JournalEntryListConverter.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / System / Windows / Navigation / JournalEntryListConverter.cs / 1305600 / JournalEntryListConverter.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// File: JournalConverter.cs
//
// Description: Implements the Converter to limit journal views to 9 items. 
//
// Created: 1/31/05 by SujalP 
// 
// Copyright (C) 2005 by Microsoft Corporation.  All rights reserved.
// 
//---------------------------------------------------------------------------

// Disable unknown #pragma warning for pragmas we use to exclude certain PreSharp violations
#pragma warning disable 1634, 1691 

using System; 
using System.Collections; 
using System.Collections.Specialized;
using System.Globalization; 
using System.ComponentModel;
using System.Windows.Data;

using MS.Internal; 

namespace System.Windows.Navigation 
{ 
    /// 
    /// This class returns an IEnumerable that is limited in length - it is used by the NavigationWindow 
    /// style to limit how many entries are shown in the back and forward drop down buttons. Not
    /// intended to be used in any other situations.
    /// 
    public sealed class JournalEntryListConverter : IValueConverter 
    {
        ///  
        /// This method from IValueConverter returns an IEnumerable which in turn will yield the 
        /// ViewLimit limited collection of journal back and forward stack entries.
        ///  
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
#pragma warning disable  6506
            return (value != null) ? ((JournalEntryStack)value).GetLimitedJournalEntryStackEnumerable() : null; 
#pragma warning restore 6506
        } 
 
        /// 
        /// This method from IValueConverter returns an IEnumerable which was originally passed to Convert 
        /// 
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return Binding.DoNothing; 
        }
    } 
 
    /// 
    ///     Describes the position of the journal entry relative to the current page. 
    /// 
    public enum JournalEntryPosition
    {
        ///  
        ///     The entry is on the BackStack
        ///  
        Back, 

        ///  
        ///     The current page
        /// 
        Current,
 
        /// 
        ///     The entry on the ForwardStack 
        ///  
        Forward,
    } 

    /// 
    /// Puts all of the journal entries into a single list, for an IE7-style menu.
    ///  
    public sealed class JournalEntryUnifiedViewConverter : IMultiValueConverter
    { 
        ///  
        ///     The DependencyProperty for the JournalEntryPosition property.
        ///  
        public static readonly DependencyProperty JournalEntryPositionProperty =
                DependencyProperty.RegisterAttached(
                        "JournalEntryPosition",
                        typeof(JournalEntryPosition), 
                        typeof(JournalEntryUnifiedViewConverter),
                        new PropertyMetadata(JournalEntryPosition.Current)); 
 
        /// 
        ///     Helper for reading the JournalEntryPosition property. 
        /// 
        public static JournalEntryPosition GetJournalEntryPosition(DependencyObject element)
        {
            if (element == null) 
            {
                throw new ArgumentNullException("element"); 
            } 

            return ((JournalEntryPosition)element.GetValue(JournalEntryPositionProperty)); 
        }

        /// 
        ///     Helper for setting the JournalEntryPosition property. 
        /// 
        public static void SetJournalEntryPosition(DependencyObject element, JournalEntryPosition position) 
        { 
            if (element == null)
            { 
                throw new ArgumentNullException("element");
            }

            element.SetValue(JournalEntryPositionProperty, position); 
        }
 
 
        /// 
        /// This method from IValueConverter returns an IEnumerable which in turn will yield the 
        /// single list containing all of the menu items.
        /// 
        public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        { 
            if (values != null && values.Length == 2)
            { 
                JournalEntryStack backStack = values[0] as JournalEntryStack; 
                JournalEntryStack forwardStack = values[1] as JournalEntryStack;
 
                if (backStack != null && forwardStack != null)
                {
                    LimitedJournalEntryStackEnumerable limitedBackStack = (LimitedJournalEntryStackEnumerable)backStack.GetLimitedJournalEntryStackEnumerable();
                    LimitedJournalEntryStackEnumerable limitedForwardStack = (LimitedJournalEntryStackEnumerable)forwardStack.GetLimitedJournalEntryStackEnumerable(); 

                    return new UnifiedJournalEntryStackEnumerable(limitedBackStack, limitedForwardStack); 
                } 
            }
 
            return null;
        }

        ///  
        /// This method is unused.
        ///  
        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture) 
        {
            return new object[] { Binding.DoNothing }; 
        }
    }

    // Merges LimitedBack and Forward Stack into one list and 
    internal class UnifiedJournalEntryStackEnumerable : IEnumerable, INotifyCollectionChanged
    { 
        internal UnifiedJournalEntryStackEnumerable(LimitedJournalEntryStackEnumerable backStack, LimitedJournalEntryStackEnumerable forwardStack) 
        {
            _backStack = backStack; 
            _backStack.CollectionChanged += new NotifyCollectionChangedEventHandler(StacksChanged);

            _forwardStack = forwardStack;
            _forwardStack.CollectionChanged += new NotifyCollectionChangedEventHandler(StacksChanged); 
        }
 
        public IEnumerator GetEnumerator() 
        {
            if (_items == null) 
            {
                // Reserve space so this will not have to reallocate. The most it will ever be is
                // 9 for the forward stack, 9 for the back stack, 1 for the title bar
                _items = new ArrayList(19); 

                // Add ForwardStack in reverse order 
                foreach (JournalEntry o in _forwardStack) 
                {
                    _items.Insert(0, o); 
                    JournalEntryUnifiedViewConverter.SetJournalEntryPosition(o, JournalEntryPosition.Forward);
                }

                DependencyObject current = new DependencyObject(); 
                current.SetValue(JournalEntry.NameProperty, SR.Get(SRID.NavWindowMenuCurrentPage));
 
                // "Current Page" 
                _items.Add(current);
 
                foreach (JournalEntry o in _backStack)
                {
                    _items.Add(o);
                    JournalEntryUnifiedViewConverter.SetJournalEntryPosition(o, JournalEntryPosition.Back); 
                }
            } 
 
            return _items.GetEnumerator();
        } 

        internal void StacksChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            _items = null; 
            if (CollectionChanged != null)
            { 
                CollectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset)); 
            }
        } 

        public event NotifyCollectionChangedEventHandler CollectionChanged;

        private LimitedJournalEntryStackEnumerable _backStack, _forwardStack; 
        private ArrayList _items;
    } 
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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JournalEntryListConverter.cs source code in C# .NET

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