ObservableCollection no admite el método AddRange, por lo que recibo notificaciones por cada elemento agregado, además, ¿qué pasa con INotifyCollectionChanging?
Quiero poder agregar un rango y actualizarme para todo el volumen.
También quiero poder cancelar la acción antes de que finalice (es decir, cambiar la colección además del "cambiado").
Relacionado P ¿ Qué colección .Net para agregar varios objetos a la vez y recibir notificaciones?
Aceptado
Consulte la versión C# 7 actualizada y optimizada . No quería eliminar la versión VB.NET, así que la publiqué en una respuesta separada.
Ir a la versión actualizada
Parece que no es compatible, lo implementé yo mismo, para su información, espero que sea útil:
Actualicé la versión de VB y de ahora en adelante genera un evento antes de cambiar la colección para que puedas arrepentirte (útil cuando se usa con y muchos más DataGrid, ListViewya que puedes mostrar una confirmación de "¿Estás seguro" al usuario), la versión de VB actualizada La versión se encuentra al final de este mensaje .
Acepte mis disculpas porque la pantalla es demasiado estrecha para contener mi código, a mí tampoco me gusta.
VB.NET:
Imports System.Collections.Specialized
Namespace System.Collections.ObjectModel
''' <summary>
''' Represents a dynamic data collection that provides notifications when items get added, removed, or when the whole list is refreshed.
''' </summary>
''' <typeparam name="T"></typeparam>
Public Class ObservableRangeCollection(Of T) : Inherits System.Collections.ObjectModel.ObservableCollection(Of T)
''' <summary>
''' Adds the elements of the specified collection to the end of the ObservableCollection(Of T).
''' </summary>
Public Sub AddRange(ByVal collection As IEnumerable(Of T))
For Each i In collection
Items.Add(i)
Next
OnCollectionChanged(New NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset))
End Sub
''' <summary>
''' Removes the first occurence of each item in the specified collection from ObservableCollection(Of T).
''' </summary>
Public Sub RemoveRange(ByVal collection As IEnumerable(Of T))
For Each i In collection
Items.Remove(i)
Next
OnCollectionChanged(New NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset))
End Sub
''' <summary>
''' Clears the current collection and replaces it with the specified item.
''' </summary>
Public Sub Replace(ByVal item As T)
ReplaceRange(New T() {item})
End Sub
''' <summary>
''' Clears the current collection and replaces it with the specified collection.
''' </summary>
Public Sub ReplaceRange(ByVal collection As IEnumerable(Of T))
Dim old = Items.ToList
Items.Clear()
For Each i In collection
Items.Add(i)
Next
OnCollectionChanged(New NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset))
End Sub
''' <summary>
''' Initializes a new instance of the System.Collections.ObjectModel.ObservableCollection(Of T) class.
''' </summary>
''' <remarks></remarks>
Public Sub New()
MyBase.New()
End Sub
''' <summary>
''' Initializes a new instance of the System.Collections.ObjectModel.ObservableCollection(Of T) class that contains elements copied from the specified collection.
''' </summary>
''' <param name="collection">collection: The collection from which the elements are copied.</param>
''' <exception cref="System.ArgumentNullException">The collection parameter cannot be null.</exception>
Public Sub New(ByVal collection As IEnumerable(Of T))
MyBase.New(collection)
End Sub
End Class
End Namespace
C#:
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.Linq;
/// <summary>
/// Represents a dynamic data collection that provides notifications when items get added, removed, or when the whole list is refreshed.
/// </summary>
/// <typeparam name="T"></typeparam>
public class ObservableRangeCollection<T> : ObservableCollection<T>
{
/// <summary>
/// Adds the elements of the specified collection to the end of the ObservableCollection(Of T).
/// </summary>
public void AddRange(IEnumerable<T> collection)
{
if (collection == null) throw new ArgumentNullException("collection");
foreach (var i in collection) Items.Add(i);
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
/// <summary>
/// Removes the first occurence of each item in the specified collection from ObservableCollection(Of T).
