[Bug] `barWidth` on time-based bar series unexpectedly expands xAxis min/max

[khazit]

Version

5.6.0

Link to Minimal Reproduction

https://echarts.apache.org/examples/en/editor.html?c=bar-simple&code=yy8oyczPU7BVqOZSUKhwrMgstgIzFRRKKgtSrRTUSzJzU9V1gCK1IKISi4qyxJzSVHWYiuLUosxUoJJosBKIQgWFlMSSRJgYCEQbmptZmBhZmBmAgI6CYSxIL7KcmZkJhhycAbU5KbEI7DQQALLDM1NKMqwUlCwNVJUgwrVAMpar1hoA&enc=deflate

Steps to Reproduce

1. Create a bar chart using Apache ECharts with a time-based xAxis.
2. Use two data points that are only a few hours apart.
3. Render the chart without barWidth and observe the xAxis padding (minimal, a few hours).
4. Add barWidth: "90%" to the bar series.
5. Re-render the chart and observe that the xAxis min/max expand by multiple days.

option = {
  xAxis: {
    type: 'time',
  },
  yAxis: {
    type: 'value'
  },
  series: [
    {
      type: 'bar',
      barWidth: '90%',
      data: [
        [1768428600000, 1],
        [1768466400000, 1],
      ],
    }
  ]
};

Current Behavior

When barWidth is explicitly set on a bar series using a time xAxis, ECharts significantly expands the computed xAxis range (min/max), resulting in several days of padding before and after the actual data points.

This does not happen when barWidth is omitted.

Expected Behavior

Setting barWidth should only affect the visual width of bars and must not influence the xAxis min/max calculation.

The xAxis range and padding should remain consistent with the default behavior when barWidth is not specified.

Environment

- OS:
- Browser:
- Framework:

Any additional comments?

No response

[helgasoft]

This is by design. ECharts is auto-sizing the time axis depending on bar width.
Change series type to 'scatter' to see the difference - the two points are placed at either end of the axis. The reason is that scatter points are "immaterial" and have no width to consider.
If you need more control over the axis, use pixel values like barWidth:11.

[khazit]

I'm really struggling to understand how this is supposed to be a feature. Did you even test the sandbox link?

Setting barWidth: "90%" expands the xAxis by multiple days That’s not auto-sizing. Why would decreasing the bar width increase the x axis?

Also, why does this only happen with two points, but not with three?

option = {
  xAxis: {
    type: 'time',
  },
  yAxis: {
    type: 'value'
  },
  series: [
    {
      data: [
        [1768428600000, 1],
        [1768466400000, 1],
        [1768506400000, 1],
      ],
      type: 'bar',
      barWidth: "90%",
    }
  ]
};

If this were an intentional sizing rule, it should behave consistently regardless of point count.
I understand that bars have width and that scatter points don’t. That still doesn’t explain why a percentage-based bar width should massively distort a time axis to this extent, and only under very specific conditions.

[helgasoft]

To help clarify a bit, API for barWidth says:
"...percent value like '60%'. The percent is based on the calculated category width."
This means that barWidth % should be used with the category axis rather than the time axis.

I agree about the inconsistency in auto-sizing behavior. Maybe the API should be updated to explain it better.