VirtualFramework/Assets/Scripts/Tools/WaterfallScrollView.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class WaterfallScrollView : MonoBehaviour
{
    [Header("<22><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>")]
    [SerializeField] private ScrollRect scrollRect;
    [SerializeField] private RectTransform viewport;
    [SerializeField] private RectTransform content;
    [SerializeField] private RectTransform itemPrefab;
    [SerializeField] private Image itemImageComponent; // Ԥ<><D4A4><EFBFBD><EFBFBD><EFBFBD>е<EFBFBD>Image<67><65><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>

    [Header("<22>ٲ<EFBFBD><D9B2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>")]
    [SerializeField] private int columnCount = 3;
    [SerializeField] private float spacingX = 10f;
    [SerializeField] private float spacingY = 10f;
    [SerializeField] private float paddingLeft = 10f;
    [SerializeField] private float paddingRight = 10f;
    [SerializeField] private float paddingTop = 10f;
    [SerializeField] private float paddingBottom = 10f;

    private List<float> columnHeights;
    private List<RectTransform> activeItems = new List<RectTransform>();
    private Dictionary<int, RectTransform> pooledItems = new Dictionary<int, RectTransform>();
    private float itemWidth;
    private float viewportHeight;
    private float contentHeight;
    private int totalItemCount = 0;
    private int visibleStartIndex = 0;
    private int visibleEndIndex = 0;
    public List<Sprite> sprites = new List<Sprite>(); // <20>洢<EFBFBD><E6B4A2><EFBFBD>о<EFBFBD><D0BE><EFBFBD>
    private List<float> itemHeights = new List<float>(); // <20>洢ÿ<E6B4A2><C3BF><EFBFBD>ļ<EFBFBD><C4BC><EFBFBD><EFBFBD>߶<EFBFBD>

    private void Start()
    {
        Initialize();
        scrollRect.onValueChanged.AddListener(OnScroll);

        // <20><>ʼ<EFBFBD><CABC><EFBFBD><EFBFBD>sprites<65>Ƿ<EFBFBD><C7B7><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
        if (sprites.Count > 0)
        {
            SetContent(sprites);
        }
        else
        {
            ClearContent();
        }
    }

    private void Initialize()
    {
        // <20><><EFBFBD><EFBFBD><EFBFBD>п<EFBFBD><D0BF>ͼ<EFBFBD><CDBC><EFBFBD>
        float availableWidth = viewport.rect.width - paddingLeft - paddingRight - (columnCount - 1) * spacingX;
        itemWidth = availableWidth / columnCount;

        // <20><>ʼ<EFBFBD><CABC><EFBFBD>и߶<D0B8><DFB6><EFBFBD><EFBFBD><EFBFBD>
        columnHeights = new List<float>(new float[columnCount]);

        // <20><>¼<EFBFBD>ӿڸ߶<DAB8><DFB6><EFBFBD><EFBFBD>ڼ<EFBFBD><DABC><EFBFBD><EFBFBD>ɼ<EFBFBD><C9BC><EFBFBD>
        viewportHeight = viewport.rect.height;
    }

    // ʹ<><CAB9><EFBFBD>ṩ<EFBFBD>ľ<EFBFBD><C4BE><EFBFBD><EFBFBD>б<EFBFBD><D0B1><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
    public void SetContent(List<Sprite> sprites)
    {
        this.sprites = sprites ?? new List<Sprite>();
        totalItemCount = this.sprites.Count;

        // <20><><EFBFBD><EFBFBD>û<EFBFBD>о<EFBFBD><D0BE>飬<EFBFBD><E9A3AC><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
        if (totalItemCount == 0)
        {
            ClearContent();
            return;
        }

        // <20><><EFBFBD><EFBFBD>ÿ<EFBFBD><C3BF><EFBFBD>ĸ߶<C4B8>
        CalculateItemHeights();

        // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ݸ߶<DDB8>
        contentHeight = CalculateContentHeight();
        content.sizeDelta = new Vector2(content.sizeDelta.x, contentHeight);

