23

我有一个控件是另一个控件的子控件（因为所有非根控件/元素都在 WPF 中）。如果我想将控件移动到另一个容器，我必须先将它与当前容器断开连接（否则会引发异常）。

如果我知道父母是什么，那么我可以将其从其 Children 集合或 Content 或其他内容中删除。但是如果我不知道父容器的类型是什么——那我该如何移除子控件呢？

在下面的代码示例中：如何在不知道父级（面板、组框...）的类型的情况下将“sp1”移动到另一个容器？

// Add the child object "sp1" to a container (of any type).
StackPanel sp1 = new StackPanel();
SomeParentControl.Children.Add(sp1);

// Somewhere else in the code. I still have a reference to "sp1" but now I don't know what container it is in. I just want to move the "sp1" object to another parent container.
AnotherParentControl.Content = sp1; // Generates exception: "Must disconnect specified child from current parent Visual before attaching to new parent Visual."

理想情况下，我只想写一些类似的东西： 

sp1.Parent.RemoveChild(sp1);

但我还没有找到类似的东西。

4

4 回答 4

24

你可以编写一个带有扩展方法的辅助类：

public static class RemoveChildHelper
{
    public static void RemoveChild(this DependencyObject parent, UIElement child)
    {
        var panel = parent as Panel;
        if (panel != null)
        {
            panel.Children.Remove(child);
            return;
        }

        var decorator = parent as Decorator;
        if (decorator != null)
        {
            if (decorator.Child == child)
            {
                decorator.Child = null;
            }
            return;
        }

        var contentPresenter = parent as ContentPresenter;
        if (contentPresenter != null)
        {
            if (contentPresenter.Content == child)
            {
                contentPresenter.Content = null;
            }
            return;
        }

        var contentControl = parent as ContentControl;
        if (contentControl != null)
        {
            if (contentControl.Content == child)
            {
                contentControl.Content = null;
            }
            return;
        }

        // maybe more
    }
}
于 2013-10-11T12:40:39.447 回答
4

新的：

我建议使用基类而不是所有其他列出的。试试这段代码，这 3 个类是最能满足您需求的用例。据我了解，它几乎与previos相同^）

  var parent = VisualTreeHelper.GetParent(child);
  var parentAsPanel = parent as Panel;
  if (parentAsPanel != null)
  {
      parentAsPanel.Children.Remove(child);
  }
  var parentAsContentControl = parent as ContentControl;
  if (parentAsContentControl != null)
  {
      parentAsContentControl.Content = null;
  }
  var parentAsDecorator = parent as Decorator;
  if (parentAsDecorator != null)
  {
      parentAsDecorator.Child = null;
  }

OLD：据我所知，您可以使用Visual类型作为父类型并尝试调用 RemoveVisualChild 方法。

于 2013-10-11T11:33:49.627 回答
0

我的@Clemens 解决方案版本：

    /// <summary>
    /// Disconnects <paramref name="child"/> from it's parent if any.
    /// </summary>
    /// <param name="child"></param>
    public static void DisconnectIt(this FrameworkElement child)
    {
        var parent = child.Parent;
        if (parent == null)
            return;

        if (parent is Panel panel)
        {
            panel.Children.Remove(child);
            return;
        }

        if (parent is Decorator decorator)
        {
            if (decorator.Child == child)
                decorator.Child = null;

            return;
        }

        if (parent is ContentPresenter contentPresenter)
        {
            if (contentPresenter.Content == child)
                contentPresenter.Content = null;
            return;
        }

        if (parent is ContentControl contentControl)
        {
            if (contentControl.Content == child)
                contentControl.Content = null;
            return;
        }

        //if (parent is ItemsControl itemsControl)
        //{
        //  itemsControl.Items.Remove(child);
        //  return;
        //}
    }
于 2019-05-10T07:47:26.560 回答
0

为了完整起见，我在 ItemsControl 检查中添加了一个 Add 方法，该方法将把孩子放回去。孩子或父母可能还没有在视觉树中，所以你必须检查视觉树和逻辑树：

    /// <summary>
    /// Adds or inserts a child back into its parent
    /// </summary>
    /// <param name="child"></param>
    /// <param name="index"></param>
    public static void AddToParent(this UIElement child, DependencyObject parent, int? index = null)
    {
        if (parent == null)
            return;

        if (parent is ItemsControl itemsControl)
            if (index == null)
                itemsControl.Items.Add(child);
            else
                itemsControl.Items.Insert(index.Value, child);
        else if (parent is Panel panel)
            if (index == null)
                panel.Children.Add(child);
            else
                panel.Children.Insert(index.Value, child);
        else if (parent is Decorator decorator)
            decorator.Child = child;
        else if (parent is ContentPresenter contentPresenter)
            contentPresenter.Content = child;
        else if (parent is ContentControl contentControl)
            contentControl.Content = child;
    }

    /// <summary>
    /// Removes the child from its parent collection or its content.
    /// </summary>
    /// <param name="child"></param>
    /// <param name="parent"></param>
    /// <returns></returns>
    public static bool RemoveFromParent(this UIElement child, out DependencyObject parent, out int? index)
    {
        parent = child.GetParent(true);
        if (parent == null)
            parent = child.GetParent(false);

        index = null;

        if (parent == null)
            return false;

        if (parent is ItemsControl itemsControl)
        {
            if (itemsControl.Items.Contains(child))
            {
                index = itemsControl.Items.IndexOf(child);
                itemsControl.Items.Remove(child);
                return true;
            }
        }
        else if (parent is Panel panel)
        {
            if (panel.Children.Contains(child))
            {
                index = panel.Children.IndexOf(child);
                panel.Children.Remove(child);
                return true;
            }
        }
        else if (parent is Decorator decorator)
        {
            if (decorator.Child == child)
            {
                decorator.Child = null;
                return true;
            }
        }
        else if (parent is ContentPresenter contentPresenter)
        {
            if (contentPresenter.Content == child)
            {
                contentPresenter.Content = null;
                return true;
            }
        }
        else if (parent is ContentControl contentControl)
        {
            if (contentControl.Content == child)
            {
                contentControl.Content = null;
                return true;
            }
        }

        return false;
    }

    public static DependencyObject GetParent(this DependencyObject depObj, bool isVisualTree)
    {
        if (isVisualTree)
        {
            if(depObj is Visual || depObj is Visual3D)
                return VisualTreeHelper.GetParent(depObj);
            return null;
        }
        else
            return LogicalTreeHelper.GetParent(depObj);
    }
于 2019-09-25T13:47:39.697 回答