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

Calculates the numeric 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#

double 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 Double

Parameters

Name	Type	Description
series	IEnumerable<Series>	All Series associated with the axis.
axisLength	Double	The length of the axis’s current 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.
visualMax	Double	The visual range’s maximum value.
wholeMin	Double	The whole range’s minimum value.
wholeMax	Double	The whole range’s maximum value.

Returns

Type	Description
Double	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 numeric 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. Design a class that implements the INumericMeasureUnitsCalculator interface and assign it to the AutomaticNumericScaleOptions.AutomaticMeasureUnitsCalculator property to use a custom measurement units calculation algorithm:

C#

public class CustomAutomaticNumericMeasureUnitsCalculator : INumericMeasureUnitsCalculator {
    public double CalculateMeasureUnit(
        IEnumerable<Series> series, 
        double axisLength, int pixelsPerUnit, 
        double visualMin, double visualMax, 
        double wholeMin, double wholeMax
    ) {
        double rawMeasureUnit = (visualMax - visualMin) * pixelsPerUnit / axisLength;
        return Math.Pow(10, GetDigitCount((int)Math.Abs(rawMeasureUnit)));
    }

    private static readonly int[] valueStops = {
        9, 99, 999, 9999, 99999, 999999, 9999999,
        99999999, 999999999, Int32.MaxValue
    };
    private static int GetDigitCount(int value) {
        for (int i = 0; ; i++)
            if (value <= valueStops[i])
                return i + 1;
    }
}

VB.NET

Class CustomAutomaticNumericMeasureUnitsCalculator
    Implements INumericMeasureUnitsCalculator
    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 Double Implements INumericMeasureUnitsCalculator.CalculateMeasureUnit
        Dim rawMeasureUnit = (visualMax - visualMin) * pixelsPerUnit / axisLength
        Return Math.Pow(10, GetDigitCount(CType(Math.Abs(rawMeasureUnit), Integer)))
    End Function

    Private Shared ReadOnly valueStops As Integer() = {
            9, 99, 999, 9999, 99999, 999999, 9999999,
            99999999, 999999999, Int32.MaxValue
    }
    Private Shared Function GetDigitCount(value As Integer) As Integer
        For i As Integer = 0 To valueStops.Length
            If (value <= valueStops(i)) Then Return i + 1
        Next
    End Function
End Class

XAML

<dxc:ChartControl>
    <dxc:XYDiagram2D>
        <dxc:XYDiagram2D.AxisX>
            <dxc:AxisX2D>
                <dxc:AxisX2D.NumericScaleOptions>
                    <dxc:AutomaticNumericScaleOptions>
                        <dxc:AutomaticNumericScaleOptions.AutomaticMeasureUnitsCalculator>
                            <view:CustomAutomaticNumericMeasureUnitsCalculator/>
                        </dxc:AutomaticNumericScaleOptions.AutomaticMeasureUnitsCalculator>
                    </dxc:AutomaticNumericScaleOptions>
                </dxc:AxisX2D.NumericScaleOptions>
            </dxc:AxisX2D>
        </dxc:XYDiagram2D.AxisX>
    </dxc:XYDiagram2D>
</dxc:ChartControl>