Speech Recognition Windows Ensure unsubscribe from events on Stop Recording (#2705)

VladislavAntonyuk · web-flow · commit a4389978abdf · 2025-06-13T22:06:17.000-07:00
diff --git a/samples/CommunityToolkit.Maui.Sample/Platforms/Windows/Package.appxmanifest b/samples/CommunityToolkit.Maui.Sample/Platforms/Windows/Package.appxmanifest
@@ -57,6 +57,7 @@
 
     <Capabilities>
         <rescap:Capability Name="runFullTrust" />
+        <DeviceCapability Name="microphone"/>
     </Capabilities>
 
 </Package>
diff --git a/samples/CommunityToolkit.Maui.Sample/ViewModels/Essentials/SpeechToTextViewModel.cs b/samples/CommunityToolkit.Maui.Sample/ViewModels/Essentials/SpeechToTextViewModel.cs
@@ -8,11 +8,9 @@
 
 namespace CommunityToolkit.Maui.Sample.ViewModels.Essentials;
 
-public partial class SpeechToTextViewModel : BaseViewModel
+public partial class SpeechToTextViewModel : BaseViewModel, IAsyncDisposable
 {
 	const string defaultLanguage = "en-US";
-	const string defaultLanguage_android = "en";
-	const string defaultLanguage_tizen = "en_US";
 
 	readonly ITextToSpeech textToSpeech;
 	readonly ISpeechToText speechToText;
@@ -55,7 +53,7 @@ async Task SetLocales(CancellationToken token)
 			Locales.Add(locale);
 		}
 
-		CurrentLocale = Locales.FirstOrDefault(x => x.Language is defaultLanguage or defaultLanguage_android or defaultLanguage_tizen) ?? Locales.FirstOrDefault();
+		CurrentLocale = Locales.FirstOrDefault();
 	}
 
 	[RelayCommand]
@@ -148,4 +146,9 @@ void HandleLocalesCollectionChanged(object? sender, NotifyCollectionChangedEvent
 	{
 		OnPropertyChanged(nameof(CurrentLocale));
 	}
+
+	public async ValueTask DisposeAsync()
+	{
+		await speechToText.DisposeAsync();
+	}
 }
diff --git a/src/CommunityToolkit.Maui.Core/Essentials/SpeechToText/OfflineSpeechToTextImplementation.windows.cs b/src/CommunityToolkit.Maui.Core/Essentials/SpeechToText/OfflineSpeechToTextImplementation.windows.cs
@@ -28,9 +28,6 @@ public SpeechToTextState CurrentState
 	public ValueTask DisposeAsync()
 	{
 		InternalStopListening();
-
-		offlineSpeechRecognizer?.Dispose();
-		offlineSpeechRecognizer = null;
 		return ValueTask.CompletedTask;
 	}
 
@@ -39,7 +36,6 @@ Task InternalStartListening(SpeechToTextOptions options, CancellationToken token
 		Initialize(options);
 
 		offlineSpeechRecognizer.AudioStateChanged += OfflineSpeechRecognizer_StateChanged;
-		offlineSpeechRecognizer.LoadGrammar(new DictationGrammar());
 
 		offlineSpeechRecognizer.InitialSilenceTimeout = TimeSpan.MaxValue;
 		offlineSpeechRecognizer.BabbleTimeout = TimeSpan.MaxValue;
@@ -48,7 +44,12 @@ Task InternalStartListening(SpeechToTextOptions options, CancellationToken token
 
 		offlineSpeechRecognizer.RecognizeCompleted += OnRecognizeCompleted;
 		offlineSpeechRecognizer.SpeechRecognized += OnSpeechRecognized;
-		offlineSpeechRecognizer.RecognizeAsync(RecognizeMode.Multiple);
+
+		if (offlineSpeechRecognizer.AudioState == AudioState.Stopped)
+		{
+			offlineSpeechRecognizer.RecognizeAsync(RecognizeMode.Multiple);
+		}
+
 		return Task.CompletedTask;
 	}
 
