Cri*_*onX 301
我结合了John Myczek使用的模板格式和上面的Tri Q算法来创建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检查,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 - 我强烈建议在测试或使用此算法检查您的工作时使用它.
Tri Q算法中存在一个小错误.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if (foundChild != null) break;在我的代码中添加了一个来处理这个条件.
/// <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.
Dre*_*kes 124
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,所以你可以只引用生成的字段,但也许你想要动态地而不是静态地查找它.
此方法也适用于模板,其中命名项目多次出现(每次使用模板一次).
Joh*_*zek 66
您可以使用VisualTreeHelper查找控件.下面是一个使用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);
Tri*_*ran 21
我可能只是在重复其他所有人,但我确实有一段很好的代码,它使用FindChild()方法扩展DependencyObject类,它将按类型和名称为您提供子类.只是包括和使用.
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);
}
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.
Gis*_*shu 18
我对代码的扩展.
资料来源: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
Urb*_*Esc 18
如果要查找特定类型的所有控件,您可能也对此代码段感兴趣
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;
}
}
}
小智 16
这将忽略一些元素 - 您应该像这样扩展它以支持更广泛的控件.有关简短的讨论,请查看此处
/// <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);
}
}
and*_*esp 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;
}
Nat*_*ips 13
虽然我喜欢一般的递归,但它在用C#编程时不如迭代效率高,所以下面的解决方案可能比John Myczek建议的更简洁？这将从给定控件中搜索层次结构以查找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;
}
像这样调用它来找到Window包含一个名为的控件ExampleTextBox:
Window window = ExampleTextBox.FindVisualAncestorOfType<Window>();
小智 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();
}
}
exciton80 ...我的代码没有通过usercontrols递归出现问题.它击中了Grid根并抛出错误.我相信这可以解决它:
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();
}
小智 8
我有这样的序列函数(这是完全一般的):
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)));
}
立即生孩子:
public static IEnumerable<DependencyObject> FindChildren(this DependencyObject obj)
{
return Enumerable.Range(0, VisualTreeHelper.GetChildrenCount(obj))
.Select(i => VisualTreeHelper.GetChild(obj, i));
}
在层级树上寻找所有孩子:
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.
收集完成后,可以使用LINQ(即OfType,Where).
由于问题足够普遍,它可能会吸引人们寻找非常微不足道的案例的答案:如果你只想要一个孩子而不是一个后代,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();
}
}
或者当然是明显的循环迭代儿童.