DataMember Class

Contains data member settings that specify from which column in a datasource to obtain data for data points, as well as how to treat this data.

Namespace: DevExpress.UI.Xaml.Charts

Assembly: DevExpress.UI.Xaml.Charts.v21.2.dll

NuGet Package: DevExpress.Uwp.Controls

Declaration

C#

public class DataMember :
    INotifyPropertyChanged

VB.NET

Public Class DataMember
    Implements INotifyPropertyChanged

Remarks

The DataMember class introduces the following properties:

• DataMember.ColumnName, which specifies from which column in a datasource to obtain data;
• DataMember.DataMemberType, which specifies for which data point attribute (argument or value) this data will be obtained;
• DataMember.ScaleType, which specifies how to treat this data (as numbers, data-time values or as strings).

Instances of the DataMember class are available in the DataMemberCollection returned by the DataSourceAdapter.DataMembers property.

For more information, refer to Providing Data.

Example

The following example demonstrates how to bind a chart to data provided by a ViewModel.

To do this, it is necessary to assign the DataSourceAdapter object to the Series.Data property and specify the datasource for the adapter via its DataSourceAdapter.DataSource property.

XAML

<Page
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:BindChart"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:Charts="using:DevExpress.UI.Xaml.Charts"
    x:Class="BindChart.MainPage"
    mc:Ignorable="d">

    <Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}">

        <Charts:CartesianChart>
            <Charts:Series>
                <Charts:Series.View>
                    <Charts:LineSeriesView/>
                </Charts:Series.View>
                <Charts:Series.Data>
                    <Charts:DataSourceAdapter DataSource="{Binding ItemsSource}">
                        <Charts:DataMember DataMemberType="Argument" ColumnName="PointArgument" 
                                           ScaleType="DateTime"/>
                        <Charts:DataMember DataMemberType="Value" ColumnName="PointValue" 
                                           ScaleType="Auto"/>
                    </Charts:DataSourceAdapter>
                </Charts:Series.Data>
            </Charts:Series>
            <Charts:CartesianChart.AxisX>
                <Charts:AxisX DateTimeGridAlignment="Year" DateTimeMeasureUnit="Hour">
                    <Charts:AxisX.LabelOptions>
                        <Charts:AxisLabelOptions Pattern="{}{V:yyyy}"/>
                    </Charts:AxisX.LabelOptions>
                </Charts:AxisX>
            </Charts:CartesianChart.AxisX>
        </Charts:CartesianChart>

    </Grid>
</Page>

C#

using System;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation;

namespace BindChart {

    public sealed partial class MainPage : Page {

        public MainPage() {
            this.InitializeComponent();
            DataContext = new ViewModel() {
                Start = 10000,
                Count = 50000,
                Step = TimeSpan.FromHours(3),
            };
        }

        protected override void OnNavigatedTo(NavigationEventArgs e) {
        }
    }
}

VB.NET

Imports System
Imports Windows.UI.Xaml.Controls
Imports Windows.UI.Xaml.Navigation


Partial Public NotInheritable Class MainPage
    Inherits Page

    Public Sub New()
        Me.InitializeComponent()
        DataContext = New ViewModel() With {.Start = 10000, .Count = 50000, .Increment = TimeSpan.FromHours(3)}
    End Sub

    Protected Overrides Sub OnNavigatedTo(ByVal e As NavigationEventArgs)
    End Sub
End Class

C#

using System;
using System.Collections;
using System.Collections.Generic;

namespace BindChart {

    public class DateTimeDataPoint {
        public DateTime PointArgument { get; set; }
        public double PointValue { get; set; }
    }

    public class ViewModel {
        DateTime start = new DateTime(2000, 1, 1);
        IEnumerable itemsSource;
        readonly Random random = new Random();


        public TimeSpan Step { get; set; }
        public int Count { get; set; }
        public double Start { get; set; }
        public IEnumerable ItemsSource { 
            get { return itemsSource ?? (itemsSource = CreateItemsSource(Count)); } 
        }

        protected IEnumerable CreateItemsSource(int count) {
            var points = new List<DateTimeDataPoint>();

            double value = GenerateStartValue(random);
            points.Add(new DateTimeDataPoint() { PointArgument = start, PointValue = value });
            for (int i = 1; i < count; i++) {
                value += GenerateAddition(random);
                start = start + Step;
                points.Add(new DateTimeDataPoint() { PointArgument = start, PointValue = value });
            }
            return points;
        }

        protected double GenerateStartValue(Random random) {
            return Start + random.NextDouble() * 100;
        }

        protected double GenerateAddition(Random random) {
            double factor = random.NextDouble();
            if (factor == 1)
                factor = 50;
            else if (factor == 0)
                factor = -50;
            return (factor - 0.5) * 50;
        }
    }
}

VB.NET

Imports System
Imports System.Collections
Imports System.Collections.Generic


Public Class DateTimeDataPoint

    Private privatePointArgument As DateTime
    Private privatePointValue As Double

    Public Property PointArgument() As DateTime
        Get
            Return privatePointArgument
        End Get
        Set(ByVal value As DateTime)
            privatePointArgument = value
        End Set
    End Property

    Public Property PointValue() As Double
        Get
            Return privatePointValue
        End Get
        Set(ByVal value As Double)
            privatePointValue = value
        End Set
    End Property

End Class

Public Class ViewModel
    Private startDate As New DateTime(2000, 1, 1)
    Private ReadOnly random1 As New Random()

    Private privateIncrement As TimeSpan
    Public Property Increment() As TimeSpan
        Get
            Return privateIncrement
        End Get
        Set(ByVal value As TimeSpan)
            privateIncrement = value
        End Set
    End Property

    Private privateCount As Integer
    Public Property Count() As Integer
        Get
            Return privateCount
        End Get
        Set(ByVal value As Integer)
            privateCount = value
        End Set
    End Property

    Private privateStart As Double
    Public Property Start() As Double
        Get
            Return privateStart
        End Get
        Set(ByVal value As Double)
            privateStart = value
        End Set
    End Property

    Private privateItemsSource As IEnumerable
    Public ReadOnly Property ItemsSource() As IEnumerable
        Get
            If privateItemsSource IsNot Nothing Then
                Return privateItemsSource
            Else
                privateItemsSource = CreateItemsSource(Count)
                Return privateItemsSource
            End If
        End Get
    End Property

    Protected Function CreateItemsSource(ByVal count As Integer) As IEnumerable
        Dim points = New List(Of DateTimeDataPoint)()

        Dim value As Double = GenerateStartValue(random1)
        points.Add(New DateTimeDataPoint() With {.PointArgument = startDate, .PointValue = value})
        For i As Integer = 1 To count - 1
            value += GenerateAddition(random1)
            startDate = startDate + Increment
            points.Add(New DateTimeDataPoint() With {.PointArgument = startDate, .PointValue = value})
        Next i
        Return points
    End Function

    Protected Function GenerateStartValue(ByVal random As Random) As Double
        Return Start + random.NextDouble() * 100
    End Function

    Protected Function GenerateAddition(ByVal random As Random) As Double
        Dim factor As Double = random.NextDouble()
        If factor = 1 Then
            factor = 50
        ElseIf factor = 0 Then
            factor = -50
        End If
        Return (factor - 0.5) * 50
    End Function

End Class

Inheritance

Object

DataMember