@@ -81,19 +82,26 @@ void InternalStopListening()
 	{
 		try
 		{
-			if (offlineSpeechRecognizer is not null)
+			if (offlineSpeechRecognizer is not null && offlineSpeechRecognizer.AudioState != AudioState.Stopped)
 			{
 				offlineSpeechRecognizer.RecognizeAsyncStop();
-
-				offlineSpeechRecognizer.AudioStateChanged -= OfflineSpeechRecognizer_StateChanged;
-				offlineSpeechRecognizer.RecognizeCompleted -= OnRecognizeCompleted;
-				offlineSpeechRecognizer.SpeechRecognized -= OnSpeechRecognized;
 			}
 		}
 		catch
 		{
 			// ignored. Recording may be already stopped
 		}
+		finally
+		{
+			if (offlineSpeechRecognizer is not null)
+			{
+				offlineSpeechRecognizer.AudioStateChanged -= OfflineSpeechRecognizer_StateChanged;
+				offlineSpeechRecognizer.RecognizeCompleted -= OnRecognizeCompleted;
+				offlineSpeechRecognizer.SpeechRecognized -= OnSpeechRecognized;
+				offlineSpeechRecognizer?.Dispose();
+				offlineSpeechRecognizer = null;
+			}
+		}
 	}
 
 	[MemberNotNull(nameof(recognitionText), nameof(offlineSpeechRecognizer), nameof(speechToTextOptions))]
@@ -102,6 +110,7 @@ void Initialize(SpeechToTextOptions options)
 		speechToTextOptions = options;
 		recognitionText = string.Empty;
 		offlineSpeechRecognizer = new SpeechRecognitionEngine(options.Culture);
+		offlineSpeechRecognizer.LoadGrammarAsync(new DictationGrammar());
 	}
 
 	void OfflineSpeechRecognizer_StateChanged(object? sender, AudioStateChangedEventArgs e)
diff --git a/src/CommunityToolkit.Maui.Core/Essentials/SpeechToText/SpeechToTextImplementation.windows.cs b/src/CommunityToolkit.Maui.Core/Essentials/SpeechToText/SpeechToTextImplementation.windows.cs
@@ -1,6 +1,5 @@
+using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
-using System.Globalization;
-using System.Speech.Recognition;
 using Microsoft.Maui.ApplicationModel;
 using Windows.Globalization;
 using Windows.Media.SpeechRecognition;
@@ -35,8 +34,6 @@ public SpeechToTextState CurrentState
 	public async ValueTask DisposeAsync()
 	{
 		await StopRecording(CancellationToken.None);
-		speechRecognizer?.Dispose();
-		speechRecognizer = null;
 	}
 
 	async Task InternalStartListeningAsync(SpeechToTextOptions options, CancellationToken cancellationToken)
@@ -48,7 +45,10 @@ async Task InternalStartListeningAsync(SpeechToTextOptions options, Cancellation
 		speechRecognizer.ContinuousRecognitionSession.Completed += OnCompleted;
 		try
 		{
-			await speechRecognizer.ContinuousRecognitionSession.StartAsync().AsTask(cancellationToken);
+			if (speechRecognizer.State == SpeechRecognizerState.Idle)
+			{
+				await speechRecognizer.ContinuousRecognitionSession.StartAsync().AsTask(cancellationToken);
+			}
 		}
 		catch (Exception ex) when ((uint)ex.HResult is privacyStatementDeclinedCode)
 		{
@@ -88,12 +88,8 @@ async Task StopRecording(CancellationToken cancellationToken)
 	{
 		try
 		{
-			if (speechRecognizer is not null)
+			if (speechRecognizer is not null && speechRecognizer.State != SpeechRecognizerState.Idle)
 			{
-				speechRecognizer.StateChanged -= SpeechRecognizer_StateChanged;
-				speechRecognizer.ContinuousRecognitionSession.ResultGenerated -= ResultGenerated;
-				speechRecognizer.ContinuousRecognitionSession.Completed -= OnCompleted;
-
 				cancellationToken.ThrowIfCancellationRequested();
 				await speechRecognizer.ContinuousRecognitionSession.StopAsync().AsTask(cancellationToken);
 			}
@@ -102,6 +98,17 @@ async Task StopRecording(CancellationToken cancellationToken)
 		{
 			// ignored. Recording may be already stopped
 		}
+		finally
+		{
+			if (speechRecognizer is not null)
+			{
+				speechRecognizer.StateChanged -= SpeechRecognizer_StateChanged;
+				speechRecognizer.ContinuousRecognitionSession.ResultGenerated -= ResultGenerated;
+				speechRecognizer.ContinuousRecognitionSession.Completed -= OnCompleted;
+				speechRecognizer?.Dispose();
+				speechRecognizer = null;
+			}
+		}
 	}
 
