我有一个控件是另一个控件的子控件(因为所有非root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(否则抛出异常)。
如果我知道父母是什么,那么我可以将其从儿童收藏品,内容或其他内容中删除。但是,如果我不知道父容器的类型是什么 - 如何删除子控件呢?
在下面的代码示例中:如何在不知道父类型(Panel,GroupBox ...)的情况下将“sp1”移动到另一个容器?</ p>
// 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,我只想写下这样的内容:
sp1.Parent.RemoveChild(sp1);
但我没有找到类似的东西。
答案 0 :(得分:20)
您可以使用扩展方法编写辅助类:
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
}
}
答案 1 :(得分:4)
NEW:
我建议使用基类而不是列出的所有其他类。试试这个代码,这3个类是最符合您需求的用例。据我了解,它与previos ^)
几乎相同 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。
答案 2 :(得分: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;
//}
}
答案 3 :(得分:0)
为了完整起见,我在ItemsControl检查中添加了一个Add方法,该方法会将子级放回原处。子级或父级可能尚未出现在可视树中,因此您必须同时检查可视树和逻辑树:
ContextAwarePoolExecutor