/// </summary>
public void RemoveRange(IEnumerable<T> collection)
{
if (collection == null) throw new ArgumentNullException("collection");
foreach (var i in collection) Items.Remove(i);
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
/// <summary>
/// Clears the current collection and replaces it with the specified item.
/// </summary>
public void Replace(T item)
{
ReplaceRange(new T[] { item });
}
/// <summary>
/// Clears the current collection and replaces it with the specified collection.
/// </summary>
public void ReplaceRange(IEnumerable<T> collection)
{
if (collection == null) throw new ArgumentNullException("collection");
Items.Clear();
foreach (var i in collection) Items.Add(i);
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
/// <summary>
/// Initializes a new instance of the System.Collections.ObjectModel.ObservableCollection(Of T) class.
/// </summary>
public ObservableRangeCollection()
: base() { }
/// <summary>
/// Initializes a new instance of the System.Collections.ObjectModel.ObservableCollection(Of T) class that contains elements copied from the specified collection.
/// </summary>
/// <param name="collection">collection: The collection from which the elements are copied.</param>
/// <exception cref="System.ArgumentNullException">The collection parameter cannot be null.</exception>
public ObservableRangeCollection(IEnumerable<T> collection)
: base(collection) { }
}
Actualización: colección de rango observable con notificación de cambio de colección
Imports System.Collections.Specialized
Imports System.ComponentModel
Imports System.Collections.ObjectModel
Public Class ObservableRangeCollection(Of T) : Inherits ObservableCollection(Of T) : Implements INotifyCollectionChanging(Of T)
''' <summary>
''' Initializes a new instance of the System.Collections.ObjectModel.ObservableCollection(Of T) class.
''' </summary>
''' <remarks></remarks>
Public Sub New()
MyBase.New()
End Sub
''' <summary>
''' Initializes a new instance of the System.Collections.ObjectModel.ObservableCollection(Of T) class that contains elements copied from the specified collection.
''' </summary>
''' <param name="collection">collection: The collection from which the elements are copied.</param>
''' <exception cref="System.ArgumentNullException">The collection parameter cannot be null.</exception>
Public Sub New(ByVal collection As IEnumerable(Of T))
MyBase.New(collection)
End Sub
''' <summary>
''' Adds the elements of the specified collection to the end of the ObservableCollection(Of T).
''' </summary>
Public Sub AddRange(ByVal collection As IEnumerable(Of T))
Dim ce As New NotifyCollectionChangingEventArgs(Of T)(NotifyCollectionChangedAction.Add, collection)
OnCollectionChanging(ce)
If ce.Cancel Then Exit Sub
Dim index = Items.Count - 1
For Each i In collection
Items.Add(i)
Next
OnCollectionChanged(New NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, collection, index))
End Sub
''' <summary>
''' Inserts the collection at specified index.
''' </summary>
Public Sub InsertRange(ByVal index As Integer, ByVal Collection As IEnumerable(Of T))
Dim ce As New NotifyCollectionChangingEventArgs(Of T)(NotifyCollectionChangedAction.Add, Collection)
OnCollectionChanging(ce)
If ce.Cancel Then Exit Sub
For Each i In Collection
Items.Insert(index, i)
Next
OnCollectionChanged(New NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset))
End Sub
''' <summary>
''' Removes the first occurence of each item in the specified collection from ObservableCollection(Of T).
''' </summary>
Public Sub RemoveRange(ByVal collection As IEnumerable(Of T))
Dim ce As New NotifyCollectionChangingEventArgs(Of T)(NotifyCollectionChangedAction.Remove, collection)
OnCollectionChanging(ce)
If ce.Cancel Then Exit Sub
For Each i In collection
Items.Remove(i)
Next
OnCollectionChanged(New NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset))
End Sub
''' <summary>
''' Clears the current collection and replaces it with the specified item.
''' </summary>
Public Sub Replace(ByVal item As T)
ReplaceRange(New T() {item})
End Sub
''' <summary>
''' Clears the current collection and replaces it with the specified collection.
