首页 > 代码库 > WindowsPhone8中LongListSelector的扩展解决其不能绑定SelectdeItem的问题
WindowsPhone8中LongListSelector的扩展解决其不能绑定SelectdeItem的问题
微软在Wp8中集成了LongListSelector， 但是该控件在ViewModel中不能实现的SelectdeItem双向绑定,因为其不是DependencyProperty没办法只能实现扩展！
1.实现LongListSelector的扩展ExtendedSelector
public enum PositionOnAdd { Top, Default, NewItem } public class ExtendedSelector : LongListSelector { public static readonly DependencyProperty SelectedItemProperty = DependencyProperty.Register("SelectedItem", typeof(object), typeof(ExtendedSelector), new PropertyMetadata(default(object))); public static readonly DependencyProperty SelectionModeProperty = DependencyProperty.Register("SelectionMode", typeof(SelectionMode), typeof(ExtendedSelector), new PropertyMetadata(SelectionMode.Single)); public static readonly DependencyProperty RepositionOnAddStyleProperty = DependencyProperty.Register("RepositionOnAddStyle", typeof(PositionOnAdd), typeof(ExtendedSelector), new PropertyMetadata(PositionOnAdd.Default)); public PositionOnAdd RepositionOnAddStyle { get { return (PositionOnAdd)GetValue(RepositionOnAddStyleProperty); } set { SetValue(RepositionOnAddStyleProperty, value); } } public SelectionMode SelectionMode { get { return (SelectionMode)GetValue(SelectionModeProperty); } set { SetValue(SelectionModeProperty, value); } } public new object SelectedItem { get { return GetValue(SelectedItemProperty); } set { SetValue(SelectedItemProperty, value); } } public ExtendedSelector() { SelectionChanged += (sender, args) => { if (SelectionMode == SelectionMode.Single) SelectedItem = args.AddedItems[0]; else if (SelectionMode == SelectionMode.Multiple) { if (SelectedItem == null) { SelectedItem = new List<object>(); } foreach (var item in args.AddedItems) { ((List<object>)SelectedItem).Add(item); } foreach (var removedItem in args.RemovedItems) { if (((List<object>)SelectedItem).Contains(removedItem)) { ((List<object>)SelectedItem).Remove(removedItem); } } } }; Loaded += (sender, args) => { ((INotifyCollectionChanged)ItemsSource).CollectionChanged += (sender2, args2) => { if (ItemsSource.Count > 0 && args2.NewItems != null) { switch (RepositionOnAddStyle) { case PositionOnAdd.NewItem: int index = ItemsSource.IndexOf(args2.NewItems[0]); if (index >= 0) ScrollTo(ItemsSource[index]); break; case PositionOnAdd.Top: ScrollTo(ItemsSource[0]); break; } } }; }; } }2.在xmal中使用 扩展ExtendedSelector
a.定义数据模板
<DataTemplate x:Name="LLSDataTemplate"> <ListBoxItem Margin="0,0,0,6"> <StackPanel> <StackPanel Margin="0,0,0,12"> <TextBlock toolkit:SlideInEffect.LineIndex="1" Foreground="{StaticResource FontGroundThemeBrush}" TextWrapping="Wrap" FontSize="30" TextTrimming="None" Text="{Binding name}" /> <TextBlock toolkit:SlideInEffect.LineIndex="2" Foreground="{StaticResource FontGroundThemeBrush}" Opacity="0.7" TextWrapping="Wrap" TextTrimming="None" FontSize="18" Text="{Binding content}" /> </StackPanel> </StackPanel> </ListBoxItem> </DataTemplate>b.定义LongListSelector的Style
<Style x:Key="JumpListStyle" TargetType="phone:LongListSelector"> <Setter Property="GridCellSize" Value="http://www.mamicode.com/111,111"/> <Setter Property="LayoutMode" Value="http://www.mamicode.com/Grid" /> <Setter Property="Margin" Value="http://www.mamicode.com/18,12,0,0"/> <Setter Property="ItemTemplate"> <Setter.Value> <DataTemplate> <Border Background="{Binding Converter={StaticResource BackgroundConverter}}" Margin="6" > <TextBlock Text="{Binding Key}" FontFamily="{StaticResource PhoneFontFamilySemiBold}" FontSize="48" Padding="11,0,0,1" Foreground="{Binding Converter={StaticResource ForegroundConverter}}" VerticalAlignment="Bottom" /> </Border> </DataTemplate> </Setter.Value> </Setter> </Style> <DataTemplate x:Key="GroupHeaderTemplate"> <Border Background="Transparent" Padding="5"> <Border Background="{StaticResource BackgroundThemeBrush}" BorderBrush="{StaticResource BackgroundThemeBrush}" Width="62" Height="62" Margin="-6,0,18,6" HorizontalAlignment="Left"> <TextBlock Text="{Binding Key}" Foreground="{StaticResource PhoneForegroundBrush}" FontSize="48" Padding="6,6,6,11" FontFamily="{StaticResource PhoneFontFamilySemiLight}" HorizontalAlignment="Left" VerticalAlignment="Center"/> </Border> </Border> </DataTemplate>c.Page页面代码的实现
<control:ExtendedSelector Margin="12,0,12,24" x:Name="ReaultListBox" ItemsSource="{Binding SearchReaultItem, Mode=TwoWay}" SelectedItem="{Binding SelectCydqItem,Mode=TwoWay}" GroupHeaderTemplate="{StaticResource GroupHeaderTemplate}" HideEmptyGroups="True" IsGroupingEnabled="True" ItemTemplate="{StaticResource LLSDataTemplate}" toolkit:TurnstileFeatherEffect.FeatheringIndex="1" JumpListStyle="{StaticResource JumpListStyle}" RepositionOnAddStyle="Top" > <i:Interaction.Triggers> <i:EventTrigger EventName="SelectionChanged"> <cmd:EventToCommand Command="{Binding SearchVM.SelectionChangedCommand,Source={StaticResource Locator}}" CommandParameter="{Binding Path=SelectedItem,ElementName=ReaultListBox}"/> </i:EventTrigger> </i:Interaction.Triggers> </control:ExtendedSelector>
实现效果：
说明： RepositionOnAddStyle="Top" 有Top,Default，NewItem ，Top 为加载完数据后展示从头部开始 NewItem为加载完数据后展示从尾部开始
WindowsPhone8中LongListSelector的扩展解决其不能绑定SelectdeItem的问题
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