 	[MemberNotNull(nameof(recognitionText), nameof(speechRecognizer), nameof(speechToTextOptions))]

Original file line number	Diff line number	Diff line change
`@@ -8,11 +8,9 @@`
`8`	`8`
`9`	`9`	`namespace CommunityToolkit.Maui.Sample.ViewModels.Essentials;`
`10`	`10`
`11`		`-public partial class SpeechToTextViewModel : BaseViewModel`
	`11`	`+public partial class SpeechToTextViewModel : BaseViewModel, IAsyncDisposable`
`12`	`12`	`{`
`13`	`13`	`const string defaultLanguage = "en-US";`
`14`		`- const string defaultLanguage_android = "en";`
`15`		`- const string defaultLanguage_tizen = "en_US";`
`16`	`14`
`17`	`15`	`readonly ITextToSpeech textToSpeech;`
`18`	`16`	`readonly ISpeechToText speechToText;`
`@@ -55,7 +53,7 @@ async Task SetLocales(CancellationToken token)`
`55`	`53`	`Locales.Add(locale);`
`56`	`54`	`}`
`57`	`55`
`58`		`- CurrentLocale = Locales.FirstOrDefault(x => x.Language is defaultLanguage or defaultLanguage_android or defaultLanguage_tizen) ?? Locales.FirstOrDefault();`
	`56`	`+ CurrentLocale = Locales.FirstOrDefault();`
`59`	`57`	`}`
`60`	`58`
`61`	`59`	`[RelayCommand]`
`@@ -148,4 +146,9 @@ void HandleLocalesCollectionChanged(object? sender, NotifyCollectionChangedEvent`
`148`	`146`	`{`
`149`	`147`	`OnPropertyChanged(nameof(CurrentLocale));`
`150`	`148`	`}`
	`149`	`+`
	`150`	`+ public async ValueTask DisposeAsync()`
	`151`	`+ {`
	`152`	`+ await speechToText.DisposeAsync();`
	`153`	`+ }`
`151`	`154`	`}`
Original file line number	Diff line number	Diff line change
`@@ -28,9 +28,6 @@ public SpeechToTextState CurrentState`
`28`	`28`	`public ValueTask DisposeAsync()`
`29`	`29`	`{`
`30`	`30`	`InternalStopListening();`
`31`		`-`
`32`		`- offlineSpeechRecognizer?.Dispose();`
`33`		`- offlineSpeechRecognizer = null;`
`34`	`31`	`return ValueTask.CompletedTask;`
`35`	`32`	`}`
`36`	`33`
`@@ -39,7 +36,6 @@ Task InternalStartListening(SpeechToTextOptions options, CancellationToken token`
`39`	`36`	`Initialize(options);`
`40`	`37`
`41`	`38`	`offlineSpeechRecognizer.AudioStateChanged += OfflineSpeechRecognizer_StateChanged;`
`42`		`- offlineSpeechRecognizer.LoadGrammar(new DictationGrammar());`
`43`	`39`
`44`	`40`	`offlineSpeechRecognizer.InitialSilenceTimeout = TimeSpan.MaxValue;`
`45`	`41`	`offlineSpeechRecognizer.BabbleTimeout = TimeSpan.MaxValue;`
`@@ -48,7 +44,12 @@ Task InternalStartListening(SpeechToTextOptions options, CancellationToken token`
`48`	`44`
`49`	`45`	`offlineSpeechRecognizer.RecognizeCompleted += OnRecognizeCompleted;`
