Question

For example, my TreeViewItem’ header consists of TextBlock and Image. How I can get references to them?

Answer 1

I’m not sure if I got you right, but if you want to get visual children of an element, try using VisualTreeHelper.GetChild and VisualTreeHelper.GetChildrenCount.

PS: usually it’s more problematic to get a reference to the TreeViewItem itself…

UPDATE (A code example for future generations):

private IEnumerable<DependencyObject> GetChildren(DependencyObject parent)
{
    var count = VisualTreeHelper.GetChildrenCount(parent);
    if (count > 0)
    {
        for (int i = 0; i < count; i++)
            yield return VisualTreeHelper.GetChild(parent, i);
    }
    else
        yield break;
}

private DependencyObject FindInTheVT(DependencyObject parent,Predicate<DependencyObject> predicate)
{
    IEnumerable<DependencyObject> layer = GetChildren(parent);

    while (layer.Any())
    {
        foreach (var d in layer)
            if (predicate(d)) return d;

        layer = layer.SelectMany(x => GetChildren(x));
    }

    return null;
}