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

120 lines
3.9 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;
namespace osu.Game.Screens.Select.Carousel
{
/// <summary>
/// A group which ensures only one item is selected.
/// </summary>
public class CarouselGroup : CarouselItem
{
public override DrawableCarouselItem? CreateDrawableRepresentation() => null;
public IReadOnlyList<CarouselItem> Items => items;
private readonly List<CarouselItem> items = new List<CarouselItem>();
/// <summary>
/// Used to assign a monotonically increasing ID to items as they are added. This member is
/// incremented whenever an item is added.
/// </summary>
private ulong currentItemID;
private Comparer<CarouselItem>? criteriaComparer;
private FilterCriteria? lastCriteria;
protected int GetIndexOfItem(CarouselItem lastSelected) => items.IndexOf(lastSelected);
public virtual void RemoveItem(CarouselItem i)
{
items.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 AddItem(CarouselItem i)
{
i.State.ValueChanged += state => ChildItemStateChanged(i, state.NewValue);
i.ItemID = ++currentItemID;
if (lastCriteria != null)
{
i.Filter(lastCriteria);
int index = items.BinarySearch(i, criteriaComparer);
if (index < 0) index = ~index; // BinarySearch hacks multiple return values with 2's complement.
items.Insert(index, i);
}
else
{
// criteria may be null for initial population. the filtering will be applied post-add.
items.Add(i);
}
}
public CarouselGroup(List<CarouselItem>? items = null)
{
if (items != null) this.items = items;
State.ValueChanged += state =>
{
switch (state.NewValue)
{
case CarouselItemState.Collapsed:
case CarouselItemState.NotSelected:
this.items.ForEach(c => c.State.Value = CarouselItemState.Collapsed);
break;
case CarouselItemState.Selected:
this.items.ForEach(c =>
{
if (c.State.Value == CarouselItemState.Collapsed) c.State.Value = CarouselItemState.NotSelected;
});
break;
}
};
}
public override void Filter(FilterCriteria criteria)
{
base.Filter(criteria);
items.ForEach(c => c.Filter(criteria));
criteriaComparer = Comparer<CarouselItem>.Create((x, y) =>
{
int comparison = x.CompareTo(criteria, y);
if (comparison != 0)
return comparison;
return x.ItemID.CompareTo(y.ItemID);
});
items.Sort(criteriaComparer);
lastCriteria = criteria;
}
protected virtual void ChildItemStateChanged(CarouselItem item, CarouselItemState value)
{
// ensure we are the only item selected
if (value == CarouselItemState.Selected)
{
foreach (var b in items)
{
if (item == b) continue;
b.State.Value = CarouselItemState.NotSelected;
}
State.Value = CarouselItemState.Selected;
}
}
}
}