更改(改变)echarts渲染出来的canvas大小(宽高)

echarts官网demo：https://www.echartsjs.com/examples/zh/index.html#chart-type-line
可以看到渲染出来的canvas全是正方形的，老人直接路过，新手但又有些基础的很多不注意看手册的估计总是忽略一个东西:
init的其他参数：

//初始化的时候传入 width 和 height 就能改变渲染出来的 canvas大小
(dom: HTMLDivElement|HTMLCanvasElement, theme?: Object|string, opts?: {
    devicePixelRatio?: number
    renderer?: string
    /***这儿***/
    width?: number|string
    height? number|string
}) => ECharts

还有一个地方：option的grid参数：width和height，init的宽高只是定义的canvas的宽高，grid定义的是内部的图标相对于canvas的宽高，不知道的小伙伴这时候就知道赶紧记录一下：

简单的写一个例子：

let cityList = ["县1县1", "县2", "县3", "县4", "县5", "县6"];
let baseList = [100000, 15000, 13000, 35000, 34000, 33000];
var dataShadow = [];
var yMax = Math.max(...baseList);
for (var i = 0; i < baseList.length; i++) {
    dataShadow.push(yMax);
}
let option = {
    color: ["#3398DB"],
    tooltip: {
        trigger: "axis",
        axisPointer: {
            // 坐标轴指示器，坐标轴触发有效
            type: "shadow" // 默认为直线，可选为：'line' | 'shadow'
        }
    },
    grid: {
        left: "3%",
        right: "4%",
        bottom: "3%",
        width: "820px",
        height: "280px",
        containLabel: true
    },
    xAxis: [
        {
            type: "category",
            data: cityList,
            axisTick: {
                alignWithLabel: true
            }
        }
    ],
    yAxis: [
        {
            type: "value"
        }
    ],
    series: [
        {
            // For shadow
            type: "bar",
            itemStyle: {
                normal: { color: "rgba(0,0,0,0.05)" }
            },
            barGap: "-100%",
            barWidth: "15px",
            barCategoryGap: "40%",
            data: dataShadow,
            animation: false
        },
        {
            name: "购买总人数",
            type: "bar",
            barWidth: "15px",
            data: baseList,
            itemStyle: {
                color: "#FDC149"
            }
        }
    ]
};
let myChart = this.$echarts.init(this.$refs.totalChart,{width:'880px',height:'300px'});
this.drawImage(myChart, option);