Highlight whole TreeViewItem line in WPF

Question

If I set TreeViewItem Background it highlights the header only. How can I highlight the whole line?

I have found a post almost solving a problem http://social.msdn.

Answer 1

Here we go, third times a charm. If you want something that look like this.

This one takes a bit more work. I'm sure there are many ways of doing this, but this method uses a Length Converter and a TreeViewItem extension method to get the Depth. Both of these are tightly coupled to the TreeViewItem visual tree, so if you start messing with the Templates then you may have troubles. Again, here is the important part, and below is the full code.

TreeViewDepth Extension

public static class TreeViewItemExtensions
{
    public static int GetDepth(this TreeViewItem item)
    {
        TreeViewItem parent;
        while ((parent = GetParent(item)) != null)
        {
            return GetDepth(parent) + 1;
        }
        return 0;
    }

    private static TreeViewItem GetParent(TreeViewItem item)
    {
        var parent = VisualTreeHelper.GetParent(item);
        while (!(parent is TreeViewItem || parent is TreeView))
        {
            parent = VisualTreeHelper.GetParent(parent);
        }
        return parent as TreeViewItem;
    }
}

LeftMarginMultiplierConverter

public class LeftMarginMultiplierConverter : IValueConverter
{
    public double Length { get; set; }

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var item = value as TreeViewItem;
        if (item == null)
            return new Thickness(0);

        return new Thickness(Length * item.GetDepth(), 0, 0, 0);
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new System.NotImplementedException();
    }
}

Control

Full TreeViewItem Style