Update DateRangePicker.cs

Author: yanjinhuagood

src/WPFDevelopers.Shared/Controls/DateRangePicker/DateRangePicker.cs

@@ -238,7 +238,7 @@ private void OnEndCalendar_PreviewMouseUp(object sender, MouseButtonEventArgs e)
                 var calendar = sender as Calendar;
                 if (e.OriginalSource is FrameworkElement fe)
                 {
-                    var dayButton = FindParent<CalendarDayButton>(fe);
+                    var dayButton = ControlsHelper.FindParent<CalendarDayButton>(fe);
                     if (dayButton != null && dayButton.DataContext is DateTime clickedDate)
                         if (!calendar.SelectedDates.Contains(clickedDate))
                         {
@@ -266,7 +266,7 @@ private void OnStartCalendar_PreviewMouseUp(object sender, MouseButtonEventArgs
                 var calendar = sender as Calendar;
                 if (e.OriginalSource is FrameworkElement fe)
                 {
-                    var dayButton = FindParent<CalendarDayButton>(fe);
+                    var dayButton = ControlsHelper.FindParent<CalendarDayButton>(fe);
                     if (dayButton != null && dayButton.DataContext is DateTime clickedDate)
                         if (!calendar.SelectedDates.Contains(clickedDate))
                         {
@@ -284,17 +284,6 @@ private void OnStartCalendar_PreviewMouseUp(object sender, MouseButtonEventArgs
             }
         }
 
-        private T FindParent<T>(DependencyObject child) where T : DependencyObject
-        {
-            var parent = VisualTreeHelper.GetParent(child);
-            if (parent == null) return null;
-
-            if (parent is T tParent)
-                return tParent;
-
-            return FindParent<T>(parent);
-        }
-
         private void OnBorder_PreviewMouseUp(object sender, MouseButtonEventArgs e)
         {
             if (e.OriginalSource is Button button)