xAxis gridlines are missing

[JCMcLovin]

I'm using Charts 3.1.1 and my line chart will not display enough xAxis gridlines to fill the viewport:

I want the chart to always display enough gridlines to fill the viewport like the chart in the Health app does:

In my example above I have just one data point and I've set my range to a minimum of 7 hoping it would force 7 xAxis gridlines to always display but it doesn't work:
chartView.setVisibleXRange(minXRange: 7.0, maxXRange: 7.0)

Is this a bug or is there some way to do this that I can't find?

[liuxuan30]

I'm not sure what's enough xAxis gridlines. besides, have you looked at computeAxisValues too see what's the xaxis entries? the grid lines only draw if there are corresponding entry values

[JCMcLovin]

@liuxuan30, Let me say it another way. Do you see in the second screenshot above (from Apple's Health app) how the chart has 8 vertical xAxis gridlines even though there's only one dataEntry?. That's what I want my chart to do. The chart should always show 'enough' gridlines to fill the viewport. If I've configured my chart to show a maximum of 8 data points, if I have less than 8 data points, there should still be 8 gridlines.

I have looked at computeAxisValues for hours and hours and I can't figure out how it actually works. It seems to be entirely dependent on the data values which suggests you must have a data point for each possible x value and that wouldn't make any sense.

Hope that helps.

[liuxuan30]

how can it be? if you have seen computeAxisValues, you know it takes min/max values from your x data range and compute the axis.entries, which are x value labels. So if you only have one data entry, just override the method or provide another way to feed axis.entries with 8 values, you are good to go.

by default, if you only have one entry, the min/max will be +- 1 of your entry. so the range is close. I tried with x = 0, and it gives me 7 vales within [-1, 1]