Windows Phone 8.1(WinRT)中可完全滚动的文本框

很久以前,我问过一个类似的问题: Scrollable TextBox in WP7 (ala Skype and Facebook) 我希望在Windows Phone 8.1上有同样的行为。

我有一个文本框,用户可以在其中键入注释,当键盘启动时,它会向上移动文本框,使其始终在视图中。问题是,如果注释太大,用户无法轻松滚动整个注释。

我不想将TextBox上移,而是想调整页面大小,以便其他元素(如应用程序标题)始终可见。显然,即使注释很大,TextBox也应该很容易滚动。

这是我的XAML:

<Page
    x:Class="ScrollableTextBox.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:ScrollableTextBox"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">

<!--LayoutRoot-->
<Grid x:Name="LayoutRoot"
      Margin="21,-6.5,19,0">

    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>

    <!--Title-->
    <TextBlock Margin="0,19,0,24"
               Style="{ThemeResource TitleTextBlockStyle}"
               Text="APP TITLE" />

    <!--ContentPanel-->
    <Grid Grid.Row="1">

        <ScrollViewer x:Name="NoteContentScrollViewer">

            <TextBox x:Name="NoteContentTextBox"
                     AcceptsReturn="True"
                     ScrollViewer.VerticalScrollMode="Disabled"
                     VerticalAlignment="Stretch"
                     GotFocus="NoteContentTextBox_GotFocus" />

        </ScrollViewer>

    </Grid>

</Grid>

下面是代码:

using Windows.UI.ViewManagement;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation;

namespace ScrollableTextBox
{
    public sealed partial class MainPage : Page
    {
        // Handle InputPane manually so the UI doesn't scroll when the keyboard appears
        InputPane inputPane = InputPane.GetForCurrentView();

        public MainPage()
        {
            this.InitializeComponent();
            this.NavigationCacheMode = NavigationCacheMode.Required;
        }

        private void NoteContentTextBox_GotFocus(object sender, RoutedEventArgs e)
        {
            // Subscribe InputPane events to handle UI scrolling
            inputPane.Showing += this.InputPaneShowing;
            inputPane.Hiding += this.InputPaneHiding;
        }

        private void InputPaneShowing(InputPane sender, InputPaneVisibilityEventArgs e)
        {
            // Set EnsuredFocusedElementInView to true so the UI doesn't scroll
            e.EnsuredFocusedElementInView = true;

            // Set new margins to LayoutRoot (to compensate keyboard)
            LayoutRoot.Margin = new Thickness(21, -6.5, 19, e.OccludedRect.Height);

            // Unsubscribe InputPane Showing event
            inputPane.Showing -= this.InputPaneShowing;
        }

        private void InputPaneHiding(InputPane sender, InputPaneVisibilityEventArgs e)
        {
            // Set EnsuredFocusedElementInView to false so the UI scrolls
            e.EnsuredFocusedElementInView = false;

            // Reset LayoutRoot margins
            LayoutRoot.Margin = new Thickness(21, -6.5, 19, 0);

            // Unsubscribe InputPane Hiding event to handle UI scrolling
            inputPane.Hiding -= this.InputPaneHiding;
        }
    }
}

这很好地工作,因为当键盘启动时,页面会被调整大小,用户可以在编辑注释时轻松滚动,并且其他UI元素不会移出视图。然而,缺少一个行为:当用户点击TextBox时,它应该滚动到插入符号位置,但现在它根本不滚动(正如我们所期望的那样)。

在WindowsPhone7上,我使用ScrollViewer.ScrollToVerticalOffset()来实现这一点,但它在WinRT上不起作用。我们应该使用ScrollViewer.ChangeView(),但我无法使其工作。

因此,简而言之,当用户点击TextBox时,我希望它滚动到插入符号位置,这样他就可以立即开始键入,而不必手动滚动(或按Enter键到达该位置)。有什么想法吗?