/Toolkit-development/Input/AutoCompleteBox/System/Windows/Controls/AutoCompleteBox.cs

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// (c) Copyright Microsoft Corporation.

// This source is subject to the Microsoft Public License (Ms-PL).

// Please see http://go.microsoft.com/fwlink/?LinkID=131993] for details.

// All other rights reserved.



using System;

using System.Collections;

using System.Collections.Generic;

using System.Collections.ObjectModel;

using System.Collections.Specialized;

using System.Diagnostics.CodeAnalysis;

using System.Globalization;

using System.Linq;

using System.Windows.Automation.Peers;

using System.Windows.Controls.Primitives;

using System.Windows.Data;

using System.Windows.Input;

using System.Windows.Interop;

using System.Windows.Markup;

using System.Windows.Media;

using System.Windows.Threading;



namespace System.Windows.Controls

{

    /// <summary>

    /// Represents a control that provides a text box for user input and a

    /// drop-down that contains possible matches based on the input in the text

    /// box.

    /// </summary>

    /// <QualityBand>Stable</QualityBand>

    [TemplatePart(Name = AutoCompleteBox.ElementSelectionAdapter, Type = typeof(ISelectionAdapter))]

    [TemplatePart(Name = AutoCompleteBox.ElementSelector, Type = typeof(Selector))]

    [TemplatePart(Name = AutoCompleteBox.ElementTextBox, Type = typeof(TextBox))]

    [TemplatePart(Name = AutoCompleteBox.ElementPopup, Type = typeof(Popup))]

    [StyleTypedProperty(Property = AutoCompleteBox.ElementTextBoxStyle, StyleTargetType = typeof(TextBox))]

    [StyleTypedProperty(Property = AutoCompleteBox.ElementItemContainerStyle, StyleTargetType = typeof(ListBox))]

    [TemplateVisualState(Name = VisualStates.StateNormal, GroupName = VisualStates.GroupCommon)]

    [TemplateVisualState(Name = VisualStates.StateMouseOver, GroupName = VisualStates.GroupCommon)]

    [TemplateVisualState(Name = VisualStates.StatePressed, GroupName = VisualStates.GroupCommon)]

    [TemplateVisualState(Name = VisualStates.StateDisabled, GroupName = VisualStates.GroupCommon)]

    [TemplateVisualState(Name = VisualStates.StateFocused, GroupName = VisualStates.GroupFocus)]

    [TemplateVisualState(Name = VisualStates.StateUnfocused, GroupName = VisualStates.GroupFocus)]

    [TemplateVisualState(Name = VisualStates.StatePopupClosed, GroupName = VisualStates.GroupPopup)]

    [TemplateVisualState(Name = VisualStates.StatePopupOpened, GroupName = VisualStates.GroupPopup)]

    [TemplateVisualState(Name = VisualStates.StateValid, GroupName = VisualStates.GroupValidation)]

    [TemplateVisualState(Name = VisualStates.StateInvalidFocused, GroupName = VisualStates.GroupValidation)]

    [TemplateVisualState(Name = VisualStates.StateInvalidUnfocused, GroupName = VisualStates.GroupValidation)]

    [SuppressMessage("Microsoft.Maintainability", "CA1506:AvoidExcessiveClassCoupling", Justification = "Large implementation keeps the components contained.")]

    [ContentProperty("ItemsSource")]

    public partial class AutoCompleteBox : Control, IUpdateVisualState

    {

        #region Template part and style names



        /// <summary>

        /// Specifies the name of the selection adapter TemplatePart.

        /// </summary>

        private const string ElementSelectionAdapter = "SelectionAdapter";



        /// <summary>

        /// Specifies the name of the Selector TemplatePart.

        /// </summary>

        private const string ElementSelector = "Selector";



        /// <summary>

        /// Specifies the name of the Popup TemplatePart.

        /// </summary>

        private const string ElementPopup = "Popup";

        

        /// <summary>

        /// The name for the text box part.

        /// </summary>

        private const string ElementTextBox = "Text";



        /// <summary>

        /// The name for the text box style.

        /// </summary>

        private const string ElementTextBoxStyle = "TextBoxStyle";



        /// <summary>

        /// The name for the adapter's item container style.

        /// </summary>

        private const string ElementItemContainerStyle = "ItemContainerStyle";



        #endregion



        /// <summary>

        /// Gets or sets a local cached copy of the items data.

        /// </summary>

        private List<object> _items;



        /// <summary>

        /// Gets or sets the observable collection that contains references to 

        /// all of the items in the generated view of data that is provided to 

        /// the selection-style control adapter.

        /// </summary>

        private ObservableCollection<object> _view;



        /// <summary>

        /// Gets or sets a value to ignore a number of pending change handlers. 

        /// The value is decremented after each use. This is used to reset the 

        /// value of properties without performing any of the actions in their 

        /// change handlers.

