MediaElement AutoPlay = "False“错误

Question

我正在解析来自XML的多个音频文件uri，并将它们绑定到MediaElement的Source属性。我有八个按钮来触发音频文件。当AutoPlay属性设置为True时，一切工作正常。每个按钮都会触发正确的音频文件。但是，由于我不希望页面一加载就开始播放音频，因此我将AutoPlay设置为False。现在什么都不能用了。页面加载，但按钮不会触发音频文件。我该如何解决这个bug呢？

代码：

public partial class MainPage : PhoneApplicationPage
{
    string name = "C";

    public MainPage()
    {
        InitializeComponent();
    }

    protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
    {
        SetPlayerSource();
        base.OnNavigatedTo(e);
    }

    private void SetPlayerSource()
    {
        XDocument audioPlayer = XDocument.Load("Audio.xml");

        var aani = (from audio in audioPlayer.Descendants("Note")
                    where audio.Attribute("id").Value == name
                    select new AudioClass
                    {
                        Audio = (string)audio.Element("url").Value

                    }).SingleOrDefault();

        player.Source = new Uri(aani.Audio, UriKind.RelativeOrAbsolute);
    }


    private void C_Key_Click(object sender, RoutedEventArgs e)
    {
        var buttonName = (sender as Button).Name;
        var underscorePos = buttonName.IndexOf('_');
        name = buttonName.Substring(0, underscorePos);
        SetPlayerSource();
        player.Play();

    }

    private void D_Key_Click(object sender, RoutedEventArgs e)
    {
        var buttonName = (sender as Button).Name;
        var underscorePos = buttonName.IndexOf('_');
        name = buttonName.Substring(0, underscorePos);
        SetPlayerSource();
        player.Play();
    }

XAML：

<Grid x:Name="ContentPanel" Grid.Row="1" Margin="41,-8,-17,8">
        <Button x:Name="C_key" Content="" HorizontalAlignment="Left" Height="220" Margin="8,0,0,8" Style="{StaticResource C}" VerticalAlignment="Bottom" Width="75" Click="C_Key_Click"/>
        <Button x:Name="D_key" Content="" HorizontalAlignment="Left" Height="220" Margin="87,0,0,8" Style="{StaticResource D}" VerticalAlignment="Bottom" Width="75" Click="D_Key_Click"/>
        <Button x:Name="E_key" Content="" HorizontalAlignment="Left" Height="220" Margin="166,0,0,8" Style="{StaticResource E}" VerticalAlignment="Bottom" Width="75" Click="E_Key_Click"/>
        <Button x:Name="F_key" Content="" HorizontalAlignment="Left" Height="220" Margin="245,0,0,8" Style="{StaticResource F}" VerticalAlignment="Bottom" Width="75" d:LayoutOverrides="Width" Click="F_Key_Click"/>
        <Button x:Name="G_key" Content="" Height="220" Margin="324,0,305,8" Style="{StaticResource G}" VerticalAlignment="Bottom" Click="G_Key_Click"/>
        <Button x:Name="A_key" Content="" HorizontalAlignment="Right" Height="220" Margin="0,0,226,8" Style="{StaticResource A}" VerticalAlignment="Bottom" Width="75" Click="A_Key_Click"/>
        <Button x:Name="B_key" Content="" HorizontalAlignment="Right" Height="220" Margin="0,0,147,8" Style="{StaticResource B}" VerticalAlignment="Bottom" Width="75" Click="B_Key_Click"/>
        <Button x:Name="C2_key" Content="" HorizontalAlignment="Right" Height="220" Margin="0,0,68,8" Style="{StaticResource C2}" VerticalAlignment="Bottom" Width="75" Click="C2_Key_Click"/>
        <MediaElement Height="120" HorizontalAlignment="Left" Margin="8,6,0,0" Name="player" VerticalAlignment="Top" Width="160" Source="{Binding Audio}" Volume="1" AutoPlay="False"/>
     </Grid>

Answer 1

根据MSDN，您应该在设置AutoPlay属性之前将false设置为Source。

在SetPlayerSource中设置Source时，可以从XAML中删除设置器。除此之外，代码看起来不错。

但是，我刚刚意识到您是在调用SetPlayerSource之后直接调用Play。这将不会给你的代码在尝试播放之前实际加载媒体的时间。

您需要在MediaOpened事件上调用Play。

Answer 2

首先，将MediaElement中的Name=player替换为x:Name=player。这有时会导致其他控件出现问题。

如果这不起作用，您可能会在音频加载完成之前尝试调用Play方法。相反，可以尝试处理MediaOpened事件并在那里播放文件。

private void player_MediaOpened(object sender, RoutedEventArgs e)
{
     player.Play();
}