using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
namespace DongWuYiXue.DaoNiaoShu
{
    public class DrawLineTool : MonoBehaviour
    {
        public Canvas canvas;
        //线段
        public RectTransform fingerLine;
        [HideInInspector]
        public RectTransform start;
        [HideInInspector]
        public RectTransform end;
        private static DrawLineTool instance;
        private void Awake()
        {
            instance = this;
        }

        //针对手指位置和对应UI控件之间的连线需要转换坐标处理
        private RectTransform SetLine(Vector3 startPos, Vector3 endPos, Color color, RectTransform lineParent)
        {
            RectTransform line = Instantiate(fingerLine, lineParent);
            if (color != null)
                line.GetComponent<Image>().color = color;
            line.gameObject.SetActive(true);
            line.pivot = new Vector2(0, 0.5f);
            line.position = startPos;
            line.eulerAngles = new Vector3(0, 0, GetAngle(startPos, endPos));
            line.sizeDelta = new Vector2(GetDistance(startPos, endPos), fingerLine.sizeDelta.y);
            return line;
        }
        //对外开放的静态方法，方便直接调用
        public static GameObject DrawLine(Vector3 startPos, Vector3 endPos, Color color, RectTransform lineParent)
        {
            return instance.SetLine(startPos, endPos, color, lineParent).gameObject;
        }
        private float GetAngle(Vector3 startPos, Vector3 endPos)
        {
            Vector3 dir = endPos - startPos;
            float angle = Vector3.Angle(Vector3.right, dir);
            Vector3 cross = Vector3.Cross(Vector3.right, dir);
            float dirF = cross.z > 0 ? 1 : -1;
            angle = angle * dirF;
            return angle;
        }
        private float GetDistance(Vector3 startPos, Vector3 endPos)
        {
            float distance = Vector3.Distance(endPos, startPos);
            return distance * 1 / canvas.transform.localScale.x;
        }
    }
}