        /// </summary>

        /// <remarks>The int is important as a value because the TextBox 

        /// TextChanged event does not immediately fire, and this will allow for

        /// nested property changes to be ignored.</remarks>

        private int _ignoreTextPropertyChange;



        /// <summary>

        /// Gets or sets a value indicating whether to ignore calling a pending 

        /// change handlers. 

        /// </summary>

        private bool _ignorePropertyChange;



        /// <summary>

        /// Gets or sets a value indicating whether to ignore the selection 

        /// changed event.

        /// </summary>

        private bool _ignoreTextSelectionChange;



        /// <summary>

        /// Gets or sets a value indicating whether to skip the text update 

        /// processing when the selected item is updated.

        /// </summary>

        private bool _skipSelectedItemTextUpdate;



        /// <summary>

        /// Gets or sets the last observed text box selection start location.

        /// </summary>

        private int _textSelectionStart;



        /// <summary>

        /// Gets or sets a value indicating whether the user initiated the 

        /// current populate call.

        /// </summary>

        private bool _userCalledPopulate;



        /// <summary>

        /// A value indicating whether the popup has been opened at least once.

        /// </summary>

        private bool _popupHasOpened;



        /// <summary>

        /// Gets or sets the DispatcherTimer used for the MinimumPopulateDelay 

        /// condition for auto completion.

        /// </summary>

        private DispatcherTimer _delayTimer;



        /// <summary>

        /// Gets or sets a value indicating whether a read-only dependency 

        /// property change handler should allow the value to be set.  This is 

        /// used to ensure that read-only properties cannot be changed via 

        /// SetValue, etc.

        /// </summary>

        private bool _allowWrite;



        /// <summary>

        /// Gets or sets the helper that provides all of the standard

        /// interaction functionality. Making it internal for subclass access.

        /// </summary>

        internal InteractionHelper Interaction { get; set; }



        /// <summary>

        /// Gets or sets the BindingEvaluator, a framework element that can

        /// provide updated string values from a single binding.

        /// </summary>

        private BindingEvaluator<string> _valueBindingEvaluator;



        /// <summary>

        /// A weak event listener for the collection changed event.

        /// </summary>

        private WeakEventListener<AutoCompleteBox, object, NotifyCollectionChangedEventArgs> _collectionChangedWeakEventListener;



        #region public int MinimumPrefixLength

        /// <summary>

        /// Gets or sets the minimum number of characters required to be entered

        /// in the text box before the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> displays

        /// possible matches.

        /// matches.

        /// </summary>

        /// <value>

        /// The minimum number of characters to be entered in the text box

        /// before the <see cref="T:System.Windows.Controls.AutoCompleteBox" />

        /// displays possible matches. The default is 1.

        /// </value>

        /// <remarks>

        /// If you set MinimumPrefixLength to -1, the AutoCompleteBox will

        /// not provide possible matches. There is no maximum value, but

        /// setting MinimumPrefixLength to value that is too large will

        /// prevent the AutoCompleteBox from providing possible matches as well.

        /// </remarks>

        public int MinimumPrefixLength

        {

            get { return (int)GetValue(MinimumPrefixLengthProperty); }

            set { SetValue(MinimumPrefixLengthProperty, value); }

        }



        /// <summary>

        /// Identifies the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.MinimumPrefixLength" />

        /// dependency property.

        /// </summary>

        /// <value>The identifier for the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.MinimumPrefixLength" />

        /// dependency property.</value>

        public static readonly DependencyProperty MinimumPrefixLengthProperty =

            DependencyProperty.Register(

                "MinimumPrefixLength",

                typeof(int),

                typeof(AutoCompleteBox),

                new PropertyMetadata(1, OnMinimumPrefixLengthPropertyChanged));



        /// <summary>

        /// MinimumPrefixLengthProperty property changed handler.

        /// </summary>

        /// <param name="d">AutoCompleteBox that changed its MinimumPrefixLength.</param>

        /// <param name="e">Event arguments.</param>

        [SuppressMessage("Microsoft.Usage", "CA2208:InstantiateArgumentExceptionsCorrectly", Justification = "MinimumPrefixLength is the name of the actual dependency property.")]

        private static void OnMinimumPrefixLengthPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)

        {

            int newValue = (int)e.NewValue;



            if (newValue < 0 && newValue != -1)

            {

                throw new ArgumentOutOfRangeException("MinimumPrefixLength");

            }

        }

        #endregion public int MinimumPrefixLength



        #region public int MinimumPopulateDelay

        /// <summary>

        /// Gets or sets the minimum delay, in milliseconds, after text is typed

        /// in the text box before the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> control

        /// populates the list of possible matches in the drop-down.

        /// </summary>

        /// <value>The minimum delay, in milliseconds, after text is typed in

        /// the text box, but before the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> populates

        /// the list of possible matches in the drop-down. The default is 0.</value>

        /// <exception cref="T:System.ArgumentException">The set value is less than 0.</exception>

        public int MinimumPopulateDelay

        {

            get { return (int)GetValue(MinimumPopulateDelayProperty); }

            set { SetValue(MinimumPopulateDelayProperty, value); }

        }



        /// <summary>

        /// Identifies the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.MinimumPopulateDelay" />

        /// dependency property.

