如何在TextToSpeak插件中使用Android TextToSpeak？

Question

我已经看到了很多关于如何在活动中使用Android TextToSpeak的例子，而且还成功地使其工作得很好。我还设法让它使用插件中的绑定服务来工作，但就我的目的而言，它似乎太复杂了。这是我的VoiceService课程：

public class VoiceService : IVoiceService, TextToSpeech.IOnInitListener
{
    public event EventHandler FinishedSpeakingEventHandler;

    private TextToSpeech _tts;

    public void Init()
    {
        // Use a speech progress listener so we get notified when the service finishes speaking the prompt
        var progressListener = new SpeechProgressListener();
        progressListener.FinishedSpeakingEventHandler += OnUtteranceCompleted;

        //_tts = new TextToSpeech(Application.Context, this);
        _tts = new TextToSpeech(Mvx.Resolve<IMvxAndroidCurrentTopActivity>().Activity, this);
        _tts.SetOnUtteranceProgressListener(progressListener);
    }

    public void OnInit(OperationResult status)
    {

        // THIS EVENT NEVER FIRES!

        Console.WriteLine("VoiceService TextToSpeech Initialised. Status: " + status);
        if (status == OperationResult.Success)
        {

        }
    }

    public void Speak(string prompt)
    {

        if (!string.IsNullOrEmpty(prompt))
        {
            var map = new Dictionary<string, string> { { TextToSpeech.Engine.KeyParamUtteranceId, new Guid().ToString() } };
            _tts.Speak(prompt, QueueMode.Flush, map);

            Console.WriteLine("tts_Speak: " + prompt);
        }
        else
        {
            Console.WriteLine("tts_Speak: PROMPT IS NULL OR EMPTY!");
        }
    }

    /// <summary>
    /// When we finish speaking, call the event handler
    /// </summary>
    public void OnUtteranceCompleted(object sender, EventArgs e)
    {
        if (FinishedSpeakingEventHandler != null)
        {
            FinishedSpeakingEventHandler(this, new EventArgs());
        }
    }

    public void Dispose()
    {
        //throw new NotImplementedException();
    }

    public IntPtr Handle { get; private set; }
}

请注意，OnInit方法从未被调用过。

在我的视图模型中，我想这样做：

            _voiceService.Init();
            _voiceService.FinishedSpeakingEventHandler += _voiceService_FinishedSpeakingEventHandler;

            ... and then later ...

            _voiceService.Speak(prompt);

当我这样做时，我会在输出中得到以下消息：

10-13 08:13:59.734 I/TextToSpeech( 2298)：成功地绑定到com.google.android.tts (当我创建新的TTS对象时发生)

和

10-13 08:14:43.924 W/TextToSpeech( 2298)：通话失败:未绑定到TTS引擎(当我调用tts.Speak(提示))

如果我使用的是一个活动，我会创建一个意图，使这个工作，但我不知道如何在一个插件。

提前谢谢你，

大卫

Answer 1

不要自己实现Handle，而是从Java.Lang.Object派生

public class VoiceService : Java.Lang.Object, IVoiceService, TextToSpeech.IOnInitListener

并删除Dispose()和Handle实现。

更多信息在这里：wrappers/

此外，我建议您在实现服务时采用异步方法，这将使从视图模型调用它类似于

await MvxResolve<ITextToSpeechService>().SpeakAsync(text);