controls wpf教學 - 我怎樣才能找到名稱或類型的WPF控件?




wpf範例 wpf書 (16)

這將消除一些元素 - 你應該像這樣擴展它,以便支持更廣泛的控制。 有關簡要討論,請看看here

 /// <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);
   }
}

我需要為WPF控件層次結構搜索匹配給定名稱或類型的控件。 我怎樣才能做到這一點?


這些選項已經討論了遍歷C#中的可視化樹。 它可能使用RelativeSource標記擴展來遍歷xaml中的可視化樹。 msdn

按類型查找

Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type <TypeToFind>}}}" 

此代碼只是修復@CrimsonX答案的錯誤:

 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;
    }  

如果類型匹配但名稱不匹配,則只需遞歸地繼續調用方法(當您將FrameworkElement作為T傳遞時,會發生這種情況)。 否則它會返回null ,這是錯誤的。


這是一個使用靈活謂詞的解決方案:

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;
}

你可以舉例如下:

var child = FindChild(parent, child =>
{
    var textBlock = child as TextBlock;
    if (textBlock != null && textBlock.Name == "MyTextBlock")
        return true;
    else
        return false;
}) as TextBlock;

嘗試這個

<TextBlock x:Name="txtblock" FontSize="24" >Hai Welcom to this page
</TextBlock>

代碼在後面

var txtblock = sender as Textblock;
txtblock.Foreground = "Red"

我可能只是重複其他人,但我確實有一段很漂亮的代碼,它用一個方法FindChild()來擴展DependencyObject類,它將按類型和名稱為您提供子代。 只包括和使用。

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;
    }
}

希望你覺得它有用。


您可以使用VisualTreeHelper查找控件。 以下是使用VisualTreeHelper查找指定類型的父控件的方法。 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);
      }
   }
}

像這樣調用它:

Window owner = UIHelper.FindVisualParent<Window>(myControl);

既然這個問題已經足夠普遍了,以至於它可能會吸引那些尋找非常微不足道的案例的答案的人們:如果你只想要一個孩子而不是後代,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();
    }
}

或者當然是循環遍歷Children的循環。


exciton80 ...我的代碼有問題,不能通過usercontrols遞歸。 它擊中網格根並拋出錯誤。 我相信這為我解決了這個問題:

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();
}

我將John Myczek和Tri Q的算法使用的模板格式合併在一起,創建一個可以在任何父級上使用的findChild算法。 請記住,向下遞歸搜索樹可能是一個漫長的過程。 我只在WPF應用程序中進行了特別檢查,請評論您可能發現的任何錯誤,並且我會更正我的代碼。

WPF Snoop是查看可視化樹的有用工具 - 我強烈建議在測試或使用此算法檢查您的工作時使用它。

Tri Q的算法有一個小錯誤。 找到孩子後,如果childrenCount> 1,我們再次迭代,我們可以覆蓋正確找到的孩子。 因此我添加了一個if (foundChild != null) break; 進入我的代碼來處理這種情況。

/// <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;
}

像這樣調用它:

TextBox foundTextBox = 
   UIHelper.FindChild<TextBox>(Application.Current.MainWindow, "myTextBoxName");

注意Application.Current.MainWindow可以是任何父窗口。


要從代碼中查找給定類型的祖先,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;
    }
}

該實現使用迭代而不是遞歸,可以稍微快一點。

如果您使用的是C#7,則可以稍微縮短一點:

[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;
    }
}

雖然我喜歡一般的遞歸,但在使用C#編程時不如迭代有效,所以下面的解決方案可能比上面的John Myczek提出的解決方案更加整潔。

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;
}

這是我的代碼,通過Type來控制我們進入層次結構的深度(maxDepth == 0意味著無限深)。

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();
    }
}

我有這樣的序列函數(這是完全一般的):

    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)));
    }

讓直系孩子:

    public static IEnumerable<DependencyObject> FindChildren(this DependencyObject obj)
    {
        return Enumerable.Range(0, VisualTreeHelper.GetChildrenCount(obj))
            .Select(i => VisualTreeHelper.GetChild(obj, i));
    }

尋找所有的兒童在這個層次樹:

    public static IEnumerable<DependencyObject> FindAllChildren(this DependencyObject obj)
    {
        return obj.FindChildren().SelectAllRecursively(o => o.FindChildren());
    }

你可以在Window上調用它來獲得所有的控件。

收集完成後,您可以使用LINQ(即OfType,Where)。


如果您想查找特定類型的所有控件,您可能也對此片段感興趣

    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;
            }
        }
    }

雖然上述方法不能解決Mac OS X的問題,因為Mac OS X不支持-readable開關,因此您可以在輸出中避免“權限被拒絕”錯誤。 這可能有助於某人。

find / -type f -name "your_pattern" 2>/dev/null

例如,如果您正在使用find命令來查找某個模式的文件的大小,那麼2>/dev/null仍然可以如下所示工作。

find . -type f -name "your_pattern" -exec du -ch {} + 2>/dev/null | grep total$ find . -type f -name "your_pattern" -exec du -ch {} + 2>/dev/null | grep total$

這將返回給定模式文件的總大小。 注意find命令結尾的2>/dev/null





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