        /// </summary>

        /// <value>The identifier for the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.MinimumPopulateDelay" />

        /// dependency property.</value>

        public static readonly DependencyProperty MinimumPopulateDelayProperty =

            DependencyProperty.Register(

                "MinimumPopulateDelay",

                typeof(int),

                typeof(AutoCompleteBox),

                new PropertyMetadata(OnMinimumPopulateDelayPropertyChanged));



        /// <summary>

        /// MinimumPopulateDelayProperty property changed handler. Any current 

        /// dispatcher timer will be stopped. The timer will not be restarted 

        /// until the next TextUpdate call by the user.

        /// </summary>

        /// <param name="d">AutoCompleteTextBox that changed its 

        /// MinimumPopulateDelay.</param>

        /// <param name="e">Event arguments.</param>

        [SuppressMessage("Microsoft.Usage", "CA2208:InstantiateArgumentExceptionsCorrectly", Justification = "The exception is most likely to be called through the CLR property setter.")]

        private static void OnMinimumPopulateDelayPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)

        {

            AutoCompleteBox source = d as AutoCompleteBox;



            if (source._ignorePropertyChange)

            {

                source._ignorePropertyChange = false;

                return;

            }



            int newValue = (int)e.NewValue;

            if (newValue < 0)

            {

                source._ignorePropertyChange = true;

                d.SetValue(e.Property, e.OldValue);



                throw new ArgumentException(string.Format(CultureInfo.InvariantCulture, Properties.Resources.AutoComplete_OnMinimumPopulateDelayPropertyChanged_InvalidValue, newValue), "value");

            }



            // Stop any existing timer

            if (source._delayTimer != null)

            {

                source._delayTimer.Stop();

                

                if (newValue == 0)

                {

                    source._delayTimer = null;

                }

            }



            // Create or clear a dispatcher timer instance

            if (newValue > 0 && source._delayTimer == null)

            {

                source._delayTimer = new DispatcherTimer();

                source._delayTimer.Tick += source.PopulateDropDown;

            }



            // Set the new tick interval

            if (newValue > 0 && source._delayTimer != null)

            {

                source._delayTimer.Interval = TimeSpan.FromMilliseconds(newValue);

            }

        }

        #endregion public int MinimumPopulateDelay

        

        #region public bool IsTextCompletionEnabled

        /// <summary>

        /// Gets or sets a value indicating whether the first possible match

        /// found during the filtering process will be displayed automatically

        /// in the text box.

        /// </summary>

        /// <value>

        /// True if the first possible match found will be displayed

        /// automatically in the text box; otherwise, false. The default is

        /// false.

        /// </value>

        public bool IsTextCompletionEnabled

        {

            get { return (bool)GetValue(IsTextCompletionEnabledProperty); }

            set { SetValue(IsTextCompletionEnabledProperty, value); }

        }



        /// <summary>

        /// Identifies the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.IsTextCompletionEnabled" />

        /// dependency property.

        /// </summary>

        /// <value>The identifier for the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.IsTextCompletionEnabled" />

        /// dependency property.</value>

        public static readonly DependencyProperty IsTextCompletionEnabledProperty =

            DependencyProperty.Register(

                "IsTextCompletionEnabled",

                typeof(bool),

                typeof(AutoCompleteBox),

                new PropertyMetadata(false, null));



        #endregion public bool IsTextCompletionEnabled



        #region public DataTemplate ItemTemplate

        /// <summary>

        /// Gets or sets the <see cref="T:System.Windows.DataTemplate" /> used

        /// to display each item in the drop-down portion of the control.

        /// </summary>

        /// <value>The <see cref="T:System.Windows.DataTemplate" /> used to

        /// display each item in the drop-down. The default is null.</value>

        /// <remarks>

        /// You use the ItemTemplate property to specify the visualization 

        /// of the data objects in the drop-down portion of the AutoCompleteBox 

        /// control. If your AutoCompleteBox is bound to a collection and you 

        /// do not provide specific display instructions by using a 

        /// DataTemplate, the resulting UI of each item is a string 

        /// representation of each object in the underlying collection. 

        /// </remarks>

        public DataTemplate ItemTemplate

        {

            get { return GetValue(ItemTemplateProperty) as DataTemplate; }

            set { SetValue(ItemTemplateProperty, value); }

        }



        /// <summary>

        /// Identifies the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemTemplate" />

        /// dependency property.

        /// </summary>

        /// <value>The identifier for the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemTemplate" />

        /// dependency property.</value>

        public static readonly DependencyProperty ItemTemplateProperty =

            DependencyProperty.Register(

                "ItemTemplate",

                typeof(DataTemplate),

                typeof(AutoCompleteBox),

                new PropertyMetadata(null));



        #endregion public DataTemplate ItemTemplate



        #region public Style ItemContainerStyle

        /// <summary>

        /// Gets or sets the <see cref="T:System.Windows.Style" /> that is

        /// applied to the selection adapter contained in the drop-down portion

        /// of the <see cref="T:System.Windows.Controls.AutoCompleteBox" />

        /// control.

