Function expandLine

expandLine(line, lineWidth): {
    expandPoints: any[];
    leftPoints: any[];
    offsetPoints: any[];
    rightPoints: any[];
}
根据线的坐标扩展左右边 .
Parameters
- line: [number, number, number?][]
  线的坐标
- lineWidth: number | [number, number][]
  线的总宽度或左右宽数组
Returns {
    expandPoints: any[];
    leftPoints: any[];
    offsetPoints: any[];
    rightPoints: any[];
}
- expandPoints: any[]
- leftPoints: any[]
- offsetPoints: any[]
- rightPoints: any[]