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/ DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Framework / MS / Internal / Annotations / AnnotationObservableCollection.cs / 1 / AnnotationObservableCollection.cs
//---------------------------------------------------------------------------- // //// Copyright (C) 2003 by Microsoft Corporation. All rights reserved. // // // // Description: Subclass of ObservableCollectionwhich also registers for // INotifyPropertyChanged on each of its items (if T implements // INotifyPropertyChanged) and passes on the events via the // ItemChanged event. // // History: // 03/10/2005 : [....] - created // //--------------------------------------------------------------------------- using System; using System.Collections; using System.Collections.Generic; using System.Collections.ObjectModel; using System.Collections.Specialized; using System.ComponentModel; using System.Diagnostics; using System.Windows; using System.Windows.Data; namespace MS.Internal.Annotations { // An internal extension of INotifyPropertyChanged introduced in order to keep // our use of it internal and not publicly expose this interface on our OM. internal interface INotifyPropertyChanged2 : INotifyPropertyChanged { } /// /// internal class AnnotationObservableCollection: ObservableCollection where T : INotifyPropertyChanged2, IOwnedObject { //----------------------------------------------------- // // Constructors // //----------------------------------------------------- #region Constructors /// /// Initializes a new instance of AnnotationObservableCollection that is empty and has default initial capacity. /// public AnnotationObservableCollection() : base() { _listener = new PropertyChangedEventHandler(OnItemPropertyChanged); } ////// Initializes a new instance of the AnnotationObservableCollection class /// that contains elements copied from the specified list /// /// The list whose elements are copied to the new list. ////// The elements are copied onto the AnnotationObservableCollection in the /// same order they are read by the enumerator of the list. /// ///list is a null reference public AnnotationObservableCollection(Listlist) : base(list) { _listener = new PropertyChangedEventHandler(OnItemPropertyChanged); } #endregion Constructors //------------------------------------------------------ // // Public Events // //----------------------------------------------------- //------------------------------------------------------ // // Protected Methods // //------------------------------------------------------ #region Protected Methods /// /// called by base class Collection<T> when the list is being cleared; /// raises a CollectionChanged event to any listeners /// protected override void ClearItems() { foreach (INotifyPropertyChanged2 item in this) { SetOwned(item, false); } ProtectedClearItems(); } ////// called by base class Collection<T> when an item is removed from list; /// raises a CollectionChanged event to any listeners /// protected override void RemoveItem(int index) { T removedItem = this[index]; SetOwned(removedItem, false); base.RemoveItem(index); } ////// called by base class Collection<T> when an item is added to list; /// raises a CollectionChanged event to any listeners /// protected override void InsertItem(int index, T item) { if (ItemOwned(item)) throw new ArgumentException(SR.Get(SRID.AlreadyHasParent)); base.InsertItem(index, item); SetOwned(item, true); } ////// called by base class Collection<T> when an item is added to list; /// raises a CollectionChanged event to any listeners /// protected override void SetItem(int index, T item) { if (ItemOwned(item)) throw new ArgumentException(SR.Get(SRID.AlreadyHasParent)); T originalItem = this[index]; SetOwned(originalItem, false); ProtectedSetItem(index, item); SetOwned(item, true); } ////// Virtual methods allowing subclasses to change the eventing /// behavior for the ClearItems method. The default behavior /// is to call ObservableCollection's method. /// protected virtual void ProtectedClearItems() { // Use the standard built-in event base.ClearItems(); } ////// Virtual methods allowing subclasses to change the eventing /// behavior for the SetItem method. The default behavior /// is to call Collection's defaut method and fire a single /// event. /// /// index of the item being set /// item to set at that index protected virtual void ProtectedSetItem(int index, T item) { // We only want to fire one event here - this collection contains items that // are within a Resource so an assignment means one resource change, period. Items[index] = item; // directly set Collectioninner Items collection OnPropertyChanged(new PropertyChangedEventArgs(CountString)); OnPropertyChanged(new PropertyChangedEventArgs(IndexerName)); OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset)); } /// /// Allows subclasses to call superclass's SetItem method without /// any additional functionality added by this class. /// /// index of item being set /// item to set in that index protected void ObservableCollectionSetItem(int index, T item) { base.SetItem(index, item); } // raise CollectionChanged event to any listeners ////// When an item we contain fires a PropertyChanged event we fire /// a collection changed event letting listeners know the collection /// has changed in some way. We don't care about the particulars of /// the event - just want to pass up the chain of objects that something /// has changed. /// /// the object whose property changed /// the event args describing the property that changed protected virtual void OnItemPropertyChanged(object sender, PropertyChangedEventArgs e) { OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset)); } #endregion Protected Methods //----------------------------------------------------- // // Private Methods // //------------------------------------------------------ #region Private Methods // returns whether this item already belongs to a parent object private bool ItemOwned(Object item) { if (item != null) { IOwnedObject obj = item as IOwnedObject; return obj.Owned; } return false; } // sets whether this object belongs to a parent object private void SetOwned(Object item, bool owned) { if (item != null) { IOwnedObject obj = item as IOwnedObject; obj.Owned = owned; if (owned) { ((INotifyPropertyChanged2)item).PropertyChanged += _listener; } else { ((INotifyPropertyChanged2)item).PropertyChanged -= _listener; } } } #endregion Private Methods //----------------------------------------------------- // // Private Fields // //----------------------------------------------------- #region Private & Internal Fields private readonly PropertyChangedEventHandler _listener = null; internal readonly string CountString = "Count"; internal readonly string IndexerName = "Item[]"; #endregion Private & Internal Fields } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
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