ScrollViewer ChangeView on SizeChanged

我有DataTemplate，我在HubSection中使用：

<DataTemplate x:Name="dataTemplate2">
    <Grid x:Name="greedy">
        <ScrollViewer x:Name="scroller" SizeChanged="ScrollViewer_SizeChanged" Height="{Binding Height,ElementName=greedy}" >
            <ItemsControl x:Name="itemsControl" 
                ItemsSource="{Binding}" 
                ItemTemplate="{StaticResource dataTemplateDetails}">
                <ItemsControl.ItemContainerTransitions>
                    <TransitionCollection>
                        <ReorderThemeTransition />
                        <NavigationThemeTransition />
                    </TransitionCollection>
                </ItemsControl.ItemContainerTransitions>
            </ItemsControl>
        </ScrollViewer>
    </Grid>
</DataTemplate>

在我的ItemsControl中，我有可以扩展的项目。我想要实现的是，当项目展开以查看有关该项目的更多详细信息时。我希望Scrollviewer向下滚动(用于ScrollViewer的大小更改量(。

SizeChanged事件的代码隐藏：

private void ScrollViewer_SizeChanged(object sender, SizeChangedEventArgs e)
{
     ScrollViewer myScroll = (ScrollViewer)sender;
     myScroll.ChangeView(null, myScroll.ScrollableHeight, null, false);
}

我现在所做的并没有达到我的预期。我现在向下滚动到最后。但问题是，只有当项目扩展了可用视图的大小时，它才会滚动(显示滚动条(。然后，如果我展开另一个项目，它就不起作用了。如果我隐藏项目的详细信息(滚动条也隐藏(并再次展开它，它将再次工作。这就像SizeChanged事件只发生在ScrollViewer开始工作时，但高度无限，不会改变。

我尝试过将行设置为"*"的网格，它不会改变任何内容。现在，我尝试通过将其绑定到ItemsControl的高度来设置高度——仍然是相同的行为。

你能帮我找到解决方案，展示思考的路径，或者给我一些变通方法吗？

编辑：

我准备了一些代码来进行操作，看看到底发生了什么。

1( 创建新项目->应用商店(c#(->Windows Phone 8.1(空白应用程序(并将其命名为"滚动">

2( 将此代码粘贴到MainPage.xaml

<Page
x:Class="scroll.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:scroll"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
Background="DarkOliveGreen">
<Page.Resources>
    <DataTemplate x:Name="dataTemplateDetails">
        <Grid Name="grido" Grid.Row="1" Margin="10,10,10,10">
            <Grid.RowDefinitions>
                <RowDefinition Height="50" />
                <RowDefinition Height="Auto" />
                <RowDefinition Height="50" />
                <RowDefinition Height="50" />
            </Grid.RowDefinitions>
            <Border Grid.Row="0" Background="Black" CornerRadius="10" Opacity="0.4" />
            <Border Grid.Row="1" Background="Black" CornerRadius="10" Opacity="0.3" />
            <Border Grid.Row="2" Background="Black" CornerRadius="10" Opacity="0.2" />
            <Border Grid.Row="3" Background="Black" CornerRadius="10" Opacity="0.1" />
            <TextBlock Grid.Row="0" Text="{Binding Name}" Style="{StaticResource BaseTextBlockStyle}" HorizontalAlignment="Center"/>
            <Grid Grid.Row="1" HorizontalAlignment="Center">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto" />
                    <ColumnDefinition Width="*" />
                </Grid.ColumnDefinitions>
                <TextBlock Grid.Column="0" Margin="5,0,5,0" Text="Description:" Style="{StaticResource BaseTextBlockStyle}"/>
                <TextBlock Grid.Column="1" Text="{Binding Description}" Style="{StaticResource BaseTextBlockStyle}"/>
            </Grid>
            <TextBlock Grid.Row="2" Text="Next row" Style="{StaticResource BaseTextBlockStyle}" HorizontalAlignment="Center"/>
            <TextBlock Grid.Row="3" Text="Next row" Style="{StaticResource BaseTextBlockStyle}" HorizontalAlignment="Center"/>
        </Grid>
    </DataTemplate>
    <DataTemplate x:Name="dataTemplate2">
        <Grid x:Name="greedy" >
            <ScrollViewer x:Name="scroller" SizeChanged="ScrollViewer_SizeChanged" VerticalAlignment="Top">
                <ItemsControl x:Name="itemsControl" 
                    ItemsSource="{Binding}" 
                    ItemTemplate="{StaticResource dataTemplateDetails}">
                    <ItemsControl.ItemContainerTransitions>
                        <TransitionCollection>
                            <ReorderThemeTransition />
                            <NavigationThemeTransition />
                        </TransitionCollection>
                    </ItemsControl.ItemContainerTransitions>
                </ItemsControl>
            </ScrollViewer>
        </Grid>
    </DataTemplate>
</Page.Resources>
<Page.BottomAppBar>
    <CommandBar Background="Black" Opacity="0.6" x:Name="myCommandBar">
        <AppBarButton Icon="Add" Label="Add" x:Name="AddItem" Click="Add_Click"/>
        <AppBarButton Icon="Delete" Label="Delete" x:Name="RemoveItem" Click="Delete_Click"/>
    </CommandBar>
</Page.BottomAppBar>
<Grid>
    <Hub x:Name="myHub" Header="Test">
        <HubSection x:Uid="myDetailsHubsection" x:Name="myDetailsHubsection" Header="Details" DataContext="{Binding Items}" ContentTemplate="{StaticResource dataTemplate2}" />
    </Hub>
</Grid>

3( 将此代码粘贴到MainPage.xaml.cs 中

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
namespace scroll
{
public sealed partial class MainPage : Page
{
    public static Details dataContextItems;
    public MainPage()
    {
        this.InitializeComponent();
        this.NavigationCacheMode = NavigationCacheMode.Required;
        dataContextItems = new Details();
    }
    public class TestItem
    {
        public string Name { get; set; }
        public string Description { get; set; }
        public TestItem(string n, string d)
        {
            Name = n;
            Description = d;
        }
    }
    public class Details : INotifyPropertyChanged
    {
        private ObservableCollection<TestItem> _items;
        public ObservableCollection<TestItem> Items
        {
            set
            {
                _items = value;
                NotifyPropertyChanged("Items");
            }
            get
            {
                return _items;
            }
        }
        public Details()
        {
            _items = new ObservableCollection<TestItem>();
        }
        public event PropertyChangedEventHandler PropertyChanged;
        private void NotifyPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }
    protected override void OnNavigatedTo(NavigationEventArgs e)
    {
        this.DataContext = dataContextItems;
    }
    private void Add_Click(object sender, RoutedEventArgs e)
    {
        TestItem iAmAnItem = new TestItem("Name of an item", "Long and detailed description of an item");
        dataContextItems.Items.Add(iAmAnItem);
    }
    private void Delete_Click(object sender, RoutedEventArgs e)
    {
        if (dataContextItems.Items.Count > 0)
            dataContextItems.Items.RemoveAt(0);
    }
    private void ScrollViewer_SizeChanged(object sender, SizeChangedEventArgs e)
    {
        ScrollViewer myScroll = (ScrollViewer)sender;
        myScroll.ChangeView(null, myScroll.ScrollableHeight, null, false);
    }
}
}

4( 运行应用

5( 当你添加前两个项目时，你不能滚动它们，但当你添加更多项目时，当项目"需要更多空间"显示并出现滚动条时，你可以看到它会向下滚动。但是添加更多的项目是行不通的。如果您删除项目并再次添加"第三个"项目，它将向下滚动。

我希望它在每次滚动查看器的大小发生变化时向下滚动(在这种情况下，当出现新项目时，但请记住，当项目在我的原始解决方案中"扩展"时，它应该工作，并且可以同时有几个扩展项目(。