Accessing WPF Control parts from code.

Afternoon all.

As we know, a WPF listbox contains a scrollviewer.

We can access the scrollviewer in XAML such as;

<ListBox Scrollviewer.CanContentScroll="False" />

However, how would I access the scrollviewer from code?

There is no ".Scrollviewer" for me to access, so I tried casting, which failed.

Can anybody suggest how I can access the scrollviewer?

CanContentScroll is a dependency property on ScrollViewer. You can set it like this: ScrollViewer.SetCanContentScroll(listBox1, false);

OK bad example lol


 Im actually trying to get access to one of the methods (ScrollToVerticalOffset)


sorry for the rubbish example lol

jh71283 wrote:

OK bad example lol


 Im actually trying to get access to one of the methods (ScrollToVerticalOffset)


sorry for the rubbish example lol

No, unfortunately ScrollIntoView is no use to me, because I have 2 listboxes that I have to keep at identical scroll positions.

How would I go about 'walking the visual tree'?

How about

((System.Windows.Controls.ScrollViewer)listBox1).ScrollToVerticalOffset(offset);

I recommend Reflector or Visual Studio's Object Browser for examining the WPF class hierarchy.

something like this maybe?
http://www.brunowouters.be/download/ListBoxScroll.zip

Bruno - Brilliant! that is exactly what i was looking for, and works perfectly.

For reference, Bruno has used

FindVisualChild<ScrollViewer>(ListboxName);

to find the scrollviewer, and it works like a charm.

   private childItem FindVisualChild<childItem>(DependencyObject obj) where childItem : DependencyObject {
            for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++) {
                DependencyObject child = VisualTreeHelper.GetChild(obj, i);
                if (child != null && child is childItem) {
                    return (childItem)child;
                } else {
                    childItem childOfChild = FindVisualChild<childItem>(child);
                    if (childOfChild != null) {
                        return childOfChild;
                    }
                }
            }
            return null;
        }

And in VB;

Me.FindVisualChild(Of ScrollViewer)(Me.ListBoxName)


Private Function FindVisualChild(Of childItem As DependencyObject)(ByVal obj As DependencyObject) As childItem
    Dim i As Integer
    For i = 0 To VisualTreeHelper.GetChildrenCount(obj) - 1
        Dim child As DependencyObject = VisualTreeHelper.GetChild(obj, i)
        If ((Not child Is Nothing) AndAlso TypeOf child Is childItem) Then
            Return DirectCast(child, childItem)
        End If
        Dim childOfChild As childItem = Me.FindVisualChild(Of childItem)(child)
        If (Not childOfChild Is Nothing) Then
            Return childOfChild
        End If
    Next i
    Return CType(Nothing, childItem)
End Function