IDateTimeMeasureUnitsCalculator.CalculateMeasureUnit(IEnumerable<Series>, Double, Int32, Double, Double, Double, Double) Method

Calculates the date-time measurement unit that an axis should use for display.

Namespace: DevExpress.Xpf.Charts

Assembly: DevExpress.Xpf.Charts.v23.2.dll

NuGet Package: DevExpress.Wpf.Charts

Declaration

C#

DateTimeMeasureUnit CalculateMeasureUnit(
    IEnumerable<Series> series,
    double axisLength,
    int pixelsPerUnit,
    double visualMin,
    double visualMax,
    double wholeMin,
    double wholeMax
)

VB.NET

Function CalculateMeasureUnit(
    series As IEnumerable(Of Series),
    axisLength As Double,
    pixelsPerUnit As Integer,
    visualMin As Double,
    visualMax As Double,
    wholeMin As Double,
    wholeMax As Double
) As DateTimeMeasureUnit

Parameters

Name	Type	Description
series	IEnumerable<Series>	All Series associated with the axis.
axisLength	Double	The length of the axis’s visual range in pixels.
pixelsPerUnit	Int32	The minimum count of pixels that series require to draw their points correctly.
visualMin	Double	The visual range’s minimum value in milliseconds.
visualMax	Double	The visual range’s maximum value in milliseconds.
wholeMin	Double	The whole range’s minimum value in milliseconds.
wholeMax	Double	The whole range’s maximum value in milliseconds.

Returns

Type	Description
DateTimeMeasureUnit	The calculated measurement unit.

Remarks

For example, bars can overlap each other if the calculated measurement unit covers fewer pixels on the axis than the pixelPerUnit parameter specifies.

Example

The automatic date-time scale options provide the capability to use a custom measurement unit calculator to determine the current measurement unit if the predefined one does not fit your requirements. Create a class that implements the IDateTimeMeasureUnitsCalculator interface and assign it to the AutomaticDateTimeScaleOptions.AutomaticMeasureUnitsCalculator property to use a custom measurement units calculation algorithm:

C#

public class CustomAutomaticDateTimeMeasureUnitsCalculator : IDateTimeMeasureUnitsCalculator {
    public DateTimeMeasureUnit CalculateMeasureUnit(
        IEnumerable<Series> series, 
        double axisLength, int pixelsPerUnit, 
        double visualMin, double visualMax, 
        double wholeMin, double wholeMax
    ) {
        double rawMeasureUnit = ((visualMax - visualMin) * pixelsPerUnit / axisLength);
        return PickDateTimeMeasureUnit(rawMeasureUnit);
    }

    static int[] unitMultipliers = {
        1, 1000, 60, 60, 24, 7, 4, 3, 4
    };
    static DateTimeMeasureUnit PickDateTimeMeasureUnit(double milliseconds) {
        double valueStop = 1.0;
        for (int i = 0; i < unitMultipliers.Length; i++) {
            valueStop *= unitMultipliers[i];
            if (milliseconds <= valueStop)
                return (DateTimeMeasureUnit)i;
        }
        return DateTimeMeasureUnit.Year;
    }
}

VB.NET

Public Class CustomAutomaticDateTimeMeasureUnitsCalculator
    Implements IDateTimeMeasureUnitsCalculator

    Public Function CalculateMeasureUnit(
            series As IEnumerable(Of Series),
            axisLength As Double, pixelsPerUnit As Integer,
            visualMin As Double, visualMax As Double,
            wholeMin As Double, wholeMax As Double
    ) As DateTimeMeasureUnit Implements IDateTimeMeasureUnitsCalculator.CalculateMeasureUnit
        Dim rawMeasureUnit As Double = ((visualMax - visualMin) _
                    * (pixelsPerUnit / axisLength))
        Return PickDateTimeMeasureUnit(rawMeasureUnit)
    End Function


    Private Shared unitMultipliers As Integer() = {1, 1000, 60, 60, 24, 7, 4, 3, 4}
    Private Shared Function PickDateTimeMeasureUnit(milliseconds As Double) As Double
        Dim valueStop As Double = 1.0
        For i As Integer = 0 To unitMultipliers.Length
            valueStop *= unitMultipliers(i)
            If (milliseconds <= valueStop) Then Return CType(i, DateTimeMeasureUnit)
        Next
        Return DateTimeMeasureUnit.Year
    End Function
End Class

XAML

<dxc:ChartControl>
    <dxc:XYDiagram2D>
        <dxc:XYDiagram2D.AxisX>
            <dxc:AxisX2D>
                <dxc:AxisX2D.DateTimeScaleOptions>
                    <dxc:AutomaticDateTimeScaleOptions>
                        <dxc:AutomaticDateTimeScaleOptions.AutomaticMeasureUnitsCalculator>
                            <view:CustomAutomaticDateTimeMeasureUnitsCalculator/>
                        </dxc:AutomaticDateTimeScaleOptions.AutomaticMeasureUnitsCalculator>
                    </dxc:AutomaticDateTimeScaleOptions>
                </dxc:AxisX2D.DateTimeScaleOptions>
            </dxc:AxisX2D>
        </dxc:XYDiagram2D.AxisX>
    </dxc:XYDiagram2D>
</dxc:ChartControl>