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TreeView BringIntoView with MVVM

I want the user to be able to search for items in a TreeView. After entering the search text, TreeViewItem should scroll in the view.

Right now I am using the MVVM template for TreeView, for TreeViewItems and MainView.

What do I need to do to get BringIntoView functionality using MVVM? Is there any property that I can bind? (there was something like FirstVisibileItem in MFC)

We saw a "solution" with behavior. Is it really necessary?

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2 answers

The problem can be solved through behavior.

This CodeProject article describes it very well, and it works out of the box.

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In accordance with the indicated code draft article, here is an example code that shows how to customize the behavior and how to integrate the behavior in XAML.

Behavior customization:

/// <summary> /// Exposes attached behaviors that can be /// applied to TreeViewItem objects. /// </summary> public static class TreeViewItemBehavior { #region IsBroughtIntoViewWhenSelected public static bool GetIsBroughtIntoViewWhenSelected(TreeViewItem treeViewItem) { return (bool)treeViewItem.GetValue(IsBroughtIntoViewWhenSelectedProperty); } public static void SetIsBroughtIntoViewWhenSelected( TreeViewItem treeViewItem, bool value) { treeViewItem.SetValue(IsBroughtIntoViewWhenSelectedProperty, value); } public static readonly DependencyProperty IsBroughtIntoViewWhenSelectedProperty = DependencyProperty.RegisterAttached( "IsBroughtIntoViewWhenSelected", typeof(bool), typeof(TreeViewItemBehavior), new UIPropertyMetadata(false, OnIsBroughtIntoViewWhenSelectedChanged)); static void OnIsBroughtIntoViewWhenSelectedChanged(DependencyObject depObj, DependencyPropertyChangedEventArgs e) { TreeViewItem item = depObj as TreeViewItem; if (item == null) return; if (e.NewValue is bool == false) return; if ((bool)e.NewValue) item.Selected += OnTreeViewItemSelected; else item.Selected -= OnTreeViewItemSelected; } static void OnTreeViewItemSelected(object sender, RoutedEventArgs e) { // Only react to the Selected event raised by the TreeViewItem // whose IsSelected property was modified. Ignore all ancestors // who are merely reporting that a descendant Selected fired. if (!Object.ReferenceEquals(sender, e.OriginalSource)) return; TreeViewItem item = e.OriginalSource as TreeViewItem; if (item != null) item.BringIntoView(); } #endregion // IsBroughtIntoViewWhenSelected }

Then integrate TreeViewItemBehavior in XAML:

 <TreeView.ItemContainerStyle> <Style TargetType="{x:Type TreeViewItem}"> <Setter Property="local:TreeViewItemBehavior.IsBroughtIntoViewWhenSelected" Value="True"/> </Style> </TreeView.ItemContainerStyle>

Good luck :-)

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