const ctx = canvas.getContext('2d') // 创建一个 2d context

const screenWidth = wx.getSystemInfoSync().screenWidth

const screenHeight = wx.getSystemInfoSync().screenHeight

export default class Main{

constructor(){

    this.drawing()

}

drawing(){

    ctx.fillStyle = '#ffffff' // 矩形颜色

    ctx.fillRect(0, 0, screenWidth, screenHeight) // 矩形左上角顶点为(0, 0)，右下角顶点为(100, 100)

    wx.onTouchStart(function(e){

        ctx.beginPath()

        ctx.moveTo(100, 200);

        ctx.lineTo(100, 300);

        ctx.stroke()

        ctx.closePath();

    })

}

}