        // <20><><EFBFBD>¿ɼ<C2BF><C9BC><EFBFBD>
        UpdateVisibleItems();
    }

    // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
    public void ClearContent()
    {
        // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>л<D0BB><EEB6AF>
        foreach (var item in activeItems)
        {
            item.gameObject.SetActive(false);
        }
        activeItems.Clear();

        // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ݴ<EFBFBD>С
        content.sizeDelta = new Vector2(content.sizeDelta.x, 0);
        totalItemCount = 0;
        itemHeights.Clear();
    }

    private void CalculateItemHeights()
    {
        itemHeights.Clear();

        foreach (Sprite sprite in sprites)
        {
            if (sprite != null)
            {
                // <20><><EFBFBD>㱣<EFBFBD>ֿ<EFBFBD><D6BF>߱ȵĸ߶<C4B8>
                float aspectRatio = sprite.rect.width / sprite.rect.height;
                float height = itemWidth / aspectRatio;
                itemHeights.Add(height);
            }
            else
            {
                // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD>գ<EFBFBD>ʹ<EFBFBD><CAB9>Ĭ<EFBFBD>ϸ߶<CFB8>
                itemHeights.Add(150f);
            }
        }
    }

    private float CalculateContentHeight()
    {
        // <20><><EFBFBD><EFBFBD><EFBFBD>и߶<D0B8>
        for (int i = 0; i < columnCount; i++)
        {
            columnHeights[i] = paddingTop;
        }

        // ģ<>Ⲽ<EFBFBD>ּ<EFBFBD><D6BC><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ݸ߶<DDB8>
        for (int i = 0; i < totalItemCount; i++)
        {
            float height = itemHeights[i];
            int shortestColumnIndex = GetShortestColumn();
            columnHeights[shortestColumnIndex] += height + spacingY;
        }

        // <20>ҳ<EFBFBD><D2B3><EFBFBD><EFBFBD>ߵ<EFBFBD><DFB5><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><CEAA><EFBFBD>ݸ߶<DDB8>
        float maxHeight = 0;
        foreach (float height in columnHeights)
        {
            if (height > maxHeight)
            {
                maxHeight = height;
            }
        }

        return maxHeight + paddingBottom - spacingY;
    }

    private int GetShortestColumn()
    {
        int shortestIndex = 0;
        float minHeight = columnHeights[0];

        for (int i = 1; i < columnCount; i++)
        {
            if (columnHeights[i] < minHeight)
            {
                minHeight = columnHeights[i];
                shortestIndex = i;
            }
        }

        return shortestIndex;
    }

    private void UpdateVisibleItems()
    {
        // <20><><EFBFBD><EFBFBD>û<EFBFBD><C3BB><EFBFBD><EFBFBD>Ŀ<EFBFBD><C4BF><EFBFBD><EFBFBD>ִ<EFBFBD><D6B4><EFBFBD>κβ<CEBA><CEB2><EFBFBD>
        if (totalItemCount == 0)
            return;

        // <20><><EFBFBD>㵱ǰ<E3B5B1><C7B0><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>±߽<C2B1>
        float viewportTop = -content.anchoredPosition.y;
        float viewportBottom = viewportTop + viewportHeight;

        // <20><><EFBFBD><EFBFBD><EFBFBD>и߶<D0B8><DFB6><EFBFBD><EFBFBD>ڲ<EFBFBD><DAB2>ּ<EFBFBD><D6BC><EFBFBD>
        for (int i = 0; i < columnCount; i++)
        {
            columnHeights[i] = paddingTop;
        }

        // <20><><EFBFBD><EFBFBD><EFBFBD>ɼ<EFBFBD><C9BC><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʼ<EFBFBD>ͽ<EFBFBD><CDBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
        int newVisibleStartIndex = 0;
        int newVisibleEndIndex = totalItemCount - 1;
        float currentYPosition = 0;

