?.LayoutSize.Y ?? 0;
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float headerH = expandableHeaderSize + fixedHeaderSize;
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float footerH = Footer?.LayoutSize.Y ?? 0;
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if (headerH != headerHeight || footerH != footerHeight)
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{
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headerHeight = headerH;
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footerHeight = footerH;
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updateSectionsMargin();
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}
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float currentScroll = scrollContainer.Current;
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if (currentScroll != lastKnownScroll)
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{
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lastKnownScroll = currentScroll;
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// reset last clicked section because user started scrolling themselves
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if (scrollContainer.UserScrolling)
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lastClickedSection = null;
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if (ExpandableHeader != null && FixedHeader != null)
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{
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float offset = Math.Min(expandableHeaderSize, currentScroll);
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ExpandableHeader.Y = -offset;
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FixedHeader.Y = -offset + expandableHeaderSize;
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}
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headerBackgroundContainer.Height = expandableHeaderSize + fixedHeaderSize;
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headerBackgroundContainer.Y = ExpandableHeader?.Y ?? 0;
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float smallestSectionHeight = Children.Count > 0 ? Children.Min(d => d.Height) : 0;
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// scroll offset is our fixed header height if we have it plus 10% of content height
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// plus 5% to fix floating point errors and to not have a section instantly unselect when scrolling upwards
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// but the 5% can't be bigger than our smallest section height, otherwise it won't get selected correctly
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float selectionLenienceAboveSection = Math.Min(smallestSectionHeight / 2.0f, scrollContainer.DisplayableContent * 0.05f);
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float scrollCentre = fixedHeaderSize + scrollContainer.DisplayableContent * scroll_y_centre + selectionLenienceAboveSection;
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var presentChildren = Children.Where(c => c.IsPresent);
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if (lastClickedSection != null)
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SelectedSection.Value = lastClickedSection;
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else if (Precision.AlmostBigger(0, scrollContainer.Current))
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SelectedSection.Value = presentChildren.FirstOrDefault();
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else if (Precision.AlmostBigger(scrollContainer.Current, scrollContainer.ScrollableExtent))
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SelectedSection.Value = presentChildren.LastOrDefault();
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else
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{
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SelectedSection.Value = presentChildren
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.TakeWhile(section => scrollContainer.GetChildPosInContent(section) - currentScroll - scrollCentre <= 0)
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.LastOrDefault() ?? presentChildren.FirstOrDefault();
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}
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}
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}
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private void updateSectionsMargin()
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{
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if (!Children.Any()) return;
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// if a fixed header is present, apply top padding for it
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// to make the scroll container aware of its displayable area.
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// (i.e. for page up/down to work properly)
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scrollContainer.Padding = new MarginPadding { Top = FixedHeader?.LayoutSize.Y ?? 0 };
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var newMargin = originalSectionsMargin;
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newMargin.Top += (ExpandableHeader?.LayoutSize.Y ?? 0);
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newMargin.Bottom += (footerHeight ?? 0);
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scrollContentContainer.Margin = newMargin;
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}
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}
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}
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