`50`	`46`	`offlineSpeechRecognizer.SpeechRecognized += OnSpeechRecognized;`
`51`		`- offlineSpeechRecognizer.RecognizeAsync(RecognizeMode.Multiple);`
	`47`	`+`
	`48`	`+ if (offlineSpeechRecognizer.AudioState == AudioState.Stopped)`
	`49`	`+ {`
	`50`	`+ offlineSpeechRecognizer.RecognizeAsync(RecognizeMode.Multiple);`
	`51`	`+ }`
	`52`	`+`
`52`	`53`	`return Task.CompletedTask;`
`53`	`54`	`}`
`54`	`55`
`@@ -81,19 +82,26 @@ void InternalStopListening()`
`81`	`82`	`{`
`82`	`83`	`try`
`83`	`84`	`{`
`84`		`- if (offlineSpeechRecognizer is not null)`
	`85`	`+ if (offlineSpeechRecognizer is not null && offlineSpeechRecognizer.AudioState != AudioState.Stopped)`
`85`	`86`	`{`
`86`	`87`	`offlineSpeechRecognizer.RecognizeAsyncStop();`
`87`		`-`
`88`		`- offlineSpeechRecognizer.AudioStateChanged -= OfflineSpeechRecognizer_StateChanged;`
`89`		`- offlineSpeechRecognizer.RecognizeCompleted -= OnRecognizeCompleted;`
`90`		`- offlineSpeechRecognizer.SpeechRecognized -= OnSpeechRecognized;`
`91`	`88`	`}`
`92`	`89`	`}`
`93`	`90`	`catch`
`94`	`91`	`{`
`95`	`92`	`// ignored. Recording may be already stopped`
`96`	`93`	`}`
	`94`	`+ finally`
	`95`	`+ {`
	`96`	`+ if (offlineSpeechRecognizer is not null)`
	`97`	`+ {`
	`98`	`+ offlineSpeechRecognizer.AudioStateChanged -= OfflineSpeechRecognizer_StateChanged;`
	`99`	`+ offlineSpeechRecognizer.RecognizeCompleted -= OnRecognizeCompleted;`
	`100`	`+ offlineSpeechRecognizer.SpeechRecognized -= OnSpeechRecognized;`
	`101`	`+ offlineSpeechRecognizer?.Dispose();`
	`102`	`+ offlineSpeechRecognizer = null;`
	`103`	`+ }`
	`104`	`+ }`
`97`	`105`	`}`
`98`	`106`
`99`	`107`	`[MemberNotNull(nameof(recognitionText), nameof(offlineSpeechRecognizer), nameof(speechToTextOptions))]`
`@@ -102,6 +110,7 @@ void Initialize(SpeechToTextOptions options)`
`102`	`110`	`speechToTextOptions = options;`
`103`	`111`	`recognitionText = string.Empty;`
`104`	`112`	`offlineSpeechRecognizer = new SpeechRecognitionEngine(options.Culture);`
	`113`	`+ offlineSpeechRecognizer.LoadGrammarAsync(new DictationGrammar());`
`105`	`114`	`}`
`106`	`115`
`107`	`116`	`void OfflineSpeechRecognizer_StateChanged(object? sender, AudioStateChangedEventArgs e)`
Original file line number	Diff line number	Diff line change
`@@ -1,6 +1,5 @@`
	`1`	`+using System.Diagnostics;`
`1`	`2`	`using System.Diagnostics.CodeAnalysis;`
`2`		`-using System.Globalization;`
`3`		`-using System.Speech.Recognition;`
`4`	`3`	`using Microsoft.Maui.ApplicationModel;`
`5`	`4`	`using Windows.Globalization;`
`6`	`5`	`using Windows.Media.SpeechRecognition;`
