CrosshairElementGroup.HeaderElement Property

Gets the settings of crosshair group header elements to customize their appearance.

Namespace: DevExpress.Xpf.Charts

Assembly: DevExpress.Xpf.Charts.v19.2.dll

Declaration

C#

public CrosshairGroupHeaderElement HeaderElement { get; }

VB.NET

Public ReadOnly Property HeaderElement As CrosshairGroupHeaderElement

Property Value

Type	Description
CrosshairGroupHeaderElement	An object implementing the System.Collections.IEnumerable interface that represents the CrosshairGroupHeaderElement collection.

Remarks

Use the HeaderElement property to get access to the appearance settings of the crosshair group header elements when implementing the ChartControl.CustomDrawCrosshair event.

To learn more about a crosshair cursor, see Crosshair Cursor.

Example

This example shows how to provide a custom appearance for the crosshair cursor using the ChartControl.CustomDrawCrosshair event. This event is invoked when you click the Custom Draw Crosshair Cursor button on the form.

If you wish to display crosshair axis lines and labels on a chart before custom drawing the crosshair cursor, set the CrosshairOptions.ShowArgumentLabels, CrosshairOptions.ShowArgumentLine, CrosshairOptions.ShowValueLabels and CrosshairOptionsBase.ShowValueLine properties to true.

Note that the customization of the crosshair cursor is provided for the CrosshairOptions.SnapMode property set to NearestArgument.

Note

A complete sample project is available at https://github.com/DevExpress-Examples/how-to-custom-draw-a-crosshair-cursor-e4385.

MainWindow.xaml

<Window x:Class="CrosshairCustomDraw.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525" xmlns:dxc="http://schemas.devexpress.com/winfx/2008/xaml/charts">
    <Grid>
        <StackPanel>
            <dxc:ChartControl Height="269"  Name="chartControl1" CustomDrawCrosshair="chartControl1_CustomDrawCrosshair">
                <dxc:ChartControl.CrosshairOptions>
                    <dxc:CrosshairOptions ShowArgumentLabels="True" ShowArgumentLine="True" 
                        ShowValueLabels="True" ShowValueLine="True"/>
                </dxc:ChartControl.CrosshairOptions>
                <dxc:XYDiagram2D>
                <dxc:LineSeries2D DisplayName="Series1">
                    <dxc:SeriesPoint Argument="1" Value="50"/>
                    <dxc:SeriesPoint Argument="2" Value="44"/>
                    <dxc:SeriesPoint Argument="3" Value="55"/>
                    <dxc:SeriesPoint Argument="4" Value="77"/>
                </dxc:LineSeries2D>
                <dxc:LineSeries2D DisplayName="Series2">
                    <dxc:SeriesPoint Argument="1" Value="22"/>
                    <dxc:SeriesPoint Argument="2" Value="11"/>
                    <dxc:SeriesPoint Argument="3" Value="9"/>
                    <dxc:SeriesPoint Argument="4" Value="8"/>
                </dxc:LineSeries2D>
                </dxc:XYDiagram2D>
            </dxc:ChartControl>
            <Button Height="35" Content="Custom Draw Crosshair Cursor" Click="Button_Click"></Button>
        </StackPanel>
    </Grid>
</Window>

MainWindow.xaml.cs

using System.Windows;
using DevExpress.Xpf.Charts;
using System.Windows.Media;


namespace CrosshairCustomDraw {
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window {
        bool handleCustomDraw;
        public MainWindow() {
            InitializeComponent();

        }

        private void Button_Click(object sender, RoutedEventArgs e) {
            handleCustomDraw = true;
            chartControl1.CustomDrawCrosshair += chartControl1_CustomDrawCrosshair;
        }

        private void chartControl1_CustomDrawCrosshair(object sender, CustomDrawCrosshairEventArgs e) {

            if (!handleCustomDraw) return;

            // Specify the crosshair argument line color, dash style and thickness.
            e.CrosshairLineElement.Brush = Brushes.Aqua;
            e.CrosshairLineElement.LineStyle.DashStyle = DashStyles.DashDot;
            e.CrosshairLineElement.LineStyle.Thickness = 3;

            // Specify  the back color for crosshair argument label. 
            foreach (CrosshairAxisLabelElement axisLabelElement in e.CrosshairAxisLabelElements)
                axisLabelElement.Background = Brushes.Blue;

            foreach (CrosshairElementGroup group in e.CrosshairElementGroups) {
                CrosshairElement element = group.CrosshairElements[0];

