刷新视图模型中的语义缩放可观察集合

Question

使用 SemanticZoom 控件时，有没有办法在表更改后更新 ViewModel 中的 ObservableCollection？ 在 SQLite 中对表进行更改后，在同一页 (categories.xaml.cs( 中，SemanticZoom 控件不会更新。 从菜单导航重新加载页面会使用正确的数据重新加载页面。 如果控件只是将 ObservableCollection 作为其项源，则可以刷新 ObservableCollection。 使用 ViewModel 是我能找到的唯一 SemanticZoom 控件代码示例。 提前感谢！

类别.xaml

<Page.DataContext>
<vm:CategoriesViewModel></vm:CategoriesViewModel>
</Page.DataContext>
<Page.Resources>
<CollectionViewSource  x:Name="Collection" IsSourceGrouped="true" ItemsPath="Items" Source="{Binding CategoryGroups}" />
</Page.Resources>
<SemanticZoom Name="szCategories" ScrollViewer.ZoomMode="Enabled">
<SemanticZoom.ZoomedOutView>
<GridView ScrollViewer.IsHorizontalScrollChainingEnabled="False">
<GridView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Group.Name }" Foreground="Gray" Margin="5" FontSize="25" />
</DataTemplate>
</GridView.ItemTemplate>
</GridView>
</SemanticZoom.ZoomedOutView>
<SemanticZoom.ZoomedInView>
<ListView Name="lvCategories" ItemsSource="{Binding Source={StaticResource Collection}}" Tapped="lvCategories_Tapped">
<ListView.ItemTemplate>
<DataTemplate x:DataType="data:Category">
<StackPanel>
<TextBlock Text="{Binding Title}" Margin="5" />
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
<ListView.GroupStyle>
<GroupStyle>
<GroupStyle.HeaderTemplate>
<DataTemplate>
<StackPanel Orientation="Vertical">
<TextBlock Text='{Binding Name}' Foreground="Gray" FontSize="25" Margin="5,5,5,0" />
</StackPanel>
</DataTemplate>
</GroupStyle.HeaderTemplate>
</GroupStyle>
</ListView.GroupStyle>
</ListView>
</SemanticZoom.ZoomedInView>
</SemanticZoom>

类别.xaml.cs

public Categories()
{
this.InitializeComponent();
var collectionGroups = Collection.View.CollectionGroups;
((ListViewBase)this.szCategories.ZoomedOutView).ItemsSource = collectionGroups;
}

类别视图模型.cs

internal class CategoriesViewModel : BindableBase
{
public CategoriesViewModel()
{
CategoryGroups = new ObservableCollection<CategoryDataGroup>(CategoryDataGenerator.GetGroupedData());
}
private ObservableCollection<CategoryDataGroup> _groups;
public ObservableCollection<CategoryDataGroup> CategoryGroups
{
get { return _groups; }
set { SetProperty(ref _groups, value); }
}
}
public abstract class BindableBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected virtual bool SetProperty<T>(ref T storage, T value, [CallerMemberName] string propertyName = null)
{
if (object.Equals(storage, value)) return false;
storage = value;
this.OnPropertyChanged(propertyName);
return true;
}
protected void OnPropertyChanged(string propertyName)
{
var eventHandler = this.PropertyChanged;
if (eventHandler != null)
{
eventHandler(this, new PropertyChangedEventArgs(propertyName));
}
}
}

SymanticZoom.cs

internal class CategoryDataGroup
{
public string Name { get; set; }
public List<CategoryData> Items { get; set; }
}
internal class CategoryData
{
public CategoryData(string grp, string title)
{
Grp = grp;
Title = title;
}
public string Grp { get; private set; }
public string Title { get; private set; }
}
internal class CategoryDataGenerator
{
private static List<CategoryData> _data;
public static List<CategoryDataGroup> GetGroupedData()
{
if (_data != null)
_data.Clear();
GenerateData();
return _data.GroupBy(d => d.Grp[0],
(key, items) => new CategoryDataGroup() { Name = key.ToString(), Items = items.ToList() }).ToList();
}
private static void GenerateData()
{
ObservableCollection<Category> ocCategories = new ObservableCollection<Category>();
SQLiteManager.Categories.Select(ocCategories);
_data = new List<CategoryData>();
foreach (var temp in ocCategories)
{
_data.Add(new CategoryData(temp.Name.Substring(0,1), temp.Name));
}            
}
}

Answer 1

放大视图和缩小视图应同步，因此如果用户在缩小视图中选择组，则同一组的详细信息将显示在放大视图中。可以使用集合视图源或添加代码来同步视图。

有关详细信息，请参阅语义式缩放。

我们可以在页面中使用CollectionViewSource控件，它提供了一个数据源，该数据源为集合类添加了分组和当前项支持。然后我们可以将GridView.ItemSource和ListView.ItemSource绑定到CollectionViewSource。当我们为CollectionViewSource设置新数据时，SemanticZoom.ZoomedOutView中的GridView和SemanticZoom.ZoomedInView中的ListView将被更新。

xmlns:wuxdata="using:Windows.UI.Xaml.Data">
<Page.Resources>
<CollectionViewSource x:Name="ContactsCVS"  IsSourceGrouped="True" />
<DataTemplate x:Key="ZoomedInTemplate" x:DataType="data:Contact">
<StackPanel Margin="20,0,0,0">
<TextBlock Text="{x:Bind Name}" />
<TextBlock Text="{x:Bind Position}" TextWrapping="Wrap" HorizontalAlignment="Left" Width="300" />
</StackPanel>
</DataTemplate>
<DataTemplate x:Key="ZoomedInGroupHeaderTemplate" x:DataType="data:GroupInfoList">
<TextBlock Text="{x:Bind Key}"/>
</DataTemplate>
<DataTemplate x:Key="ZoomedOutTemplate" x:DataType="wuxdata:ICollectionViewGroup">
<TextBlock Text="{x:Bind Group.(data:GroupInfoList.Key)}" TextWrapping="Wrap"/>
</DataTemplate>
</Page.Resources>
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<StackPanel>
<SemanticZoom x:Name="Control1" Height="500">
<SemanticZoom.ZoomedInView>
<GridView ItemsSource="{x:Bind ContactsCVS.View,Mode=OneWay}" ScrollViewer.IsHorizontalScrollChainingEnabled="False" SelectionMode="None" 
ItemTemplate="{StaticResource ZoomedInTemplate}">
<GridView.GroupStyle>
<GroupStyle HeaderTemplate="{StaticResource ZoomedInGroupHeaderTemplate}" />
</GridView.GroupStyle>
</GridView>
</SemanticZoom.ZoomedInView>
<SemanticZoom.ZoomedOutView>
<ListView ItemsSource="{x:Bind ContactsCVS.View.CollectionGroups}" SelectionMode="None" ItemTemplate="{StaticResource ZoomedOutTemplate}" />
</SemanticZoom.ZoomedOutView>
</SemanticZoom>
</StackPanel>
</Grid>