折线图堆叠折线高亮显示echarts 折线配置项内容和展示

在鼠标移到上面的legend部分的时候相应的线条要高亮显示，这边设置了showSymbol是false 为了去除线条的圆圈为了好看，请教方法，求高亮

      option = {
    title: {
        text: '折线图堆叠'
    },
    tooltip: {
        trigger: 'axis'
    },
    legend: {
        data: ['邮件营销', '联盟广告', '视频广告', '直接访问', '搜索引擎']
    },
    grid: {
        left: '3%',
        right: '4%',
        bottom: '3%',
        containLabel: true
    },
    toolbox: {
        feature: {
            saveAsImage: {}
        }
    },
    xAxis: {
        type: 'category',
        boundaryGap: false,
        data: ['周一', '周二', '周三', '周四', '周五', '周六', '周日']
    },
    yAxis: {
        type: 'value'
    },
    series: [{
        name: '邮件营销',
        type: 'line',
        stack: '总量',
        data: [120, 132, 101, 134, 90, 230, 210],
        showSymbol: false
    }, {
        name: '联盟广告',
        type: 'line',
        stack: '总量',
        data: [220, 182, 191, 234, 290, 330, 310],
        showSymbol: false
    }, {
        name: '视频广告',
        type: 'line',
        stack: '总量',
        data: [150, 232, 201, 154, 190, 330, 410],
        showSymbol: false
    }, {
        name: '直接访问',
        type: 'line',
        stack: '总量',
        data: [320, 332, 301, 334, 390, 330, 320],
        showSymbol: false
    }, {
        name: '搜索引擎',
        type: 'line',
        stack: '总量',
        data: [820, 932, 901, 934, 1290, 1330, 1320],
        showSymbol: false
    }]
};