UIList.cs

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using System;
using System.Collections;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Terraria.UI;
 
namespace Terraria.GameContent.UI.Elements;
 
public class UIList : UIElement, IEnumerable<UIElement>, IEnumerable
{
    public delegate bool ElementSearchMethod(UIElement element);
 
    private class UIInnerList : UIElement
    {
        public override bool ContainsPoint(Vector2 point)
        {
            return true;
        }
 
        protected override void DrawChildren(SpriteBatch spriteBatch)
        {
            Vector2 position = base.Parent.GetDimensions().Position();
            Vector2 dimensions = new Vector2(base.Parent.GetDimensions().Width, base.Parent.GetDimensions().Height);
            foreach (UIElement element in Elements)
            {
                Vector2 position2 = element.GetDimensions().Position();
                Vector2 dimensions2 = new Vector2(element.GetDimensions().Width, element.GetDimensions().Height);
                if (Collision.CheckAABBvAABBCollision(position, dimensions, position2, dimensions2))
                {
                    element.Draw(spriteBatch);
                }
            }
        }
 
        public override Rectangle GetViewCullingArea()
        {
            return base.Parent.GetDimensions().ToRectangle();
        }
    }
 
    protected List<UIElement> _items = new List<UIElement>();
 
    protected UIScrollbar _scrollbar;
 
    private UIElement _innerList = new UIInnerList();
 
    private float _innerListHeight;
 
    public float ListPadding = 5f;
 
    public Action<List<UIElement>> ManualSortMethod;
 
    public int Count => _items.Count;
 
    public UIList()
    {
        _innerList.OverflowHidden = false;
        _innerList.Width.Set(0f, 1f);
        _innerList.Height.Set(0f, 1f);
        OverflowHidden = true;
        Append(_innerList);
    }
 
    public float GetTotalHeight()
    {
        return _innerListHeight;
    }
 
    public void Goto(ElementSearchMethod searchMethod)
    {
        for (int i = 0; i < _items.Count; i++)
        {
            if (searchMethod(_items[i]))
            {
                _scrollbar.ViewPosition = _items[i].Top.Pixels;
                break;
            }
        }
    }
 
    public virtual void Add(UIElement item)
    {
        _items.Add(item);
        _innerList.Append(item);
        UpdateOrder();
        _innerList.Recalculate();
    }
 
    public virtual bool Remove(UIElement item)
    {
        _innerList.RemoveChild(item);
        UpdateOrder();
        return _items.Remove(item);
    }
 
    public virtual void Clear()
    {
        _innerList.RemoveAllChildren();
        _items.Clear();
    }
 
    public override void Recalculate()
    {
        base.Recalculate();
        UpdateScrollbar();
    }
 
    public override void ScrollWheel(UIScrollWheelEvent evt)
    {
        base.ScrollWheel(evt);
        if (_scrollbar != null)
        {
            _scrollbar.ViewPosition -= evt.ScrollWheelValue;
        }
    }
 
    public override void RecalculateChildren()
    {
        base.RecalculateChildren();
        float num = 0f;
        for (int i = 0; i < _items.Count; i++)
        {
            float num2 = ((_items.Count == 1) ? 0f : ListPadding);
            _items[i].Top.Set(num, 0f);
            _items[i].Recalculate();
            num += _items[i].GetOuterDimensions().Height + num2;
        }
        _innerListHeight = num;
    }
 
    private void UpdateScrollbar()
    {
        if (_scrollbar != null)
        {
            float height = GetInnerDimensions().Height;
            _scrollbar.SetView(height, _innerListHeight);
        }
    }
 
    public void SetScrollbar(UIScrollbar scrollbar)
    {
        _scrollbar = scrollbar;
        UpdateScrollbar();
    }
 
    public void UpdateOrder()
    {
        if (ManualSortMethod != null)
        {
            ManualSortMethod(_items);
        }
        else
        {
            _items.Sort(SortMethod);
        }
        UpdateScrollbar();
    }
 
    public int SortMethod(UIElement item1, UIElement item2)
    {
        return item1.CompareTo(item2);
    }
 
    public override List<SnapPoint> GetSnapPoints()
    {
        List<SnapPoint> list = new List<SnapPoint>();
        if (GetSnapPoint(out var point))
        {
            list.Add(point);
        }
        foreach (UIElement item in _items)
        {
            list.AddRange(item.GetSnapPoints());
        }
        return list;
    }
 
    protected override void DrawSelf(SpriteBatch spriteBatch)
    {
        if (_scrollbar != null)
        {
            _innerList.Top.Set(0f - _scrollbar.GetValue(), 0f);
        }
        Recalculate();
    }
 
    public IEnumerator<UIElement> GetEnumerator()
    {
        return ((IEnumerable<UIElement>)_items).GetEnumerator();
    }
 
    IEnumerator IEnumerable.GetEnumerator()
    {
        return ((IEnumerable<UIElement>)_items).GetEnumerator();
    }
}