using UnityEngine;

[ExecuteAlways]
[RequireComponent(typeof(RectTransform))]
public class SafeAreaUI : MonoBehaviour
{

    public const int SafeWidth = 75;
    public const int SafeBottom = 15;   //竖屏下方间隔


    RectTransform _Panel;
    Rect LastRect = new Rect(0, 0, 0, 0);

    RectTransform Panel
    {
        get
        {
            if (_Panel == null)
                _Panel = GetComponent<RectTransform>();
            return _Panel;
        }
    }

    void Awake()
    {
        Refresh();
    }

    void Update()
    {
        Refresh();
    }

    void Refresh()
    {
        if (LastRect != Panel.rect)
            ApplySafeArea();
    }

    public void ApplySafeArea()
    {
        Panel.anchorMin = Vector2.zero;
        Panel.anchorMax = Vector2.one;
        //竖屏
        if (Screen.height > Screen.width)
        {
            if (Screen.height / Screen.width > 1.8)//宽屏需要适配
            {
                //上下各间隔SafeWidth
                Panel.offsetMin = new Vector2(0, SafeBottom);
                Panel.offsetMax = new Vector2(0, -SafeWidth);
            }
            else
            {
                Panel.offsetMin = new Vector2(0, 0);
                Panel.offsetMax = new Vector2(0, 0);
            }
        }
        else
        {//横屏
            if (Screen.width / Screen.height > 1.8)//宽屏需要适配
            {
                //两边各间隔SafeWidth
                Panel.offsetMin = new Vector2(SafeWidth, 0);
                Panel.offsetMax = new Vector2(-SafeWidth, 0);
            }
            else
            {
                Panel.offsetMin = new Vector2(0, 0);
                Panel.offsetMax = new Vector2(0, 0);
            }
        }
        LastRect = Panel.rect;
    }
    
}