月更

AntDesignWPF/Helpers/TreeHelper.cs

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+namespace AntDesign.WPF.Helpers
+{
+    using System.Collections.Generic;
+    using System.Windows;
+    using System.Windows.Media;
+    using System.Windows.Media.Media3D;
+
+    /// <summary>
+    /// Helper methods for UI-related tasks.
+    /// This class was obtained from Philip Sumi (a fellow WPF Disciples blog)
+    /// http://www.hardcodet.net/uploads/2009/06/UIHelper.cs
+    /// </summary>
+    public static class TreeHelper
+    {
+        #region Find Parent
+
+        /// <summary>
+        /// Finds a parent of a given item on the visual tree.
+        /// </summary>
+        /// <typeparam name="T">The type of the queried item.</typeparam>
+        /// <param name="child">A direct or indirect child of the
+        /// queried item.</param>
+        /// <returns>The first parent item that matches the submitted
+        /// type parameter. If not matching item can be found, a null
+        /// reference is being returned.</returns>
+        public static T TryFindParent<T>(this DependencyObject child)
+            where T : DependencyObject
+        {
+            //get parent item
+            var parentObject = child.GetParentObject();
+
+            //we've reached the end of the tree
+            if (parentObject == null) return null;
+
+            //check if the parent matches the type we're looking for
+            if (parentObject is T parent)
+            {
+                return parent;
+            }
+            else
+            {
+                //use recursion to proceed with next level
+                return parentObject.TryFindParent<T>();
+            }
+        }
+
+        /// <summary>
+        /// This method is an alternative to WPF's
+        /// <see cref="VisualTreeHelper.GetParent"/> method, which also
+        /// supports content elements. Keep in mind that for content element,
+        /// this method falls back to the logical tree of the element!
+        /// </summary>
+        /// <param name="child">The item to be processed.</param>
+        /// <returns>The submitted item's parent, if available. Otherwise
+        /// null.</returns>
+        public static DependencyObject GetParentObject(this DependencyObject child)
+        {
+            if (child == null) return null;
+
+            //handle content elements separately
+            if (child is ContentElement contentElement)
+            {
+                var parent = ContentOperations.GetParent(contentElement);
+                if (parent != null) return parent;
+
+                return contentElement is FrameworkContentElement fce ? fce.Parent : null;
+            }
+
+            //also try searching for parent in framework elements (such as DockPanel, etc)
+            if (child is FrameworkElement frameworkElement)
+            {
+                var parent = frameworkElement.Parent;
+                if (parent != null) return parent;
+            }
+
+            //if it's not a ContentElement/FrameworkElement, rely on VisualTreeHelper
+            return VisualTreeHelper.GetParent(child);
+        }
+
+        /// <summary>
+        /// Finds all Ancestors of a given item on the visual tree.
+        /// </summary>
+        /// <param name="child">A node in a visual tree</param>
+        /// <returns>All ancestors in visual tree of <paramref name="child"/> element</returns>
+        public static IEnumerable<DependencyObject> GetAncestors(this DependencyObject child)
+        {
+            var parent = VisualTreeHelper.GetParent(child);
+            while (parent != null)
+            {
+                yield return parent;
+                parent = VisualTreeHelper.GetParent(parent);
+            }
+        }
+
+        #endregion
+
+        #region Find children
+
+        /// <summary>
+        /// Finds a Child of a given item in the visual tree. 
+        /// </summary>
+        /// <param name="parent">A direct parent of the queried item.</param>
+        /// <typeparam name="T">The type of the queried item.</typeparam>
+        /// <param name="childName">x:Name or Name of child. </param>
+        /// <returns>The first parent item that matches the submitted type parameter. 
+        /// If not matching item can be found, 
+        /// a null parent is being returned.</returns>
+        public static T FindChild<T>(this DependencyObject parent, string childName)
+           where T : DependencyObject
+        {
+            // Confirm parent and childName are valid. 
+            if (parent == null) return null;
+
+            T foundChild = null;
+
+            var childrenCount = VisualTreeHelper.GetChildrenCount(parent);
+            for (var i = 0; i < childrenCount; i++)
+            {
+                var child = VisualTreeHelper.GetChild(parent, i);
+                // If the child is not of the request child type child
+                var childType = child as T;
+                if (childType == null)
+                {
+                    // recursively drill down the tree
+                    foundChild = child.FindChild<T>(childName);
+                    // If the child is found, break so we do not overwrite the found child. 
