How to scroll through a listbox with down and up arrow keys in WPF?

I am using an AutoCompleteBox UserControl that uses a listbox inside of a Popup. Everything works fine, the user can type in, view suggested results, and click the result which retrieves information.

i have been trying to add arrow key event handlers so they can scroll down through the listbox that pops up with up and down arrows, and hit enter to select a result.

I have a PreviewKeyDown event on the TextBox the user types in, and inside of that:

    If e.Key = Key.Up Then
        txtNamesListBox.Focus()
    End If

    If e.Key = Key.Down Then
        txtNamesListBox.Focus()
    End If

The event fires and i can rea开发者_开发技巧ch these functions by setting a break point, however it doesnt set the focus to the ListBox that pops up, and i cant scroll through the results at all. is this even possible and am i way off in my attempt? I am at a loss, thanks!

You need to get a reference of the ScrollViewer residing inside ListBox template and use it to scroll content.

Something like following should do. (NOTE: I have not tested this code.)

Example:

ScrollViewer scrollViewer = (ScrollViewer)txtNamesListBox.Template.FindControl("ScrollViewer");
// call methods on scrollViewer

Edit:

Worked out simpler soultion. Idea is wrapping the ListBox with a ScrollViewer and disabling ListBox's scrolling.

Example:

XAML:

<Window x:Class="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"
        Loaded="Window_Loaded">
    <Grid>
        <StackPanel>
            <RepeatButton Click="ScrollUp">Scroll Up</RepeatButton>
            <ScrollViewer Name="scrollViewer"
                          ScrollViewer.VerticalScrollBarVisibility="Hidden"
                          MaxHeight="200">
                <ListBox Name="txtNamesListBox"
                         ScrollViewer.HorizontalScrollBarVisibility="Disabled"
                         ScrollViewer.VerticalScrollBarVisibility="Disabled"></ListBox>
            </ScrollViewer>
                <RepeatButton Click="ScrollDown">Scroll Down</RepeatButton>
        </StackPanel>
    </Grid>
</Window>

Code Behind:

Class MainWindow
    Private Sub Window_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
        txtNamesListBox.ItemsSource = Enumerable.Range(1, 50).Select(Function(i As Int32) i.ToString())
    End Sub

    Private Sub ScrollDown(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
        scrollViewer.ScrollToVerticalOffset(scrollViewer.VerticalOffset + 10)
    End Sub

    Private Sub ScrollUp(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
        scrollViewer.ScrollToVerticalOffset(scrollViewer.VerticalOffset - 10)
    End Sub
End Class