What problem does this feature solve?

我想实现这种，斜线的区域。

What does the proposed API look like?

option = {
xAxis: {
type: 'category',
boundaryGap: false
},
yAxis: {
type: 'value',
boundaryGap: [0, '30%']
},
visualMap: {
type: 'piecewise',
dimension: 0,
pieces: [
{
gt: 1,
lt: 3,
color: 'rgba(0, 0, 180, 0.4)'
}
]
},
series: [
{
type: 'line',
smooth: 0.6,
symbol: 'none',
lineStyle: {
color: '#5470C6',
width: 1
},
markLine: {
symbol: ['none', 'none'],
label: { show: false },
data: [{ xAxis: 1 }, { xAxis: 3 }]
},
areaStyle: {
origin: 560,
},
data: [
['2019-10-10', 200],
['2019-10-11', 560],
['2019-10-12', 750],
['2019-10-13', 580],
['2019-10-14', 250],
['2019-10-15', 300],
['2019-10-16', 450],
['2019-10-17', 300],
['2019-10-18', 100]
]
}
]
};