Creating custom Label Text for points on X axis

[Administrator]

I am working with a chart control(ChartSeriesType.Column) and have 3 series of data that has multiple weeks worth of points.

I would like to have a label appear on the X axis every monday with the date. I can figure out how to determine if a given date is a monday, but cant figure out how to actually get the text to appear on just those days.

Currently my grid is using
Me.LaborChart.PrimaryXAxis.DateTimeFormat = "M/d"
which gives dates of 12/29, 12/30... to the end date

While I like the format, I dont need every point to have a date, and the start date is off.

Any suggestions?

[Davis Jebaraj]

Hi Bob,

You can handle the ChartFormatAxisLabelEvent of the ChartControl and check if the ValueAsDate is a Monday:

private void chartControl1_ChartFormatAxisLabel(object sender, Syncfusion.Windows.Forms.Chart.ChartFormatAxisLabelEventArgs e)
{
if(e.AxisOrientation == Orientation.Horizontal)//X Axis
{
if(e.ValueAsDate.DayOfWeek != DayOfWeek.Monday)
e.Label = String.Empty;
e.Handled = true;
}
}

To customize the start date of the axis, you can set a manual range for the axis by specifying:

this.chartControl1.PrimaryXAxis.DateTimeRange = new ChartDateTimeRange(rangeMin,rangeMax,60,ChartDateTimeIntervalType.Minutes);

rangeMin and rangeMax are computed start and end dates for your data.

Thanks,

Davis

[Administrator]

For some reason, your code was working fine, and then something must have changed. Can you look through this and see if something strikes you?

The two main cases are as follows: The code as is will show all the data, but there is only like 6 intervals on the X axis. And the only label printed on the X axis is the first date, none of the others show anything.

The other time is when the following line is not commented out e.LaborChart.PrimaryXAxis.DateTimeRange = New ChartDateTimeRange(startdate, enddate, 21, ChartDateTimeIntervalType.Days)

then the chart will show many intervals, it looks like it might be the correct number, ~ 52/3 since the interval is 21 days, but now no data is showing up nor do any of the labels.

Thanks!

Private Sub LaborChart_ChartFormatAxisLabel1(ByVal sender As Object, ByVal e As Syncfusion.Windows.Forms.Chart.ChartFormatAxisLabelEventArgs) Handles LaborChart.ChartFormatAxisLabel
''This code is handeling up to 1 year''s worth of daily points.
''The ''Interval'' refers to how often we want to print
''a date for a monday.

If (e.AxisOrientation = Orientation.Horizontal) Then
Dim Range, Interval As Integer
If LaborChart.Series.Count > 0 Then
Range = Me.LaborChart.Series(0).Points.Count
If Range < 61 Then
Interval = 7 '' 1 week
ElseIf Range < 190 Then '' 6 months
Interval = 7 '' 2 weeks
Else
Interval = 21 '' 3 weeks
End If
End If
Dim startdate, enddate As Date
startdate = "4/18/2005"
enddate = startdate.AddDays(Range)
''Me.LaborChart.PrimaryXAxis.DateTimeRange = New ChartDateTimeRange(startdate, enddate, 21, ChartDateTimeIntervalType.Days)

If (e.Value Mod Interval <> 0) Then
e.Label = String.Empty
e.Handled = True
Else
Dim lbl As Date = Schedule.TodayDate.AddDays(e.Value)
e.Label = lbl.Month & "/" & lbl.Day
e.Handled = True
End If

End If
End Sub

[Davis Jebaraj]

Hi Bob, It appears from your code that you are changing the axis range everytime the ChartFormatAxisLabel event is raised. This is not needed and the range only needs to be changed when data in the series is changed. Please refer to the sample linked to below: F26219ChartDateInterval_3779.zip Thanks, Davis

[Administrator]

I tried compiling the example, but there was a control or two that were not present that I couldn’t get to work. I then tried pull over some of the code from your example to see if I could get the dates to show up but it still wouldn’t work. Ive modified my code to generate some random numbers and pulled out just the chart form into a project. I renamed the chart simply ChartControl1 which will need to be added back in. Additionally I added some debug statements, and all the values were 0,50,100,150,200,250 which looks like this event is only considering the main chart lines, and not the actual data points. While it wouldn’t look as clean, I suppose it would be ok to have more vertical lines appearing at every interval. ChartExample_2875.zip

[Davis Jebaraj]

Hi Bob,

Please change the last few lines of the Fill_Chart subroutine with the code below:

''Set the Global Var Interval once per chart load
If ChartControl1.Series.Count > 0 Then
If Me.ChartControl1.Series(0).Points.Count < 61 Then '' Under 2 months
Interval = 7 '' 1 week
ElseIf Me.ChartControl1.Series(0).Points.Count < 190 Then '' Under 6 months
Interval = 14 '' 2 weeks
Else
Interval = 21 '' 3 weeks
End If
End If

Dim PointsCount As Integer
PointsCount = Me.ChartControl1.Series(0).Points.Count
Me.ChartControl1.PrimaryXAxis.RangeType = ChartAxisRangeType.Set
Me.ChartControl1.PrimaryXAxis.Range = New MinMaxInfo(0, PointsCount, Interval)

This should display the labels as desired.

Thanks,

Davis

[Administrator]

Perfect! Thanks!

[Administrator]

One slight problem that Ive been able to find.

If you zoom in on the chart then labels have a tendancy to disappear. If the chart is at the very begining then the labels will show up for whatever is present, but as soon as you scroll the the right by any amount they all dissappear.

[Davis Jebaraj]

Hi Bob,

I can see the problem with the labels not being displayed when zoomed in.

The reason the labels not appearing is that the values on the axis are not round values as in the non zoomed in range.

Non Zoomed Values: 0,14,28,42,56...
Zoomed in Values: 0, 1.27,2.54,...

With these fractional values along the axis, the labels will not get through the Mod check with the interval of 7 or 14 or 21

One workaround is to round the label value before checking for the Mod:

Dim modval As Double
Dim roundedValue As Double
roundedValue = System.Math.Round(e.Value)
modval = roundedValue Mod Interval

Even in this case, a label will be shown only if the fractional value falls within the rounding range. (For example, if 41.2 is a label vale, that will round to 42 and be displayed. However, if during another zoom, the label is at 40.8, that would round to 41 and no label would be displayed).

Thanks,

Davis