`@@ -35,8 +34,6 @@ public SpeechToTextState CurrentState`
`35`	`34`	`public async ValueTask DisposeAsync()`
`36`	`35`	`{`
`37`	`36`	`await StopRecording(CancellationToken.None);`
`38`		`- speechRecognizer?.Dispose();`
`39`		`- speechRecognizer = null;`
`40`	`37`	`}`
`41`	`38`
`42`	`39`	`async Task InternalStartListeningAsync(SpeechToTextOptions options, CancellationToken cancellationToken)`
`@@ -48,7 +45,10 @@ async Task InternalStartListeningAsync(SpeechToTextOptions options, Cancellation`
`48`	`45`	`speechRecognizer.ContinuousRecognitionSession.Completed += OnCompleted;`
`49`	`46`	`try`
`50`	`47`	`{`
`51`		`- await speechRecognizer.ContinuousRecognitionSession.StartAsync().AsTask(cancellationToken);`
	`48`	`+ if (speechRecognizer.State == SpeechRecognizerState.Idle)`
	`49`	`+ {`
	`50`	`+ await speechRecognizer.ContinuousRecognitionSession.StartAsync().AsTask(cancellationToken);`
	`51`	`+ }`
`52`	`52`	`}`
`53`	`53`	`catch (Exception ex) when ((uint)ex.HResult is privacyStatementDeclinedCode)`
`54`	`54`	`{`
`@@ -88,12 +88,8 @@ async Task StopRecording(CancellationToken cancellationToken)`
`88`	`88`	`{`
`89`	`89`	`try`
`90`	`90`	`{`
`91`		`- if (speechRecognizer is not null)`
	`91`	`+ if (speechRecognizer is not null && speechRecognizer.State != SpeechRecognizerState.Idle)`
`92`	`92`	`{`
`93`		`- speechRecognizer.StateChanged -= SpeechRecognizer_StateChanged;`
`94`		`- speechRecognizer.ContinuousRecognitionSession.ResultGenerated -= ResultGenerated;`
`95`		`- speechRecognizer.ContinuousRecognitionSession.Completed -= OnCompleted;`
`96`		`-`
`97`	`93`	`cancellationToken.ThrowIfCancellationRequested();`
`98`	`94`	`await speechRecognizer.ContinuousRecognitionSession.StopAsync().AsTask(cancellationToken);`
`99`	`95`	`}`
`@@ -102,6 +98,17 @@ async Task StopRecording(CancellationToken cancellationToken)`
`102`	`98`	`{`
`103`	`99`	`// ignored. Recording may be already stopped`
`104`	`100`	`}`
	`101`	`+ finally`
	`102`	`+ {`
	`103`	`+ if (speechRecognizer is not null)`
	`104`	`+ {`
	`105`	`+ speechRecognizer.StateChanged -= SpeechRecognizer_StateChanged;`
	`106`	`+ speechRecognizer.ContinuousRecognitionSession.ResultGenerated -= ResultGenerated;`
	`107`	`+ speechRecognizer.ContinuousRecognitionSession.Completed -= OnCompleted;`
	`108`	`+ speechRecognizer?.Dispose();`
	`109`	`+ speechRecognizer = null;`
	`110`	`+ }`
	`111`	`+ }`
`105`	`112`	`}`
`106`	`113`
`107`	`114`	`[MemberNotNull(nameof(recognitionText), nameof(speechRecognizer), nameof(speechToTextOptions))]`