更新

WPFDark/Internals/DependencyObjectExtensions.cs

@@ -0,0 +1,119 @@
+using System;
+using System.Buffers;
+using System.Collections.Generic;
+using System.Runtime.CompilerServices;
+using System.Windows;
+using System.Windows.Controls.Primitives;
+using System.Windows.Media;
+
+namespace WPFDark.Internals
+{
+    // http://blog.xin9le.net/entry/2013/10/29/222336 を参考にしました
+
+    internal static class DependencyObjectExtensions
+    {
+        public static IEnumerable<DependencyObject> Children(this DependencyObject obj)
+        {
+            if (obj is null)
+                throw new ArgumentNullException(nameof(obj));
+
+            if (obj is Popup popup)
+                if (popup.Child != null)
+                    yield return popup.Child;
+
+            var count = VisualTreeHelper.GetChildrenCount(obj);
+            if (count == 0)
+                yield break;
+
+            for (var i = 0; i != count; i++)
+            {
+                var child = VisualTreeHelper.GetChild(obj, i);
+                yield return child;
+            }
+        }
+
+        public static IEnumerable<DependencyObject> Descendants(this DependencyObject obj)
+        {
+            if (obj is null)
+                throw new ArgumentNullException(nameof(obj));
+
+            var children = ArrayPool<DependencyObject>.Shared.Rent(obj.MaximumChildrenCount());
+
+            try
+            {
+                var childrenCount = obj.Children(children);
+
+                for (var i = 0; i != childrenCount; ++i)
+                {
+                    var child = children[i];
+
+                    yield return child;
+
+                    foreach (var grandChild in child.Descendants())
+                        yield return grandChild;
+                }
+            }
+            finally
+            {
+                ArrayPool<DependencyObject>.Shared.Return(children);
+            }
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static int MaximumChildrenCount(this DependencyObject obj)
+        {
+            return VisualTreeHelper.GetChildrenCount(obj) + 1;
+        }
+
+        private static int Children(this DependencyObject obj, Span<DependencyObject> result)
+        {
+            var count = 0;
+
+            if (obj is Popup popup)
+                if (popup.Child != null)
+                    result[count++] = popup.Child;
+
+            var childrenCount = VisualTreeHelper.GetChildrenCount(obj);
+
+            for (var i = 0; i != childrenCount; i++)
+                result[count++] = VisualTreeHelper.GetChild(obj, i);
+
+            return count;
+        }
+        /// <summary>
+        /// 获取父元素
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <param name="self"></param>
+        /// <returns></returns>
+        public static T? GetParent<T>(this DependencyObject self) where T : class
+        {
+            var parent = self;
+
+            do
+            {
+                if (parent is T tp)
+                    return tp;
+
+                parent = VisualTreeHelper.GetParent(parent);
+            } while (parent != null);
+
+            return null;
+        }
+
+        public static DependencyObject? GetParent(this DependencyObject self, Type type)
+        {
+            var parent = self;
+
+            do
+            {
+                if (parent.GetType().IsSubclassOf(type))
+                    return parent;
+
+                parent = VisualTreeHelper.GetParent(parent);
+            } while (parent != null);
+
+            return null;
+        }
+    }
+}