ValueIndicatorBase.IsHitTestVisible Property

Gets or sets a value that defines whether an indicator can be returned as a hit-testing result.

Namespace: DevExpress.Xpf.Gauges

Assembly: DevExpress.Xpf.Gauges.v20.2.dll

NuGet Packages: DevExpress.WindowsDesktop.Wpf.Gauges, DevExpress.Wpf.Gauges

Declaration

C#

public bool IsHitTestVisible { get; set; }

VB.NET

Public Property IsHitTestVisible As Boolean

Property Value

Type	Description
Boolean	true in case the indicator can be shown as the result of hit testing; otherwise false.

Remarks

If the IsHitTestVisible property is set to false, the indicator ignores any input events and hit testing. So, by default, this property is set to true.

Example

This example demonstrates how to show a tooltip with the current value of a needle on a circular gauge.

To do this, it is necessary to handle the MouseMove and MouseLeave events for the CircularGaugeControl object and obtain the current mouse position on a scale via the CircularGaugeControl.CalcHitInfo method. After that, if the mouse pointer hovers over the needle, it becomes possible to invoke the tooltip that displays the current needle’s value.

Note that this approach is applicable to only those gauge elements whose ValueIndicatorBase.IsHitTestVisible property is set to True (this is the default option). If the IsHitTestVisible property is set to False, this element is excluded from the hit-testing algorithm. To explore this behavior in action, mark and unmark the “Show tooltips for a needle” CheckEdit (whose check state is bound to the needle’s IsHitTestVisible property). So, the unmarked CheckEdit’s state means that tooltips are not displayed for a needle.

View Example

MainWindow.xaml.vb

Imports Microsoft.VisualBasic
Imports System.Windows
Imports System.Windows.Controls.Primitives
Imports System.Windows.Input
Imports DevExpress.Xpf.Gauges

Namespace DXGauges_ShowTooltips

    Partial Public Class MainWindow
        Inherits Window
        Public Sub New()
            InitializeComponent()
        End Sub


        Private Sub circularGaugeControl1_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs)
                Dim hitInfo As CircularGaugeHitInfo = circularGaugeControl1.CalcHitInfo(e.GetPosition(circularGaugeControl1))

            If hitInfo.InNeedle Then
                tooltip_text.Text = "Value: " & hitInfo.Needle.Value.ToString("n2")
                tooltip.Placement = PlacementMode.Mouse

                tooltip.IsOpen = True
            Else
                tooltip.IsOpen = False
            End If

        End Sub

        Private Sub circularGaugeControl1_MouseLeave(ByVal sender As Object, ByVal e As MouseEventArgs)
            tooltip.IsOpen = False
        End Sub

    End Class
End Namespace

MainWindow.xaml)

<Window x:Class="DXGauges_ShowTooltips.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:dxga="http://schemas.devexpress.com/winfx/2008/xaml/gauges"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:dxe="http://schemas.devexpress.com/winfx/2008/xaml/editors" 
        Title="MainWindow" Height="350" Width="525" >

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="30"/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <dxe:CheckEdit x:Name="hitTestCheckBox" Grid.Row="0" IsChecked="True" >
            Show tooltips for a needle
        </dxe:CheckEdit>
        <dxga:CircularGaugeControl Name="circularGaugeControl1" Grid.Row="1" 
                                   MouseMove="circularGaugeControl1_MouseMove" 
                                   MouseLeave="circularGaugeControl1_MouseLeave">
            <dxga:CircularGaugeControl.Scales>
                <dxga:ArcScale>
                    <dxga:ArcScale.Needles>
                        <dxga:ArcScaleNeedle IsInteractive="True" 
                                             IsHitTestVisible="{Binding ElementName=hitTestCheckBox, Path=IsChecked}" />
                    </dxga:ArcScale.Needles>
                </dxga:ArcScale>
            </dxga:CircularGaugeControl.Scales>
        </dxga:CircularGaugeControl>
        <Popup x:Name="tooltip" AllowsTransparency="True">
                <Border CornerRadius="9" Background="White" BorderBrush="Black" BorderThickness="1" Padding="5">
                <TextBlock x:Name="tooltip_text" />
            </Border>
        </Popup>
    </Grid>
</Window>

MainWindow.xaml.cs

using System.Windows;
using System.Windows.Controls.Primitives;
using System.Windows.Input;
using DevExpress.Xpf.Gauges;

namespace DXGauges_ShowTooltips {

    public partial class MainWindow : Window {
        public MainWindow() {
            InitializeComponent();
        }


        private void circularGaugeControl1_MouseMove(object sender, MouseEventArgs e) {
                CircularGaugeHitInfo hitInfo = 
                circularGaugeControl1.CalcHitInfo(e.GetPosition(circularGaugeControl1));

            if (hitInfo.InNeedle) {
                tooltip_text.Text = "Value: " + hitInfo.Needle.Value.ToString("n2");
                tooltip.Placement = PlacementMode.Mouse;

                tooltip.IsOpen = true;
            }
            else {
                tooltip.IsOpen = false;
            }

        }

        private void circularGaugeControl1_MouseLeave(object sender, MouseEventArgs e) {
            tooltip.IsOpen = false;
        }

    }
}

Related GitHub Examples

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the IsHitTestVisible property.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

XAML

how-to-display-tooltips-for-gauge-elements-e3406/CS/DXGauges_ShowTooltips/MainWindow.xaml#L25

    <dxga:ArcScaleNeedle IsInteractive="True"
                         IsHitTestVisible="{Binding ElementName=hitTestCheckBox, Path=IsChecked}" />
</dxga:ArcScale.Needles>