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
这里有一些我经常使用的方法。
用法:
// Starts the search from thisUiElement (might be a UserContol, Window, etc..)
var combobox = thisUiElement.ChildOfType<ComboBox>();
var employeesListBox = thisUiElement.ChildOfName("EmployeesListBox");
// Starts the search from MainWindow to find the first DataGrid
var dataGrid = WpfUtils.ChildOfType<DataGrid>();
// Starts the search from MainWindow to find the all ListViews
List<ComboBox> allListViews = WpfUtils.ChildOfType<ListView>();
// Starts the search from MainWindow to find the element of name EmployeesComboBox
var combobox = WpfUtils.ChildOfName("EmployeesComboBox");
实现:
/*
using System.Collections.Generic;
using System.Windows;
using System.Windows.Media;
namespace WpfUtilities;
*/
public static class WpfUtils{
public static Window AppMainWindow =>
Application.Current?.MainWindow;
#region Find By Type
// Start the search from MainWindow, example usage: var combobox = WpfUtils.ChildOfType<ComboBox>();
public static T ChildOfType<T>() where T : DependencyObject =>
ChildOfType<T>(AppMainWindow);
/// This will return the first child of type T
public static T ChildOfType<T>(this DependencyObject parent)
where T : DependencyObject
{
if (parent == null) return null;
T child = default;
var numVisuals = VisualTreeHelper.GetChildrenCount(parent);
for (var i = 0; i < numVisuals; i++)
{
var v = VisualTreeHelper.GetChild(parent, i);
child = v as T ?? v.ChildOfType<T>();
if (child != null)
break;
}
return child;
}
// Start the search from MainWindow, example usage: List<ComboBox> comboboxes = WpfUtils.ChildOfType<ComboBox>();
public static IEnumerable<T> ChildrenOfType<T>() where T : DependencyObject =>
ChildrenOfType<T>(AppMainWindow);
/// This will not break the search when finding the first kid of type T, but it will keep searching to return all kids of type T
public static IEnumerable<T> ChildrenOfType<T>(
this DependencyObject parent) where T : DependencyObject
{
if (parent == null) yield break;
var numVisuals = VisualTreeHelper.GetChildrenCount(parent);
for (var i = 0; i < numVisuals; i++)
{
var child = VisualTreeHelper.GetChild(parent, i);
if (child is T dependencyObject)
yield return dependencyObject;
foreach (var childOfChild in child.ChildrenOfType<T>())
yield return childOfChild;
}
}
#endregion
#region Find By Name
/// If parent is null, the search will start from MainWindow, example usage: var combobox = WpfUtils.ChildOfName("EmployeesCombobox");
public static FrameworkElement ChildOfName(string childName,
DependencyObject parent = null)
{
parent ??= AppMainWindow;
object child = null;
var numVisuals = VisualTreeHelper.GetChildrenCount(parent);
for (var i = 0; i < numVisuals; i++)
{
var v = VisualTreeHelper.GetChild(parent, i);
child = v is FrameworkElement f && f.Name == childName
? f
: ChildOfName(childName, v);
if (child != null)
break;
}
return child as FrameworkElement;
}
#endregion
#region
// Yet another useful method, if you are writing code in a .xaml.cs file and you want to get the parent of a type.. example usage: this.ParentOfType<Grid>(); this.ParentOfType<UserControl>(); this.ParentOfType<Window>();
public static T ParentOfType<T>(this DependencyObject child) where T : DependencyObject
{
var parentDepObj = child;
do
{
parentDepObj = VisualTreeHelper.GetParent(parentDepObj);
if (parentDepObj is T parent) return parent;
} while (parentDepObj != null);
return null;
}
#endregion
}
其他回答
您可以使用VisualTreeHelper来查找控件。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);
}
}
}
这样叫它:
Window owner = UIHelper.FindVisualParent<Window>(myControl);
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。
这些选项已经讨论了如何在c#中遍历可视化树。 使用RelativeSource标记扩展也可以遍历xaml中的可视树。msdn
按类型查找
Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type <TypeToFind>}}}"
我将John Myczek使用的模板格式和Tri Q上面的算法结合起来，创建了一个findChild算法，它可以用于任何父类。请记住，递归向下搜索树可能是一个漫长的过程。我只是在一个WPF应用程序上进行了抽查，请对您可能发现的任何错误进行评论，我会纠正我的代码。
WPF Snoop是一个查看可视化树的有用工具——我强烈建议在测试时使用它，或者使用这个算法来检查你的工作。
在Tri Q算法中有一个小错误。找到子对象后，如果childrenCount为> 1，然后再次迭代，就可以覆盖正确找到的子对象。因此，我添加了一个if (foundChild != null) break;加入我的代码来处理这种情况。
/// <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;
}
这样叫它:
TextBox foundTextBox =
UIHelper.FindChild<TextBox>(Application.Current.MainWindow, "myTextBoxName");
注意:Application.Current.MainWindow可以是任何父窗口。
这里有一些我经常使用的方法。
用法:
// Starts the search from thisUiElement (might be a UserContol, Window, etc..)