''' </summary>
Public Sub ReplaceRange(ByVal collection As IEnumerable(Of T))
Dim ce As New NotifyCollectionChangingEventArgs(Of T)(NotifyCollectionChangedAction.Replace, Items)
OnCollectionChanging(ce)
If ce.Cancel Then Exit Sub
Items.Clear()
For Each i In collection
Items.Add(i)
Next
OnCollectionChanged(New NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset))
End Sub
Protected Overrides Sub ClearItems()
Dim e As New NotifyCollectionChangingEventArgs(Of T)(NotifyCollectionChangedAction.Reset, Items)
OnCollectionChanging(e)
If e.Cancel Then Exit Sub
MyBase.ClearItems()
End Sub
Protected Overrides Sub InsertItem(ByVal index As Integer, ByVal item As T)
Dim ce As New NotifyCollectionChangingEventArgs(Of T)(NotifyCollectionChangedAction.Add, item)
OnCollectionChanging(ce)
If ce.Cancel Then Exit Sub
MyBase.InsertItem(index, item)
End Sub
Protected Overrides Sub MoveItem(ByVal oldIndex As Integer, ByVal newIndex As Integer)
Dim ce As New NotifyCollectionChangingEventArgs(Of T)()
OnCollectionChanging(ce)
If ce.Cancel Then Exit Sub
MyBase.MoveItem(oldIndex, newIndex)
End Sub
Protected Overrides Sub RemoveItem(ByVal index As Integer)
Dim ce As New NotifyCollectionChangingEventArgs(Of T)(NotifyCollectionChangedAction.Remove, Items(index))
OnCollectionChanging(ce)
If ce.Cancel Then Exit Sub
MyBase.RemoveItem(index)
End Sub
Protected Overrides Sub SetItem(ByVal index As Integer, ByVal item As T)
Dim ce As New NotifyCollectionChangingEventArgs(Of T)(NotifyCollectionChangedAction.Replace, Items(index))
OnCollectionChanging(ce)
If ce.Cancel Then Exit Sub
MyBase.SetItem(index, item)
End Sub
Protected Overrides Sub OnCollectionChanged(ByVal e As Specialized.NotifyCollectionChangedEventArgs)
If e.NewItems IsNot Nothing Then
For Each i As T In e.NewItems
If TypeOf i Is INotifyPropertyChanged Then AddHandler DirectCast(i, INotifyPropertyChanged).PropertyChanged, AddressOf Item_PropertyChanged
Next
End If
MyBase.OnCollectionChanged(e)
End Sub
Private Sub Item_PropertyChanged(ByVal sender As T, ByVal e As ComponentModel.PropertyChangedEventArgs)
OnCollectionChanged(New NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset, sender, IndexOf(sender)))
End Sub
Public Event CollectionChanging(ByVal sender As Object, ByVal e As NotifyCollectionChangingEventArgs(Of T)) Implements INotifyCollectionChanging(Of T).CollectionChanging
Protected Overridable Sub OnCollectionChanging(ByVal e As NotifyCollectionChangingEventArgs(Of T))
RaiseEvent CollectionChanging(Me, e)
End Sub
End Class
Public Interface INotifyCollectionChanging(Of T)
Event CollectionChanging(ByVal sender As Object, ByVal e As NotifyCollectionChangingEventArgs(Of T))
End Interface
Public Class NotifyCollectionChangingEventArgs(Of T) : Inherits CancelEventArgs
Public Sub New()
m_Action = NotifyCollectionChangedAction.Move
m_Items = New T() {}
End Sub
Public Sub New(ByVal action As NotifyCollectionChangedAction, ByVal item As T)
m_Action = action
m_Items = New T() {item}
End Sub
Public Sub New(ByVal action As NotifyCollectionChangedAction, ByVal items As IEnumerable(Of T))
m_Action = action
m_Items = items
End Sub
Private m_Action As NotifyCollectionChangedAction
Public ReadOnly Property Action() As NotifyCollectionChangedAction
Get
Return m_Action
End Get
End Property
Private m_Items As IList
Public ReadOnly Property Items() As IEnumerable(Of T)
Get
Return m_Items
End Get
End Property
End Class
En primer lugar, vote y comente sobre la solicitud de API en el repositorio de .NET.
