GaugeHitInfoBase Class

A base class for classes that contains information about a specific point within a gauge.

Namespace: DevExpress.Xpf.Gauges

Assembly: DevExpress.Xpf.Gauges.v21.2.dll

NuGet Package: DevExpress.Wpf.Gauges

Declaration

C#

public abstract class GaugeHitInfoBase

VB.NET

Public MustInherit Class GaugeHitInfoBase

Remarks

The GaugeHitInfoBase class provides all functionality that is common for a specific point within a gauge derived from it: CircularGaugeHitInfo and LinearGaugeHitInfo.

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;
        }

    }
}

Inheritance

Object

GaugeHitInfoBase

CircularGaugeHitInfo

LinearGaugeHitInfo