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/ DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Framework / System / Windows / Data / CollectionContainer.cs / 2 / CollectionContainer.cs
//---------------------------------------------------------------------------- // //// Copyright (C) 2003 by Microsoft Corporation. All rights reserved. // // // // Description: Holds an existing collection structure // (e.g. ObservableCollection or DataSet) inside the ItemCollection. // // See specs at [....]/connecteddata/M5%20General%20Docs/ItemCollection.mht // [....]/connecteddata/M5%20Specs/IDataCollection.mht // // History: // 07/14/2003 : [....] - Created // //--------------------------------------------------------------------------- using System.Collections; using System.Collections.Specialized; using System.ComponentModel; using System.Diagnostics; using System.Windows; using System.Windows.Controls; using MS.Utility; using MS.Internal; // Invariant.Assert using MS.Internal.Utility; using MS.Internal.Data; // IndexedEnumerable using System; namespace System.Windows.Data { ////// Holds an existing collection structure /// (e.g. ObservableCollection or DataSet) for use under a CompositeCollection. /// public class CollectionContainer : DependencyObject, INotifyCollectionChanged, IWeakEventListener { //----------------------------------------------------- // // Dynamic properties and events // //----------------------------------------------------- ////// Collection to be added into flattened ItemCollection /// public static readonly DependencyProperty CollectionProperty = DependencyProperty.Register( "Collection", typeof(IEnumerable), typeof(CollectionContainer), new FrameworkPropertyMetadata(new PropertyChangedCallback(OnCollectionChanged))); //------------------------------------------------------ // // Constructors // //----------------------------------------------------- static CollectionContainer() { } //------------------------------------------------------ // // Public Properties // //------------------------------------------------------ #region Public Properties // public IEnumerable Collection { get { return (IEnumerable) GetValue(CollectionContainer.CollectionProperty); } set { SetValue(CollectionContainer.CollectionProperty, value); } } ////// This method is used by TypeDescriptor to determine if this property should /// be serialized. /// [EditorBrowsable(EditorBrowsableState.Never)] public bool ShouldSerializeCollection() { if (Collection == null) { return false; } // Try to see if there is an item in the Collection without // creating an enumerator. ICollection collection = Collection as ICollection; if (collection != null && collection.Count == 0) { return false; } // If MoveNext returns true, then the enumerator is non-empty. IEnumerator enumerator = Collection.GetEnumerator(); return enumerator.MoveNext(); } #endregion Public Properties //----------------------------------------------------- // // Internal Properties // //------------------------------------------------------ #region Internal Properties internal ICollectionView View { get { return _view; } } internal int ViewCount { get { if (View == null) return 0; CollectionView cv = View as CollectionView; if (cv != null) return cv.Count; ICollection coll = View as ICollection; if (coll != null) return coll.Count; // As a last resort, use the IList interface or IndexedEnumerable to find the count. if (ViewList != null) return ViewList.Count; return 0; } } internal bool ViewIsEmpty { get { if (View == null) return true; ICollectionView cv = View as ICollectionView; if (cv != null) return cv.IsEmpty; ICollection coll = View as ICollection; if (coll != null) return (coll.Count == 0); // As a last resort, use the IList interface or IndexedEnumerable to find the count. if (ViewList != null) { IndexedEnumerable le = ViewList as IndexedEnumerable; if (le != null) return le.IsEmpty; else return (ViewList.Count == 0); } return true; } } #endregion Internal Properties //----------------------------------------------------- // // Internal Methods // //----------------------------------------------------- #region Internal Methods internal object ViewItem(int index) { Invariant.Assert(index >= 0 && View != null); CollectionView cv = View as CollectionView; if (cv != null) { return cv.GetItemAt(index); } // As a last resort, use the IList interface or IndexedEnumerable to iterate to the nth item. if (ViewList != null) return ViewList[index]; return null; } internal int ViewIndexOf(object