                // Specify the color, dash style and thickness for the crosshair value lines. 
                element.LineElement.Brush = Brushes.DarkViolet;
                element.LineElement.LineStyle.DashStyle = DashStyles.Dash;
                element.LineElement.LineStyle.Thickness = 2;

                // Specify the  font size and background for the crosshair value labels.
                element.AxisLabelElement.FontSize = 14;
                element.AxisLabelElement.Background = Brushes.Red;

                // Specify the foreground and  font size for the crosshair  cursor label that shows series. 
                element.LabelElement.Foreground = Brushes.Green;
                element.LabelElement.FontSize = 14;
            }

            foreach (CrosshairElementGroup group in e.CrosshairElementGroups) {
                CrosshairGroupHeaderElement groupHeaderElement = group.HeaderElement;

                // Specify the text, text color and font for the crosshair group header element. 
                groupHeaderElement.Text = "Custom draw";
                groupHeaderElement.Foreground = Brushes.Red;
                groupHeaderElement.FontSize = 15;
            }
        }
    }
}

Application.xaml.vb

Imports System
Imports System.Collections.Generic
Imports System.Configuration
Imports System.Data
Imports System.Linq
Imports System.Windows

Namespace CrosshairCustomDraw
    ''' <summary>
    ''' Interaction logic for App.xaml
    ''' </summary>
    Partial Public Class App
        Inherits Application

    End Class
End Namespace

Application.xaml

<Application x:Class="CrosshairCustomDraw.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             StartupUri="MainWindow.xaml">
    <Application.Resources>

    </Application.Resources>
</Application>

MainWindow.xaml.vb

Imports System.Windows
Imports DevExpress.Xpf.Charts
Imports System.Windows.Media


Namespace CrosshairCustomDraw
    ''' <summary>
    ''' Interaction logic for MainWindow.xaml
    ''' </summary>
    Partial Public Class MainWindow
        Inherits Window

        Private handleCustomDraw As Boolean
        Public Sub New()
            InitializeComponent()

        End Sub

        Private Sub Button_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
            handleCustomDraw = True
            AddHandler chartControl1.CustomDrawCrosshair, AddressOf chartControl1_CustomDrawCrosshair
        End Sub

        Private Sub chartControl1_CustomDrawCrosshair(ByVal sender As Object, ByVal e As CustomDrawCrosshairEventArgs)

            If Not handleCustomDraw Then
                Return
            End If

            ' Specify the crosshair argument line color, dash style and thickness.
            e.CrosshairLineElement.Brush = Brushes.Aqua
            e.CrosshairLineElement.LineStyle.DashStyle = DashStyles.DashDot
            e.CrosshairLineElement.LineStyle.Thickness = 3

            ' Specify  the back color for crosshair argument label. 
            For Each axisLabelElement As CrosshairAxisLabelElement In e.CrosshairAxisLabelElements
                axisLabelElement.Background = Brushes.Blue
            Next axisLabelElement

            For Each group As CrosshairElementGroup In e.CrosshairElementGroups
                Dim element As CrosshairElement = group.CrosshairElements(0)

                ' Specify the color, dash style and thickness for the crosshair value lines. 
                element.LineElement.Brush = Brushes.DarkViolet
                element.LineElement.LineStyle.DashStyle = DashStyles.Dash
                element.LineElement.LineStyle.Thickness = 2

                ' Specify the  font size and background for the crosshair value labels.
                element.AxisLabelElement.FontSize = 14
                element.AxisLabelElement.Background = Brushes.Red

                ' Specify the foreground and  font size for the crosshair  cursor label that shows series. 
                element.LabelElement.Foreground = Brushes.Green
                element.LabelElement.FontSize = 14
            Next group

            For Each group As CrosshairElementGroup In e.CrosshairElementGroups
                Dim groupHeaderElement As CrosshairGroupHeaderElement = group.HeaderElement

                ' Specify the text, text color and font for the crosshair group header element. 
                groupHeaderElement.Text = "Custom draw"
                groupHeaderElement.Foreground = Brushes.Red
                groupHeaderElement.FontSize = 15
            Next group
        End Sub
    End Class
End Namespace