问：

步骤

• 订阅 TextBox 焦点事件

_associatedObject.GotKeyboardFocus += OnAssociatedObjectGotKeyboardFocus;
_associatedObject.LostKeyboardFocus += OnAssociatedObjectLostKeyboardFocus;

_associatedObject.GotFocus += (s,e) =>
{
    System.Diagnostics.Debug.WriteLine("GotFocus");
};

_associatedObject.LostFocus += (s, e) =>
{
    System.Diagnostics.Debug.WriteLine("LostFocus");
};

_associatedObject.IsKeyboardFocusedChanged += (s, e) =>
{
    System.Diagnostics.Debug.WriteLine("IsKeyboardFocusedChanged");
};

_associatedObject.IsKeyboardFocusWithinChanged += (s, e) =>
{
    System.Diagnostics.Debug.WriteLine("IsKeyboardFocusWithinChanged");
};

• 在 LostKeyboardFocus 之后引发 LostFocusEvent

private void OnAssociatedObjectLostKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
{
    _associatedObject.RaiseEvent(new RoutedEventArgs(UIElement.LostFocusEvent));
    Keyboard.ClearFocus();
    System.Diagnostics.Debug.WriteLine("LostKeyboardFocus");
}

• 打开程序并单击 文本框;
• 元素获得焦点后，单击桌面或任何其他应用程序中，从 TextBox 元素中删除焦点;
• 再次将焦点放回您的应用程序。

期望值

聚焦窗口后，不应向调试窗口添加任何内容，因为该元素已为 LostFocus。

结果

IsKeyboardFocusWithinChanged
IsKeyboardFocusedChanged
GotKeyboardFocus
IsKeyboardFocusWithinChanged
IsKeyboardFocusedChanged
LostFocus
LostKeyboardFocus
LostFocus