Aquí está mi versión optimizada de (versión optimizada de laObservableRangeCollection de James Montemagno ).
Funciona muy rápido y está destinado a reutilizar elementos existentes cuando sea posible y evitar eventos innecesarios o agruparlos en uno solo cuando sea posible. El ReplaceRangemétodo reemplaza/elimina/agrega los elementos requeridos por los índices apropiados y agrupa los posibles eventos.
Probado en la interfaz de usuario de Xamarin.Forms con excelentes resultados para actualizaciones muy frecuentes de la colección grande (5 a 7 actualizaciones por segundo).
Nota: Dado que WPF no está acostumbrado a trabajar con operaciones de rango, generará un NotSupportedException, cuando use el ObservableRangeCollectionde abajo en trabajos relacionados con la interfaz de usuario de WPF, como vincularlo a un ListBoxetc. (aún puede usar el ObservableRangeCollection<T>si no está vinculado a la interfaz de usuario) .
Sin embargo, puede utilizar la WpfObservableRangeCollection<T>solución alternativa.
La verdadera solución sería crear un equipo CollectionViewque sepa cómo lidiar con operaciones de rango, pero todavía no tuve tiempo para implementarlo.
Código RAW : ábralo como Raw, luego hagaCtrl+Apara seleccionar todo, luegoCtrl+Cpara copiar.
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Diagnostics;
namespace System.Collections.ObjectModel
{
/// <summary>
/// Implementation of a dynamic data collection based on generic Collection<T>,
/// implementing INotifyCollectionChanged to notify listeners
/// when items get added, removed or the whole list is refreshed.
/// </summary>
public class ObservableRangeCollection<T> : ObservableCollection<T>
{
//------------------------------------------------------
//
// Private Fields
//
//------------------------------------------------------
#region Private Fields
[NonSerialized]
private DeferredEventsCollection _deferredEvents;
#endregion Private Fields
//------------------------------------------------------
//
// Constructors
//
//------------------------------------------------------
#region Constructors
/// <summary>
/// Initializes a new instance of ObservableCollection that is empty and has default initial capacity.
/// </summary>
public ObservableRangeCollection() { }
/// <summary>
/// Initializes a new instance of the ObservableCollection class that contains
/// elements copied from the specified collection and has sufficient capacity
/// to accommodate the number of elements copied.
/// </summary>
/// <param name="collection">The collection whose elements are copied to the new list.</param>
/// <remarks>
/// The elements are copied onto the ObservableCollection in the
/// same order they are read by the enumerator of the collection.
/// </remarks>
/// <exception cref="ArgumentNullException"> collection is a null reference </exception>
public ObservableRangeCollection(IEnumerable<T> collection) : base(collection) { }
/// <summary>
/// Initializes a new instance of the ObservableCollection class
/// that contains elements copied from the specified list
/// </summary>
/// <param name="list">The list whose elements are copied to the new list.</param>
/// <remarks>
/// The elements are copied onto the ObservableCollection in the
/// same order they are read by the enumerator of the list.
/// </remarks>
/// <exception cref="ArgumentNullException"> list is a null reference </exception>
public ObservableRangeCollection(List<T> list) : base(list) { }
#endregion Constructors
//------------------------------------------------------
//
// Public Methods
//
//------------------------------------------------------
#region Public Methods
/// <summary>
/// Adds the elements of the specified collection to the end of the <see cref="ObservableCollection{T}"/>.
/// </summary>
/// <param name="collection">
/// The collection whose elements should be added to the end of the <see cref="ObservableCollection{T}"/>.
/// The collection itself cannot be null, but it can contain elements that are null, if type T is a reference type.
/// </param>
/// <exception cref="ArgumentNullException"><paramref name="collection"/> is null.</exception>
public void AddRange(IEnumerable<T> collection)
{
InsertRange(Count, collection);
}
/// <summary>
/// Inserts the elements of a collection into the <see cref="ObservableCollection{T}"/> at the specified index.
