WPF 得到子指定元素方法和得到指定子元素集合方法MvvM得到焦点

public class UIHelper {     /// <summary>     /// 在Visual里找到想要的元素     /// childName可为空，不为空就按名字找     /// </summary>     public static T FindChild<T>(DependencyObject parent, string childName)        where T : DependencyObject     {         if (parent == null) return null;           T foundChild = null;           int childrenCount = VisualTreeHelper.GetChildrenCount(parent);         for (int i = 0; i < childrenCount; i++)         {             var child = VisualTreeHelper.GetChild(parent, i);               T childType = child as T;             if (childType == null)             {                 // 住下查要找的元素                 foundChild = FindChild<T>(child, childName);                   // 如果找不到就反回                 if (foundChild != null) break;             }             else if (!string.IsNullOrEmpty(childName))             {                 var frameworkElement = child as FrameworkElement;                 // 看名字是不是一样                 if (frameworkElement != null && frameworkElement.Name == childName)                 {                     //如果名字一样返回                     foundChild = (T)child;                     break;                 }             }             else             {                 // 找到相应的元素了就返回                 foundChild = (T)child;                 break;             }         }           return foundChild;     }       /// <summary>     /// 得到指定元素的集合     /// </summary>     /// <typeparam name="T"></typeparam>     /// <param name="depObj"></param>     /// <returns></returns>     public static IEnumerable<T> FindVisualChildren<T>(DependencyObject depObj)         where T : DependencyObject     {         if (depObj != null)         {             for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)             {                 DependencyObject child = VisualTreeHelper.GetChild(depObj, i);                 if (child != null && child is T)                 {                     yield return (T)child;                 }                   foreach (T childOfChild in FindVisualChildren<T>(child))                 {                     yield return childOfChild;                 }             }         }     } }

　　

public class FocusAdvancement    {        public static bool GetAdvancesByEnterKey(DependencyObject obj)        {            return (bool)obj.GetValue(AdvancesByEnterKeyProperty);        }          public static void SetAdvancesByEnterKey(DependencyObject obj, bool value)        {            obj.SetValue(AdvancesByEnterKeyProperty, value);        }          public static readonly DependencyProperty AdvancesByEnterKeyProperty =            DependencyProperty.RegisterAttached("AdvancesByEnterKey", typeof(bool), typeof(FocusAdvancement),            new UIPropertyMetadata(OnAdvancesByEnterKeyPropertyChanged));          static void OnAdvancesByEnterKeyPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)        {            var element = d as UIElement;            if (element == null) return;              if ((bool)e.NewValue) element.KeyDown += Keydown;            else element.KeyDown -= Keydown;        }          static void Keydown(object sender, KeyEventArgs e)        {            if (!e.Key.Equals(Key.Enter)) return;              var element = sender as UIElement;                         if (element != null) element.MoveFocus(new TraversalRequest(FocusNavigationDirection.Next));        }      }

xmlns:FOU="clr-namespace:WPFAppVM.AppViews.AppCustomViews"   <TextBox FOU:FocusAdvancement.AdvancesByEnterKey="True" Width="120"></TextBox> <TextBox IsReadOnly="True" FOU:FocusAdvancement.AdvancesByEnterKey="True" Width="120"></TextBox> <Button Height="30" Width="80" FOU:FocusAdvancement.AdvancesByEnterKey="True">保存</Button>

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