        /// </summary>

        /// <value>The <see cref="T:System.Windows.Style" /> applied to the

        /// selection adapter contained in the drop-down portion of the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> control.

        /// The default is null.</value>

        /// <remarks>

        /// The default selection adapter contained in the drop-down is a 

        /// ListBox control. 

        /// </remarks>

        public Style ItemContainerStyle

        {

            get { return GetValue(ItemContainerStyleProperty) as Style; }

            set { SetValue(ItemContainerStyleProperty, value); }

        }



        /// <summary>

        /// Identifies the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemContainerStyle" />

        /// dependency property.

        /// </summary>

        /// <value>The identifier for the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemContainerStyle" />

        /// dependency property.</value>

        public static readonly DependencyProperty ItemContainerStyleProperty =

            DependencyProperty.Register(

                ElementItemContainerStyle,

                typeof(Style),

                typeof(AutoCompleteBox),

                new PropertyMetadata(null, null));



        #endregion public Style ItemContainerStyle



        #region public Style TextBoxStyle

        /// <summary>

        /// Gets or sets the <see cref="T:System.Windows.Style" /> applied to

        /// the text box portion of the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> control.

        /// </summary>

        /// <value>The <see cref="T:System.Windows.Style" /> applied to the text

        /// box portion of the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> control.

        /// The default is null.</value>

        public Style TextBoxStyle

        {

            get { return GetValue(TextBoxStyleProperty) as Style; }

            set { SetValue(TextBoxStyleProperty, value); }

        }



        /// <summary>

        /// Identifies the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.TextBoxStyle" />

        /// dependency property.

        /// </summary>

        /// <value>The identifier for the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.TextBoxStyle" />

        /// dependency property.</value>

        public static readonly DependencyProperty TextBoxStyleProperty =

            DependencyProperty.Register(

                ElementTextBoxStyle,

                typeof(Style),

                typeof(AutoCompleteBox),

                new PropertyMetadata(null));



        #endregion public Style TextBoxStyle



        #region public double MaxDropDownHeight

        /// <summary>

        /// Gets or sets the maximum height of the drop-down portion of the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> control.

        /// </summary>

        /// <value>The maximum height of the drop-down portion of the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> control.

        /// The default is <see cref="F:System.Double.PositiveInfinity" />.</value>

        /// <exception cref="T:System.ArgumentException">The specified value is less than 0.</exception>

        public double MaxDropDownHeight

        {

            get { return (double)GetValue(MaxDropDownHeightProperty); }

            set { SetValue(MaxDropDownHeightProperty, value); }

        }



        /// <summary>

        /// Identifies the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.MaxDropDownHeight" />

        /// dependency property.

        /// </summary>

        /// <value>The identifier for the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.MaxDropDownHeight" />

        /// dependency property.</value>

        public static readonly DependencyProperty MaxDropDownHeightProperty =

            DependencyProperty.Register(

                "MaxDropDownHeight",

                typeof(double),

                typeof(AutoCompleteBox),

                new PropertyMetadata(double.PositiveInfinity, OnMaxDropDownHeightPropertyChanged));



        /// <summary>

        /// MaxDropDownHeightProperty property changed handler.

        /// </summary>

        /// <param name="d">AutoCompleteTextBox that changed its MaxDropDownHeight.</param>

        /// <param name="e">Event arguments.</param>

        [SuppressMessage("Microsoft.Usage", "CA2208:InstantiateArgumentExceptionsCorrectly", Justification = "The exception will be called through a CLR setter in most cases.")]

        private static void OnMaxDropDownHeightPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)

        {

            AutoCompleteBox source = d as AutoCompleteBox;

            if (source._ignorePropertyChange)

            {

                source._ignorePropertyChange = false;

                return;

            }



            double newValue = (double)e.NewValue;

            

            // Revert to the old value if invalid (negative)

            if (newValue < 0)

            {

                source._ignorePropertyChange = true;

                source.SetValue(e.Property, e.OldValue);



                throw new ArgumentException(string.Format(CultureInfo.InvariantCulture, Properties.Resources.AutoComplete_OnMaxDropDownHeightPropertyChanged_InvalidValue, e.NewValue), "value");

            }



            source.OnMaxDropDownHeightChanged(newValue);

        }

        #endregion public double MaxDropDownHeight



        #region public bool IsDropDownOpen

        /// <summary>

        /// Gets or sets a value indicating whether the drop-down portion of

        /// the control is open.

        /// </summary>

        /// <value>

        /// True if the drop-down is open; otherwise, false. The default is

        /// false.

        /// </value>

        public bool IsDropDownOpen

        {

            get { return (bool)GetValue(IsDropDownOpenProperty); }

            set { SetValue(IsDropDownOpenProperty, value); }

        }



        /// <summary>

        /// Identifies the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.IsDropDownOpen" />

        /// dependency property.