        // <20>ҵ<EFBFBD><D2B5><EFBFBD>һ<EFBFBD><D2BB><EFBFBD>ɼ<EFBFBD><C9BC><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
        for (int i = 0; i < totalItemCount; i++)
        {
            float height = itemHeights[i];
            int columnIndex = GetShortestColumn();
            float xPosition = paddingLeft + columnIndex * (itemWidth + spacingX);
            float yPosition = -columnHeights[columnIndex]; // ע<><D7A2>UI<55><49><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><CEAA>

            columnHeights[columnIndex] += height + spacingY;

            float itemTop = yPosition;
            float itemBottom = yPosition - height;

            // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڿ<EFBFBD><DABF><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڻ<EFBFBD><DABB><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>н<EFBFBD><D0BD><EFBFBD>
            if (itemBottom <= viewportBottom && itemTop >= viewportTop - viewportHeight) // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><D2BB><EFBFBD><EFBFBD>Ļ<EFBFBD>߶ȵ<DFB6><C8B5><EFBFBD><EFBFBD><EFBFBD>
            {
                newVisibleStartIndex = i;
                break;
            }
        }

        // <20><><EFBFBD><EFBFBD><EFBFBD>и߶<D0B8><DFB6>ٴμ<D9B4><CEBC><EFBFBD>
        for (int i = 0; i < columnCount; i++)
        {
            columnHeights[i] = paddingTop;
        }

        // <20>ҵ<EFBFBD><D2B5><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><D2BB><EFBFBD>ɼ<EFBFBD><C9BC><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
        for (int i = 0; i < totalItemCount; i++)
        {
            float height = itemHeights[i];
            int columnIndex = GetShortestColumn();
            float xPosition = paddingLeft + columnIndex * (itemWidth + spacingX);
            float yPosition = -columnHeights[columnIndex]; // ע<><D7A2>UI<55><49><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><CEAA>

            columnHeights[columnIndex] += height + spacingY;

            float itemTop = yPosition;
            float itemBottom = yPosition - height;

            // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڿ<EFBFBD><DABF><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڻ<EFBFBD><DABB><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>н<EFBFBD><D0BD><EFBFBD>
            if (itemBottom <= viewportBottom + viewportHeight && itemTop >= viewportTop) // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><D2BB><EFBFBD><EFBFBD>Ļ<EFBFBD>߶ȵ<DFB6><C8B5><EFBFBD><EFBFBD><EFBFBD>
            {
                newVisibleEndIndex = i;
            }
            else if (i > newVisibleStartIndex) // <20>Ѿ<EFBFBD><D1BE>ҵ<EFBFBD><D2B5><EFBFBD>ʼ<EFBFBD><CABC><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ſ<EFBFBD>ʼ<EFBFBD>жϽ<D0B6><CFBD><EFBFBD>
            {
                break;
            }
        }

        // <20><><EFBFBD><EFBFBD><EFBFBD>ɼ<EFBFBD><C9BC>Χû<CEA7>б仯<D0B1>򲻸<EFBFBD><F2B2BBB8><EFBFBD>
        if (newVisibleStartIndex == visibleStartIndex && newVisibleEndIndex == visibleEndIndex)
        {
            return;
        }

        visibleStartIndex = newVisibleStartIndex;
        visibleEndIndex = newVisibleEndIndex;

        // <20><><EFBFBD>ղ<EFBFBD><D5B2>ٿɼ<D9BF><C9BC><EFBFBD><EFBFBD><EFBFBD>
        RecycleInvisibleItems();

        // <20><><EFBFBD><EFBFBD><EFBFBD>и߶<D0B8><DFB6>ٴμ<D9B4><CEBC>㣬<EFBFBD><E3A3AC><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD>ʲ<EFBFBD><CAB2><EFBFBD>
        for (int i = 0; i < columnCount; i++)
        {
            columnHeights[i] = paddingTop;
        }

        // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>¿ɼ<C2BF><C9BC><EFBFBD>
        for (int i = 0; i < totalItemCount; i++)
        {
            float height = itemHeights[i];
            int columnIndex = GetShortestColumn();
            float xPosition = paddingLeft + columnIndex * (itemWidth + spacingX);
            float yPosition = -columnHeights[columnIndex]; // ע<><D7A2>UI<55><49><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><CEAA>

            columnHeights[columnIndex] += height + spacingY;

            // ֻ<><D6BB><EFBFBD><EFBFBD><EFBFBD>ɼ<EFBFBD><C9BC><EFBFBD>Χ<EFBFBD>ڵ<EFBFBD><DAB5><EFBFBD>
            if (i >= visibleStartIndex && i <= visibleEndIndex)
            {
                CreateOrUpdateItem(i, xPosition, yPosition, itemWidth, height);
            }
        }
    }

    private void CreateOrUpdateItem(int index, float x, float y, float width, float height)
    {
        RectTransform item;
        if (!pooledItems.TryGetValue(index, out item))
        {
            // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
            item = Instantiate(itemPrefab, content);
            item.name = "Item_" + index;
            pooledItems[index] = item;
            activeItems.Add(item);
        }
        else if (!activeItems.Contains(item))
        {
            // <20>ӳ<EFBFBD><D3B3><EFBFBD>ȡ<EFBFBD><C8A1>
            item.gameObject.SetActive(true);
            activeItems.Add(item);
        }

        // <20><><EFBFBD><EFBFBD>λ<EFBFBD>úʹ<C3BA>С
        item.anchorMin = new Vector2(0, 1);
        item.anchorMax = new Vector2(0, 1);
        item.pivot = new Vector2(0, 1);
        item.anchoredPosition = new Vector2(x, y);
        item.sizeDelta = new Vector2(width, height);

        // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
        UpdateItemContent(item, index);
    }

    private void UpdateItemContent(RectTransform item, int index)
    {
        // <20><>ȡImage<67><65><EFBFBD><EFBFBD>
        Image image = item.GetComponentInChildren<Image>();
        if (image == null && itemImageComponent != null)
        {
            // <20><><EFBFBD><EFBFBD>û<EFBFBD><C3BB><EFBFBD>ҵ<EFBFBD>Image<67><65><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD><CAB9>Ԥ<EFBFBD><D4A4><EFBFBD><EFBFBD><EFBFBD>е<EFBFBD><D0B5><EFBFBD><EFBFBD><EFBFBD>
            image = Instantiate(itemImageComponent, item);
            image.rectTransform.anchorMin = Vector2.zero;
            image.rectTransform.anchorMax = Vector2.one;
            image.rectTransform.sizeDelta = Vector2.zero;
        }

        if (image && index < sprites.Count && sprites[index] != null)
        {
            // <20><><EFBFBD>þ<EFBFBD><C3BE><EFBFBD>
            image.sprite = sprites[index];
            image.SetNativeSize();

            // <20><><EFBFBD><EFBFBD>Image<67><65><EFBFBD><EFBFBD>Ϊ<EFBFBD><CEAA><EFBFBD>ֿ<EFBFBD><D6BF>߱<EFBFBD>
            image.preserveAspect = true;
        }
    }

    private void RecycleInvisibleItems()
    {
        // <20>ҳ<EFBFBD><D2B3><EFBFBD>Ҫ<EFBFBD><D2AA><EFBFBD>յ<EFBFBD><D5B5><EFBFBD>
        List<RectTransform> itemsToRecycle = new List<RectTransform>();
        foreach (RectTransform item in activeItems)
        {
            string[] nameParts = item.name.Split('_');
            if (nameParts.Length >= 2 && int.TryParse(nameParts[1], out int itemIndex))
            {
                if (itemIndex < visibleStartIndex || itemIndex > visibleEndIndex)
                {
                    itemsToRecycle.Add(item);
                }
            }
        }

        // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
        foreach (RectTransform item in itemsToRecycle)
        {
            item.gameObject.SetActive(false);
            activeItems.Remove(item);
        }
    }

    private void OnScroll(Vector2 scrollPosition)
    {
        UpdateVisibleItems();
    }
}