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。我怎样才能做到这一点？
alex2k8
问问题
367614 次
20 回答
332
我将 John Myczek 使用的模板格式和上面的 Tri Q 算法结合起来创建了一个可以在任何父级上使用的 findChild 算法。请记住，向下递归搜索树可能是一个漫长的过程。我只是在 WPF 应用程序上对此进行了抽查，请对您可能发现的任何错误发表评论，我将更正我的代码。
WPF Snoop是查看可视化树的有用工具 - 我强烈建议在测试时使用它或使用此算法检查您的工作。
Tri Q 的算法有一个小错误。找到孩子后，如果 childrenCount > 1 并且我们再次迭代，我们可以覆盖正确找到的孩子。因此，我在if (foundChild != null) break;代码中添加了一个来处理这种情况。
/// <summary>
/// Finds a Child of a given item in the visual tree.
/// </summary>
/// <param name="parent">A direct parent of the queried item.</param>
/// <typeparam name="T">The type of the queried item.</typeparam>
/// <param name="childName">x:Name or Name of child. </param>
/// <returns>The first parent item that matches the submitted type parameter.
/// If not matching item can be found,
/// a null parent is being returned.</returns>
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;
}
}
else
{
// child element found.
foundChild = (T)child;
break;
}
}
return foundChild;
}
像这样称呼它：
TextBox foundTextBox =
UIHelper.FindChild<TextBox>(Application.Current.MainWindow, "myTextBoxName");
注意Application.Current.MainWindow可以是任何父窗口。
于 2009-11-18T23:42:25.657 回答
158
您还可以使用FrameworkElement.FindName(string)按名称查找元素。
鉴于：
<UserControl ...>
<TextBlock x:Name="myTextBlock" />
</UserControl>
在代码隐藏文件中，您可以编写：
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，但也许您希望动态而不是静态地查找它。
这种方法也可用于模板，其中命名项目出现多次（每次使用模板一次）。
于 2009-09-25T12:48:51.857 回答
70
您可以使用VisualTreeHelper来查找控件。下面是使用 VisualTreeHelper 查找指定类型的父控件的方法。您也可以使用 VisualTreeHelper 以其他方式查找控件。
public static class UIHelper
{
/// <summary>
/// Finds a parent of a given item on the visual tree.
/// </summary>
/// <typeparam name="T">The type of the queried item.</typeparam>
/// <param name="child">A direct or indirect child of the queried item.</param>
/// <returns>The first parent item that matches the submitted type parameter.
/// If not matching item can be found, a null reference is being returned.</returns>
public static T FindVisualParent<T>(DependencyObject child)
where T : DependencyObject
{
// get parent item
DependencyObject parentObject = VisualTreeHelper.GetParent(child);
// we’ve reached the end of the tree
if (parentObject == null) return null;
// check if the parent matches the type we’re looking for
T parent = parentObject as T;
if (parent != null)
{
return parent;
}
else
{
// use recursion to proceed with next level
return FindVisualParent<T>(parentObject);
}
}
}
像这样称呼它：
Window owner = UIHelper.FindVisualParent<Window>(myControl);
于 2009-03-11T21:28:37.663 回答
22
我可能只是在重复其他人，但我确实有一段漂亮的代码，它使用 FindChild() 方法扩展 DependencyObject 类，该方法将通过类型和名称为您获取孩子。只需包含并使用。
public static class UIChildFinder
{
public static DependencyObject FindChild(this DependencyObject reference, string childName, Type childType)
{
DependencyObject foundChild = null;
if (reference != null)
{
int childrenCount = VisualTreeHelper.GetChildrenCount(reference);
for (int i = 0; i < childrenCount; i++)
{
var child = VisualTreeHelper.GetChild(reference, i);
// If the child is not of the request child type child
if (child.GetType() != childType)
{
// recursively drill down the tree
foundChild = FindChild(child, childName, childType);
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 = child;
break;
}
}
else
{
// child element found.
foundChild = child;
break;
}
}
}
return foundChild;
}
}
希望你觉得它有用。
于 2009-10-01T00:52:54.687 回答
19
如果您想查找特定类型的所有控件，您可能也对此片段感兴趣
public static IEnumerable<T> FindVisualChildren<T>(DependencyObject parent)
where T : DependencyObject
{
int childrenCount = VisualTreeHelper.GetChildrenCount(parent);
for (int i = 0; i < childrenCount; i++)
{
var child = VisualTreeHelper.GetChild(parent, i);
var childType = child as T;
if (childType != null)
{
yield return (T)child;
}
foreach (var other in FindVisualChildren<T>(child))
{
yield return other;
}
}
}
于 2012-02-10T14:23:23.087 回答
18
我对代码的扩展。
- 添加重载以按类型、按类型和条件（谓词）查找一个子项，查找符合条件的所有类型的子项
- FindChildren 方法除了是 DependencyObject 的扩展方法外，还是一个迭代器
- FindChildren 也会遍历逻辑子树。请参阅博客文章中链接的 Josh Smith 的文章。
来源： https ://code.google.com/p/gishu-util/source/browse/#git%2FWPF%2FUtilities
解释性博客文章： http: //madcoderspeak.blogspot.com/2010/04/wpf-find-child-control-of-specific-type.html
于 2010-04-20T08:10:18.370 回答
16
这将消除一些元素 - 您应该像这样扩展它以支持更广泛的控件。对于一个简短的讨论，看看这里
/// <summary>
/// Helper methods for UI-related tasks.