        /// </summary>

        /// <value>The identifier for the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.IsDropDownOpen" />

        /// dependency property.</value>

        public static readonly DependencyProperty IsDropDownOpenProperty =

            DependencyProperty.Register(

                "IsDropDownOpen",

                typeof(bool),

                typeof(AutoCompleteBox),

                new PropertyMetadata(false, OnIsDropDownOpenPropertyChanged));



        /// <summary>

        /// IsDropDownOpenProperty property changed handler.

        /// </summary>

        /// <param name="d">AutoCompleteTextBox that changed its IsDropDownOpen.</param>

        /// <param name="e">Event arguments.</param>

        private static void OnIsDropDownOpenPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)

        {

            AutoCompleteBox source = d as AutoCompleteBox;



            // Ignore the change if requested

            if (source._ignorePropertyChange)

            {

                source._ignorePropertyChange = false;

                return;

            }



            bool oldValue = (bool)e.OldValue;

            bool newValue = (bool)e.NewValue;



            if (newValue)

            {

                source.TextUpdated(source.Text, true);

            }

            else

            {

                source.ClosingDropDown(oldValue);

            }



            source.UpdateVisualState(true);

        }

        #endregion public bool IsDropDownOpen



        #region public IEnumerable ItemsSource

        /// <summary>

        /// Gets or sets a collection that is used to generate the items for the

        /// drop-down portion of the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> control.

        /// </summary>

        /// <value>The collection that is used to generate the items of the

        /// drop-down portion of the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> control.</value>

        public IEnumerable ItemsSource

        {

            get { return GetValue(ItemsSourceProperty) as IEnumerable; }

            set { SetValue(ItemsSourceProperty, value); }

        }



        /// <summary>

        /// Identifies the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemsSource" />

        /// dependency property.

        /// </summary>

        /// <value>The identifier for the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemsSource" />

        /// dependency property.</value>

        public static readonly DependencyProperty ItemsSourceProperty =

            DependencyProperty.Register(

                "ItemsSource",

                typeof(IEnumerable),

                typeof(AutoCompleteBox),

                new PropertyMetadata(OnItemsSourcePropertyChanged));



        /// <summary>

        /// ItemsSourceProperty property changed handler.

        /// </summary>

        /// <param name="d">AutoCompleteBox that changed its ItemsSource.</param>

        /// <param name="e">Event arguments.</param>

        private static void OnItemsSourcePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)

        {

            AutoCompleteBox autoComplete = d as AutoCompleteBox;

            autoComplete.OnItemsSourceChanged((IEnumerable)e.OldValue, (IEnumerable)e.NewValue);

        }



        #endregion public IEnumerable ItemsSource



        #region public object SelectedItem

        /// <summary>

        /// Gets or sets the selected item in the drop-down.

        /// </summary>

        /// <value>The selected item in the drop-down.</value>

        /// <remarks>

        /// If the IsTextCompletionEnabled property is true and text typed by 

        /// the user matches an item in the ItemsSource collection, which is 

        /// then displayed in the text box, the SelectedItem property will be 

        /// a null reference.

        /// </remarks>

        public object SelectedItem

        {

            get { return GetValue(SelectedItemProperty) as object; }

            set { SetValue(SelectedItemProperty, value); }

        }



        /// <summary>

        /// Identifies the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.SelectedItem" />

        /// dependency property.

        /// </summary>

        /// <value>The identifier the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.SelectedItem" />

        /// dependency property.</value>

        public static readonly DependencyProperty SelectedItemProperty =

            DependencyProperty.Register(

                "SelectedItem",

                typeof(object),

                typeof(AutoCompleteBox),

                new PropertyMetadata(OnSelectedItemPropertyChanged));



        /// <summary>

        /// SelectedItemProperty property changed handler. Fires the 

        /// SelectionChanged event. The event data will contain any non-null

        /// removed items and non-null additions.

        /// </summary>

        /// <param name="d">AutoCompleteBox that changed its SelectedItem.</param>

        /// <param name="e">Event arguments.</param>

        private static void OnSelectedItemPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)

        {

            AutoCompleteBox source = d as AutoCompleteBox;



            if (source._ignorePropertyChange)

            {

                source._ignorePropertyChange = false;

                return;

            }



            // Update the text display

            if (source._skipSelectedItemTextUpdate)

            {

                source._skipSelectedItemTextUpdate = false;

            }

            else

            {

                source.OnSelectedItemChanged(e.NewValue);

            }



            // Fire the SelectionChanged event

            List<object> removed = new List<object>();

            if (e.OldValue != null)

            {

                removed.Add(e.OldValue);

            }

            

            List<object> added = new List<object>();

            if (e.NewValue != null)

            {

                added.Add(e.NewValue);

            }



            source.OnSelectionChanged(new SelectionChangedEventArgs(

#if !SILVERLIGHT

                SelectionChangedEvent,

#endif

                removed,

                added));

        }



        /// <summary>

        /// Called when the selected item is changed, updates the text value

        /// that is displayed in the text box part.

