Force the last chart tick to have a label

[Paul]

We are binding data collections to a ChartView. The data collections contain measurements taken over a period of time. Those time periods (currently) are four hours, one day, one week and one month. 

When the user chooses a different time period, we refresh the collection and change some of the chart properties to make more sense (LabelFormat, LabelInterval). But because the number of measurements can vary the LabelInterval may end up causing the last gridpoint to not have a label. (I have attached screenshots of a sample showing month, week, day, and four hour renderings.

Is there any way to force the last label to show no matter how many datapoints there are?

 

<telerik:RadCartesianChart x:Name="radChart" Margin="0,0,0,0" Height="340">
    <telerik:RadCartesianChart.HorizontalAxis>
        <telerik:DateTimeContinuousAxis
            LabelInterval="{Binding ChartSettingsViewModel.LabelInterval}"
            LabelFormat="{Binding ChartSettingsViewModel.LabelFormat}"
            PlotMode="OnTicksPadded"
            >
        </telerik:DateTimeContinuousAxis>
    </telerik:RadCartesianChart.HorizontalAxis>
    <telerik:RadCartesianChart.VerticalAxis>
        <telerik:LinearAxis Title="{Binding SeriesTitle}">
        </telerik:LinearAxis>
    </telerik:RadCartesianChart.VerticalAxis>
    <telerik:RadCartesianChart.Grid>
        <telerik:CartesianChartGrid MajorLinesVisibility="Y" MajorYLineDashArray="3,4" StripLinesVisibility="Y" />
    </telerik:RadCartesianChart.Grid>
    <telerik:RadCartesianChart.Series>
        <chartView:LineSeries ItemsSource="{Binding Measurements}" Stroke="{Binding LineColor}">
            <chartView:LineSeries.ValueBinding>
                <telerik:PropertyNameDataPointBinding PropertyName="Value"/>
            </chartView:LineSeries.ValueBinding>
            <chartView:LineSeries.CategoryBinding>
                <telerik:PropertyNameDataPointBinding PropertyName="LocalDateTime"/>
            </chartView:LineSeries.CategoryBinding>
        </chartView:LineSeries>
    </telerik:RadCartesianChart.Series>
</telerik:RadCartesianChart>

[Martin Ivanov]

Hello Paul,

To achieve your requirement you can set the Maximum of the axis to a value that can be multiplied by the label interval. For example, if the axis was numerical and it has the range between 1 and 11 and you apply an interval of 3, you will get labels on the following values: 1, 5, 9. There won't be a label for the last value. But, if you extend the maximum a bit you will get a label position there. For example, you can set the maximum to 13.

I hope that helps.

Regards,
Martin Ivanov
Progress Telerik

[Paul]

But, it is a time-based axis. And the maximum time is determined by the measurements that are bound to the grid. I understand how your solution would work for a static axis, but I don't understand how I would do it for this scenario.

[Martin Ivanov]

Hello Paul,

The same approach could work also with the DateTimeContinuousAxis but I haven't taken into account that the auto calculated major step of the axis will change when you change the maximum. To get the desired functionality you can manually calculate and set the Minimum, Maximum, MajorStep and MajorStepUnit properties of the axis so that the range meets your requirement. As an alternative approach for showing a label on the maximum regardless of the label interval you can use a custom annotation and draw it on the maximum value. You can get the actual maximum when the axis is auto ranged via its ActualRange property.

Regards,
Martin Ivanov
Progress Telerik

[Paul]

Okay, I'm still having issues with this.

How do I create my own X axis labels if I know the start date/time and end date/time and the number of ticks between?

Is there an example of how to do this?

Paul

 

[Martin Ivanov]

Hello Paul,

There is no example how to create custom labels with annotations. However, I prepared a small example showing this and attached it here. I hope it helps.

Regards,
Martin Ivanov
Progress Telerik