[Feature] data sampling in dataZoomSlider #18754
Description
What problem does this feature solve?
Consider the following example (or via echarts examples):
let data = [];
for (let i = 1; i < 20000; i++) {
data.push([i, Math.sin((i / 5) * Math.PI)]);
}
option = {
xAxis: {},
yAxis: {},
dataZoom: [
{
start: 0,
end: 5
}
],
series: [
{
type: 'line',
symbol: 'none',
data: data
}
]
};
As the above image shows, the shadow polyline in dataZoom slider does not reflect the correct "shape" (or "outline") of the actual data.
Update: this problem only occurs at specific dimensions, e.g. when #chart-container is width: 1480px.
The data in shadow is resampled here as this._shadowPolygonPts and this._shadowPolylinePts.
This can be improved by applying sampling like lttb.
What does the proposed API look like?
in option:
{
dataZoom: {
dataSampling: '', // default none, can be lttb, average, max, min, sum
}
}or just
{
dataZoom: {
sampling: '', // default none, can be lttb, average, max, min, sum
}
}