我在Windows Phone 8中有一个LongListSelector，我想将两个ObservableCollections绑定到LongListSelector。问题是我如何支持LongListSelector中的多重绑定
在互联网上搜索...有人建议使用CompositeCollection，windows phone dev env无法识别CompositeCollection，windows phone是否支持CompositeCollection？
<phone:LongListSelector
x:Name="articleList"
Grid.Row="1"
Margin="0,0,-12,0"
DataContext="{StaticResource viewModel}"
ItemTemplate="{StaticResource ResultItemTemplate}"
ItemsSource="{Binding ArticleCollection}"
ItemRealized="articleList_ItemRealized"
SelectionChanged="LongListSelector_SelectionChanged"
>
<DataTemplate x:Key="ResultItemTemplate">
<Grid Margin="0,6,0,0">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Rectangle Fill="Gray" Height="50" Width="50" Grid.Row="0" Grid.Column="0"
VerticalAlignment="Top" Margin="0,7,7,0"
Grid.RowSpan="2">
</Rectangle>
<Image Source="{Binding ImageUriCollection.ImageSource}" Height="50" Width="50" Grid.Row="0" Grid.Column="0"
VerticalAlignment="Top" Margin="0,7,7,0"
Grid.RowSpan="2">
<!--
<Image.Source>
<BitmapImage UriSource="{Binding Path= ImageUriCollection.ImageSource, Mode=TwoWay}"
CreateOptions="BackgroundCreation"/>
</Image.Source>
-->
</Image>
<TextBlock Text="{Binding Path=Subject, Mode=TwoWay}" Grid.Row="0" Grid.Column="1"
Foreground="{StaticResource PhoneAccentBrush}" VerticalAlignment="Top"/>
<TextBlock Text="{Binding Path=Words, Mode=TwoWay}" TextWrapping="Wrap"
Grid.Row="1" Grid.Column="1"
VerticalAlignment="Top"
/>
</Grid>
</DataTemplate>
viewmodel中的代码是
public ObservableCollection<Article> ArticleCollection
{
get;
private set;
}
public ObservableCollection<Photo> ImageUriCollection
{
get;
private set;
}
模型是
public class Article : INotifyPropertyChanged
{
private int _Id;
public int ID
{
get { return _Id; }
set
{
if (_Id != value)
{
_Id = value;
NotifyPropertyChanged();
}
}
}
private string _subject;
public string Subject
{
get
{
return _subject;
}
set
{
if (_subject != value)
{
_subject = value;
NotifyPropertyChanged();
}
}
}
private string _words;
public string Words
{
get
{
return _words;
}
set
{
if (_words != value)
{
_words = value;
NotifyPropertyChanged();
}
}
}
private DateTime _publishDate;
public DateTime PublishDate
{
get
{ return _publishDate; }
set
{
if (_publishDate != value)
{
_publishDate = value;
NotifyPropertyChanged();
}
}
}
private string _imagePath;
public string ImagePath
{
get { return _imagePath; }
set
{
if (_imagePath != value)
{
_imagePath = value;
NotifyPropertyChanged();
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
{
PropertyChangedEventHandler handler = PropertyChanged;
if (null != handler)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}
public class Photo
{
public string Title { get; set; }
public Uri ImageSource { get; set; }
public DateTime TimeStamp { get; set; }
}
答案 0 :(得分：0)
我不认为CompositeCollection在Windows Phone上可用，我认为它也不适合您的问题。 CompositeCollection可用于连接多个集合。例如，如果您有包含5个蔬菜的列表和包含3个水果的列表，您可以加入它们以显示8个项目的列表。
在你的情况下，我想，你想加入文章和照片成为一个项目。为什么不在Article类中添加Photo属性？
答案 1 :(得分：0)
就像@venerik said - CompositeCollection在Windows Phone上不可用。
但我的建议是编写自己的Composite类。我已成功构建a simple example：
在XAML中： - 简单的ListBox（当然它可以是LLS）
<Grid x:Name="LayoutRoot" Background="Transparent">
<ListBox Name="myList" >
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
在代码背后： - 自定义类
public class myComposite<T> : ICollection<T>
{
ObservableCollection<T> firstCollection;
ObservableCollection<T> secondCollection;
public myComposite(ObservableCollection<T> first, ObservableCollection<T> second)
{
firstCollection = first;
secondCollection = second;
}
IEnumerator IEnumerable.GetEnumerator() { return new myEnum<T>(this); }
public IEnumerator<T> GetEnumerator() { return new myEnum<T>(this); }
public int Count { get { return firstCollection.Count + secondCollection.Count; } }
public T this[int i]
{
get
{
if (i <= firstCollection.Count - 1) return firstCollection[i];
else return secondCollection[i - firstCollection.Count];
}
set
{
if (i <= firstCollection.Count - 1) firstCollection[i] = value;
else secondCollection[i - firstCollection.Count - 1] = value;
}
}
public void Add(T item) { throw new NotImplementedException(); }
public void Clear() { throw new NotImplementedException(); }
public bool Contains(T item) { throw new NotImplementedException(); }
public void CopyTo(T[] array, int arrayIndex) { throw new NotImplementedException(); }
public bool IsReadOnly { get { throw new NotImplementedException(); } }
public bool Remove(T item) { throw new NotImplementedException(); }
private class myEnum<T> : IEnumerator<T>
{
public myComposite<T> _items;
int position = -1;
public myEnum(myComposite<T> list) { _items = list; }
public bool MoveNext()
{
position++;
return (position < _items.Count);
}
public void Reset() { position = -1; }
object IEnumerator.Current { get { return Current; } }
public T Current
{
get
{
try { return _items[position]; }
catch (IndexOutOfRangeException)
{ throw new InvalidOperationException(); }
}
}
public void Dispose() { }
}
}
和MainPage： - 进行测试
public partial class MainPage : PhoneApplicationPage
{
ObservableCollection<string> listOne = new ObservableCollection<string>();
ObservableCollection<string> listTwo = new ObservableCollection<string>();
myComposite<string> composite;
public myComposite<string> Composite
{
get { return composite; }
set { composite = value; }
}
public MainPage()
{
InitializeComponent();
listOne.Add("First");
listOne.Add("Second");
listOne.Add("Third");
listTwo.Add("Fourth");
composite = new myComposite<string>(listOne, listTwo);
myList.ItemsSource = Composite;
}
}
请注意，这只是一个非常基本的示例 - 它缺少INotifyPropertyChanged和大多数应该实现的方法。但希望它会告诉你它是如何工作的。
当然，所有收藏品必须包含相同类型的物品。