DateTime Values

1. If you want to use DateTime values as X, Y or Y2 data for your chart you do that the same way as you would add numeric values. MindFusion.Charting for WPF supports DateTime values given in any of these formats:

• as double values that are representation of a DateTime value in an OLE Automation format.

C#

DateTime myDateTime = new DateTime(2011, 12, 1);
lineSeries[0].XData.Add(myDateTime.ToOADate());

VB.NET

Dim myDateTime As New DateTime(2011, 12, 1)
lineSeries(0).XData.Add(myDateTime.ToOADate())

• as DateTime objects

C#

DateTime myDateTime = new DateTime(2011, 12, 1);
lineSeries[0].XData.Add(myDateTime);

VB.NET

Dim myDateTime As New DateTime(2011, 12, 1)
lineSeries(0).XData.Add(myDateTime)

• as long integer values that are representation of a DateTime value in ticks.

C#

lineSeries[0].XData.Add(myDateTime.Ticks);

VB.NET

lineSeries(0).XData.Add(myDateTime.Ticks)

2. You must set the ValueFormat property of the Axis object for the respective X, Y, X2 or Y2 axis at which DateTime data will be shown to ValueFormat.DateTime:

C#

Axis xAxis = new Axis();
......
xAxis.ValueFormat = ValueFormat.DateTime;

VB.NET

lineChart1.XAxisSettings.ValueFormat = ValueFormat.DateTime

3. The start and end values of the respective axis must be set to the desired DateTime value. The properties for that - Axis.MinValue and Axis.MaxValue accept only double values. When the ValueFormat is ValueFormat.DateTime the control expects OLE Automation representation of the values for the properties:

C#

DateTime start = new DateTime(2011, 3, 1);
DateTime end = new DateTime(2011, 10, 31);
Axis xAxis = new Axis();
xAxis.MinValue = start.ToOADate();
xAxis.MaxValue = end.ToOADate();

VB.NET

Dim start As New DateTime(2011, 3, 1)
Dim [end] As New DateTime(2011, 10, 31)
lineChart1.XAxisSettings.MinValue = start.ToOADate()
lineChart1.XAxisSettings.MaxValue = [end].ToOADate()

The size of the interval among the scale divisions of the axis depends on the number of divisions we want to see:

C#

xAxis.Interval = (end.ToOADate() - start.ToOADate()) / 8;

VB.NET

lineChart1.XAxisSettings.Interval = ([end].ToOADate() - start.ToOADate()) / 8

4. Then we select the type of labels to appear at the axis and rotate them at 35 degrees because formatted as DateTime values they are too long. We use the LabelRotationAngle property for that:

C#

xAxis.Interval = (end.ToOADate() - start.ToOADate())/8;
xAxis.LabelRotationAngle = 35;

VB.NET

lineChart1.XAxisSettings.Interval = ([end].ToOADate() - start.ToOADate()) / 8
lineChart1.XAxisSettings.LabelRotationAngle = 35

5. Finally, don't forget to add the axis to the respective X/Y/X2/Y2 collection:

C#

myLineChart.XAxes.Add(xAxis);

Using DateTime values in a chart is shown in detail in the DateTimeValues sample that is installed with the control.