/// </summary>
public static class UIHelper
{
/// <summary>
/// Finds a parent of a given item on the visual tree.
/// </summary>
/// <typeparam name="T">The type of the queried item.</typeparam>
/// <param name="child">A direct or indirect child of the
/// queried item.</param>
/// <returns>The first parent item that matches the submitted
/// type parameter. If not matching item can be found, a null
/// reference is being returned.</returns>
public static T TryFindParent<T>(DependencyObject child)
where T : DependencyObject
{
//get parent item
DependencyObject parentObject = GetParentObject(child);
//we've reached the end of the tree
if (parentObject == null) return null;
//check if the parent matches the type we're looking for
T parent = parentObject as T;
if (parent != null)
{
return parent;
}
else
{
//use recursion to proceed with next level
return TryFindParent<T>(parentObject);
}
}
/// <summary>
/// This method is an alternative to WPF's
/// <see cref="VisualTreeHelper.GetParent"/> method, which also
/// supports content elements. Do note, that for content element,
/// this method falls back to the logical tree of the element!
/// </summary>
/// <param name="child">The item to be processed.</param>
/// <returns>The submitted item's parent, if available. Otherwise
/// null.</returns>
public static DependencyObject GetParentObject(DependencyObject child)
{
if (child == null) return null;
ContentElement contentElement = child as ContentElement;
if (contentElement != null)
{
DependencyObject parent = ContentOperations.GetParent(contentElement);
if (parent != null) return parent;
FrameworkContentElement fce = contentElement as FrameworkContentElement;
return fce != null ? fce.Parent : null;
}
//if it's not a ContentElement, rely on VisualTreeHelper
return VisualTreeHelper.GetParent(child);
}
}
于 2009-06-25T09:40:10.950 回答
16
我编辑了 CrimsonX 的代码，因为它不适用于超类类型：
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;
}
于 2010-06-10T13:57:32.390 回答
14
虽然我总体上喜欢递归，但在 C# 中编程时它不如迭代高效，所以也许以下解决方案比 John Myczek 建议的解决方案更简洁？这会从给定控件向上搜索层次结构，以找到特定类型的祖先控件。
public static T FindVisualAncestorOfType<T>(this DependencyObject Elt)
where T : DependencyObject
{
for (DependencyObject parent = VisualTreeHelper.GetParent(Elt);
parent != null; parent = VisualTreeHelper.GetParent(parent))
{
T result = parent as T;
if (result != null)
return result;
}
return null;
}
像这样调用它以找到Window包含一个名为的控件ExampleTextBox：
Window window = ExampleTextBox.FindVisualAncestorOfType<Window>();
于 2011-09-06T12:31:17.443 回答
9
这是我的代码，用于按类型查找控件，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();
}
}
于 2010-10-20T10:17:24.867 回答
9
exciton80 ...我遇到了您的代码没有通过用户控件递归的问题。它击中了 Grid 根并引发了错误。我相信这为我解决了这个问题：
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;
if (String.Equals(childrenProperty, "Content") || String.Equals(childrenProperty, "Children"))
{
var collection = o.GetType().GetProperty(childrenProperty).GetValue(o, null);
if (collection is System.Windows.Controls.UIElementCollection) // snelson 6/6/11
{
foreach (var c in (IEnumerable)collection)
{
if (c.GetType().FullName == childType.FullName)
list.Add(c);
if (maxDepth == 0 || depth < maxDepth)
list.AddRange(RecursiveFindControls(
c, childType, depth + 1, maxDepth));
}
}
else if (collection != null && collection.GetType().BaseType.Name == "Panel") // snelson 6/6/11; added because was skipping control (e.g., System.Windows.Controls.Grid)
{
if (maxDepth == 0 || depth < maxDepth)
list.AddRange(RecursiveFindControls(
collection, childType, depth + 1, maxDepth));
}
}
}
return list.ToArray();
