echarts颜色渐变

itemStyle: {
normal: {
color: new this.$echarts.graphic.LinearGradient(1, 0, 0, 0, [{
offset: 0,
color:'#1794e4'
},{
offset: 0.6,
color: '#1794e42d'
}, {
offset: 1,
color: '#1794e40a'
}], false)
}
},