Make the TTS package dependency optional

Author: keveleigh

UnityProjects/MRTKDevTemplate/Packages/packages-lock.json

@@ -445,7 +445,6 @@
       "depth": 0,
       "source": "local",
       "dependencies": {
-        "com.microsoft.mrtk.tts.windows": "1.0.4",
         "org.mixedrealitytoolkit.core": "3.2.2"
       }
     },

org.mixedrealitytoolkit.windowsspeech/CHANGELOG.md

@@ -2,6 +2,12 @@
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
+## [Unreleased]
+
+### Changed
+
+* Made the dependency on com.microsoft.mrtk.tts.windows optional. [PR #1060](https://github.com/MixedRealityToolkit/MixedRealityToolkit-Unity/pull/1060)
+
 ## [3.0.4] - 2025-11-12
 
 ### Changed

org.mixedrealitytoolkit.windowsspeech/MRTK.Speech.Windows.asmdef

@@ -18,6 +18,11 @@
             "name": "com.microsoft.mixedreality.openxr",
             "expression": "1.5.0",
             "define": "MSFT_OPENXR_1_5_0_OR_NEWER"
+        },
+        {
+            "name": "com.microsoft.mrtk.tts.windows",
+            "expression": "",
+            "define": "MSFT_TTS_WIN_PRESENT"
         }
     ],
     "noEngineReferences": false

org.mixedrealitytoolkit.windowsspeech/Subsystems/TextToSpeech/WindowsTextToSpeechSubsystem.cs

@@ -2,15 +2,13 @@
 // Licensed under the BSD 3-Clause
 
 using MixedReality.Toolkit.Subsystems;
-using System;
-using System.Runtime.InteropServices;
 using System.Threading.Tasks;
-using System.Linq;
 using UnityEngine;
 using UnityEngine.Scripting;
 
 #if WINDOWS_UWP
-using Windows.Foundation;
+using System;
+using System.Linq;
 using Windows.Media.SpeechSynthesis;
 using Windows.Storage.Streams;
 #endif // WINDOWS_UWP
@@ -41,7 +39,7 @@ static void Register()
             // Fetch subsystem metadata from the attribute.
             var cinfo = XRSubsystemHelpers.ConstructCinfo<WindowsTextToSpeechSubsystem, TextToSpeechSubsystemCinfo>();
 
-            if (!WindowsTextToSpeechSubsystem.Register(cinfo))
+            if (!Register(cinfo))
             {
                 Debug.LogError($"Failed to register the {cinfo.Name} subsystem.");
             }
@@ -72,6 +70,7 @@ public override void Start()
 #endif
             }
 
+            /// <inheritdoc/>
             public override void Destroy()
             {
 #if WINDOWS_UWP
@@ -85,7 +84,7 @@ public override void Destroy()
 
             #region ITextToSpeechSubsystem implementation
 
-#if !(WINDOWS_UWP || UNITY_STANDALONE_WIN || UNITY_EDITOR_WIN)
+#if !(WINDOWS_UWP || ((UNITY_STANDALONE_WIN || UNITY_EDITOR_WIN) && MSFT_TTS_WIN_PRESENT))
             private bool haveLogged = false;
 #endif
 
@@ -124,7 +123,7 @@ public override async Task<bool> TrySpeak(string phrase, AudioSource audioSource
                     sampleRate);
 
                 audioSource.Play();
-                
+
                 return true;
             }
 
@@ -186,17 +185,17 @@ private async Task<byte[]> Synthesize(string phrase)
                 }
 
                 return waveData;
-#elif (UNITY_STANDALONE_WIN || UNITY_EDITOR_WIN)
-                return await Task<byte[]>.Run(() =>
+#elif (UNITY_STANDALONE_WIN || UNITY_EDITOR_WIN) && MSFT_TTS_WIN_PRESENT
+                return await Task.Run(() =>
                 {
-                    if (!Microsoft.MixedReality.Toolkit.Speech.Windows.WinRTTextToSpeechPInvokes.TrySynthesizePhraseWithCustomVoice(phrase, config.VoiceName, out IntPtr nativeData, out int length))
+                    if (!Microsoft.MixedReality.Toolkit.Speech.Windows.WinRTTextToSpeechPInvokes.TrySynthesizePhraseWithCustomVoice(phrase, config.VoiceName, out System.IntPtr nativeData, out int length))
                     {
                         Debug.LogError("Failed to synthesize the phrase");
                         return null;
                     }
 
                     byte[] waveData = new byte[length];
-                    Marshal.Copy(nativeData, waveData, 0, length);
+                    System.Runtime.InteropServices.Marshal.Copy(nativeData, waveData, 0, length);
                     // We can safely free the native data.
                     Microsoft.MixedReality.Toolkit.Speech.Windows.WinRTTextToSpeechPInvokes.FreeSynthesizedData(nativeData);
 

org.mixedrealitytoolkit.windowsspeech/package.json

@@ -1,6 +1,6 @@
 {
   "name": "org.mixedrealitytoolkit.windowsspeech",
-  "version": "3.0.4-development",
+  "version": "3.1.0-development",
   "description": "Speech subsystem implementation for native Windows speech APIs enables native Windows text-to-speech and speech recognition features, producing events to drive XRI interactions using speech.",
   "displayName": "MRTK Windows Speech",
   "msftFeatureCategory": "MRTK3",
@@ -17,7 +17,6 @@
   "unityRelease": "26f1",
   "documentationUrl": "https://www.mixedrealitytoolkit.org",
   "dependencies": {
-    "com.microsoft.mrtk.tts.windows": "1.0.4",
     "org.mixedrealitytoolkit.core": "3.2.2"
   }
 }