/// </summary>
/// <param name="index">The zero-based index at which the new elements should be inserted.</param>
/// <param name="collection">The collection whose elements should be inserted into the List<T>.
/// The collection itself cannot be null, but it can contain elements that are null, if type T is a reference type.</param>
/// <exception cref="ArgumentNullException"><paramref name="collection"/> is null.</exception>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> is not in the collection range.</exception>
public void InsertRange(int index, IEnumerable<T> collection)
{
if (collection == null)
throw new ArgumentNullException(nameof(collection));
if (index < 0)
throw new ArgumentOutOfRangeException(nameof(index));
if (index > Count)
throw new ArgumentOutOfRangeException(nameof(index));
if (collection is ICollection<T> countable)
{
if (countable.Count == 0)
{
return;
}
}
else if (!ContainsAny(collection))
{
return;
}
CheckReentrancy();
//expand the following couple of lines when adding more constructors.
var target = (List<T>)Items;
target.InsertRange(index, collection);
OnEssentialPropertiesChanged();
if (!(collection is IList list))
list = new List<T>(collection);
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, list, index));
}
/// <summary>
/// Removes the first occurence of each item in the specified collection from the <see cref="ObservableCollection{T}"/>.
/// </summary>
/// <param name="collection">The items to remove.</param>
/// <exception cref="ArgumentNullException"><paramref name="collection"/> is null.</exception>
public void RemoveRange(IEnumerable<T> collection)
{
if (collection == null)
throw new ArgumentNullException(nameof(collection));
if (Count == 0)
{
return;
}
else if (collection is ICollection<T> countable)
{
if (countable.Count == 0)
return;
else if (countable.Count == 1)
using (IEnumerator<T> enumerator = countable.GetEnumerator())
{
enumerator.MoveNext();
Remove(enumerator.Current);
return;
}
}
else if (!(ContainsAny(collection)))
{
return;
}
CheckReentrancy();
var clusters = new Dictionary<int, List<T>>();
var lastIndex = -1;
List<T> lastCluster = null;
foreach (T item in collection)
{
var index = IndexOf(item);
if (index < 0)
{
continue;
}
Items.RemoveAt(index);
if (lastIndex == index && lastCluster != null)
{
lastCluster.Add(item);
}
else
{
clusters[lastIndex = index] = lastCluster = new List<T> { item };
}
}
OnEssentialPropertiesChanged();
if (Count == 0)
OnCollectionReset();
else
foreach (KeyValuePair<int, List<T>> cluster in clusters)
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, cluster.Value, cluster.Key));
}
/// <summary>
/// Iterates over the collection and removes all items that satisfy the specified match.
/// </summary>
/// <remarks>The complexity is O(n).</remarks>
/// <param name="match"></param>
/// <returns>Returns the number of elements that where </returns>
/// <exception cref="ArgumentNullException"><paramref name="match"/> is null.</exception>
public int RemoveAll(Predicate<T> match)
{
return RemoveAll(0, Count, match);
}
/// <summary>
/// Iterates over the specified range within the collection and removes all items that satisfy the specified match.
/// </summary>
/// <remarks>The complexity is O(n).</remarks>
/// <param name="index">The index of where to start performing the search.</param>
/// <param name="count">The number of items to iterate on.</param>
/// <param name="match"></param>
/// <returns>Returns the number of elements that where </returns>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> is out of range.</exception>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="count"/> is out of range.</exception>
/// <exception cref="ArgumentNullException"><paramref name="match"/> is null.</exception>
public int RemoveAll(int index, int count, Predicate<T> match)
{
if (index < 0)
throw new ArgumentOutOfRangeException(nameof(index));
if (count < 0)
throw new ArgumentOutOfRangeException(nameof(count));
if (index + count > Count)
throw new ArgumentOutOfRangeException(nameof(index));
if (match == null)
throw new ArgumentNullException(nameof(match));
if (Count == 0)
return 0;
List<T> cluster = null;
var clusterIndex = -1;
var removedCount = 0;
using (BlockReentrancy())
using (DeferEvents())
{
for (var i = 0; i < count; i++, index++)
{
T item = Items[index];
if (match(item))
{
Items.RemoveAt(index);
removedCount++;
if (clusterIndex == index)
{
Debug.Assert(cluster != null);
cluster.Add(item);
}
else
{
cluster = new List<T> { item };
clusterIndex = index;
}
index--;
}
else if (clusterIndex > -1)
{
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, cluster, clusterIndex));
clusterIndex = -1;
cluster = null;
}
}
if (clusterIndex > -1)
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, cluster, clusterIndex));
}
if (removedCount > 0)
OnEssentialPropertiesChanged();
return removedCount;
}
/// <summary>
/// Removes a range of elements from the <see cref="ObservableCollection{T}"/>>.
