在WPF中实现一个弹出层自动获取焦点，弹出层实现是通过其UserControl的依赖属性Visibility的绑定实现的，让UserControl上的TextBox获取焦点，初始实现代码如下：
public Visibility IsVisibile
{
get { return (Visibility)GetValue(IsVisibileProperty); }
set { SetValue(IsVisibileProperty, value); }
}
public static readonly DependencyProperty IsVisibileProperty =
DependencyProperty.Register("IsVisibile", typeof(Visibility), typeof(WordsKeyboard), new PropertyMetadata(Visibility.Collapsed,new PropertyChangedCallback((d,e)=>
{
if((Visibility)e.NewValue==Visibility.Visibile)
(d as MainUserControl).textBox.Focus();
})));
但是第一次弹出该层的时候焦点未在textBox上，除了第一次弹出未获取到焦点后面的弹出都获取到了，为了解决第一次弹出层的TextBox未获取到焦点采用了定时器延时的方法，解决方案如下：
/// <summary> /// 定义个定时器 /// </summary> DispatcherTimer timer = new DispatcherTimer(); /// <summary> /// 构造方法 /// </summary> public MainUserContrl() { InitializeComponent(); timer.Interval = new TimeSpan(500); timer.Tick += timer_Tick; } /// <summary> /// 定时器间隔执行方法 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> void timer_Tick(object sender, EventArgs e) { this.MainText.Focus(); timer.Stop(); } /// <summary> /// 控制改用户控件显示隐藏的依赖属性 /// </summary> public Visibility IsVisibile { get { return (Visibility)GetValue(IsVisibileProperty); } set { SetValue(IsVisibileProperty, value); } } public static readonly DependencyProperty IsVisibileProperty = DependencyProperty.Register("IsVisibile", typeof(Visibility), typeof(WordsKeyboard), new PropertyMetadata(Visibility.Collapsed,new PropertyChangedCallback((d,e)=> { if((Visibility)e.NewValue==Visibility.Collapsed) (d as WordsKeyboard).KillKeyboard(); else { (d as MainUserControl).timer.Start();//开启定时器，让textBox获取到焦点 } })));
通过延时的方法就可以解决掉弹出层第一次无法获取焦点的问题了！而后面让textbox在能使用的情况下不能失去焦点（除非点击弹出层的关闭按钮，让弹出层消失），初始实现代码如下：
/// <summary> /// textBox失去焦点事件 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> private void textBox_LostFocus(object sender,RoutedEventArgs e) { if(textBox.IsEnabled&&!btnCancle.IsFocused) textBox.Focus(); }
上述实现，会出现死循环，假如不出现死循环btnCancle.IsFocused的值一直是false，因为取消按钮一直没有获取到焦点！而解决方案实现如下：
DispatcherTimer timerLoseFocuse = new DispatcherTimer(); timerLoseFocuse.Interval = new TimeSpan(0,0,0,0,100); timerLoseFocuse.Tick+=(s,e)=> { if(CardNumArea.IsEnabled&&!BtnCancel.IsFocused) { this.Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Render,new Action(()=> { t.extBox.Focus(); }));//改方法能解决掉LoseFocuse出现死循环的问题 } timerLoseFocuse.Stop(); }; /// <summary> ///失去焦点事件 /// </summary> private void textBox_LostFocus(object sender, RoutedEventArgs e) { timerLoseFocuse.Start(); }
通过定时器解决取消按钮无法获取到获取到焦点的问题，否则点击取消无法执行其点击事件