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osu-lazer/osu.Game/Graphics/Containers/SectionsContainer.cs

281 lines
9.5 KiB
C#

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