CODEWITHSUNDEEP
c#.netwpf
Vaccano
Vaccano

Reputation: 82291

Detect when focus is moved via keyboard to outside the captured element

I have this code:

Mouse.AddPreviewMouseDownOutsideCapturedElementHandler(this, 
                                                      OnMouseDownOutsideCapture);

And it fully captures when a mouse click happens outside my WPF Popup (so I can close it).

private void OnMouseDownOutsideCapture(object sender, MouseButtonEventArgs e)
{
   if (Mouse.Captured is ComboBox) return;

   if (IsOpen) 
       IsOpen = false;

   ReleaseMouseCapture();
}

But I need some way to know if the focus is moved outside my popup via the keyboard. More specifically by an shortcut (ie Alt + T).

Right now, my popup does not close when the user moves focus off it that way. Any ideas?

Upvotes: 2

Views: 367

Answers (2)

Vaccano
Vaccano

Reputation: 82291

This is how I did it:

Add this to the constructor:

EventManager.RegisterClassHandler(typeof(UIElement),
          Keyboard.PreviewGotKeyboardFocusEvent, 
          (KeyboardFocusChangedEventHandler)OnPreviewAnyControlGotKeyboardFocus);

Then add this event handler:

    /// <summary>
    /// When focus is lost, make sure that we close the popup if needed.
    /// </summary>
    private void OnPreviewAnyControlGotKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
    {
        // If we are not open then we are done.  No need to go further
        if (!IsOpen) return;

        // See if our new control is on a popup
        var popupParent = VLTreeWalker.FindParentControl<Popup>((DependencyObject)e.NewFocus);

        // If the new control is not the same popup in our current instance then we want to close.
        if ((popupParent == null) || (this.popup != popupParent))
        {
            popupParent.IsOpen = false;
        }
    }

VLTreeWalker is a custom class that walks up the visual tree looking for a match to the passed in generic type and then (if it does not find a matching item, will walk up the logical tree.) Sadly, I can't easily post the source for that here.

this.popup is the instance that you are comparing against (that you want to know if it should close).

Upvotes: 1

tonyjmnz
tonyjmnz

Reputation: 536

You could add a KeyDown event and check if alt+tab were pressed.

Upvotes: 0

Related Questions