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osu-lazer/osu.Game/Screens/Select/Carousel/CarouselGroup.cs

92 lines
3.2 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.Collections.Generic;
using System.Linq;
namespace osu.Game.Screens.Select.Carousel
{
/// <summary>
/// A group which ensures only one child is selected.
/// </summary>
public class CarouselGroup : CarouselItem
{
public override DrawableCarouselItem CreateDrawableRepresentation() => null;
public IReadOnlyList<CarouselItem> Children => InternalChildren;
protected List<CarouselItem> InternalChildren = new List<CarouselItem>();
/// <summary>
/// Used to assign a monotonically increasing ID to children as they are added. This member is
/// incremented whenever a child is added.
/// </summary>
private ulong currentChildID;
public virtual void RemoveChild(CarouselItem i)
{
InternalChildren.Remove(i);
// it's important we do the deselection after removing, so any further actions based on
// State.ValueChanged make decisions post-removal.
i.State.Value = CarouselItemState.Collapsed;
}
public virtual void AddChild(CarouselItem i)
{
i.State.ValueChanged += state => ChildItemStateChanged(i, state.NewValue);
i.ChildID = ++currentChildID;
InternalChildren.Add(i);
}
public CarouselGroup(List<CarouselItem> items = null)
{
if (items != null) InternalChildren = items;
State.ValueChanged += state =>
{
switch (state.NewValue)
{
case CarouselItemState.Collapsed:
case CarouselItemState.NotSelected:
InternalChildren.ForEach(c => c.State.Value = CarouselItemState.Collapsed);
break;
case CarouselItemState.Selected:
InternalChildren.ForEach(c =>
{
if (c.State.Value == CarouselItemState.Collapsed) c.State.Value = CarouselItemState.NotSelected;
});
break;
}
};
}
public override void Filter(FilterCriteria criteria)
{
base.Filter(criteria);
InternalChildren.ForEach(c => c.Filter(criteria));
// IEnumerable<T>.OrderBy() is used instead of List<T>.Sort() to ensure sorting stability
var criteriaComparer = Comparer<CarouselItem>.Create((x, y) => x.CompareTo(criteria, y));
InternalChildren = InternalChildren.OrderBy(c => c, criteriaComparer).ToList();
}
protected virtual void ChildItemStateChanged(CarouselItem item, CarouselItemState value)
{
// ensure we are the only item selected
if (value == CarouselItemState.Selected)
{
foreach (var b in InternalChildren)
{
if (item == b) continue;
b.State.Value = CarouselItemState.NotSelected;
}
State.Value = CarouselItemState.Selected;
}
}
}
}