重构到扩展方法（4）：轻松遍历WPF可视树与逻辑树

 

public static class VisualExtension
    {
        public static T FindAncestor<T>(this DependencyObject dependencyObject) where T : class
        {
            while (dependencyObject != null && !(dependencyObject is T))
            {
                dependencyObject = VisualTreeHelper.GetParent(dependencyObject);
            }

            return dependencyObject as T;
        }
        
        public static T FindAncestor<T>(this Visual visual) where T : Visual
        {
            while (visual != null && !(visual is T))
            {
                visual = (Visual)VisualTreeHelper.GetParent(visual);
            }
            return (T)visual;
        }

        public static T FindAncestor<T>(this Visual visual, Predicate<T> predicate) where T : Visual
        {
            while (visual != null && !predicate(visual as T))
            {
                visual = (Visual)VisualTreeHelper.GetParent(visual);
            }
            return (T)visual;
        }

        public static T FindAncestorByLogicalTree<T>(this Visual visual) where T : Visual
        {
            while (visual != null && !(visual is T))
            {
                visual = (Visual)LogicalTreeHelper.GetParent(visual);
            }
            return (T)visual;
        }

        public static T FindVisualChild<T>(this DependencyObject obj) where T : DependencyObject
        {
            for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
            {
                DependencyObject child = VisualTreeHelper.GetChild(obj, i);
                if (child != null && child is T)
                    return (T)child;
                else
                {
                    T childOfChild = child.FindVisualChild<T>();
                    if (childOfChild != null)
                        return childOfChild;
                }
            }
            return null;
        }

    }