线性渐变:http://blog.csdn.net/u013808809/article/details/59634694
数据渐变: itemStyle
填充区域渐变:areaStyle
itemStyle: {
normal: {
color: new echarts.graphic.LinearGradient(0, 0, 0, 1, [{
// 0% 处的颜色
offset: 0, color: 'red' },
{
// 100% 处的颜色
offset: 1, color: 'blue'
}], false)
}
},