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