Question

我有一个UserControl帽子包含几个元素（ListBoxes，Buttons）和一个带有ComboBoxes和Buttons的弹出窗口。

我尝试失去对用户控件的关注，但只要UserControl中的焦点发生变化，就会触发Lost（Keyboard）Focus事件。

但我不想知道孩子何时失去对UserControl的另一个孩子的焦点，但我想知道，当键盘焦点移动到UserControl外的元素并且它是Popup时。

有没有办法检测到它，而不检查每个元素的LostFocus？

Answer 1

此解决方案适合您吗？我在UserControl中创建了一个名为LostFocusIgnoreChildren的新事件，仅当新的焦点元素不是此UserControl的子元素时才会触发。

UserControl1.cs

  public partial class UserControl1 : UserControl
    {
        public UserControl1()
        {
            InitializeComponent();
        }

        public event RoutedEventHandler LostFocusIgnoreChildren;
        private void UserControl_LostFocus(object sender, RoutedEventArgs e)
        {
            var focused_element = FocusManager.GetFocusedElement(Application.Current.Windows.OfType<Window>().SingleOrDefault(x => x.IsActive));
            var parent = (focused_element as FrameworkElement).TryFindParent<UserControl1>();
            if (parent == null && LostFocusIgnoreChildren != null)
                LostFocusIgnoreChildren(this, e);
        }
    }

VisualTreeHelper扩展

 public static class VisualTreeHelperExt
    {
        public static T TryFindParent<T>(this DependencyObject child)
    where T : DependencyObject
        {
            DependencyObject parentObject = GetParentObject(child);
            if (parentObject == null) return null;
            T parent = parentObject as T;
            if (parent != null)
            {
                return parent;
            }
            else
            {
                return TryFindParent<T>(parentObject);
            }
        }

        public static DependencyObject GetParentObject(this DependencyObject child)
        {
            if (child == null) return null;
            ContentElement contentElement = child as ContentElement;
            if (contentElement != null)
            {
                DependencyObject parent = ContentOperations.GetParent(contentElement);
                if (parent != null) return parent;
                FrameworkContentElement fce = contentElement as FrameworkContentElement;
                return fce != null ? fce.Parent : null;
            }
            FrameworkElement frameworkElement = child as FrameworkElement;
            if (frameworkElement != null)
            {
                DependencyObject parent = frameworkElement.Parent;
                if (parent != null) return parent;
            }
            return VisualTreeHelper.GetParent(child);
        }
    }

WPF UserControl检测忽略子项

1 个答案: