本文介绍了LongListSelector分组中的Windows Phone 7或Windows Phone 8使用的CollectionView的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我面临同样的问题在下面列出的标签
I am facing the same problem as listed in the below tag
的
我用下面的代码与分组绑定的 LongListSelector 的。
I use the following code to bind the LongListSelector with grouping.
CollectionViewSource cv = new CollectionViewSource();
cv.Source = comments;
cv.GroupDescriptions.Add(new PropertyGroupDescription("Filter"));
listSelector.HideEmptyGroups = true;
listSelector.ItemsSource = cv.View.Groups;
但它并不显示任何内容。任何人都可以请你帮我在这？
But it does not display anything. Anyone can you please help me on this ?
推荐答案
它不被设计支持的ICollectionView。控制预计，一组实现IEnumerable这CollectionViewGroup没有。 CollectionViewGroup是所有的ICollectionView组的基类。
It doesn't support ICollectionView by design. The control expects that a group implements IEnumerable which CollectionViewGroup doesn't. CollectionViewGroup is the base class for all ICollectionView groups.
所以，你必须使周围的ICollectionView的包装为LongListSelector预计该接口提供支持或修改LongListSelector源代码。
So you have to make a wrapper around ICollectionView to provide support for the interfaces LongListSelector expects or modify the LongListSelector source code.
下面是我的快速和肮脏的实施包装的：
Here is my quick and dirty implementation of the wrapper:
namespace PresentationModel
{
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Linq;
using System.Windows.Data;
public class GroupViewItem : IList, INotifyCollectionChanged
{
private readonly CollectionViewGroup group;
public GroupViewItem(CollectionViewGroup group)
{
this.group = group;
((INotifyCollectionChanged)this.group.Items).CollectionChanged += HandleCollectionViewGroupChanged;
}
private void HandleCollectionViewGroupChanged(object sender, NotifyCollectionChangedEventArgs e)
{
OnCollectionChanged(e);
}
public object Name { get { return this.group.Name; } }
public int Count { get { return this.group.ItemCount; } }
public IEnumerator GetEnumerator()
{
return this.group.Items.GetEnumerator();
}
public event NotifyCollectionChangedEventHandler CollectionChanged;
private void OnCollectionChanged(NotifyCollectionChangedEventArgs args)
{
var collectionChanged = this.CollectionChanged;
if (collectionChanged != null)
{
collectionChanged(this, args);
}
}
int IList.Add(object value)
{
throw new NotSupportedException();
}
void IList.Clear()
{
throw new NotSupportedException();
}
bool IList.Contains(object value)
{
throw new NotSupportedException();
}
int IList.IndexOf(object value)
{
throw new NotSupportedException();
}
void IList.Insert(int index, object value)
{
throw new NotSupportedException();
}
bool IList.IsFixedSize
{
get
{
throw new NotSupportedException();
}
}
bool IList.IsReadOnly
{
get
{
throw new NotSupportedException();
}
}
void IList.Remove(object value)
{
throw new NotSupportedException();
}
void IList.RemoveAt(int index)
{
throw new NotSupportedException();
}
object IList.this[int index]
{
get
{
throw new NotSupportedException();
}
set
{
throw new NotSupportedException();
}
}
void ICollection.CopyTo(System.Array array, int index)
{
throw new NotSupportedException();
}
bool ICollection.IsSynchronized
{
get
{
throw new NotSupportedException();
}
}
object ICollection.SyncRoot
{
get
{
throw new NotSupportedException();
}
}
}
public class GroupView : IEnumerable, INotifyCollectionChanged
{
private readonly ICollectionView collectionView;
private readonly List<GroupViewItem> items;
public GroupView(ICollectionView collectionView)
{
this.items = new List<GroupViewItem>();
this.collectionView = collectionView;
((INotifyCollectionChanged)this.collectionView.Groups).CollectionChanged += HandleCollectionViewGroupsChanged;
ResetGroups(notify: false);
}
private void HandleCollectionViewGroupsChanged(object sender, NotifyCollectionChangedEventArgs e)
{
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
AddGroups(e);
break;
case NotifyCollectionChangedAction.Remove:
RemoveGroups(e);
break;
case NotifyCollectionChangedAction.Replace:
ReplaceGroups(e);
break;
case NotifyCollectionChangedAction.Reset:
ResetGroups();
break;
}
}
private IList<GroupViewItem> AddGroups(NotifyCollectionChangedEventArgs e, bool notify = true)
{
var newGroups = e.NewItems
.Cast<CollectionViewGroup>()
.Select(cvg => new GroupViewItem(cvg))
.ToArray();
this.items.InsertRange(e.NewStartingIndex, newGroups);
if (notify)
{
for (var i = 0; i != newGroups.Length; ++i)
{
OnCollectionChanged(new NotifyCollectionChangedEventArgs(
NotifyCollectionChangedAction.Add,
newGroups[i],
e.NewStartingIndex + i));
}
}
return newGroups;
}
private IList<GroupViewItem> RemoveGroups(NotifyCollectionChangedEventArgs e, bool notify = true)
{
var oldGroups = this.items.GetRange(e.OldStartingIndex, e.OldItems.Count);
this.items.RemoveRange(e.OldStartingIndex, e.OldItems.Count);
if (notify)
{
for (var i = 0; i != oldGroups.Count; ++i)
{
OnCollectionChanged(new NotifyCollectionChangedEventArgs(
NotifyCollectionChangedAction.Remove,
oldGroups[i],
e.OldStartingIndex + i));
}
}
return oldGroups;
}
private void ReplaceGroups(NotifyCollectionChangedEventArgs e)
{
var oldGroups = RemoveGroups(e, notify: false);
var newGroups = AddGroups(e, notify: false);
if (oldGroups.Count != newGroups.Count)
{
OnCollectionChanged(new NotifyCollectionChangedEventArgs(
NotifyCollectionChangedAction.Reset));
}
else
{
for (var i = 0; i != newGroups.Count; ++i)
{
OnCollectionChanged(new NotifyCollectionChangedEventArgs(
NotifyCollectionChangedAction.Replace,
newGroups[i], oldGroups[i],
e.NewStartingIndex + i));
}
}
}
private void ResetGroups(bool notify = true)
{
this.items.Clear();
this.items.AddRange(
this.collectionView.Groups
.Cast<CollectionViewGroup>()
.Select(cvg => new GroupViewItem(cvg)));
if (notify)
{
OnCollectionChanged(new NotifyCollectionChangedEventArgs(
NotifyCollectionChangedAction.Reset));
}
}
public event NotifyCollectionChangedEventHandler CollectionChanged;
public IEnumerator GetEnumerator()
{
return this.items.GetEnumerator();
}
private void OnCollectionChanged(NotifyCollectionChangedEventArgs args)
{
var collectionChanged = this.CollectionChanged;
if (collectionChanged != null)
{
collectionChanged(this, args);
}
}
}
}
这篇关于LongListSelector分组中的Windows Phone 7或Windows Phone 8使用的CollectionView的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！