VB.Net Tutorial - WPF Listbox using Scrollintoview
Scrolling the WPF listbox is not that easy as we do in Windows forms applications. But the same time it is not impossible also. With the help of Scrollintoview we can achieve scrolling.
Scrollintoview Function
WPF controls are little different than normal web form controls and windows forms controls. The list box in windows can be scrolled by changing the selected index easily. But in wpf selection and scrolling are handled differently. So in order to scroll while selecting the control we need to write codes separately.
Note
Another point to note is, though the following code snippet will work as is. It is not working in a specific scenario, if the item you would like to scroll to is loaded inside the list box but not visible on the screen, then the scroll won’t work. I am finding a solution. From the initial analysis, the following seems to be working
Begin Invoke
Private Delegate Sub ScrollDelegate(ByVal ItemIndexToBeScrolled As Integer)
Dispatcher.BeginInvoke(New ScrollDelegate(AddressOf ScrollFeedbackViewToLastItem), New Object() {IndexToScroll})
Private Sub ScrollFeedbackViewToLastItem(ByVal IndexToScroll As Integer)
If (IndexToScroll >= lstSongs.Items.Count) Then Return
lstSongs.ScrollIntoView(lstSongs.Items(IndexToScroll))
End Sub
Screen Capture
Source code
Markup (.xaml)
<Window x:
Class=
"Window1" xmlns=
"http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x=
"http://schemas.microsoft.com/winfx/2006/xaml" Title=
"Window1" Height=
"300" Width=
"697" Name=
"Window1">
<Grid>
<ListBox Margin=
"10,10,101,11" Name=
"ListBox1" >
<ListBox.ItemTemplate>
<DataTemplate>
<Label Content=
"{Binding ProductName}">
</Label>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<ScrollBar HorizontalAlignment=
"Right" Margin=
"0,42,38,47" Name=
"ScrollBar1" Width=
"18" />
<Button Height=
"23" HorizontalAlignment=
"Right" Margin=
"0,10,17,0" Name=
"btnTop" VerticalAlignment=
"Top" Width=
"75">Top</Button>
<Button Height=
"23" HorizontalAlignment=
"Right" Margin=
"0,0,17,20" Name=
"btnBottom" VerticalAlignment=
"Bottom" Width=
"75">Bottom</Button>
</Grid>
</Window>
Code behind (xaml.Vb)
Class Window1
Private Sub Window1_Loaded(ByVal sender As System.Object, _
ByVal e As RoutedEventArgs) Handles MyBase.Loaded
Dim NorthwindData As New NorthwindDataContext
ListBox1.ItemsSource = NorthwindData.Products
ScrollBar1.SmallChange = 1
ScrollBar1.LargeChange = NorthwindData.Products.Count / 10
ScrollBar1.Minimum = 0
ScrollBar1.Maximum = NorthwindData.Products.Count
End Sub
Private Sub ScrollBar1_ValueChanged(ByVal sender As System.Object, _
ByVal e As RoutedPropertyChangedEventArgs(Of System.Double)) _
Handles ScrollBar1.ValueChanged
ScrollToIndex(e.NewValue)
End Sub
Private Sub ScrollToIndex(ByVal Index As Integer)
If (Index >= ListBox1.Items.Count) Then Return
ListBox1.ScrollIntoView(ListBox1.Items(Index))
End Sub
Private Sub btnTop_Click(ByVal sender As System.Object, _
ByVal e As RoutedEventArgs) Handles btnTop.Click
ScrollToIndex(0)
End Sub
Private Sub btnBottom_Click(ByVal sender As System.Object, _
ByVal e As RoutedEventArgs) Handles btnBottom.Click
ScrollToIndex(ListBox1.Items.Count - 1)
End Sub
End Class