item) { if (View == null) return -1; CollectionView cv = View as CollectionView; if (cv != null) { return cv.IndexOf(item); } // As a last resort, use the IList interface or IndexedEnumerable to look for the item. if (ViewList != null) return ViewList.IndexOf(item); return -1; } #endregion Internal Methods #region INotifyCollectionChanged ////// Occurs when the contained collection changes /// event NotifyCollectionChangedEventHandler INotifyCollectionChanged.CollectionChanged { add { CollectionChanged += value; } remove { CollectionChanged -= value; } } ////// Occurs when the contained collection changes /// protected virtual event NotifyCollectionChangedEventHandler CollectionChanged; ////// Called when the contained collection changes /// protected virtual void OnContainedCollectionChanged(NotifyCollectionChangedEventArgs args) { if (CollectionChanged != null) CollectionChanged(this, args); } #endregion INotifyCollectionChanged #region IWeakEventListener ////// Handle events from the centralized event table /// bool IWeakEventListener.ReceiveWeakEvent(Type managerType, object sender, EventArgs e) { return ReceiveWeakEvent(managerType, sender, e); } ////// Handle events from the centralized event table /// protected virtual bool ReceiveWeakEvent(Type managerType, object sender, EventArgs e) { if (managerType == typeof(CollectionChangedEventManager)) { // forward the event to CompositeCollections that use this container OnContainedCollectionChanged((NotifyCollectionChangedEventArgs)e); } else { return false; // unrecognized event } return true; } #endregion IWeakEventListener //----------------------------------------------------- // // Private Properties // //------------------------------------------------------ #region Private Properties private IndexedEnumerable ViewList { get { if (_viewList == null && View != null) { _viewList = new IndexedEnumerable(View); } return _viewList; } } #endregion //----------------------------------------------------- // // Private Methods // //------------------------------------------------------ #region Private Methods // called when value of CollectionProperty is required by property store private static object OnGetCollection(DependencyObject d) { return ((CollectionContainer) d).Collection; } // Called when CollectionProperty is changed on "d." private static void OnCollectionChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { CollectionContainer cc = (CollectionContainer) d; cc.HookUpToCollection((IEnumerable) e.NewValue, true); } // To prevent CollectionContainer memory leak: // HookUpToCollection() is called to start listening to CV only when // the Container is being used by a CompositeCollectionView. // When the last CCV stops using the container (or the CCV is GC'ed), // HookUpToCollection() is called to stop listening to its CV, so that // this container can be GC'ed if no one else is holding on to it. // unhook old collection/view and hook up new collection/view private void HookUpToCollection(IEnumerable newCollection, bool shouldRaiseChangeEvent) { // clear cached helper _viewList = null; // unhook from the old collection view if (View != null) { CollectionChangedEventManager.RemoveListener(View, this); if (_traceLog != null) _traceLog.Add("Unsubscribe to CollectionChange from {0}", TraceLog.IdFor(View)); } // change to the new view if (newCollection != null) _view = CollectionViewSource.GetDefaultCollectionView(newCollection, this); else _view = null; // hook up to the new collection view if (View != null) { CollectionChangedEventManager.AddListener(View, this); if (_traceLog != null) _traceLog.Add("Subscribe to CollectionChange from {0}", TraceLog.IdFor(View)); } if (shouldRaiseChangeEvent) // it's as if this were a refresh of the container's collection OnContainedCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset)); } #endregion Private Methods // this method is here just to avoid the compiler error // error CS0649: Warning as Error: Field '..._traceLog' is never assigned to, and will always have its default value null void InitializeTraceLog() { _traceLog = new TraceLog(20); } //------------------------------------------------------ // // Private Fields // //----------------------------------------------------- #region Private Fields private TraceLog _traceLog; private ICollectionView _view; private IndexedEnumerable _viewList; // cache of list wrapper for view #endregion Private Fields } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. 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