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using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Media;
namespace Xamarin.PropertyEditing.Windows
{
internal static class XamlHelper
{
public static IEnumerable<T> GetDescendants<T> (this UIElement self)
where T : UIElement
{
if (self == null)
throw new ArgumentNullException (nameof (self));
var childCount = VisualTreeHelper.GetChildrenCount (self);
for (var i = 0; i < childCount; i++) {
if (VisualTreeHelper.GetChild (self, i) is UIElement child) {
if (child is T correctlyTypedChild) yield return correctlyTypedChild;
IEnumerable<T> grandChildren = GetDescendants<T> (child);
foreach (T grandChild in grandChildren) yield return grandChild;
}
}
}
public static T FindChildOrSelf<T> (this UIElement self)
where T : UIElement
{
if (self == null)
throw new ArgumentNullException (nameof(self));
if (self is T t)
return t;
int count = VisualTreeHelper.GetChildrenCount (self);
for (int i = 0; i < count; i++) {
if (VisualTreeHelper.GetChild (self, i) is UIElement element) {
var child = FindChildOrSelf<T> (element);
if (child != null)
return child;
}
}
return null;
}
public static T FindParent<T> (this UIElement self)
where T : UIElement
{
UIElement parent = VisualTreeHelper.GetParent (self) as UIElement;
if (parent == null)
return default(T);
return parent.FindParentOrSelf<T>();
}
public static FrameworkElement FindPropertiesHost (this FrameworkElement self)
{
DependencyObject parent = self;
while (!(parent is IPropertiesHost) && parent != null) {
parent = VisualTreeHelper.GetParent (parent);
}
return (FrameworkElement)parent;
}
public static T FindParentOrSelf<T> (this UIElement self)
where T : UIElement
{
if (self == null)
throw new ArgumentNullException (nameof (self));
DependencyObject parent = self;
while (!(parent is T) && parent != null) {
parent = VisualTreeHelper.GetParent (parent);
}
return (T)parent;
}
public static TParent FindParentUnless<TParent,TUnless> (this UIElement self)
where TParent : UIElement
where TUnless : UIElement
{
if (self == null)
throw new ArgumentNullException (nameof (self));
DependencyObject parent = VisualTreeHelper.GetParent (self);
while (!(parent is TParent) && parent != null) {
if (parent is TUnless)
return default(TParent);
parent = VisualTreeHelper.GetParent (parent);
}
return (TParent)parent;
}
}
}
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