using Cysharp.Threading.Tasks;
using UnityEngine;
using UnityEngine.UI;

//控制目标的最大最小尺寸
[ExecuteAlways]
public class LayoutElementSizeClamp : LayoutElement
{
    [SerializeField] bool m_ClampEnable;
    public bool clampEnable { get { return m_ClampEnable; } set { m_ClampEnable = value; } }

    [SerializeField] Clamp m_Clamp;
    public Clamp clamp { get { return m_Clamp; } }

    [SerializeField] RectTransform m_Target;


    protected override void OnEnable()
    {
        base.OnEnable();
        if (clampEnable && m_Target != null)
        {
            UpdateRect().Forget();
        }

    }

    async UniTask UpdateRect()
    {
        await UniTask.DelayFrame(1);
        preferredHeight = -1;
        preferredWidth = -1;
        //频繁调用ForceRebuildLayoutImmediate的原因是
        // 如Text要自适应宽高又要限制宽高, 先要处理宽度刷新后才能计算换行
        // 强制重新计算布局
        LayoutRebuilder.ForceRebuildLayoutImmediate(transform.parent as RectTransform);
        preferredWidth = Mathf.Clamp(m_Target.rect.width, m_Clamp.minX, m_Clamp.maxX);
        // 强制重新计算布局
        LayoutRebuilder.ForceRebuildLayoutImmediate(transform.parent as RectTransform);
        preferredHeight = Mathf.Clamp(m_Target.rect.height, m_Clamp.minY, m_Clamp.maxY);

    }


    [System.Serializable]
    public struct Clamp
    {
        public float minX;
        public float maxX;
        public float minY;
        public float maxY;
    }

}