/// </summary>
/// <param name="index">The zero-based starting index of the range of elements to remove.</param>
/// <param name="count">The number of elements to remove.</param>
/// <exception cref="ArgumentOutOfRangeException">The specified range is exceeding the collection.</exception>
public void RemoveRange(int index, int count)
{
if (index < 0)
throw new ArgumentOutOfRangeException(nameof(index));
if (count < 0)
throw new ArgumentOutOfRangeException(nameof(count));
if (index + count > Count)
throw new ArgumentOutOfRangeException(nameof(index));
if (count == 0)
return;
if (count == 1)
{
RemoveItem(index);
return;
}
//Items will always be List<T>, see constructors
var items = (List<T>)Items;
List<T> removedItems = items.GetRange(index, count);
CheckReentrancy();
items.RemoveRange(index, count);
OnEssentialPropertiesChanged();
if (Count == 0)
OnCollectionReset();
else
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, removedItems, index));
}
/// <summary>
/// Clears the current collection and replaces it with the specified collection,
/// using the default <see cref="EqualityComparer{T}"/>.
/// </summary>
/// <param name="collection">The items to fill the collection with, after clearing it.</param>
/// <exception cref="ArgumentNullException"><paramref name="collection"/> is null.</exception>
public void ReplaceRange(IEnumerable<T> collection)
{
ReplaceRange(0, Count, collection, EqualityComparer<T>.Default);
}
/// <summary>
/// Clears the current collection and replaces it with the specified collection,
/// using the specified comparer to skip equal items.
/// </summary>
/// <param name="collection">The items to fill the collection with, after clearing it.</param>
/// <param name="comparer">An <see cref="IEqualityComparer{T}"/> to be used
/// to check whether an item in the same location already existed before,
/// which in case it would not be added to the collection, and no event will be raised for it.</param>
/// <exception cref="ArgumentNullException"><paramref name="collection"/> is null.</exception>
/// <exception cref="ArgumentNullException"><paramref name="comparer"/> is null.</exception>
public void ReplaceRange(IEnumerable<T> collection, IEqualityComparer<T> comparer)
{
ReplaceRange(0, Count, collection, comparer);
}
/// <summary>
/// Removes the specified range and inserts the specified collection,
/// ignoring equal items (using <see cref="EqualityComparer{T}.Default"/>).
/// </summary>
/// <param name="index">The index of where to start the replacement.</param>
/// <param name="count">The number of items to be replaced.</param>
/// <param name="collection">The collection to insert in that location.</param>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> is out of range.</exception>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="count"/> is out of range.</exception>
/// <exception cref="ArgumentNullException"><paramref name="collection"/> is null.</exception>
public void ReplaceRange(int index, int count, IEnumerable<T> collection)
{
ReplaceRange(index, count, collection, EqualityComparer<T>.Default);
}
/// <summary>
/// Removes the specified range and inserts the specified collection in its position, leaving equal items in equal positions intact.
