using UnityEngine;
using UnityEngine.UI;

public class ImageMoveSX : MonoBehaviour
{
    public Image targetImage;       
    public float speed = 100f;      
    public float topLimit = 200f;   
    public float bottomLimit = -200f;

    private RectTransform rectTransform;
    private Vector3 initialPosition;
    private int direction = 1; 

    void Start()
    {
        if (targetImage == null)
        {
            return;
        }

        rectTransform = targetImage.GetComponent<RectTransform>();
        initialPosition = rectTransform.anchoredPosition;
    }

    void Update()
    {
        if (targetImage == null) return;

        // 上下移动
        rectTransform.anchoredPosition += new Vector2(0, direction * speed * Time.deltaTime);

        // 检查边界，反转方向
        if (rectTransform.anchoredPosition.y > initialPosition.y + topLimit)
        {
            rectTransform.anchoredPosition = new Vector2(rectTransform.anchoredPosition.x, initialPosition.y + topLimit);
            direction = -1; // 向下
        }
        else if (rectTransform.anchoredPosition.y < initialPosition.y + bottomLimit)
        {
            rectTransform.anchoredPosition = new Vector2(rectTransform.anchoredPosition.x, initialPosition.y + bottomLimit);
            direction = 1; // 向上
        }
    }
}