WPF - add scrollviewer to panel with codebehind

Question

For certain reasons I need to add elements to my form with codebehind.

There is a main panel. By clicking a button - I am adding some content to it as below:

    private void AddCodeKlantFieldButtonOnClick(object sender, RoutedEventArgs routedEventArgs)
    {
        var button = sender as Button;
        if (button != null)
        {
            var panel = (StackPanel)button.Tag;
            var stackPanel = new StackPanel { Orientation = Orientation.Horizontal };
            AddLabel(stackPanel, "Klant van:", 135);
            opzoekenLandVan = new OpzoekenCode(OpzoekenCodeTable.Klant, "");
            opzoekenLandTot = new OpzoekenCode(OpzoekenCodeTable.Klant, "");
            stackPanel.Children.Add(opzoekenLandVan);
            AddLabel(stackPanel, "tot en met:", 100);
            stackPanel.Children.Add(opzoekenLandTot);
            var count = panel.Children.Count;                
            panel.Children.Insert(8, stackPanel);
        }
    }

That works fine! But if I add too much items, there is not enough space on the form - so a scrollviewer would be needed. I am quite new and can not figure out how to handle it. I tried this:

        var scrollViewer = new ScrollViewer();
        scrollViewer.Content = panel;
        scrollViewer.Visibility = Visibility.Visible;
        scrollViewer.VerticalScrollBarVisibility = ScrollBarVisibility.Visible;
        scrollViewer.CanContentScroll = true;

But the scrollbar does not appear. If I try to add it to the form

panel.Children.Add(scrollViewer);

I am getting an error:

An exception of type 'System.InvalidOperationException' occurred in PresentationFramework.dll but was not handled in user code

Additional information: Logical tree depth exceeded while traversing the tree. This could indicate a cycle in the tree.

Well there's your problem right there... www.tinyurl.com/jmdw9lf — DotNetRussell
– DotNetRussell, Commented Jun 23, 2016 at 17:19

user2880486 · Accepted Answer · 2016-06-23 19:31:25Z

2

In the code below, you did not add the scrollViewer to the visual tree so it's not displaying

    var scrollViewer = new ScrollViewer();
    scrollViewer.Content = panel;  //this does not add to visualtree
    scrollViewer.Visibility = Visibility.Visible;
    scrollViewer.VerticalScrollBarVisibility = ScrollBarVisibility.Visible;
    scrollViewer.CanContentScroll = true;

one of the lines above is

scrollViewer.Content = panel;

so you will get an error on trying to add it to panel's children.

panel.Children.Add(scrollViewer);

You see the circular issue? First line, you put panel inside scrollViewer, next line you put the same scrollViewer in the panel.

Try commenting out scrollViewer.Content = panel but leave panel.Children.Add(scrollViwer) in, this should add the scrollViewer to the visualtree. But it'll probably be invisible due to 0 width or height since it has no content and is in a stackpanel.

edited Jun 23, 2016 at 19:31

answered Jun 23, 2016 at 19:25

user2880486

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2 Comments

15ee8f99-57ff-4f92-890c-b56153 Over a year ago

The only problem with infinite recursion is infinite recursion.

Denis Over a year ago

Thank you so much! I understand the issue now. I followed your advice and it worked! I created another panel, which contains the actual content(which is dynamically added/removed) and set that new panel as a content of scrollviewer, which is added to the main panel. So it does what I want now! Thanks again!

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