How to: Use a Custom Measure Units in Automatic Date-Time Scale Mode

Jun 07, 2019
2 minutes to read

To specify a custom Date-Time measure unit for automatic scale mode, assign an object of a class implementing the IDateTimeMeasureUnitsCalculator interface to the AutomaticDateTimeScaleOptions.AutomaticMeasureUnitsCalculator property of an AutomaticDateTimeScaleOptions object assigned to the AxisX2D.DateTimeScaleOptions.

MainWindow.xaml
DateTimeMeasureUnitsCalculator.cs
DateTimeMeasureUnitsCalculator.vb

xaml

<dxc:XYDiagram2D.AxisX>
    <dxc:AxisX2D>
        <dxc:AxisX2D.DateTimeScaleOptions>
            <dxc:AutomaticDateTimeScaleOptions>
                <dxc:AutomaticDateTimeScaleOptions.AutomaticMeasureUnitsCalculator>
                    <local:CustomDateTimeMeasureUnitsCalculator/>
                </dxc:AutomaticDateTimeScaleOptions.AutomaticMeasureUnitsCalculator>
            </dxc:AutomaticDateTimeScaleOptions>
        </dxc:AxisX2D.DateTimeScaleOptions>
        <dxc:AxisX2D.Label>
            <dxc:AxisLabel TextPattern="{}{A:MMMM yy}"/>
        </dxc:AxisX2D.Label>
    </dxc:AxisX2D>
</dxc:XYDiagram2D.AxisX>

csharp

using DevExpress.Xpf.Charts;
using System;
using System.Collections.Generic;

namespace CustomDateTimeMeasureUnitsCalcuslatorSample {
    class CustomDateTimeMeasureUnitsCalculator : IDateTimeMeasureUnitsCalculator {
        const int daysInWeek = 7;
        const int daysInMonth = 30;
        const int daysInQuarter = 4 * daysInMonth;
        const int daysInYear = 365;

        const int minCount = 5;

        public DateTimeMeasureUnit CalculateMeasureUnit(
                IEnumerable<Series> series,
                double axisLength,
                int pixelsPerUnit,
                double visualMin,
                double visualMax,
                double wholeMin,
                double wholeMax) {
            // Calculate visual range in msecs.
            double visualRange = visualMax - visualMin;
            TimeSpan ts = TimeSpan.FromMilliseconds(visualRange);
            if (ts.TotalDays >= 1.0d) {
                if (ts.TotalDays <= minCount * daysInWeek)
                    return DateTimeMeasureUnit.Day;
                if (ts.TotalDays <= minCount * daysInMonth)
                    return DateTimeMeasureUnit.Week;
                if (ts.TotalDays <= minCount * daysInQuarter)
                    return DateTimeMeasureUnit.Month;
                if (ts.TotalDays <= minCount * daysInYear)
                    return DateTimeMeasureUnit.Quarter;
                else
                    return DateTimeMeasureUnit.Year;
            }
            else if (ts.TotalHours >= 20.0d)
                return DateTimeMeasureUnit.Hour;
            else if (ts.TotalMinutes >= 20.0d)
                return DateTimeMeasureUnit.Minute;
            else if (ts.TotalSeconds >= 20.0d)
                return DateTimeMeasureUnit.Second;
            else
                return DateTimeMeasureUnit.Millisecond;
        }
    }
}

Imports DevExpress.Xpf.Charts
Imports System
Imports System.Collections.Generic

Namespace CustomDateTimeMeasureUnitsCalcuslatorSample
    Friend Class CustomDateTimeMeasureUnitsCalculator
        Implements IDateTimeMeasureUnitsCalculator

        Private Const daysInWeek As Integer = 7
        Private Const daysInMonth As Integer = 30
        Private Const daysInQuarter As Integer = 4 * daysInMonth
        Private Const daysInYear As Integer = 365

        Private Const minCount As Integer = 5

        Public Function CalculateMeasureUnit(
                ByVal series As IEnumerable(Of Series),
                ByVal axisLength As Double,
                ByVal pixelsPerUnit As Integer,
                ByVal visualMin As Double,
                ByVal visualMax As Double,
                ByVal wholeMin As Double,
                ByVal wholeMax As Double) As DateTimeMeasureUnit Implements IDateTimeMeasureUnitsCalculator.CalculateMeasureUnit
            ' Calculate visual range in msecs.
            Dim visualRange As Double = visualMax - visualMin
            Dim ts As TimeSpan = TimeSpan.FromMilliseconds(visualRange)
            If ts.TotalDays >= 1.0R Then
                If ts.TotalDays <= minCount * daysInWeek Then
                    Return DateTimeMeasureUnit.Day
                End If
                If ts.TotalDays <= minCount * daysInMonth Then
                    Return DateTimeMeasureUnit.Week
                End If
                If ts.TotalDays <= minCount * daysInQuarter Then
                    Return DateTimeMeasureUnit.Month
                End If
                If ts.TotalDays <= minCount * daysInYear Then
                    Return DateTimeMeasureUnit.Quarter
                Else
                    Return DateTimeMeasureUnit.Year
                End If
            ElseIf ts.TotalHours >= 20.0R Then
                Return DateTimeMeasureUnit.Hour
            ElseIf ts.TotalMinutes >= 20.0R Then
                Return DateTimeMeasureUnit.Minute
            ElseIf ts.TotalSeconds >= 20.0R Then
                Return DateTimeMeasureUnit.Second
            Else
                Return DateTimeMeasureUnit.Millisecond
            End If
        End Function
    End Class
End Namespace