如何在C＃Metro应用程序的AppBar中聚焦文本框？

Question

我有以下代码：

<Page.BottomAppBar>
    <AppBar x:Name="MyAppBar" Height="32" IsOpen="True" Opened="MyAppBar_Opened">
        <TextBox x:Name="SearchBar" Grid.Row="2" KeyDown="SearchBar_KeyDown"/>
    </AppBar>
</Page.BottomAppBar>

问题是，当应用程序打开时它没有焦点，当我右键单击两次以关闭并再次打开它时，它也没有焦点。

我目前在MyAppBar_Opened和OnNavigatedTo中都具有以下代码：

if (MyAppBar == null)
    return;

MyAppBar.Focus(Windows.UI.Xaml.FocusState.Keyboard);

if (SearchBar == null)
    return;

SearchBar.Focus(Windows.UI.Xaml.FocusState.Keyboard);

但这似乎没有任何效果，其他枚举值（例如Mouse或Programmatic也不起作用。 我做错了什么导致无法激活？

我知道以前可以使用的替代方法，但是Metro FocusManager没有SetFocusedElement吗？

Answer 1

这对我有用：

XAML：

<Page
    x:Class="Application5.BlankPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:Application5"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Background="{StaticResource ApplicationPageBackgroundBrush}">
        <AppBar
            x:Name="MyAppBar"
            Height="32"
            IsOpen="True"
            Opened="MyAppBar_Opened"
            Loaded="MyAppBar_Loaded"
            VerticalAlignment="Bottom">
            <TextBox
                x:Name="SearchBar"
                HorizontalAlignment="Stretch" />
        </AppBar>
    </Grid>
</Page>

后面的代码：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
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;

// The Blank Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=234238

namespace Application5
{
    /// <summary>
    /// An empty page that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class BlankPage : Page
    {
        public BlankPage()
        {
            this.InitializeComponent();
        }

        /// <summary>
        /// Invoked when this page is about to be displayed in a Frame.
        /// </summary>
        /// <param name="e">Event data that describes how this page was reached.  The Parameter
        /// property is typically used to configure the page.</param>
        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
        }

        private void MyAppBar_Opened(object sender, object e)
        {
            if (SearchBar != null)
                SearchBar.Focus(Windows.UI.Xaml.FocusState.Programmatic);
        }

        private void MyAppBar_Loaded(object sender, RoutedEventArgs e)
        {
            if (SearchBar != null)
                SearchBar.Focus(Windows.UI.Xaml.FocusState.Programmatic);
        }
    }
}