NavBarViewBase.ActiveGroupChanged Event

Fires after the active group has been changed.

Namespace: DevExpress.Xpf.NavBar

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

NuGet Packages: DevExpress.WindowsDesktop.Wpf.NavBar, DevExpress.Wpf.Navigation

Declaration

C#

public event NavBarActiveGroupChangedEventHandler ActiveGroupChanged

VB.NET

Public Event ActiveGroupChanged As NavBarActiveGroupChangedEventHandler

Event Data

The ActiveGroupChanged event's data class is NavBarActiveGroupChangedEventArgs. The following properties provide information specific to this event:

Property	Description
Group	Gets a group object related to the event.
Handled	Gets or sets a value that indicates the present state of the event handling for a routed event as it travels the route. Inherited from RoutedEventArgs.
OriginalSource	Gets the original reporting source as determined by pure hit testing, before any possible Source adjustment by a parent class. Inherited from RoutedEventArgs.
RoutedEvent	Gets or sets the RoutedEvent associated with this RoutedEventArgs instance. Inherited from RoutedEventArgs.
Source	Gets or sets a reference to the object that raised the event. Inherited from RoutedEventArgs.

The event data class exposes the following methods:

Method	Description
InvokeEventHandler(Delegate, Object)	When overridden in a derived class, provides a way to invoke event handlers in a type-specific way, which can increase efficiency over the base implementation. Inherited from RoutedEventArgs.
OnSetSource(Object)	When overridden in a derived class, provides a notification callback entry point whenever the value of the Source property of an instance changes. Inherited from RoutedEventArgs.

Remarks

Write an ActiveGroupChanged event handler to perform specific actions each time the active group changes within the NavBarControl.

Example

In this example, a simple navigation interface is implemented using standard Button controls to activate groups within the NavBarControl. Note that navigation to the first and last groups is performed by executing specific commands of the NavbarControl. Navigation between the previous and next groups is implemented by changing the NavBarControl.ActiveGroup property. The NavBarViewBase.ActiveGroupChanged event is handled to determine the availability state of navigation buttons.

The following image shows the implemented interface.

View Example

Window1.xaml

<DockPanel>
    <StackPanel Orientation="Horizontal" DockPanel.Dock="Top">
        <Button Name="btnFirst" Command="dxn:NavBarCommands.SetActiveGroup" CommandTarget="{Binding Path=View, ElementName=navBarControl1}" CommandParameter="{Binding ElementName=firstGroup}">First Group</Button>
        <Button Name="btnNext" Click="button_Click">Next Group</Button>        
        <Button Name="btnPrev" Click="button_Click">Prev Group</Button>
        <Button Name="btnLast" Command="dxn:NavBarCommands.SetActiveGroup" CommandTarget="{Binding Path=View, ElementName=navBarControl1}" CommandParameter="{Binding ElementName=lastGroup}">Last Group</Button>
    </StackPanel>

    <dxn:NavBarControl Name="navBarControl1">
        <dxn:NavBarControl.View>
            <dxn:NavigationPaneView ActiveGroupChanged="NavigationPaneView_ActiveGroupChanged" />
        </dxn:NavBarControl.View>

        <dxn:NavBarControl.Groups>
            <dxn:NavBarGroup Header="Group1" x:Name="firstGroup">
                <dxn:NavBarItem>Item1</dxn:NavBarItem>
            </dxn:NavBarGroup>
        <dxn:NavBarGroup Header="Group2">
            <dxn:NavBarItem>Item1</dxn:NavBarItem>
            <dxn:NavBarItem>Item2</dxn:NavBarItem>
        </dxn:NavBarGroup>
        <dxn:NavBarGroup Header="Group3">
            <dxn:NavBarItem>Item1</dxn:NavBarItem>
            <dxn:NavBarItem>Item2</dxn:NavBarItem>
            <dxn:NavBarItem>Item3</dxn:NavBarItem>
        </dxn:NavBarGroup>
        <dxn:NavBarGroup Header="Group4" x:Name="lastGroup">
            <dxn:NavBarItem>Item1</dxn:NavBarItem>
            <dxn:NavBarItem>Item2</dxn:NavBarItem>
            <dxn:NavBarItem>Item3</dxn:NavBarItem>
            <dxn:NavBarItem>Item4</dxn:NavBarItem>
        </dxn:NavBarGroup>
    </dxn:NavBarControl.Groups>
</dxn:NavBarControl>

</DockPanel>

Window1.xaml.vb

Public Sub New()
    InitializeComponent()
    CheckButtonAvailability()
End Sub

Private Sub button_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
    Dim activegroupIndex As Integer = navBarControl1.Groups.IndexOf(navBarControl1.ActiveGroup)
    If sender Is btnNext Then
        navBarControl1.ActiveGroup = navBarControl1.Groups(activegroupIndex + 1)
    End If
    If sender Is btnPrev Then
        navBarControl1.ActiveGroup = navBarControl1.Groups(activegroupIndex - 1)
    End If
End Sub

Private Sub CheckButtonAvailability()
    btnNext.IsEnabled = Not(navBarControl1.Groups.IndexOf(navBarControl1.ActiveGroup) = navBarControl1.Groups.Count - 1)
    btnPrev.IsEnabled = Not(navBarControl1.Groups.IndexOf(navBarControl1.ActiveGroup) = 0)
End Sub

Private Sub NavigationPaneView_ActiveGroupChanged(ByVal sender As Object, ByVal e As NavBarActiveGroupChangedEventArgs)
    CheckButtonAvailability()
End Sub

Window1.xaml.cs

public Window1(){
    InitializeComponent();
    CheckButtonAvailability();
}

private void button_Click(object sender, RoutedEventArgs e){
    int activegroupIndex = navBarControl1.Groups.IndexOf(navBarControl1.ActiveGroup);
    if (sender == btnNext) navBarControl1.ActiveGroup = navBarControl1.Groups[activegroupIndex + 1];
    if (sender == btnPrev) navBarControl1.ActiveGroup = navBarControl1.Groups[activegroupIndex - 1];
}

private void CheckButtonAvailability(){
    btnNext.IsEnabled = !(navBarControl1.Groups.IndexOf(navBarControl1.ActiveGroup) == navBarControl1.Groups.Count - 1);
    btnPrev.IsEnabled = !(navBarControl1.Groups.IndexOf(navBarControl1.ActiveGroup) == 0);
}

private void NavigationPaneView_ActiveGroupChanged(object sender, NavBarActiveGroupChangedEventArgs e){
    CheckButtonAvailability();
}