Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / System / Windows / Controls / DataGridColumnHeaderCollection.cs / 1305600 / DataGridColumnHeaderCollection.cs
//---------------------------------------------------------------------------- // // Copyright (C) Microsoft Corporation. All rights reserved. // //--------------------------------------------------------------------------- using System; using System.Collections; using System.Collections.ObjectModel; using System.Collections.Specialized; using System.ComponentModel; using System.Diagnostics; using System.Windows; namespace System.Windows.Controls { ////// Collection used as the ItemsSource of The DataGridColumnHeadersPresenter. This is a wrapper around the Column collection; each item /// returns the corresponding Column.Header. /// internal class DataGridColumnHeaderCollection : IEnumerable, INotifyCollectionChanged, IDisposable { public DataGridColumnHeaderCollection(ObservableCollectioncolumns) { _columns = columns; if (_columns != null) { _columns.CollectionChanged += OnColumnsChanged; } } public DataGridColumn ColumnFromIndex(int index) { if (index >= 0 && index < _columns.Count) { return _columns[index]; } return null; } #region Notification Propagation /// /// Called when the Header property on a Column changes. Causes us to fire a CollectionChanged event to specify that an item has been replaced. /// /// internal void NotifyHeaderPropertyChanged(DataGridColumn column, DependencyPropertyChangedEventArgs e) { Debug.Assert(e.Property == DataGridColumn.HeaderProperty, "We only want to know about the header property changing"); Debug.Assert(_columns.Contains(column)); NotifyCollectionChangedEventArgs args = new NotifyCollectionChangedEventArgs( NotifyCollectionChangedAction.Replace, e.NewValue, e.OldValue, _columns.IndexOf(column)); FireCollectionChanged(args); } #endregion #region IDisposable Members public void Dispose() { GC.SuppressFinalize(this); if (_columns != null) { _columns.CollectionChanged -= OnColumnsChanged; } } #endregion #region IEnumerable Members public IEnumerator GetEnumerator() { return new ColumnHeaderCollectionEnumerator(_columns); } private class ColumnHeaderCollectionEnumerator : IEnumerator, IDisposable { public ColumnHeaderCollectionEnumerator(ObservableCollectioncolumns) { if (columns != null) { _columns = columns; _columns.CollectionChanged += OnColumnsChanged; } _current = -1; } #region IEnumerator Members public object Current { get { if (IsValid) { DataGridColumn column = _columns[_current]; if (column != null) { return column.Header; } return null; } throw new InvalidOperationException(); } } public bool MoveNext() { if (HasChanged) { throw new InvalidOperationException(); } if (_columns != null && _current < _columns.Count - 1) { _current++; return true; } return false; } public void Reset() { if (HasChanged) { throw new InvalidOperationException(); } _current = -1; } #endregion #region IDisposable Members public void Dispose() { GC.SuppressFinalize(this); if (_columns != null) { _columns.CollectionChanged -= OnColumnsChanged; } } #endregion #region Helpers private bool HasChanged { get { return _columnsChanged; } } private bool IsValid { get { return _columns != null && _current >= 0 && _current < _columns.Count && !HasChanged; } } private void OnColumnsChanged(object sender, NotifyCollectionChangedEventArgs e) { _columnsChanged = true; } #endregion #region Data private int _current; private bool _columnsChanged; private ObservableCollection _columns; #endregion } #endregion #region INotifyCollectionChanged Members /// /// INotifyCollectionChanged CollectionChanged event /// public event NotifyCollectionChangedEventHandler CollectionChanged; ////// Helper to raise a CollectionChanged event when the columns collection has changed /// /// /// private void OnColumnsChanged(object sender, NotifyCollectionChangedEventArgs e) { NotifyCollectionChangedEventArgs newArgs; switch (e.Action) { case NotifyCollectionChangedAction.Add: newArgs = new NotifyCollectionChangedEventArgs(e.Action, HeadersFromColumns(e.NewItems), e.NewStartingIndex); break; case NotifyCollectionChangedAction.Remove: newArgs = new NotifyCollectionChangedEventArgs(e.Action, HeadersFromColumns(e.OldItems), e.OldStartingIndex); break; case NotifyCollectionChangedAction.Move: newArgs = new NotifyCollectionChangedEventArgs(e.Action, HeadersFromColumns(e.OldItems), e.NewStartingIndex, e.OldStartingIndex); break; case NotifyCollectionChangedAction.Replace: newArgs = new NotifyCollectionChangedEventArgs(e.Action, HeadersFromColumns(e.NewItems), HeadersFromColumns(e.OldItems), e.OldStartingIndex); break; default: newArgs = new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset); break; } FireCollectionChanged(newArgs); } private void FireCollectionChanged(NotifyCollectionChangedEventArgs args) { if (CollectionChanged != null) { CollectionChanged(this, args); } } private static object[] HeadersFromColumns(IList columns) { object[] headers = new object[columns.Count]; for (int i = 0; i < columns.Count; i++) { DataGridColumn column = columns[i] as DataGridColumn; if (column != null) { headers[i] = column.Header; } else { headers[i] = null; } } return headers; } #endregion private ObservableCollection_columns; } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. 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