/// </summary>
/// <param name="index">The index of where to start the replacement.</param>
/// <param name="count">The number of items to be replaced.</param>
/// <param name="collection">The collection to insert in that location.</param>
/// <param name="comparer">The comparer to use when checking for equal items.</param>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> is out of range.</exception>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="count"/> is out of range.</exception>
/// <exception cref="ArgumentNullException"><paramref name="collection"/> is null.</exception>
/// <exception cref="ArgumentNullException"><paramref name="comparer"/> is null.</exception>
public void ReplaceRange(int index, int count, IEnumerable<T> collection, IEqualityComparer<T> comparer)
{
if (index < 0)
throw new ArgumentOutOfRangeException(nameof(index));
if (count < 0)
throw new ArgumentOutOfRangeException(nameof(count));
if (index + count > Count)
throw new ArgumentOutOfRangeException(nameof(index));
if (collection == null)
throw new ArgumentNullException(nameof(collection));
if (comparer == null)
throw new ArgumentNullException(nameof(comparer));
if (collection is ICollection<T> countable)
{
if (countable.Count == 0)
{
RemoveRange(index, count);
return;
}
}
else if (!ContainsAny(collection))
{
RemoveRange(index, count);
return;
}
if (index + count == 0)
{
InsertRange(0, collection);
return;
}
if (!(collection is IList<T> list))
list = new List<T>(collection);
using (BlockReentrancy())
using (DeferEvents())
{
var rangeCount = index + count;
var addedCount = list.Count;
var changesMade = false;
List<T>
newCluster = null,
oldCluster = null;
int i = index;
for (; i < rangeCount && i - index < addedCount; i++)
{
//parallel position
T old = this[i], @new = list[i - index];
if (comparer.Equals(old, @new))
{
OnRangeReplaced(i, newCluster, oldCluster);
continue;
}
else
{
Items[i] = @new;
if (newCluster == null)
{
Debug.Assert(oldCluster == null);
newCluster = new List<T> { @new };
oldCluster = new List<T> { old };
}
else
{
newCluster.Add(@new);
oldCluster.Add(old);
}
changesMade = true;
}
}
OnRangeReplaced(i, newCluster, oldCluster);
//exceeding position
if (count != addedCount)
{
var items = (List<T>)Items;
if (count > addedCount)
{
var removedCount = rangeCount - addedCount;
T[] removed = new T[removedCount];
items.CopyTo(i, removed, 0, removed.Length);
items.RemoveRange(i, removedCount);
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, removed, i));
}
else
{
var k = i - index;
T[] added = new T[addedCount - k];
for (int j = k; j < addedCount; j++)
{
T @new = list[j];
added[j - k] = @new;
}
items.InsertRange(i, added);
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, added, i));
}
OnEssentialPropertiesChanged();
}
else if (changesMade)
{
OnIndexerPropertyChanged();
}
}
}
#endregion Public Methods
//------------------------------------------------------
//
// Protected Methods
//
//------------------------------------------------------
#region Protected Methods
/// <summary>
/// Called by base class Collection<T> when the list is being cleared;
/// raises a CollectionChanged event to any listeners.
/// </summary>
protected override void ClearItems()
{
if (Count == 0)
return;
CheckReentrancy();
base.ClearItems();
OnEssentialPropertiesChanged();
OnCollectionReset();
}
/// <summary>
/// Called by base class Collection<T> when an item is set in list;
/// raises a CollectionChanged event to any listeners.
/// </summary>
protected override void SetItem(int index, T item)
{
if (Equals(this[index], item))
return;
CheckReentrancy();
T originalItem = this[index];
base.SetItem(index, item);
OnIndexerPropertyChanged();
OnCollectionChanged(NotifyCollectionChangedAction.Replace, originalItem, item, index);
}
/// <summary>
/// Raise CollectionChanged event to any listeners.
/// Properties/methods modifying this ObservableCollection will raise
/// a collection changed event through this virtual method.
/// </summary>
/// <remarks>
/// When overriding this method, either call its base implementation
/// or call <see cref="BlockReentrancy"/> to guard against reentrant collection changes.
/// </remarks>
protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
{
if (_deferredEvents != null)
{
_deferredEvents.Add(e);
return;
}
base.OnCollectionChanged(e);
}
protected virtual IDisposable DeferEvents() => new DeferredEventsCollection(this);
#endregion Protected Methods
//------------------------------------------------------
//
// Private Methods
//
//------------------------------------------------------
#region Private Methods
/// <summary>
/// Helper function to determine if a collection contains any elements.
