WPF: How to programmatically remove focus from a TextBox - wpf

Question

I want to add a simple (at least I thought it was) behaviour to my WPF TextBox.
When the user presses Escape I want the TextBox he is editing to have the text it had when the user started editing, AND I want to remove the focus from the TextBox.
I don't have any problem setting the text for the value it had in the beginning of the edit.
The problem is to remove the focus of the element. I don't want to move the focus to any other component, I just want the TextBox to lose focus. Will I have to have an invisible element to set the focus so my TextBox can lose focus?

Answer 1

in .NET Framework 4 just Keyboard.ClearFocus();

Answer 2

The code I have been using :
// Move to a parent that can take focus
FrameworkElement parent = (FrameworkElement)textBox.Parent;
while (parent != null && parent is IInputElement && !((IInputElement)parent).Focusable)
{
parent = (FrameworkElement)parent.Parent;
}
DependencyObject scope = FocusManager.GetFocusScope(textBox);
FocusManager.SetFocusedElement(scope, parent as IInputElement);

Answer 3

Since none of the above answers worked for me and the accepted answer does work only for a keyboard focus, I came to the following approach:
// Kill logical focus
FocusManager.SetFocusedElement(FocusManager.GetFocusScope(textBox), null);
// Kill keyboard focus
Keyboard.ClearFocus();
Kills both, logical as well as the keyboard focus.

Answer 4

A bit late to the party, but it was helpful to me so here it goes.
Since .Net 3.0, FrameworkElement has a MoveFocus function which did the trick for me.

Answer 5

You can set the focus to a focusable ancestor. This code will work even if the textbox is inside a template with no focusable ancestors inside that same template:
DependencyObject ancestor = textbox.Parent;
while (ancestor != null)
{
var element = ancestor as UIElement;
if (element != null && element.Focusable)
{
element.Focus();
break;
}
ancestor = VisualTreeHelper.GetParent(ancestor);
}

Answer 6

AFAIK, it is not possible to completely remove the focus. Something in your Window will always have the focus.

Answer 7

For me, it's quite tricky, especially when using with LostFocus binding.
However, my workaround is to add an empty label and focus on it.
<Label Name="ResetFocusArea" Focusable="True" FocusVisualStyle="{x:Null}" />
...
OnKeyDown(object sender, RoutedEventArgs e)
{
//if is Esc
ResetFocusArea.Focus();
}

Answer 8

Using LPL's answer worked for me, but it would also make me unable to select any options in dropdown menues. To combat this, I added a check to see if the focused element was a textbox.
Doing the same check for when pressing enter, my final code looked like this:
public Menu()
{
InitializeComponent();
this.PreviewMouseDown += PreviewMouseDownEventHandler;
this.KeyDown += WindowKeyDownHandler;
}
void ClearFocus()
{
UIElement elementWithFocus = Keyboard.FocusedElement as UIElement;
if (elementWithFocus is System.Windows.Controls.TextBox tb)
{
if (Keyboard.FocusedElement != null)
{
Keyboard.FocusedElement.RaiseEvent(new RoutedEventArgs(UIElement.LostFocusEvent));
Keyboard.ClearFocus();
}
}
}
private void PreviewMouseDownEventHandler(object sender, MouseButtonEventArgs e)
{
ClearFocus();
}
private void WindowKeyDownHandler(object sender, System.Windows.Input.KeyEventArgs e)
{
if (e.Key == Key.Enter)
{
ClearFocus();
}
}
With this, I didn't need to add a focuslost to every textbox, and it can easily extend to other elements without breaking compatability with other parts of the program.

Answer 9

In Windows Phone Development, I just did Focus() or this.Focus() in the PhoneApplicationPage and it worked like a charm.

Answer 10

My answer does not adress the above question directly, however, I feel that the wording of it has caused it to become "The Question" about programmatically getting rid of focus. A common scenario where this is needed is for the user to be able to clear focus upon left-clicking the background of a root control, like window.
So, to achieve this, you can create an Attached Behavior that will switch focus to a dynamically created control (in my case, an empty label). It is preferrable to use this behavior on the highest-level elements like windows, as it iterates through it's children to find a panel it can add a dummy label to.
public class LoseFocusOnLeftClick : Behavior<FrameworkElement>
{
private readonly MouseBinding _leftClick;
private readonly Label _emptyControl = new Label() { Focusable = true, HorizontalAlignment = HorizontalAlignment.Left, VerticalAlignment = VerticalAlignment.Top };
public LoseFocusOnLeftClick()
{
_leftClick = new MouseBinding(new RelayCommand(LoseFocus), new MouseGesture(MouseAction.LeftClick));
}
protected override void OnAttached()
{
AssociatedObject.InputBindings.Add(_leftClick);
AssociatedObject.Loaded += AssociatedObject_Loaded;
}
protected override void OnDetaching()
{
AssociatedObject.InputBindings.Remove(_leftClick);
AssociatedObject.Loaded -= AssociatedObject_Loaded;
}
private void AssociatedObject_Loaded(object sender, RoutedEventArgs e)
{
AssociatedObject.Loaded -= AssociatedObject_Loaded;
AttachEmptyControl();
}
private void AttachEmptyControl()
{
DependencyObject currentElement = AssociatedObject;
while (!(currentElement is Panel))
{
currentElement = VisualTreeHelper.GetChild(currentElement, 0);
}
((Panel)currentElement).Children.Add(_emptyControl);
}
private void LoseFocus()
{
_emptyControl.Focus();
}
}

Answer 11

If you want to remove focus from a certain TextBox, just add this line..
textBox.Focusable = false;