How to: Custom Draw a Crosshair Cursor

• Jun 07, 2019
• 3 minutes to read

This example shows how to use the ChartControl.CustomDrawCrosshair event to customize the crosshair cursor. For example, you can use this event to paint crosshair label items depending on the highlighted point value. In this example, the ChartControl.CustomDrawCrosshair event is invoked when you click the Custom Draw Crosshair Cursor button on the form.

Enable the following properties before the crosshair is customized to display crosshair axis lines and labels:

• CrosshairOptions.ShowArgumentLabels
• CrosshairOptions.ShowArgumentLine
• CrosshairOptions.ShowValueLabels
• CrosshairOptions.ShowValueLine

View Example

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"
        xmlns:dxc="http://schemas.devexpress.com/winfx/2008/xaml/charts"
        Title="MainWindow" Height="414" Width="525">
    <Grid>
        <StackPanel>
            <dxc:ChartControl Name="chartControl1" Height="340" 
                              CustomDrawCrosshair="chartControl1_CustomDrawCrosshair">
                <dxc:ChartControl.CrosshairOptions>
                    <dxc:CrosshairOptions ShowArgumentLabels="True" 
                                          ShowArgumentLine="True" 
                                          ShowValueLabels="True" 
                                          ShowValueLine="True"/>
                </dxc:ChartControl.CrosshairOptions>
                <dxc:XYDiagram2D>
                    <dxc:XYDiagram2D.AxisX>
                        <dxc:AxisX2D>
                            <dxc:AxisX2D.CrosshairAxisLabelOptions>
                                <dxc:CrosshairAxisLabelOptions Pattern="{}{V:f1}"/>
                            </dxc:AxisX2D.CrosshairAxisLabelOptions>
                        </dxc:AxisX2D>
                    </dxc:XYDiagram2D.AxisX>
                    <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 DevExpress.Xpf.Charts;
using System.Windows;
using System.Windows.Media;

namespace CrosshairCustomDraw {
    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. 
                if (element.SeriesPoint.Value > 50) {
                    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;
            }
        }
    }
}

MainWindow.xaml.vb

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

Namespace CrosshairCustomDraw

    Public Partial Class MainWindow
        Inherits Window

        Private handleCustomDraw As Boolean

        Public Sub New()
            Me.InitializeComponent()
        End Sub

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

        Private Sub chartControl1_CustomDrawCrosshair(ByVal sender As Object, ByVal e As CustomDrawCrosshairEventArgs)
            If Not handleCustomDraw Then 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. 
            For Each axisLabelElement As CrosshairAxisLabelElement In e.CrosshairAxisLabelElements
                axisLabelElement.Background = Brushes.Blue
            Next

            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. 
                If element.SeriesPoint.Value > 50 Then
                    element.LabelElement.Foreground = Brushes.Green
                    element.LabelElement.FontSize = 14
                End If
            Next

            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
        End Sub
    End Class
End Namespace