在 Windows Store Apps 的 DataTemplate 更改中保留子列表中的选定项目

Question

我在 Windows Phone 8.1 中生成了一个可扩展的列表视图。我在更改项目选择和单击项目时切换模板。

    <ListView Name="FiltersListview" ItemContainerStyle="{StaticResource StretchItemStyle}" ItemTemplate="{StaticResource CollapsedTemplate}" SelectionChanged="FiltersListview_SelectionChanged" IsItemClickEnabled="True" ItemClick="FiltersListview_ItemClick" Grid.Row="1" Grid.ColumnSpan="2"/>

<DataTemplate x:Name="CollapsedTemplate">
            <Grid Height="50">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="3*"/>
                    <ColumnDefinition Width="*"/>
                </Grid.ColumnDefinitions>
                <TextBlock Text="{Binding Name}" VerticalAlignment="Center" Style="{StaticResource PageTextStyle}"/>
                <Image Margin="10" Grid.Column="1" Source="/Images/arrow-down.png"/>
                <Rectangle Fill="Black" VerticalAlignment="Bottom" Height="1" Grid.ColumnSpan="2"/>
            </Grid>
        </DataTemplate>
        <DataTemplate x:Name="ExpandedTemplate">
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="3*"/>
                    <ColumnDefinition Width="*"/>
                </Grid.ColumnDefinitions>
                <Grid.RowDefinitions>
                    <RowDefinition Height="50"/>
                    <RowDefinition/>
                </Grid.RowDefinitions>
                <TextBlock Text="{Binding Name}" VerticalAlignment="Center" Style="{StaticResource PageTextStyle}"/>
                <Image Margin="10" Grid.Column="1" Source="/Images/arrow-up.png"/>
                <ListView Margin="20,0" Grid.Row="1" RequestedTheme="Light" Grid.ColumnSpan="2" ItemsSource="{Binding SubList}" SelectionMode="Multiple">
                    <ListView.ItemContainerStyle>
                        <Style TargetType="ListViewItem">
                            <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
                            <Setter Property="FontSize" Value="22"/>
                            <Setter Property="VerticalContentAlignment" Value="Center"/>
                            <Setter Property="Foreground" Value="Black"/>
                        </Style>
                    </ListView.ItemContainerStyle>
                </ListView>
            </Grid>
        </DataTemplate>

然后模板更改

DataTemplate dtSmall, dtLarge;
private void FiltersListview_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            try
            {
                if (e.RemovedItems.Count > 0)
                {
                    foreach (var item in e.RemovedItems)
                    {
                        ((ListViewItem)(sender as ListView).ContainerFromItem(item)).ContentTemplate = dtSmall;
                    }
                }
                if (e.AddedItems.Count > 0)
                {
                    foreach (var item in e.AddedItems)
                    {
                        ((ListViewItem)(sender as ListView).ContainerFromItem(item)).ContentTemplate = dtLarge;
                    }
                }
            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.WriteLine(ex.Message);
            }
        }

        private void FiltersListview_ItemClick(object sender, ItemClickEventArgs e)
        {
            try
            {
                if ((sender as ListView).SelectedItem != null)
                {
                    if ((sender as ListView).SelectedItem.Equals(e.ClickedItem))
                        (sender as ListView).SelectedItem = null;
                    else
                        (sender as ListView).SelectedItem = e.ClickedItem;
                }
                else
                    (sender as ListView).SelectedItem = e.ClickedItem;
            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.WriteLine(ex.Message);
            }
        }

现在，当打开可扩展列表时，我想在子列表中保留所选项目的状态，但是随着模板的更改和新列表视图的创建，它不会保留所选项目。有人可以帮忙吗？

Answer 1

哇。你有点像在这里用压路机敲碎坚果。为什么不创建一个复杂的数据模板，而不是切换模板，选择后会显示次要内容？

如果您从 ListView 派生，则可以覆盖 PrepareContainer：

public class MyListView : Windows.UI.Xaml.Controls.ListView
{
    protected override void PrepareContainerForItemOverride(DependencyObject element, object item)
    {
        var item = element as Windows.UI.Xaml.Controls.ListViewItem;
        base.PrepareContainerForItemOverride(element, item);
    }
}

在这里，您可以访问 IsSelected 属性，您可以将其绑定到您的模型（只需创建一个属性）并显示在您的数据模板中。使用此值，您可以在数据模板中的内容之间切换。

我会使用行为，这样我就不必费心思考这个问题。像这样：

<Grid>
    <Interactivity:Interaction.Behaviors>
        <Core:DataTriggerBehavior Binding="{Binding IsSelected}" Value="True">
            <Core:ChangePropertyAction TargetObject="{Binding ElementName=view1}" PropertyName="Visibility" Value="Visible"/>
            <Core:ChangePropertyAction TargetObject="{Binding ElementName=view2}" PropertyName="Visibility" Value="Collapsed"/>
        </Core:DataTriggerBehavior>
        <Core:DataTriggerBehavior Binding="{Binding IsSelected}" Value="False">
            <Core:ChangePropertyAction TargetObject="{Binding ElementName=view1}" PropertyName="Visibility" Value="Visible"/>
            <Core:ChangePropertyAction TargetObject="{Binding ElementName=view2}" PropertyName="Visibility" Value="Collapsed"/>
        </Core:DataTriggerBehavior>
    </Interactivity:Interaction.Behaviors>
</Grid>

由于您的上下文从未真正改变，因此您的列表索引也不会改变。

祝你好运！

在 Windows Store Apps 的 DataTemplate 更改中保留子列表中的选定项目

Retaining selected item in sublist in DataTemplate change in Windows Store Apps

c#

winrt-xaml

windows-store-apps

windows-phone-8.1