Find all controls in WPF Window by type

Question

I'm looking for a way to find all controls on Window by their type,
for example: find all TextBoxes, find all controls implementing specific interface etc.

Thanks

Answer 1

Use the helper classes VisualTreeHelper or LogicalTreeHelper depending on which tree you're interested in. They both provide methods for getting the children of an element (although the syntax differs a little). I often use these classes for finding the first occurrence of a specific type, but you could easily modify it to find all objects of that type:

public static DependencyObject FindInVisualTreeDown(DependencyObject obj, Type type)
{
    if (obj != null)
    {
        if (obj.GetType() == type)
        {
            return obj;
        }

        for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
        {
            DependencyObject childReturn = FindInVisualTreeDown(VisualTreeHelper.GetChild(obj, i), type);
            if (childReturn != null)
            {
                return childReturn;
            }
        }
    }

    return null;
}

Answer 2

And this is how it works upwards

    private T FindParent<T>(DependencyObject item, Type StopAt) where T : class
    {
        if (item is T)
        {
            return item as T;
        }
        else
        {
            DependencyObject _parent = VisualTreeHelper.GetParent(item);
            if (_parent == null)
            {
                return default(T);
            }
            else
            {
                Type _type = _parent.GetType();
                if (StopAt != null)
                {
                    if ((_type.IsSubclassOf(StopAt) == true) || (_type == StopAt))
                    {
                        return null;
                    }
                }

                if ((_type.IsSubclassOf(typeof(T)) == true) || (_type == typeof(T)))
                {
                    return _parent as T;
                }
                else
                {
                    return FindParent<T>(_parent, StopAt);
                }
            }
        }
    }

Answer 3

This should do the trick

public static IEnumerable<T> FindVisualChildren<T>(DependencyObject depObj) where T : DependencyObject
{
    if (depObj != null)
    {
        for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
        {
            DependencyObject child = VisualTreeHelper.GetChild(depObj, i);
            if (child != null && child is T)
            {
                yield return (T)child;
            }

            foreach (T childOfChild in FindVisualChildren<T>(child))
            {
                yield return childOfChild;
            }
        }
    }
}

then you enumerate over the controls like so

foreach (TextBlock tb in FindVisualChildren<TextBlock>(window))
{
    // do something with tb here
}

Answer 4

This is the easiest way:

IEnumerable<myType> collection = control.Children.OfType<myType>();

where control is the root element of the window.

Answer 5

Do note that using the VisualTreeHelper does only work on controls that derive from Visual or Visual3D. If you also need to inspect other elements (e.g. TextBlock, FlowDocument etc.), using VisualTreeHelper will throw an exception.

Here's an alternative that falls back to the logical tree if necessary:

http://www.hardcodet.net/2009/06/finding-elements-in-wpf-tree-both-ways

Answer 6

To get a list of all childs of a specific type you can use:

private static IEnumerable<DependencyObject> FindInVisualTreeDown(DependencyObject obj, Type type)
{
    if (obj != null)
    {
        if (obj.GetType() == type)
        {
            yield return obj;
        }

        for (var i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
        {
            foreach (var child in FindInVisualTreeDown(VisualTreeHelper.GetChild(obj, i), type))
            {
                if (child != null)
                {
                    yield return child;
                }
            }
        }
    }

    yield break;
}