/// </summary>
/// <param name="collection">The collection to evaluate.</param>
/// <returns></returns>
private static bool ContainsAny(IEnumerable<T> collection)
{
using (IEnumerator<T> enumerator = collection.GetEnumerator())
return enumerator.MoveNext();
}
/// <summary>
/// Helper to raise Count property and the Indexer property.
/// </summary>
private void OnEssentialPropertiesChanged()
{
OnPropertyChanged(EventArgsCache.CountPropertyChanged);
OnIndexerPropertyChanged();
}
/// <summary>
/// /// Helper to raise a PropertyChanged event for the Indexer property
/// /// </summary>
private void OnIndexerPropertyChanged() =>
OnPropertyChanged(EventArgsCache.IndexerPropertyChanged);
/// <summary>
/// Helper to raise CollectionChanged event to any listeners
/// </summary>
private void OnCollectionChanged(NotifyCollectionChangedAction action, object oldItem, object newItem, int index) =>
OnCollectionChanged(new NotifyCollectionChangedEventArgs(action, newItem, oldItem, index));
/// <summary>
/// Helper to raise CollectionChanged event with action == Reset to any listeners
/// </summary>
private void OnCollectionReset() =>
OnCollectionChanged(EventArgsCache.ResetCollectionChanged);
/// <summary>
/// Helper to raise event for clustered action and clear cluster.
/// </summary>
/// <param name="followingItemIndex">The index of the item following the replacement block.</param>
/// <param name="newCluster"></param>
/// <param name="oldCluster"></param>
//TODO should have really been a local method inside ReplaceRange(int index, int count, IEnumerable<T> collection, IEqualityComparer<T> comparer),
//move when supported language version updated.
private void OnRangeReplaced(int followingItemIndex, ICollection<T> newCluster, ICollection<T> oldCluster)
{
if (oldCluster == null || oldCluster.Count == 0)
{
Debug.Assert(newCluster == null || newCluster.Count == 0);
return;
}
OnCollectionChanged(
new NotifyCollectionChangedEventArgs(
NotifyCollectionChangedAction.Replace,
new List<T>(newCluster),
new List<T>(oldCluster),
followingItemIndex - oldCluster.Count));
oldCluster.Clear();
newCluster.Clear();
}
#endregion Private Methods
//------------------------------------------------------
//
// Private Types
//
//------------------------------------------------------
#region Private Types
private sealed class DeferredEventsCollection : List<NotifyCollectionChangedEventArgs>, IDisposable
{
private readonly ObservableRangeCollection<T> _collection;
public DeferredEventsCollection(ObservableRangeCollection<T> collection)
{
Debug.Assert(collection != null);
Debug.Assert(collection._deferredEvents == null);
_collection = collection;
_collection._deferredEvents = this;
}
public void Dispose()
{
_collection._deferredEvents = null;
foreach (var args in this)
_collection.OnCollectionChanged(args);
}
}
#endregion Private Types
}
/// <remarks>
/// To be kept outside <see cref="ObservableCollection{T}"/>, since otherwise, a new instance will be created for each generic type used.
/// </remarks>
internal static class EventArgsCache
{
internal static readonly PropertyChangedEventArgs CountPropertyChanged = new PropertyChangedEventArgs("Count");
internal static readonly PropertyChangedEventArgs IndexerPropertyChanged = new PropertyChangedEventArgs("Item[]");
internal static readonly NotifyCollectionChangedEventArgs ResetCollectionChanged = new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset);
}
}
Creo que AddRange se implementa mejor así:
public void AddRange(IEnumerable<T> collection)
{
foreach (var i in collection) Items.Add(i);
OnCollectionChanged(
new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
Le guarda una copia de la lista. Además, si desea microoptimizar, puede agregar hasta N elementos y, si se agregaron más de N elementos, realizar un reinicio.