        /// </summary>

        /// <param name="newItem">The new item.</param>

        private void OnSelectedItemChanged(object newItem)

        {

            string text;



            if (newItem == null)

            {

                text = SearchText;

            }

            else

            {

                text = FormatValue(newItem, true);

            }



            // Update the Text property and the TextBox values

            UpdateTextValue(text);



            // Move the caret to the end of the text box

            if (TextBox != null && Text != null)

            {

                TextBox.SelectionStart = Text.Length;

            }

        }



        #endregion public object SelectedItem



        #region public string Text

        /// <summary>

        /// Gets or sets the text in the text box portion of the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> control.

        /// </summary>

        /// <value>The text in the text box portion of the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> control.</value>

        public string Text

        {

            get { return GetValue(TextProperty) as string; }

            set { SetValue(TextProperty, value); }

        }



        /// <summary>

        /// Identifies the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.Text" />

        /// dependency property.

        /// </summary>

        /// <value>The identifier for the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.Text" />

        /// dependency property.</value>

        public static readonly DependencyProperty TextProperty =

            DependencyProperty.Register(

                "Text",

                typeof(string),

                typeof(AutoCompleteBox),

                new PropertyMetadata(string.Empty, OnTextPropertyChanged));



        /// <summary>

        /// TextProperty property changed handler.

        /// </summary>

        /// <param name="d">AutoCompleteBox that changed its Text.</param>

        /// <param name="e">Event arguments.</param>

        private static void OnTextPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)

        {

            AutoCompleteBox source = d as AutoCompleteBox;

            source.TextUpdated((string)e.NewValue, false);

        }



        #endregion public string Text



        #region public string SearchText

        /// <summary>

        /// Gets the text that is used to filter items in the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemsSource" />

        /// item collection.

        /// </summary>

        /// <value>The text that is used to filter items in the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemsSource" />

        /// item collection.</value>

        /// <remarks>

        /// The SearchText value is typically the same as the 

        /// Text property, but is set after the TextChanged event occurs 

        /// and before the Populating event.

        /// </remarks>

        public string SearchText

        {

            get { return (string)GetValue(SearchTextProperty); }



            private set

            {

                try

                {

                    _allowWrite = true;

                    SetValue(SearchTextProperty, value);

                }

                finally

                {

                    _allowWrite = false;

                }

            }

        }



        /// <summary>

        /// Identifies the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.SearchText" />

        /// dependency property.

        /// </summary>

        /// <value>The identifier for the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.SearchText" />

        /// dependency property.</value>

        public static readonly DependencyProperty SearchTextProperty =

            DependencyProperty.Register(

                "SearchText",

                typeof(string),

                typeof(AutoCompleteBox),

                new PropertyMetadata(string.Empty, OnSearchTextPropertyChanged));



        /// <summary>

        /// OnSearchTextProperty property changed handler.

        /// </summary>

        /// <param name="d">AutoCompleteBox that changed its SearchText.</param>

        /// <param name="e">Event arguments.</param>

        private static void OnSearchTextPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)

        {

            AutoCompleteBox source = d as AutoCompleteBox;

            if (source._ignorePropertyChange)

            {

                source._ignorePropertyChange = false;

                return;

            }



            // Ensure the property is only written when expected

            if (!source._allowWrite)

            {

                // Reset the old value before it was incorrectly written

                source._ignorePropertyChange = true;

                source.SetValue(e.Property, e.OldValue);



                throw new InvalidOperationException(Properties.Resources.AutoComplete_OnSearchTextPropertyChanged_InvalidWrite);

            }

        }

        #endregion public string SearchText



        #region public AutoCompleteFilterMode FilterMode

        /// <summary>

        /// Gets or sets how the text in the text box is used to filter items

        /// specified by the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemsSource" />

        /// property for display in the drop-down.

        /// </summary>

        /// <value>One of the

        /// <see cref="T:System.Windows.Controls.AutoCompleteFilterMode" />

        /// values The default is

        /// <see cref="F:System.Windows.Controls.AutoCompleteFilterMode.StartsWith" />.</value>

        /// <exception cref="T:System.ArgumentException">The specified value is

        /// not a valid

        /// <see cref="T:System.Windows.Controls.AutoCompleteFilterMode" />.</exception>

        /// <remarks>

        /// Use the FilterMode property to specify how possible matches are 

        /// filtered. For example, possible matches can be filtered in a 

        /// predefined or custom way. The search mode is automatically set to 

        /// Custom if you set the ItemFilter property. 

        /// </remarks>

        public AutoCompleteFilterMode FilterMode

        {

            get { return (AutoCompleteFilterMode)GetValue(FilterModeProperty); }

            set { SetValue(FilterModeProperty, value); }

        }



        /// <summary>

        /// Gets the identifier for the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.FilterMode" />

        /// dependency property.

