add FindVisualChild

Author: yanjinhuagood

src/WPFDevelopers.Shared/Core/Helpers/ControlsHelper.cs

@@ -12,8 +12,6 @@
 using System.Windows.Media;
 using System.Windows.Media.Animation;
 using System.Windows.Media.Imaging;
-using WPFDevelopers.Controls;
-using WPFDevelopers.Utilities;
 
 namespace WPFDevelopers.Helpers
 {
@@ -254,6 +252,21 @@ public static Thickness GetPadding(FrameworkElement element)
             return new Thickness();
         }
 
+        public static T FindVisualChild<T>(DependencyObject parent) where T : DependencyObject
+        {
+            int childCount = VisualTreeHelper.GetChildrenCount(parent);
+            for (int i = 0; i < childCount; i++)
+            {
+                var child = VisualTreeHelper.GetChild(parent, i);
+                if (child is T typedChild)
+                    return typedChild;
+                var result = FindVisualChild<T>(child);
+                if (result != null)
+                    return result;
+            }
+            return null;
+        }
+
 
     }