var combobox = thisUiElement.ChildOfType<ComboBox>();
var employeesListBox = thisUiElement.ChildOfName("EmployeesListBox");
// Starts the search from MainWindow to find the first DataGrid
var dataGrid = WpfUtils.ChildOfType<DataGrid>();
// Starts the search from MainWindow to find the all ListViews
List<ComboBox> allListViews = WpfUtils.ChildOfType<ListView>();
// Starts the search from MainWindow to find the element of name EmployeesComboBox
var combobox = WpfUtils.ChildOfName("EmployeesComboBox");
实现:
/*
using System.Collections.Generic;
using System.Windows;
using System.Windows.Media;
namespace WpfUtilities;
*/
public static class WpfUtils{
public static Window AppMainWindow =>
Application.Current?.MainWindow;
#region Find By Type
// Start the search from MainWindow, example usage: var combobox = WpfUtils.ChildOfType<ComboBox>();
public static T ChildOfType<T>() where T : DependencyObject =>
ChildOfType<T>(AppMainWindow);
/// This will return the first child of type T
public static T ChildOfType<T>(this DependencyObject parent)
where T : DependencyObject
{
if (parent == null) return null;
T child = default;
var numVisuals = VisualTreeHelper.GetChildrenCount(parent);
for (var i = 0; i < numVisuals; i++)
{
var v = VisualTreeHelper.GetChild(parent, i);
child = v as T ?? v.ChildOfType<T>();
if (child != null)
break;
}
return child;
}
// Start the search from MainWindow, example usage: List<ComboBox> comboboxes = WpfUtils.ChildOfType<ComboBox>();
public static IEnumerable<T> ChildrenOfType<T>() where T : DependencyObject =>
ChildrenOfType<T>(AppMainWindow);
/// This will not break the search when finding the first kid of type T, but it will keep searching to return all kids of type T
public static IEnumerable<T> ChildrenOfType<T>(
this DependencyObject parent) where T : DependencyObject
{
if (parent == null) yield break;
var numVisuals = VisualTreeHelper.GetChildrenCount(parent);
for (var i = 0; i < numVisuals; i++)
{
var child = VisualTreeHelper.GetChild(parent, i);
if (child is T dependencyObject)
yield return dependencyObject;
foreach (var childOfChild in child.ChildrenOfType<T>())
yield return childOfChild;
}
}
#endregion
#region Find By Name
/// If parent is null, the search will start from MainWindow, example usage: var combobox = WpfUtils.ChildOfName("EmployeesCombobox");
public static FrameworkElement ChildOfName(string childName,
DependencyObject parent = null)
{
parent ??= AppMainWindow;
object child = null;
var numVisuals = VisualTreeHelper.GetChildrenCount(parent);
for (var i = 0; i < numVisuals; i++)
{
var v = VisualTreeHelper.GetChild(parent, i);
child = v is FrameworkElement f && f.Name == childName
? f
: ChildOfName(childName, v);
if (child != null)
break;
}
return child as FrameworkElement;
}
#endregion
#region
// Yet another useful method, if you are writing code in a .xaml.cs file and you want to get the parent of a type.. example usage: this.ParentOfType<Grid>(); this.ParentOfType<UserControl>(); this.ParentOfType<Window>();
public static T ParentOfType<T>(this DependencyObject child) where T : DependencyObject
{
var parentDepObj = child;
do
{
parentDepObj = VisualTreeHelper.GetParent(parentDepObj);
if (parentDepObj is T parent) return parent;
} while (parentDepObj != null);
return null;
}
#endregion
}
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