        /// </summary>

        public static readonly DependencyProperty FilterModeProperty =

            DependencyProperty.Register(

                "FilterMode",

                typeof(AutoCompleteFilterMode),

                typeof(AutoCompleteBox),

                new PropertyMetadata(AutoCompleteFilterMode.StartsWith, OnFilterModePropertyChanged));



        /// <summary>

        /// FilterModeProperty property changed handler.

        /// </summary>

        /// <param name="d">AutoCompleteBox that changed its FilterMode.</param>

        /// <param name="e">Event arguments.</param>

        [SuppressMessage("Microsoft.Usage", "CA2208:InstantiateArgumentExceptionsCorrectly", Justification = "The exception will be thrown when the CLR setter is used in most situations.")]

        private static void OnFilterModePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)

        {

            AutoCompleteBox source = d as AutoCompleteBox;

            AutoCompleteFilterMode mode = (AutoCompleteFilterMode)e.NewValue;



            if (mode != AutoCompleteFilterMode.Contains &&

                mode != AutoCompleteFilterMode.ContainsCaseSensitive &&

                mode != AutoCompleteFilterMode.ContainsOrdinal &&

                mode != AutoCompleteFilterMode.ContainsOrdinalCaseSensitive &&

                mode != AutoCompleteFilterMode.Custom && 

                mode != AutoCompleteFilterMode.Equals &&

                mode != AutoCompleteFilterMode.EqualsCaseSensitive &&

                mode != AutoCompleteFilterMode.EqualsOrdinal &&

                mode != AutoCompleteFilterMode.EqualsOrdinalCaseSensitive &&

                mode != AutoCompleteFilterMode.None &&

                mode != AutoCompleteFilterMode.StartsWith &&

                mode != AutoCompleteFilterMode.StartsWithCaseSensitive &&

                mode != AutoCompleteFilterMode.StartsWithOrdinal &&

                mode != AutoCompleteFilterMode.StartsWithOrdinalCaseSensitive)

            {

                source.SetValue(e.Property, e.OldValue);



                throw new ArgumentException(Properties.Resources.AutoComplete_OnFilterModePropertyChanged_InvalidValue, "value");

            }



            // Sets the filter predicate for the new value

            AutoCompleteFilterMode newValue = (AutoCompleteFilterMode)e.NewValue;

            source.TextFilter = AutoCompleteSearch.GetFilter(newValue);

        }

        #endregion public AutoCompleteFilterMode FilterMode



        #region public AutoCompleteFilterPredicate ItemFilter

        /// <summary>

        /// Gets or sets the custom method that uses user-entered text to filter

        /// the items specified by the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemsSource" />

        /// property for display in the drop-down.

        /// </summary>

        /// <value>The custom method that uses the user-entered text to filter

        /// the items specified by the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemsSource" />

        /// property. The default is null.</value>

        /// <remarks>

        /// The filter mode is automatically set to Custom if you set the 

        /// ItemFilter property. 

        /// </remarks>

        public AutoCompleteFilterPredicate<object> ItemFilter

        {

            get { return GetValue(ItemFilterProperty) as AutoCompleteFilterPredicate<object>; }

            set { SetValue(ItemFilterProperty, value); }

        }



        /// <summary>

        /// Identifies the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemFilter" />

        /// dependency property.

        /// </summary>

        /// <value>The identifier for the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemFilter" />

        /// dependency property.</value>

        public static readonly DependencyProperty ItemFilterProperty =

            DependencyProperty.Register(

                "ItemFilter",

                typeof(AutoCompleteFilterPredicate<object>),

                typeof(AutoCompleteBox),

                new PropertyMetadata(OnItemFilterPropertyChanged));



        /// <summary>

        /// ItemFilterProperty property changed handler.

        /// </summary>

        /// <param name="d">AutoCompleteBox that changed its ItemFilter.</param>

        /// <param name="e">Event arguments.</param>

        private static void OnItemFilterPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)

        {

            AutoCompleteBox source = d as AutoCompleteBox;

            AutoCompleteFilterPredicate<object> value = e.NewValue as AutoCompleteFilterPredicate<object>;

            

            // If null, revert to the "None" predicate

            if (value == null)

            {

                source.FilterMode = AutoCompleteFilterMode.None;

            }

            else

            {

                source.FilterMode = AutoCompleteFilterMode.Custom;

                source.TextFilter = null;

            }

        }

        #endregion public AutoCompleteFilterPredicate ItemFilter



        #region public AutoCompleteStringFilterPredicate TextFilter

        /// <summary>

        /// Gets or sets the custom method that uses the user-entered text to

        /// filter items specified by the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemsSource" />

        /// property in a text-based way for display in the drop-down.

        /// </summary>

        /// <value>The custom method that uses the user-entered text to filter

        /// items specified by the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.ItemsSource" />

        /// property in a text-based way for display in the drop-down.</value>

        /// <remarks>

        /// The search mode is automatically set to Custom if you set the 

        /// TextFilter property. 