}
于 2011-06-06T23:26:57.030 回答
8
我有一个这样的序列函数（这是完全通用的）：
public static IEnumerable<T> SelectAllRecursively<T>(this IEnumerable<T> items, Func<T, IEnumerable<T>> func)
{
return (items ?? Enumerable.Empty<T>()).SelectMany(o => new[] { o }.Concat(SelectAllRecursively(func(o), func)));
}
获得直系子女：
public static IEnumerable<DependencyObject> FindChildren(this DependencyObject obj)
{
return Enumerable.Range(0, VisualTreeHelper.GetChildrenCount(obj))
.Select(i => VisualTreeHelper.GetChild(obj, i));
}
查找层次结构树下的所有孩子：
public static IEnumerable<DependencyObject> FindAllChildren(this DependencyObject obj)
{
return obj.FindChildren().SelectAllRecursively(o => o.FindChildren());
}
您可以在 Window 上调用它来获取所有控件。
有了集合之后，就可以使用LINQ（即OfType，Where）了。
于 2014-08-20T15:45:01.940 回答
6
由于这个问题很笼统，它可能会吸引人们寻找非常琐碎案例的答案：如果您只想要一个孩子而不是后代，您可以使用 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();
}
}
或者当然是明显的 for 循环遍历儿童。
于 2011-03-06T13:03:18.413 回答
4
这些选项已经讨论了在 C# 中遍历可视化树。也可以使用 RelativeSource 标记扩展来遍历 xaml 中的可视化树。微软
按类型查找
Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type <TypeToFind>}}}"
于 2015-04-02T15:04:21.537 回答
2
这是一个使用灵活谓词的解决方案：
public static DependencyObject FindChild(DependencyObject parent, Func<DependencyObject, bool> predicate)
{
if (parent == null) return null;
int childrenCount = VisualTreeHelper.GetChildrenCount(parent);
for (int i = 0; i < childrenCount; i++)
{
var child = VisualTreeHelper.GetChild(parent, i);
if (predicate(child))
{
return child;
}
else
{
var foundChild = FindChild(child, predicate);
if (foundChild != null)
return foundChild;
}
}
return null;
}
例如，您可以这样称呼它：
var child = FindChild(parent, child =>
{
var textBlock = child as TextBlock;
if (textBlock != null && textBlock.Name == "MyTextBlock")
return true;
else
return false;
}) as TextBlock;
于 2015-09-09T15:54:59.930 回答
1
我无法使用 @CrimsonX 或 @Drew Noakes 方法找到我的控件，因为我的 ControlTemplate 位于单独的 XAML 文件中。我使用以下方法找到了控件：
private Image backImage;
private void Diagram_Loaded(object sender, System.Windows.RoutedEventArgs e)
{
// here is the example of the ControlTemplate declaration
//<ControlTemplate x:Key="DiagramControlTemplate1" TargetType="{x:Type Diagram}">
var ctrlTemplate = (ControlTemplate)FindResource("DiagramControlTemplate1");
// diagram is the x:Name of TemplatedControl and, "backImage" is the name of control that I want to find.
var imageControl = ctrlTemplate.FindName("backImage", diagram);
if (imageControl != null)
{
this.backImage = (Image)imageControl;
}
}
这对我有用。
于 2021-03-15T02:05:41.223 回答
0
要从代码中查找给定类型的祖先，您可以使用：
[CanBeNull]
public static T FindAncestor<T>(DependencyObject d) where T : DependencyObject
{
while (true)
{
d = VisualTreeHelper.GetParent(d);
if (d == null)
return null;
var t = d as T;
if (t != null)
return t;
}
}
此实现使用迭代而不是递归，这可能会稍微快一些。
如果您使用的是 C# 7，则可以稍微缩短一点：
[CanBeNull]
public static T FindAncestor<T>(DependencyObject d) where T : DependencyObject
{
while (true)
{
d = VisualTreeHelper.GetParent(d);
if (d == null)
return null;
if (d is T t)
return t;
}
}
于 2017-03-07T12:54:57.223 回答
0
这段代码只是修复了@CrimsonX 答案的错误：
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;
}
如果类型匹配但名称不匹配，您只需要继续递归调用该方法（当您传递FrameworkElementas时会发生这种情况T）。否则它会返回null，这是错误的。
于 2017-11-21T21:17:55.353 回答
-2
我能够使用下面的代码按名称查找对象。
stkMultiChildControl = stkMulti.FindChild<StackPanel>("stkMultiControl_" + couter.ToString());
于 2020-12-26T20:56:11.083 回答
-8
试试这个
<TextBlock x:Name="txtblock" FontSize="24" >Hai Welcom to this page
</TextBlock>
代码背后
var txtblock = sender as Textblock;
txtblock.Foreground = "Red"
于 2015-03-23T05:57:03.007 回答