ScrollRect 滚动后单个item坐标计算

因为item的坐标已经被引擎计算过了
所以只需要处理LayoutGroup的Padding即可
实际的坐标只需要先计算content的坐标再计算子元素偏移
最后相加就是实际item当前位置

using UnityEngine;
using UnityEngine.UI;
public class NewBehaviourScript : MonoBehaviour
{
    
    
    public int index;
    public Transform itemPrefab;
    public RectTransform img;
    ScrollRect scrollRect;
    RectTransform content;
    VerticalLayoutGroup layoutGroup;
    Rect displayArea;
    void Start()
    {
    
    
        scrollRect = GetComponent<ScrollRect>();
        content = scrollRect.content;

        layoutGroup = content.GetComponent<VerticalLayoutGroup>();
        itemPrefab.gameObject.SetActive(false);
        for (var i = 0; i < 20; i++)
        {
    
    
            var go = GameObject.Instantiate(itemPrefab.gameObject);
            go.SetActive(true);
            go.gameObject.name = i.ToString();
            go.transform.SetParent(content);
            go.GetComponentInChildren<Text>().text = i.ToString();
        }
    }

    private void LateUpdate()
    {
    
    
        displayArea = new Rect(Vector2.zero, (scrollRect.transform as RectTransform).sizeDelta + scrollRect.viewport.sizeDelta);
        if (scrollRect.content.childCount < index)
            return;

        var contentPos = content.anchoredPosition + GetPivotOffset(content) + GetPaddingOffset();
        var itrmTr = (scrollRect.content.GetChild(index) as RectTransform);
        var pos = itrmTr.anchoredPosition + GetPivotOffset(itrmTr);

        img.anchoredPosition = pos + contentPos;
        img.sizeDelta = itrmTr.sizeDelta;

        //由于Y方向不同需要 乘以 -1
        Debug.Log($"{
      
      index}是否显示:{
      
      displayArea.Overlaps(new Rect(img.anchoredPosition * new Vector2(1, -1), img.sizeDelta))}");
    }
    //垂直布局偏移
    Vector2 GetPaddingOffset()
    {
    
    
        return new Vector2(layoutGroup.padding.left, -layoutGroup.padding.top);
    }
    //中心点偏移
    Vector2 GetPivotOffset(RectTransform tr)
    {
    
    
        return (new Vector2(0, 1) - tr.pivot) * tr.sizeDelta;
    }
}

跳转到子对象

var itrmTr = (scrollRect.content.GetChild(index) as RectTransform);
var pos = itrmTr.anchoredPosition + GetPivotOffset(itrmTr);
scrollRect.content.anchoredPosition = new Vector2(0,-pos.y);