DescendentsWalkerBase.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Framework / System / Windows / DescendentsWalkerBase.cs / 2 / DescendentsWalkerBase.cs
                        

                        
                            using System; 
using System.Collections;
using System.Diagnostics;
using System.Windows;
using System.Windows.Media; 
using MS.Utility;
 
namespace System.Windows 
{
    ///  
    ///     This is a base class to the DescendentsWalker. It is factored out so that
    ///     FrameworkContextData can store and retrieve it from context local storage
    ///     in a type agnostic manner.
    ///  
    internal class DescendentsWalkerBase
    { 
        #region Construction 

        protected DescendentsWalkerBase(TreeWalkPriority priority) 
        {
            _startNode = null;
            _priority = priority;
            _recursionDepth = 0; 
            _nodes = new FrugalStructList();
        } 
 
        #endregion Construction
 
        internal bool WasVisited(DependencyObject d)
        {
            DependencyObject ancestor = d;
 
            while ((ancestor != _startNode) && (ancestor != null))
            { 
                DependencyObject logicalParent; 

                if (FrameworkElement.DType.IsInstanceOfType(ancestor)) 
                {
                    FrameworkElement fe = ancestor as FrameworkElement;
                    logicalParent = fe.Parent;
                    // FrameworkElement 
                    DependencyObject dependencyObjectParent = VisualTreeHelper.GetParent(fe);
                    if (dependencyObjectParent != null && logicalParent != null && dependencyObjectParent != logicalParent) 
                    { 
                        return _nodes.Contains(ancestor);
                    } 

                    // Follow visual tree if not null otherwise we follow logical tree
                    if (dependencyObjectParent != null)
                    { 
                        ancestor = dependencyObjectParent;
                        continue; 
                    } 
                }
                else 
                {
                    // FrameworkContentElement
                    FrameworkContentElement ancestorFCE = ancestor as FrameworkContentElement;
                    logicalParent = (ancestorFCE != null) ? ancestorFCE.Parent : null; 
                }
                ancestor = logicalParent; 
            } 
            return (ancestor != null);
        } 


        internal DependencyObject _startNode;
        internal TreeWalkPriority _priority; 

        internal FrugalStructList _nodes; 
        internal int _recursionDepth; 

        internal const int MAX_TREE_DEPTH = 250; 
    }

    /// 
    ///     Enum specifying whether visual tree needs 
    ///     to be travesed first or the logical tree
    ///  
    internal enum TreeWalkPriority 
    {
        ///  
        ///     Traverse Logical Tree first
        /// 
        LogicalTree,
 
        /// 
        ///     Traverse Visual Tree first 
        ///  
        VisualTree
    } 
}



// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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