我需要在WPF控件层次结构中搜索与给定名称或类型匹配的控件。我该怎么做呢?


当前回答

因为这个问题很普遍,它可能会吸引人们去寻找非常琐碎的情况的答案:如果你只想要一个孩子而不是后代,你可以使用Linq:

private void ItemsControlItem_Loaded(object sender, RoutedEventArgs e)
{
    if (SomeCondition())
    {
        var children = (sender as Panel).Children;
        var child = (from Control child in children
                 where child.Name == "NameTextBox"
                 select child).First();
        child.Focus();
    }
}

或者显然的for循环遍历Children。

其他回答

我编辑了CrimsonX的代码,因为它不能处理超类类型:

public static T FindChild<T>(DependencyObject depObj, string childName)
   where T : DependencyObject
{
    // Confirm obj is valid. 
    if (depObj == null) return null;

    // success case
    if (depObj is T && ((FrameworkElement)depObj).Name == childName)
        return depObj as T;

    for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
    {
        DependencyObject child = VisualTreeHelper.GetChild(depObj, i);

        //DFS
        T obj = FindChild<T>(child, childName);

        if (obj != null)
            return obj;
    }

    return null;
}

下面是我的代码,通过类型来查找控件,同时控制我们进入层次结构的深度 (maxDepth == 0表示无限深)。

public static class FrameworkElementExtension
{
    public static object[] FindControls(
        this FrameworkElement f, Type childType, int maxDepth)
    {
        return RecursiveFindControls(f, childType, 1, maxDepth);
    }

    private static object[] RecursiveFindControls(
        object o, Type childType, int depth, int maxDepth = 0)
    {
        List<object> list = new List<object>();
        var attrs = o.GetType()
            .GetCustomAttributes(typeof(ContentPropertyAttribute), true);
        if (attrs != null && attrs.Length > 0)
        {
            string childrenProperty = (attrs[0] as ContentPropertyAttribute).Name;
            foreach (var c in (IEnumerable)o.GetType()
                .GetProperty(childrenProperty).GetValue(o, null))
            {
                if (c.GetType().FullName == childType.FullName)
                    list.Add(c);
                if (maxDepth == 0 || depth < maxDepth)
                    list.AddRange(RecursiveFindControls(
                        c, childType, depth + 1, maxDepth));
            }
        }
        return list.ToArray();
    }
}

因为这个问题很普遍,它可能会吸引人们去寻找非常琐碎的情况的答案:如果你只想要一个孩子而不是后代,你可以使用Linq:

private void ItemsControlItem_Loaded(object sender, RoutedEventArgs e)
{
    if (SomeCondition())
    {
        var children = (sender as Panel).Children;
        var child = (from Control child in children
                 where child.Name == "NameTextBox"
                 select child).First();
        child.Focus();
    }
}

或者显然的for循环遍历Children。

这段代码只是修复了@CrimsonX回答的错误:

 public static T FindChild<T>(DependencyObject parent, string childName)
       where T : DependencyObject
    {    
      // Confirm parent and childName are valid. 
      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);
        // If the child is not of the request child type child
        T childType = child as T;
        if (childType == null)
        {
          // recursively drill down the tree
          foundChild = FindChild<T>(child, childName);

          // If the child is found, break so we do not overwrite the found child. 
          if (foundChild != null) break;
        }
        else if (!string.IsNullOrEmpty(childName))
        {
          var frameworkElement = child as FrameworkElement;
          // If the child's name is set for search
          if (frameworkElement != null && frameworkElement.Name == childName)
          {
            // if the child's name is of the request name
            foundChild = (T)child;
            break;
          }

 // recursively drill down the tree
          foundChild = FindChild<T>(child, childName);

          // If the child is found, break so we do not overwrite the found child. 
          if (foundChild != null) break;


        else
        {
          // child element found.
          foundChild = (T)child;
          break;
        }
      }

      return foundChild;
    }  

你只需要继续递归调用方法,如果类型匹配,但名称不匹配(这发生在你传递FrameworkElement作为T时),否则它将返回null,这是错误的。

您还可以使用FrameworkElement.FindName(string)按名称查找元素。

考虑到:

<UserControl ...>
    <TextBlock x:Name="myTextBlock" />
</UserControl>

在代码隐藏文件中,你可以这样写:

var myTextBlock = (TextBlock)this.FindName("myTextBlock");

当然,因为它是使用x:Name定义的,所以您可以只引用生成的字段,但是您可能希望动态而不是静态地查找它。

这种方法也可用于模板,其中命名项出现多次(每次使用模板一次)。