按类型查找WPF窗口中的所有控件

使用helper类VisualTreeHelper或LogicalTreeHelper，这取决于你对哪个树感兴趣。它们都提供了获取元素的子元素的方法(尽管语法略有不同)。我经常使用这些类来查找特定类型的第一个出现，但你可以很容易地修改它来查找该类型的所有对象:

public static DependencyObject FindInVisualTreeDown(DependencyObject obj, Type type)
{
if (obj != null)
{
if (obj.GetType() == type)
{
return obj;
}


for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
{
DependencyObject childReturn = FindInVisualTreeDown(VisualTreeHelper.GetChild(obj, i), type);
if (childReturn != null)
{
return childReturn;
}
}
}


return null;
}

这就是它向上的工作原理

    private T FindParent<T>(DependencyObject item, Type StopAt) where T : class
{
if (item is T)
{
return item as T;
}
else
{
DependencyObject _parent = VisualTreeHelper.GetParent(item);
if (_parent == null)
{
return default(T);
}
else
{
Type _type = _parent.GetType();
if (StopAt != null)
{
if ((_type.IsSubclassOf(StopAt) == true) || (_type == StopAt))
{
return null;
}
}


if ((_type.IsSubclassOf(typeof(T)) == true) || (_type == typeof(T)))
{
return _parent as T;
}
else
{
return FindParent<T>(_parent, StopAt);
}
}
}
}

这应该可以达到目的:

public static IEnumerable<T> FindVisualChilds<T>(DependencyObject depObj) where T : DependencyObject
{
if (depObj == null) yield return (T)Enumerable.Empty<T>();
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
{
DependencyObject ithChild = VisualTreeHelper.GetChild(depObj, i);
if (ithChild == null) continue;
if (ithChild is T t) yield return t;
foreach (T childOfChild in FindVisualChilds<T>(ithChild)) yield return childOfChild;
}
}

然后像这样枚举控件

foreach (TextBlock tb in FindVisualChildren<TextBlock>(window))
{
// do something with tb here
}

这是最简单的方法:

IEnumerable<myType> collection = control.Children.OfType<myType>();

其中控件是窗口的根元素。

编辑-正如评论中指出的那样。这只是一个层次的深度。查看一个更深入的选项的公认答案。

请注意，使用VisualTreeHelper仅适用于派生自Visual或Visual3D的控件。如果你还需要检查其他元素(例如TextBlock, FlowDocument等)，使用VisualTreeHelper将抛出一个异常。

如果有必要，这里有一个回到逻辑树的替代方案:

http://www.hardcodet.net/2009/06/finding-elements-in-wpf-tree-both-ways

要获得特定类型的所有子元素的列表，您可以使用:

private static IEnumerable<DependencyObject> FindInVisualTreeDown(DependencyObject obj, Type type)
{
if (obj != null)
{
if (obj.GetType() == type)
{
yield return obj;
}


for (var i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
{
foreach (var child in FindInVisualTreeDown(VisualTreeHelper.GetChild(obj, i), type))
{
if (child != null)
{
yield return child;
}
}
}
}


yield break;
}

我发现在上面几个例子中使用的VisualTreeHelper.GetChildrenCount(depObj);行不会为GroupBoxes返回非零计数，特别是当GroupBox包含Grid，而Grid包含子元素时。我相信这可能是因为GroupBox不允许包含一个以上的子元素，并且它存储在它的Content属性中。没有GroupBox.Children类型的属性。我确信我没有非常有效地做到这一点，但我修改了这个链中的第一个“FindVisualChildren”示例如下:

public IEnumerable<T> FindVisualChildren<T>(DependencyObject depObj) where T : DependencyObject
{
if (depObj != null)
{
int depObjCount = VisualTreeHelper.GetChildrenCount(depObj);
for (int i = 0; i <depObjCount; i++)
{
DependencyObject child = VisualTreeHelper.GetChild(depObj, i);
if (child != null && child is T)
{
yield return (T)child;
}


if (child is GroupBox)
{
GroupBox gb = child as GroupBox;
Object gpchild = gb.Content;
if (gpchild is T)
{
yield return (T)child;
child = gpchild as T;
}
}


foreach (T childOfChild in FindVisualChildren<T>(child))
{
yield return childOfChild;
}
}
}
}

对递归做了一点小小的改变，例如，你可以找到一个标签控件的子标签控件。

    public static DependencyObject FindInVisualTreeDown(DependencyObject obj, Type type)
{
if (obj != null)
{
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
{
DependencyObject child = VisualTreeHelper.GetChild(obj, i);


if (child.GetType() == type)
{
return child;
}


DependencyObject childReturn = FindInVisualTreeDown(child, type);
if (childReturn != null)
{
return childReturn;
}
}
}


return null;
}

我改编了@Bryce Kahle的回答，遵循@Mathias Lykkegaard Lorenzen的建议，并使用LogicalTreeHelper。

看起来还行。；）

public static IEnumerable<T> FindLogicalChildren<T> ( DependencyObject depObj ) where T : DependencyObject
{
if( depObj != null )
{
foreach( object rawChild in LogicalTreeHelper.GetChildren( depObj ) )
{
if( rawChild is DependencyObject )
{
DependencyObject child = (DependencyObject)rawChild;
if( child is T )
{
yield return (T)child;
}


foreach( T childOfChild in FindLogicalChildren<T>( child ) )
{
yield return childOfChild;
}
}
}
}
}

