正负区域不同颜色编码echarts 折线配置项内容和展示

https://github.com/ecomfe/echarts/issues/4535#issuecomment-262132298

      var base = +new Date(1968, 9, 3);
var oneDay = 24 * 3600 * 1000;
var date = [];

var data = [Math.random() * 300];

for (var i = 1; i < 20000; i++) {
    var now = new Date(base += oneDay);
    date.push([now.getFullYear(), now.getMonth() + 1, now.getDate()].join('/'));
    data.push(Math.round((Math.random() - 0.5) * 100 + data[i - 1]));
}

option = {
    tooltip: {
        trigger: 'axis',
        position: function (pt) {
            return [pt[0], '10%'];
        }
    },
    title: {
        left: 'center',
        text: '大数据量面积图',
    },
    legend: {
        top: 'bottom',
        data:['意向']
    },
    toolbox: {
        feature: {
            dataZoom: {
                yAxisIndex: 'none'
            },
            restore: {},
            saveAsImage: {}
        }
    },
    xAxis: {
        type: 'category',
        boundaryGap: false,
        data: date
    },
    yAxis: {
        type: 'value',
        boundaryGap: [0, '100%']
    },
    dataZoom: [{
        type: 'inside',
        start: 0,
        end: 10
    }, {
        start: 0,
        end: 10,
        handleIcon: 'M10.7,11.9v-1.3H9.3v1.3c-4.9,0.3-8.8,4.4-8.8,9.4c0,5,3.9,9.1,8.8,9.4v1.3h1.3v-1.3c4.9-0.3,8.8-4.4,8.8-9.4C19.5,16.3,15.6,12.2,10.7,11.9z M13.3,24.4H6.7V23h6.6V24.4z M13.3,19.6H6.7v-1.4h6.6V19.6z',
        handleSize: '80%',
        handleStyle: {
            color: '#fff',
            shadowBlur: 3,
            shadowColor: 'rgba(0, 0, 0, 0.6)',
            shadowOffsetX: 2,
            shadowOffsetY: 2
        }
    }],
  	visualMap: {
    	pieces: [{
       		lt: 0,
	        color: 'rgb(255, 158, 68)'
        }, {
          	gte: 0,
			color: 'rgb(255, 70, 131)'
        }]
    },
    series: [
        {
            name:'模拟数据',
            type:'line',
            smooth:true,
            symbol: 'none',
            sampling: 'average',
            lineStyle: {
                normal: {
                    color: 'rgb(255, 70, 131)'
                }
            },
          	areaStyle: { normal: {} },
            data: data
        }
    ]
};