        /// </remarks>

        public AutoCompleteFilterPredicate<string> TextFilter

        {

            get { return GetValue(TextFilterProperty) as AutoCompleteFilterPredicate<string>; }

            set { SetValue(TextFilterProperty, value); }

        }



        /// <summary>

        /// Identifies the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.TextFilter" />

        /// dependency property.

        /// </summary>

        /// <value>The identifier for the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.TextFilter" />

        /// dependency property.</value>

        public static readonly DependencyProperty TextFilterProperty =

            DependencyProperty.Register(

                "TextFilter",

                typeof(AutoCompleteFilterPredicate<string>),

                typeof(AutoCompleteBox),

                new PropertyMetadata(AutoCompleteSearch.GetFilter(AutoCompleteFilterMode.StartsWith)));

        #endregion public AutoCompleteStringFilterPredicate TextFilter



        #region Template parts



        /// <summary>

        /// Gets or sets the drop down popup control.

        /// </summary>

        private PopupHelper DropDownPopup { get; set; }



        /// <summary>

        /// The TextBox template part.

        /// </summary>

        private TextBox _text;



        /// <summary>

        /// The SelectionAdapter.

        /// </summary>

        private ISelectionAdapter _adapter;



        /// <summary>

        /// Gets or sets the Text template part.

        /// </summary>

        internal TextBox TextBox

        {

            get { return _text; }

            set

            {

                // Detach existing handlers

                if (_text != null)

                {

                    _text.SelectionChanged -= OnTextBoxSelectionChanged;

                    _text.TextChanged -= OnTextBoxTextChanged;

                }



                _text = value;



                // Attach handlers

                if (_text != null)

                {

                    _text.SelectionChanged += OnTextBoxSelectionChanged;

                    _text.TextChanged += OnTextBoxTextChanged;



                    if (Text != null)

                    {

                        UpdateTextValue(Text);

                    }

                }

            }

        }



        /// <summary>

        /// Gets or sets the selection adapter used to populate the drop-down

        /// with a list of selectable items.

        /// </summary>

        /// <value>The selection adapter used to populate the drop-down with a

        /// list of selectable items.</value>

        /// <remarks>

        /// You can use this property when you create an automation peer to 

        /// use with AutoCompleteBox or deriving from AutoCompleteBox to 

        /// create a custom control.

        /// </remarks>

        protected internal ISelectionAdapter SelectionAdapter 

        { 

            get { return _adapter; }

            set

            {

                if (_adapter != null)

                {

                    _adapter.SelectionChanged -= OnAdapterSelectionChanged;

                    _adapter.Commit -= OnAdapterSelectionComplete;

                    _adapter.Cancel -= OnAdapterSelectionCanceled;

                    _adapter.Cancel -= OnAdapterSelectionComplete;

                    _adapter.ItemsSource = null;

                }



                _adapter = value;



                if (_adapter != null)

                {

                    _adapter.SelectionChanged += OnAdapterSelectionChanged;

                    _adapter.Commit += OnAdapterSelectionComplete;

                    _adapter.Cancel += OnAdapterSelectionCanceled;

                    _adapter.Cancel += OnAdapterSelectionComplete;

                    _adapter.ItemsSource = _view;

                }

            }

        }



        #endregion



        /// <summary>

        /// Occurs when the text in the text box portion of the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> changes.

        /// </summary>

#if SILVERLIGHT

        public event RoutedEventHandler TextChanged;

#else

        public static readonly RoutedEvent TextChangedEvent = EventManager.RegisterRoutedEvent("TextChanged", RoutingStrategy.Bubble, typeof(RoutedEventHandler), typeof(AutoCompleteBox));



        /// <summary>

        /// Occurs when the text in the text box portion of the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> changes.

        /// </summary>

        public event RoutedEventHandler TextChanged

        {

            add { AddHandler(TextChangedEvent, value); }

            remove { RemoveHandler(TextChangedEvent, value); }

        }

#endif



        /// <summary>

        /// Occurs when the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> is

        /// populating the drop-down with possible matches based on the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.Text" />

        /// property.

        /// </summary>

        /// <remarks>

        /// If the event is canceled, by setting the PopulatingEventArgs.Cancel 

        /// property to true, the AutoCompleteBox will not automatically 

        /// populate the selection adapter contained in the drop-down. 

        /// In this case, if you want possible matches to appear, you must 

        /// provide the logic for populating the selection adapter.

        /// </remarks>

#if SILVERLIGHT

        public event PopulatingEventHandler Populating;

#else

        public static readonly RoutedEvent PopulatingEvent = EventManager.RegisterRoutedEvent("Populating", RoutingStrategy.Bubble, typeof(PopulatingEventHandler), typeof(AutoCompleteBox));



        /// <summary>

        /// Occurs when the

        /// <see cref="T:System.Windows.Controls.AutoCompleteBox" /> is

        /// populating the drop-down with possible matches based on the

        /// <see cref="P:System.Windows.Controls.AutoCompleteBox.Text" />

        /// property.

        /// </summary>

        /// <remarks>

        //…

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