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
因为这个问题很普遍,它可能会吸引人们去寻找非常琐碎的情况的答案:如果你只想要一个孩子而不是后代,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();
}
}
或者显然的for循环遍历Children。
其他回答
下面是一个使用灵活谓词的解决方案:
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;
}
例如,你可以这样称呼它:
var child = FindChild(parent, child =>
{
var textBlock = child as TextBlock;
if (textBlock != null && textBlock.Name == "MyTextBlock")
return true;
else
return false;
}) as TextBlock;
下面是我的代码,通过类型来查找控件,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();
}
}
我编辑了CrimsonX的代码,因为它不能处理超类类型:
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;
}
如果您希望找到特定类型的ALL控件,那么您可能也会对这个代码段感兴趣
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;
}
}
}
试试这个
<TextBlock x:Name="txtblock" FontSize="24" >Hai Welcom to this page
</TextBlock>
后面的代码
var txtblock = sender as Textblock;
txtblock.Foreground = "Red"
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