+                    if (foundChild != null) break;
+                }
+                else if (!string.IsNullOrEmpty(childName))
+                {
+                    var frameworkInputElement = child as IFrameworkInputElement;
+                    // If the child's name is set for search
+                    if (frameworkInputElement != null && frameworkInputElement.Name == childName)
+                    {
+                        // if the child's name is of the request name
+                        foundChild = (T)child;
+                        break;
+                    }
+                    else
+                    {
+                        // recursively drill down the tree
+                        foundChild = child.FindChild<T>(childName);
+                        // If the child is found, break so we do not overwrite the found child. 
+                        if (foundChild != null) break;
+                    }
+                }
+                else
+                {
+                    // child element found.
+                    foundChild = (T)child;
+                    break;
+                }
+            }
+
+            return foundChild;
+        }
+
+        /// <summary>
+        /// Analyzes both visual and logical tree in order to find all elements of a given
+        /// type that are descendants of the <paramref name="source"/> item.
+        /// </summary>
+        /// <typeparam name="T">The type of the queried items.</typeparam>
+        /// <param name="source">The root element that marks the source of the search. If the
+        /// source is already of the requested type, it will not be included in the result.</param>
+        /// <returns>All descendants of <paramref name="source"/> that match the requested type.</returns>
+        public static IEnumerable<T> FindChildren<T>(this DependencyObject source) where T : DependencyObject
+        {
+            if (source != null)
+            {
+                var childs = source.GetChildObjects();
+                foreach (var child in childs)
+                {
+                    //analyze if children match the requested type
+                    if (child != null && child is T)
+                    {
+                        yield return (T)child;
+                    }
+
+                    //recurse tree
+                    foreach (var descendant in child.FindChildren<T>())
+                    {
+                        yield return descendant;
+                    }
+                }
+            }
+        }
+
+
+        /// <summary>
+        /// This method is an alternative to WPF's
+        /// <see cref="VisualTreeHelper.GetChild"/> method, which also
+        /// supports content elements. Keep in mind that for content elements,
+        /// this method falls back to the logical tree of the element.
+        /// </summary>
+        /// <param name="parent">The item to be processed.</param>
+        /// <param name="forceUsingTheVisualTreeHelper">Sometimes it's better to search in the VisualTree (e.g. in tests)</param>
+        /// <returns>The submitted item's child elements, if available.</returns>
+        public static IEnumerable<DependencyObject> GetChildObjects(this DependencyObject parent, bool forceUsingTheVisualTreeHelper = false)
+        {
+            if (parent == null) yield break;
+
+            if (!forceUsingTheVisualTreeHelper && (parent is ContentElement || parent is FrameworkElement))
+            {
+                //use the logical tree for content / framework elements
+                foreach (var obj in LogicalTreeHelper.GetChildren(parent))
+                {
+                    var depObj = obj as DependencyObject;
+                    if (depObj != null) yield return (DependencyObject)obj;
+                }
+            }
+            else if (parent is Visual || parent is Visual3D)
+            {
+                //use the visual tree per default
+                var count = VisualTreeHelper.GetChildrenCount(parent);
+                for (var i = 0; i < count; i++)
+                {
+                    yield return VisualTreeHelper.GetChild(parent, i);
+                }
+            }
+        }
+
+        #endregion
+
+        #region Find From Point
+
+        /// <summary>
+        /// Tries to locate a given item within the visual tree,
+        /// starting with the dependency object at a given position. 
+        /// </summary>
+        /// <typeparam name="T">The type of the element to be found
+        /// on the visual tree of the element at the given location.</typeparam>
+        /// <param name="reference">The main element which is used to perform
+        /// hit testing.</param>
+        /// <param name="point">The position to be evaluated on the origin.</param>
+        public static T TryFindFromPoint<T>(UIElement reference, Point point)
+            where T : DependencyObject
+        {
+
+            if (!(reference.InputHitTest(point) is DependencyObject element)) return null;
+            else if (element is T) return (T)element;
+            else return element.TryFindParent<T>();
+        }
+
+        #endregion
+    }
+}