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

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。

其他回答

我找不到@CrimsonX或@Drew Noakes方法的控件,因为我的ControlTemplate位于一个单独的XAML文件中。 我用下面的方法找到了控件:

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;
    }
}

这对我很有用。

对代码的扩展。

增加了重载,以按类型、按类型和标准(谓词)查找一个子元素,查找符合标准的所有类型的子元素 FindChildren方法除了是DependencyObject的扩展方法外,还是一个迭代器 FindChildren还遍历逻辑子树。请参阅博客中链接的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

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
}

exciton80……我有一个问题,你的代码不递归通过用户控件。它击中了网格根并抛出了一个错误。我相信这能解决我的问题:

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();
}

我能够找到对象的名称使用下面的代码。

stkMultiChildControl = stkMulti.FindChild(“<StackPanel>stkMultiControl_” + couter.ToString());