(它仍然不会检查标签控件或组框内的网格@Benjamin Berry &@David R) (也遵循了@noonand的建议&移除多余的子元素!= null)

下面是另一个紧凑的版本，使用泛型语法:

    public static IEnumerable<T> FindLogicalChildren<T>(DependencyObject obj) where T : DependencyObject
{
if (obj != null) {
if (obj is T)
yield return obj as T;


foreach (DependencyObject child in LogicalTreeHelper.GetChildren(obj).OfType<DependencyObject>())
foreach (T c in FindLogicalChildren<T>(child))
yield return c;
}
}

foreach (TextBlock tb in FindVisualChildren<TextBlock>(window))
{
// do something with tb here
tb.Text = ""; //this will overwrite Button.Content and render the
//Button.Content{set} permanently disabled.
}

要解决这个问题，您可以尝试使用XAML“文本框”并添加方法(或事件)来模拟XAMAL按钮。XAML“TextBox”不是通过搜索“TextBlock”收集的。

我发现没有Visual Tree Helpers更容易:

foreach (UIElement element in MainWindow.Children) {
if (element is TextBox) {
if ((element as TextBox).Text != "")
{
//Do something
}
}
};

我的c++ /CLI版本

template < class T, class U >
bool Isinst(U u)
{
return dynamic_cast< T >(u) != nullptr;
}


template <typename T>
T FindVisualChildByType(Windows::UI::Xaml::DependencyObject^ element, Platform::String^ name)
{
if (Isinst<T>(element) && dynamic_cast<Windows::UI::Xaml::FrameworkElement^>(element)->Name == name)
{
return dynamic_cast<T>(element);
}
int childcount = Windows::UI::Xaml::Media::VisualTreeHelper::GetChildrenCount(element);
for (int i = 0; i < childcount; ++i)
{
auto childElement = FindVisualChildByType<T>(Windows::UI::Xaml::Media::VisualTreeHelper::GetChild(element, i), name);
if (childElement != nullptr)
{
return childElement;
}
}
return nullptr;
};

public static void FindVisualChildren<T>(this ICollection<T> children, DependencyObject depObj) where T : DependencyObject
{
if (depObj != null)
{
var brethren = LogicalTreeHelper.GetChildren(depObj);
var brethrenOfType = LogicalTreeHelper.GetChildren(depObj).OfType<T>();
foreach (var childOfType in brethrenOfType)
{
children.Add(childOfType);
}


foreach (var rawChild in brethren)
{
if (rawChild is DependencyObject)
{
var child = rawChild as DependencyObject;
FindVisualChildren<T>(children, child);
}
}
}
}

希望能有所帮助。

@Bryce，回答得很好。

VB。净版:

Public Shared Iterator Function FindVisualChildren(Of T As DependencyObject)(depObj As DependencyObject) As IEnumerable(Of T)
If depObj IsNot Nothing Then
For i As Integer = 0 To VisualTreeHelper.GetChildrenCount(depObj) - 1
Dim child As DependencyObject = VisualTreeHelper.GetChild(depObj, i)
If child IsNot Nothing AndAlso TypeOf child Is T Then
Yield DirectCast(child, T)
End If
For Each childOfChild As T In FindVisualChildren(Of T)(child)
Yield childOfChild
Next
Next
End If
End Function

用法(这将禁用窗口中的所有文本框):

        For Each tb As TextBox In FindVisualChildren(Of TextBox)(Me)
tb.IsEnabled = False
Next

接受的答案通过尽可能深入地跟踪第一个子分支，返回或多或少无序的已发现元素，同时在返回并重复尚未解析的树枝的步骤之前，沿途生成已发现的元素。

如果你需要降序排列中的后代元素，其中直接子元素将首先产生，然后是它们的子元素，依此类推，以下算法将工作:

public static IEnumerable<T> GetVisualDescendants<T>(DependencyObject parent, bool applyTemplates = false)
where T : DependencyObject
{
if (parent == null || !(child is Visual || child is Visual3D))
yield break;


var descendants = new Queue<DependencyObject>();
descendants.Enqueue(parent);


while (descendants.Count > 0)
{
var currentDescendant = descendants.Dequeue();


if (applyTemplates)
(currentDescendant as FrameworkElement)?.ApplyTemplate();


for (var i = 0; i < VisualTreeHelper.GetChildrenCount(currentDescendant); i++)
{
var child = VisualTreeHelper.GetChild(currentDescendant, i);


if (child is Visual || child is Visual3D)
descendants.Enqueue(child);


if (child is T foundObject)
yield return foundObject;
}
}
}

var foundElement = GetDescendants<StackPanel>(someElement)
.FirstOrDefault(o => o.SomeProperty == SomeState);

对于这个和更多的用例，你可以添加流动扩展方法到你的库:

 public static List<DependencyObject> FindAllChildren(this DependencyObject dpo, Predicate<DependencyObject> predicate)
{
var results = new List<DependencyObject>();
if (predicate == null)
return results;




for (int i = 0; i < VisualTreeHelper.GetChildrenCount(dpo); i++)
{
var child = VisualTreeHelper.GetChild(dpo, i);
if (predicate(child))
results.Add(child);


var subChildren = child.FindAllChildren(predicate);
results.AddRange(subChildren);
}
return results;
}

举个例子:

 var children = dpObject.FindAllChildren(child => child is TextBox);