Question

经过一段时间的搜索，我发现了很多来源，但没有人可以帮助我...对不起，如果我错过了帖子那么。

我有一个UWP应用程序，应该在我说话时启动摄像头。

语音识别正常;一个启动相机的按钮也可以。但是，在语音事件回调失败时调用VisualStateManager.GoToState()：/

我写了一个清理过的脚本示例（所有'使用'也被删除了）：

MainPage.xaml中

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

    <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
        <VisualStateManager.VisualStateGroups>
            <VisualStateGroup x:Name="FaceProcessingState">
                <VisualState x:Name="Stopped" />
                <VisualState x:Name="Playing">
                    <VisualState.Setters>
                        <Setter Target="btnPlay.(UIElement.Visibility)" Value="Collapsed" />
                        <Setter Target="btnStop.(UIElement.Visibility)" Value="Visible" />
                    </VisualState.Setters>
                </VisualState>
            </VisualStateGroup>
        </VisualStateManager.VisualStateGroups>
        <Grid.RowDefinitions>
            <RowDefinition Height="5*" />
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <CaptureElement x:Name="captureElement" Width="320" Height="240" Grid.ColumnSpan="3" Grid.RowSpan="3" />
        <Viewbox Grid.Row="1" Grid.Column="1">
            <StackPanel Orientation="Horizontal" Grid.Column="1" Grid.Row="1">
                <Button x:Name="btnPlay" Click="OnStart">
                    <SymbolIcon Symbol="Play" />
                </Button>
                <Button x:Name="btnStop" Click="OnStopAsync" Visibility="Collapsed">
                    <SymbolIcon Symbol="Stop" />
                </Button>
            </StackPanel>
        </Viewbox>        
    </Grid>
</Page>

MainPage.xaml.cs中

namespace Test
{
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
            StartSpeech();
        }

        async void OnStart(object sender, RoutedEventArgs e)
        {
            VisualStateManager.GoToState(this, "Playing", false);
        }

        async void OnStopAsync(object sender, RoutedEventArgs e)
        {
            await this.cameraPreviewManager.StopPreviewAsync();

            VisualStateManager.GoToState(this, "Stopped", false);
        }
        void OnStop(object sender, RoutedEventArgs e)
        {
            this.requestStopCancellationToken.Cancel();
        }

        private async void StartSpeech()
        {
            SpeechListener speechRecognition = new SpeechListener();
            speechRecognition.Recognize += OnRecognize;

            // [...] Start speech recognition [...]
        }

        private async void OnRecognize(object sender, SpeechContinuousRecognitionResultGeneratedEventArgs e)
        {
            if (e.Result.Confidence.ToString() == "Medium" || e.Result.Confidence.ToString() == "High")
            {
                VisualStateManager.GoToState(this, "Playing", false);
            }
        }
    }
}

SpeechListener.cs

namespace Test {
    class SpeechListener
    {
        public delegate void RecognizeEventHandler(object sender, SpeechContinuousRecognitionResultGeneratedEventArgs e);

        public event RecognizeEventHandler Recognize;

        public SpeechListener()
        {
        }

        public async Task PrepareRecognizer()
        {
            recognizer = new SpeechRecognizer();

            // [...]
            recognizer.ContinuousRecognitionSession.ResultGenerated += Recognizer_ContinuousRecognitionSession_ResultGenerated;

            // [...]
        }

        private void Recognizer_ContinuousRecognitionSession_ResultGenerated(SpeechContinuousRecognitionSession sender, SpeechContinuousRecognitionResultGeneratedEventArgs args)
        {
            Recognize?.Invoke(this, args);
        }
    }
}

如果我手动按下按钮，则会调用“OnStart”，并且“GoToState”执行得很好。

如果我说话，则会调用回调“OnRecognize”，并且对“GoToState”的调用会引发系统异常......

有任何线索吗？我不是真正的C＃专家......

谢谢！

修改 @Nico Zhu answer指出了问题，我的具体案例问题在评论中得到解决;）

Answer 1

语音识别正常;一个启动相机的按钮也可以。但是，在语音事件回调上调用VisualStateManager.GoToState（）失败：/

由于语音识别器引发的事件发生在后台线程上，因此请创建对调度程序的引用以获取UI线程的更新。

if (e.Result.Confidence.ToString() == "Medium" || e.Result.Confidence.ToString() == "High")
{
    await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
     {
         VisualStateManager.GoToState(this, "Playing", false);
     });
}

有关详情，请参阅Continuous dictation。

使用C＃

1 个答案: