Bump version and windows dependency.

Fixed a panic in SpeechDispatcher.voices()

.github/workflows/release.yml

@@ -6,64 +6,16 @@ on:
       - "v*"
 
 jobs:
-
-  build_linux:
-    name: Build Linux
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - run: |
-          sudo apt-get update
-          sudo apt-get install -y libspeechd-dev
-          cargo build --release
-          rustup target add wasm32-unknown-unknown
-          cargo build --release --target wasm32-unknown-unknown
-
-  build_windows:
-    name: Build Windows
-    runs-on: windows-latest
-    steps:
-      - uses: actions/checkout@v2
-      - run: |
-          choco install -y llvm
-          cargo build --release
-
-  build_macos:
-    name: Build MacOS
-    runs-on: macos-latest
-    steps:
-      - uses: actions/checkout@v2
-      - run: |
-          cargo build --release
-          rustup target add aarch64-apple-ios x86_64-apple-ios
-          cargo install cargo-lipo
-          cargo lipo --release
-
-  publish_winrt_bindings:
-    name: Publish winrt_bindings
-    runs-on: windows-latest
-    needs: [build_windows]
-    env:
-      CARGO_TOKEN: ${{ secrets.CARGO_TOKEN }}
-    steps:
-      - uses: actions/checkout@v2
-      - run: |
-          choco install -y llvm
-          cargo login $CARGO_TOKEN
-          cd winrt_bindings
-          cargo package
-          cargo publish || true
-
   publish:
     name: Publish
-    runs-on: ubuntu-latest
-    needs: [build_linux, build_windows, build_macos]
+    runs-on: ubuntu-22.04
     env:
       CARGO_TOKEN: ${{ secrets.CARGO_TOKEN }}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - run: |
           sudo apt-get update
           sudo apt-get install -y libspeechd-dev
           cargo login $CARGO_TOKEN
+          rustup toolchain install stable
           cargo publish

.github/workflows/test.yml

@@ -5,35 +5,58 @@ on:
   pull_request:
 
 jobs:
-
-  build_linux:
-    name: Build Linux
-    runs-on: ubuntu-latest
+  check_formatting:
+    name: Check Formatting
+    runs-on: ubuntu-22.04
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
+      - run: |
+          rustup toolchain install stable
+          cargo fmt --all --check
+          cd examples/web
+          cargo fmt --all --check
+
+  check:
+    name: Check
+    strategy:
+      matrix:
+        os: [windows-latest, ubuntu-22.04, macos-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+      - run: sudo apt-get update; sudo apt-get install -y libspeechd-dev
+        if: ${{ runner.os == 'Linux' }}
+      - run: |
+          rustup toolchain install stable
+          cargo clippy --all-targets
+
+  check_web:
+    name: Check Web
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v4
       - run: |
-          sudo apt-get update
-          sudo apt-get install -y libspeechd-dev
-          cargo build --release
           rustup target add wasm32-unknown-unknown
-          cargo build --release --target wasm32-unknown-unknown
+          rustup toolchain install stable
+          cargo clippy --all-targets --target wasm32-unknown-unknown
 
-  build_windows:
-    name: Build Windows
-    runs-on: windows-latest
+  check_android:
+    name: Check Android
+    runs-on: ubuntu-22.04
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - run: |
-          choco install -y llvm
-          cargo build --release
+          rustup target add aarch64-linux-android
+          rustup toolchain install stable
+          cargo clippy --all-targets --target aarch64-linux-android
 
-  build_macos:
-    name: Build MacOS
-    runs-on: macos-latest
+  check_web_example:
+    name: Check Web Example
+    runs-on: ubuntu-22.04
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - run: |
-          cargo build --release
-          rustup target add aarch64-apple-ios x86_64-apple-ios
-          cargo install cargo-lipo
-          cargo lipo --release
+          rustup target add wasm32-unknown-unknown
+          rustup toolchain install stable
+          cd examples/web
+          cargo build --target wasm32-unknown-unknown

.gitignore

@@ -1,2 +1,3 @@
 Cargo.lock
 target
+*.dll

Cargo.toml

@@ -1,36 +1,71 @@
 [package]
 name = "tts"
-version = "0.6.0"
+version = "0.26.3"
 authors = ["Nolan Darilek <nolan@thewordnerd.info>"]
 repository = "https://github.com/ndarilek/tts-rs"
 description = "High-level Text-To-Speech (TTS) interface"
+documentation = "https://docs.rs/tts"
 license = "MIT"
 exclude = ["*.cfg", "*.yml"]
-edition = "2018"
+edition = "2021"
 
 [lib]
-crate-type = ["lib", "staticlib"]
+crate-type = ["lib", "cdylib", "staticlib"]
+
+[features]
+speech_dispatcher_0_9 = ["speech-dispatcher/0_9"]
+speech_dispatcher_0_10 = ["speech-dispatcher/0_10"]
+speech_dispatcher_0_11 = ["speech-dispatcher/0_11"]
+default = ["speech_dispatcher_0_11"]
 
 [dependencies]
+dyn-clonable = "0.9"
+oxilangtag = "0.1"
+lazy_static = "1"
 log = "0.4"
+serde = { version = "1", optional = true, features = ["derive"] }
 thiserror = "1"
 
 [dev-dependencies]
-env_logger = "0.7"
+env_logger = "0.11"
 
 [target.'cfg(windows)'.dependencies]
-tolk = "0.2"
-winrt = "0.7"
-tts_winrt_bindings = { version = "0.1", path="winrt_bindings" }
+tolk = { version = "0.5", optional = true }
+windows = { version = "0.58", features = [
+    "Foundation",
+    "Foundation_Collections",
+    "Media_Core",
+    "Media_Playback",
+    "Media_SpeechSynthesis",
+    "Storage_Streams",
+] }
 
 [target.'cfg(target_os = "linux")'.dependencies]
-speech-dispatcher = "0.4"
+speech-dispatcher = { version = "0.16", default-features = false }
 
 [target.'cfg(any(target_os = "macos", target_os = "ios"))'.dependencies]
 cocoa-foundation = "0.1"
+core-foundation = "0.9"
 libc = "0.2"
-objc = "0.2"
+objc = { version = "0.2", features = ["exception"] }
 
 [target.wasm32-unknown-unknown.dependencies]
 wasm-bindgen = "0.2"
-web-sys = { version = "0.3", features = ["SpeechSynthesis", "SpeechSynthesisUtterance", "Window", ] }
+web-sys = { version = "0.3", features = [
+    "EventTarget",
+    "SpeechSynthesis",
+    "SpeechSynthesisErrorCode",
+    "SpeechSynthesisErrorEvent",
+    "SpeechSynthesisEvent",
+    "SpeechSynthesisUtterance",
+    "SpeechSynthesisVoice",
+    "Window",
+] }
+
+[target.'cfg(target_os="android")'.dependencies]
+jni = "0.21"
+ndk-context = "0.1"
+
+[package.metadata.docs.rs]
+no-default-features = true
+features = ["speech_dispatcher_0_11"]

Makefile.toml

@@ -0,0 +1,33 @@
+[tasks.build-android-example]
+script = [
+    "cd examples/android",
+    "./gradlew assembleDebug",
+]
+
+[tasks.run-android-example]
+script = [
+    "cd examples/android",
+    "./gradlew runDebug",
+]
+
+[tasks.log-android]
+command = "adb"
+args = ["logcat", "RustStdoutStderr:D", "*:S"]
+
+[tasks.install-trunk]
+install_crate = { crate_name = "trunk", binary = "trunk", test_arg = "--help" }
+
+[tasks.install-wasm-bindgen-cli]
+install_crate = { crate_name = "wasm-bindgen-cli", binary = "wasm-bindgen", test_arg = "--help" }
+
+[tasks.build-web-example]
+dependencies = ["install-trunk", "install-wasm-bindgen-cli"]
+cwd = "examples/web"
+command = "trunk"
+args = ["build"]
+
+[tasks.run-web-example]
+dependencies = ["install-trunk", "install-wasm-bindgen-cli"]
+cwd = "examples/web"
+command = "trunk"
+args = ["serve"]

README.md

@@ -3,10 +3,23 @@
 This library provides a high-level Text-To-Speech (TTS) interface supporting various backends. Currently supported backends are:
 
 * Windows
-  * Screen readers/SAPI via Tolk
+  * Screen readers/SAPI via Tolk (requires `tolk` Cargo feature)
   * WinRT
 * Linux via [Speech Dispatcher](https://freebsoft.org/speechd)
-* MacOS
+* MacOS/iOS
   * AppKit on MacOS 10.13 and below
   * AVFoundation on MacOS 10.14 and above, and iOS
+* Android
 * WebAssembly
+
+## Android Setup
+
+On most platforms, this library is plug-and-play. Because of JNI's complexity, Android setup is a bit more involved. In general, look to the Android example for guidance. Here are some rough steps to get going:
+
+* Set up _Cargo.toml_ as the example does. Be sure to depend on `ndk-glue`.
+* Place _Bridge.java_ appropriately in your app. This is needed to support various Android TTS callbacks.
+* Create a main activity similar to _MainActivity.kt_. In particular, you need to derive `android.app.NativeActivity`, and you need a `System.loadLibrary(...)` call appropriate for your app. `System.loadLibrary(...)` is needed to trigger `JNI_OnLoad`.
+* * Even though you've loaded the library in your main activity, add a metadata tag to your activity in _AndroidManifest.xml_ referencing it. Yes, this is redundant but necessary.
+* Set if your various build.gradle scripts to reference the plugins, dependencies, etc. from the example. In particular, you'll want to set up [cargo-ndk-android-gradle](https://github.com/willir/cargo-ndk-android-gradle/) and either [depend on androidx.annotation](https://developer.android.com/reference/androidx/annotation/package-summary) or otherwise configure your app to keep the class _rs.tts.Bridge_.
+
+And I think that should about do it. Good luck!

build.rs

@@ -1,15 +1,11 @@
-// Copyright 2013-2015 The Servo Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
 fn main() {
     if std::env::var("TARGET").unwrap().contains("-apple") {
-        println!("cargo:rustc-link-lib=framework=AppKit");
         println!("cargo:rustc-link-lib=framework=AVFoundation");
+        if !std::env::var("CARGO_CFG_TARGET_OS")
+            .unwrap()
+            .contains("ios")
+        {
+            println!("cargo:rustc-link-lib=framework=AppKit");
+        }
     }
 }

examples/99bottles.rs

@@ -0,0 +1,39 @@
+use std::io;
+use std::{thread, time};
+
+#[cfg(target_os = "macos")]
+use cocoa_foundation::base::id;
+#[cfg(target_os = "macos")]
+use cocoa_foundation::foundation::NSRunLoop;
+#[cfg(target_os = "macos")]
+use objc::{msg_send, sel, sel_impl};
+
+use tts::*;
+
+fn main() -> Result<(), Error> {
+    env_logger::init();
+    let mut tts = Tts::default()?;
+    let mut bottles = 99;
+    while bottles > 0 {
+        tts.speak(format!("{} bottles of beer on the wall,", bottles), false)?;
+        tts.speak(format!("{} bottles of beer,", bottles), false)?;
+        tts.speak("Take one down, pass it around", false)?;
+        tts.speak("Give us a bit to drink this...", false)?;
+        let time = time::Duration::from_secs(15);
+        thread::sleep(time);
+        bottles -= 1;
+        tts.speak(format!("{} bottles of beer on the wall,", bottles), false)?;
+    }
+    let mut _input = String::new();
+    // The below is only needed to make the example run on MacOS because there is no NSRunLoop in this context.
+    // It shouldn't be needed in an app or game that almost certainly has one already.
+    #[cfg(target_os = "macos")]
+    {
+        let run_loop: id = unsafe { NSRunLoop::currentRunLoop() };
+        unsafe {
+            let _: () = msg_send![run_loop, run];
+        }
+    }
+    io::stdin().read_line(&mut _input)?;
+    Ok(())
+}

examples/android/.gitignore

@@ -0,0 +1,16 @@
+*.iml
+.gradle
+/local.properties
+/.idea/caches
+/.idea/libraries
+/.idea/modules.xml
+/.idea/workspace.xml
+/.idea/navEditor.xml
+/.idea/assetWizardSettings.xml
+.DS_Store
+/build
+/captures
+.externalNativeBuild
+.cxx
+local.properties
+Cargo.lock

examples/android/.idea/.gitignore

@@ -0,0 +1,3 @@
+# Default ignored files
+/shelf/
+/workspace.xml

examples/android/.idea/compiler.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="CompilerConfiguration">
+    <bytecodeTargetLevel target="1.6" />
+  </component>
+</project>

examples/android/.idea/gradle.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="GradleMigrationSettings" migrationVersion="1" />
+  <component name="GradleSettings">
+    <option name="linkedExternalProjectsSettings">
+      <GradleProjectSettings>
+        <option name="testRunner" value="PLATFORM" />
+        <option name="distributionType" value="DEFAULT_WRAPPED" />
+        <option name="externalProjectPath" value="$PROJECT_DIR$" />
+        <option name="gradleJvm" value="11" />
+        <option name="modules">
+          <set>
+            <option value="$PROJECT_DIR$" />
+          </set>
+        </option>
+        <option name="resolveModulePerSourceSet" value="false" />
+        <option name="useQualifiedModuleNames" value="true" />
+      </GradleProjectSettings>
+    </option>
+  </component>
+</project>

examples/android/.idea/jarRepositories.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="RemoteRepositoriesConfiguration">
+    <remote-repository>
+      <option name="id" value="central" />
+      <option name="name" value="Maven Central repository" />
+      <option name="url" value="https://repo1.maven.org/maven2" />
+    </remote-repository>
+    <remote-repository>
+      <option name="id" value="jboss.community" />
+      <option name="name" value="JBoss Community repository" />
+      <option name="url" value="https://repository.jboss.org/nexus/content/repositories/public/" />
+    </remote-repository>
+    <remote-repository>
+      <option name="id" value="BintrayJCenter" />
+      <option name="name" value="BintrayJCenter" />
+      <option name="url" value="https://jcenter.bintray.com/" />
+    </remote-repository>
+    <remote-repository>
+      <option name="id" value="Google" />
+      <option name="name" value="Google" />
+      <option name="url" value="https://dl.google.com/dl/android/maven2/" />
+    </remote-repository>
+  </component>
+</project>

examples/android/.idea/misc.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_6" default="false" project-jdk-name="1.8" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/build/classes" />
+  </component>
+  <component name="ProjectType">
+    <option name="id" value="Android" />
+  </component>
+</project>

examples/android/.idea/vcs.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$/../.." vcs="Git" />
+  </component>
+</project>

examples/android/app/.gitignore

@@ -0,0 +1 @@
+/build

examples/android/app/build.gradle

@@ -0,0 +1,56 @@
+plugins {
+    id "com.android.application"
+    id "org.mozilla.rust-android-gradle.rust-android"
+}
+
+android {
+    namespace "rs.tts"
+    compileSdkVersion 33
+    ndkVersion "25.1.8937393"
+    defaultConfig {
+        applicationId "rs.tts"
+        minSdkVersion 21
+        targetSdkVersion 33
+        versionCode 1
+        versionName "1.0"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile("proguard-android-optimize.txt"), "proguard-rules.pro"
+        }
+    }
+}
+
+dependencies {
+    implementation "androidx.core:core-ktx:1.2.0"
+    implementation "androidx.annotation:annotation:1.1.0"
+    implementation "com.google.android.material:material:1.1.0"
+    implementation "androidx.constraintlayout:constraintlayout:1.1.3"
+}
+
+apply plugin: "org.mozilla.rust-android-gradle.rust-android"
+
+cargo {
+    module  = "."
+    libname = "tts"
+    targets = ["arm", "x86"]
+}
+
+tasks.whenTaskAdded { task ->
+    if ((task.name == 'javaPreCompileDebug' || task.name == 'javaPreCompileRelease')) {
+        task.dependsOn "cargoBuild"
+    }
+}
+
+project.afterEvaluate {
+    android.applicationVariants.all { variant ->
+        task "run${variant.name.capitalize()}"(type: Exec, dependsOn: "install${variant.name.capitalize()}", group: "run") {
+            commandLine = ["adb", "shell", "monkey", "-p", variant.applicationId + " 1"]
+            doLast {
+                println "Launching ${variant.applicationId}"
+            }
+        }
+    }
+}

examples/android/app/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

examples/android/app/src/main/.gitignore

@@ -0,0 +1 @@
+jniLibs

examples/android/app/src/main/AndroidManifest.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <application android:allowBackup="true" android:label="@string/app_name">
+        <activity android:name=".MainActivity" android:exported="true">
+            <meta-data android:name="android.app.lib_name" android:value="hello_world" />
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+</manifest>

examples/android/app/src/main/java/rs/tts/Bridge.java

@@ -0,0 +1,24 @@
+package rs.tts;
+
+import android.speech.tts.TextToSpeech;
+import android.speech.tts.UtteranceProgressListener;
+
+@androidx.annotation.Keep
+public class Bridge extends UtteranceProgressListener implements TextToSpeech.OnInitListener {
+    public int backendId;
+
+    public Bridge(int backendId) {
+        this.backendId = backendId;
+    }
+
+    public native void onInit(int status);
+
+    public native void onStart(String utteranceId);
+
+    public native void onStop(String utteranceId, Boolean interrupted);
+
+    public native void onDone(String utteranceId);
+
+    public native void onError(String utteranceId) ;
+
+}

examples/android/app/src/main/java/rs/tts/MainActivity.kt

@@ -0,0 +1,11 @@
+package rs.tts
+
+import android.app.NativeActivity
+
+class MainActivity : NativeActivity() {
+    companion object {
+        init {
+            System.loadLibrary("hello_world")
+        }
+    }
+}

examples/android/app/src/main/res/values/strings.xml

@@ -0,0 +1,3 @@
+<resources>
+    <string name="app_name">TTS-RS</string>
+</resources>

examples/android/build.gradle

@@ -0,0 +1,29 @@
+// Top-level build file where you can add configuration options common to all sub-projects/modules.
+
+buildscript {                                                                                                                                                                 
+    repositories {                                                                                                                                                            
+        google()                                                                                                                                                              
+        mavenCentral()                                                                                                                                                        
+        maven {
+            url "https://plugins.gradle.org/m2/"
+        }
+    }                                                                                                                                                                         
+}                                                                                                                                                                             
+
+plugins {
+    id "com.android.application" version "7.3.0" apply false
+    id "com.android.library" version "7.3.0" apply false
+    id "org.jetbrains.kotlin.android" version "1.7.21" apply false
+    id "org.mozilla.rust-android-gradle.rust-android" version "0.9.3" apply false
+}
+
+allprojects {
+    repositories {
+        google()
+        mavenCentral()
+    }                                                                                                                                                                         
+}                                                                                                                                                                             
+
+task clean(type: Delete) {
+    delete rootProject.buildDir
+}

examples/android/cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "hello_world"
+version = "0.1.0"
+authors = ["Nolan Darilek <nolan@thewordnerd.info>"]
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[lib]
+crate-type = ["dylib"]
+
+[dependencies]
+ndk-glue = "0.7"
+tts = { path = "../.." }

examples/android/gradle.properties

@@ -0,0 +1,21 @@
+# Project-wide Gradle settings.
+# IDE (e.g. Android Studio) users:
+# Gradle settings configured through the IDE *will override*
+# any settings specified in this file.
+# For more details on how to configure your build environment visit
+# http://www.gradle.org/docs/current/userguide/build_environment.html
+# Specifies the JVM arguments used for the daemon process.
+# The setting is particularly useful for tweaking memory settings.
+org.gradle.jvmargs=-Xmx2048m -Dfile.encoding=UTF-8
+# When configured, Gradle will run in incubating parallel mode.
+# This option should only be used with decoupled projects. More details, visit
+# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
+# org.gradle.parallel=true
+# AndroidX package structure to make it clearer which packages are bundled with the
+# Android operating system, and which are packaged with your app"s APK
+# https://developer.android.com/topic/libraries/support-library/androidx-rn
+android.useAndroidX=true
+# Automatically convert third-party libraries to use AndroidX
+android.enableJetifier=true
+# Kotlin code style for this project: "official" or "obsolete":
+kotlin.code.style=official

examples/android/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,6 @@
+#Mon Dec 28 17:32:22 CST 2020
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.5.1-bin.zip

examples/android/gradlew

@@ -0,0 +1,172 @@
+#!/usr/bin/env sh
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=$(save "$@")
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
+  cd "$(dirname "$0")"
+fi
+
+exec "$JAVACMD" "$@"

examples/android/gradlew.bat

@@ -0,0 +1,84 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

examples/android/settings.gradle

@@ -0,0 +1,8 @@
+pluginManagement {
+    repositories {
+        gradlePluginPortal()
+        google()
+        mavenCentral()
+    }
+}
+include ":app"

examples/android/src/lib.rs

@@ -0,0 +1,70 @@
+use tts::*;
+
+// The `loop {}` below only simulates an app loop.
+// Without it, the `TTS` instance gets dropped before callbacks can run.
+#[allow(unreachable_code)]
+fn run() -> Result<(), Error> {
+    let mut tts = Tts::default()?;
+    let Features {
+        utterance_callbacks,
+        ..
+    } = tts.supported_features();
+    if utterance_callbacks {
+        tts.on_utterance_begin(Some(Box::new(|utterance| {
+            println!("Started speaking {:?}", utterance)
+        })))?;
+        tts.on_utterance_end(Some(Box::new(|utterance| {
+            println!("Finished speaking {:?}", utterance)
+        })))?;
+        tts.on_utterance_stop(Some(Box::new(|utterance| {
+            println!("Stopped speaking {:?}", utterance)
+        })))?;
+    }
+    let Features { is_speaking, .. } = tts.supported_features();
+    if is_speaking {
+        println!("Are we speaking? {}", tts.is_speaking()?);
+    }
+    tts.speak("Hello, world.", false)?;
+    let Features { rate, .. } = tts.supported_features();
+    if rate {
+        let original_rate = tts.get_rate()?;
+        tts.speak(format!("Current rate: {}", original_rate), false)?;
+        tts.set_rate(tts.max_rate())?;
+        tts.speak("This is very fast.", false)?;
+        tts.set_rate(tts.min_rate())?;
+        tts.speak("This is very slow.", false)?;
+        tts.set_rate(tts.normal_rate())?;
+        tts.speak("This is the normal rate.", false)?;
+        tts.set_rate(original_rate)?;
+    }
+    let Features { pitch, .. } = tts.supported_features();
+    if pitch {
+        let original_pitch = tts.get_pitch()?;
+        tts.set_pitch(tts.max_pitch())?;
+        tts.speak("This is high-pitch.", false)?;
+        tts.set_pitch(tts.min_pitch())?;
+        tts.speak("This is low pitch.", false)?;
+        tts.set_pitch(tts.normal_pitch())?;
+        tts.speak("This is normal pitch.", false)?;
+        tts.set_pitch(original_pitch)?;
+    }
+    let Features { volume, .. } = tts.supported_features();
+    if volume {
+        let original_volume = tts.get_volume()?;
+        tts.set_volume(tts.max_volume())?;
+        tts.speak("This is loud!", false)?;
+        tts.set_volume(tts.min_volume())?;
+        tts.speak("This is quiet.", false)?;
+        tts.set_volume(tts.normal_volume())?;
+        tts.speak("This is normal volume.", false)?;
+        tts.set_volume(original_volume)?;
+    }
+    tts.speak("Goodbye.", false)?;
+    loop {}
+    Ok(())
+}
+
+#[cfg_attr(target_os = "android", ndk_glue::main(backtrace = "on"))]
+pub fn main() {
+    run().expect("Failed to run");
+}

examples/clone_drop.rs

@@ -0,0 +1,89 @@
+use std::io;
+
+#[cfg(target_os = "macos")]
+use cocoa_foundation::base::id;
+#[cfg(target_os = "macos")]
+use cocoa_foundation::foundation::NSRunLoop;
+#[cfg(target_os = "macos")]
+use objc::{msg_send, sel, sel_impl};
+
+use tts::*;
+
+fn main() -> Result<(), Error> {
+    env_logger::init();
+    let tts = Tts::default()?;
+    if Tts::screen_reader_available() {
+        println!("A screen reader is available on this platform.");
+    } else {
+        println!("No screen reader is available on this platform.");
+    }
+    let Features {
+        utterance_callbacks,
+        ..
+    } = tts.supported_features();
+    if utterance_callbacks {
+        tts.on_utterance_begin(Some(Box::new(|utterance| {
+            println!("Started speaking {:?}", utterance)
+        })))?;
+        tts.on_utterance_end(Some(Box::new(|utterance| {
+            println!("Finished speaking {:?}", utterance)
+        })))?;
+        tts.on_utterance_stop(Some(Box::new(|utterance| {
+            println!("Stopped speaking {:?}", utterance)
+        })))?;
+    }
+    let mut tts_clone = tts.clone();
+    drop(tts);
+    let Features { is_speaking, .. } = tts_clone.supported_features();
+    if is_speaking {
+        println!("Are we speaking? {}", tts_clone.is_speaking()?);
+    }
+    tts_clone.speak("Hello, world.", false)?;
+    let Features { rate, .. } = tts_clone.supported_features();
+    if rate {
+        let original_rate = tts_clone.get_rate()?;
+        tts_clone.speak(format!("Current rate: {}", original_rate), false)?;
+        tts_clone.set_rate(tts_clone.max_rate())?;
+        tts_clone.speak("This is very fast.", false)?;
+        tts_clone.set_rate(tts_clone.min_rate())?;
+        tts_clone.speak("This is very slow.", false)?;
+        tts_clone.set_rate(tts_clone.normal_rate())?;
+        tts_clone.speak("This is the normal rate.", false)?;
+        tts_clone.set_rate(original_rate)?;
+    }
+    let Features { pitch, .. } = tts_clone.supported_features();
+    if pitch {
+        let original_pitch = tts_clone.get_pitch()?;
+        tts_clone.set_pitch(tts_clone.max_pitch())?;
+        tts_clone.speak("This is high-pitch.", false)?;
+        tts_clone.set_pitch(tts_clone.min_pitch())?;
+        tts_clone.speak("This is low pitch.", false)?;
+        tts_clone.set_pitch(tts_clone.normal_pitch())?;
+        tts_clone.speak("This is normal pitch.", false)?;
+        tts_clone.set_pitch(original_pitch)?;
+    }
+    let Features { volume, .. } = tts_clone.supported_features();
+    if volume {
+        let original_volume = tts_clone.get_volume()?;
+        tts_clone.set_volume(tts_clone.max_volume())?;
+        tts_clone.speak("This is loud!", false)?;
+        tts_clone.set_volume(tts_clone.min_volume())?;
+        tts_clone.speak("This is quiet.", false)?;
+        tts_clone.set_volume(tts_clone.normal_volume())?;
+        tts_clone.speak("This is normal volume.", false)?;
+        tts_clone.set_volume(original_volume)?;
+    }
+    tts_clone.speak("Goodbye.", false)?;
+    let mut _input = String::new();
+    // The below is only needed to make the example run on MacOS because there is no NSRunLoop in this context.
+    // It shouldn't be needed in an app or game that almost certainly has one already.
+    #[cfg(target_os = "macos")]
+    {
+        let run_loop: id = unsafe { NSRunLoop::currentRunLoop() };
+        unsafe {
+            let _: () = msg_send![run_loop, run];
+        }
+    }
+    io::stdin().read_line(&mut _input)?;
+    Ok(())
+}

examples/hello_world.rs

@@ -11,7 +11,31 @@ use tts::*;
 
 fn main() -> Result<(), Error> {
     env_logger::init();
-    let mut tts = TTS::default()?;
+    let mut tts = Tts::default()?;
+    if Tts::screen_reader_available() {
+        println!("A screen reader is available on this platform.");
+    } else {
+        println!("No screen reader is available on this platform.");
+    }
+    let Features {
+        utterance_callbacks,
+        ..
+    } = tts.supported_features();
+    if utterance_callbacks {
+        tts.on_utterance_begin(Some(Box::new(|utterance| {
+            println!("Started speaking {:?}", utterance)
+        })))?;
+        tts.on_utterance_end(Some(Box::new(|utterance| {
+            println!("Finished speaking {:?}", utterance)
+        })))?;
+        tts.on_utterance_stop(Some(Box::new(|utterance| {
+            println!("Stopped speaking {:?}", utterance)
+        })))?;
+    }
+    let Features { is_speaking, .. } = tts.supported_features();
+    if is_speaking {
+        println!("Are we speaking? {}", tts.is_speaking()?);
+    }
     tts.speak("Hello, world.", false)?;
     let Features { rate, .. } = tts.supported_features();
     if rate {
@@ -47,8 +71,27 @@ fn main() -> Result<(), Error> {
         tts.speak("This is normal volume.", false)?;
         tts.set_volume(original_volume)?;
     }
+    let Features { voice, .. } = tts.supported_features();
+    if voice {
+        let voices = tts.voices()?;
+        println!("Available voices:\n===");
+        for v in &voices {
+            println!("{:?}", v);
+        }
+        let Features { get_voice, .. } = tts.supported_features();
+        let original_voice = if get_voice { tts.voice()? } else { None };
+        for v in &voices {
+            tts.set_voice(v)?;
+            tts.speak(format!("This is {}.", v.name()), false)?;
+        }
+        if let Some(original_voice) = original_voice {
+            tts.set_voice(&original_voice)?;
+        }
+    }
     tts.speak("Goodbye.", false)?;
     let mut _input = String::new();
+    // The below is only needed to make the example run on MacOS because there is no NSRunLoop in this context.
+    // It shouldn't be needed in an app or game that almost certainly has one already.
     #[cfg(target_os = "macos")]
     {
         let run_loop: id = unsafe { NSRunLoop::currentRunLoop() };

examples/latency.rs

@@ -0,0 +1,14 @@
+use std::io;
+
+use tts::*;
+
+fn main() -> Result<(), Error> {
+    env_logger::init();
+    let mut tts = Tts::default()?;
+    println!("Press Enter and wait for speech.");
+    loop {
+        let mut _input = String::new();
+        io::stdin().read_line(&mut _input)?;
+        tts.speak("Hello, world.", true)?;
+    }
+}

examples/ramble.rs

@@ -0,0 +1,32 @@
+#[cfg(target_os = "macos")]
+use cocoa_foundation::base::id;
+#[cfg(target_os = "macos")]
+use cocoa_foundation::foundation::NSDefaultRunLoopMode;
+#[cfg(target_os = "macos")]
+use cocoa_foundation::foundation::NSRunLoop;
+#[cfg(target_os = "macos")]
+use objc::class;
+#[cfg(target_os = "macos")]
+use objc::{msg_send, sel, sel_impl};
+use std::{thread, time};
+use tts::*;
+
+fn main() -> Result<(), Error> {
+    env_logger::init();
+    let mut tts = Tts::default()?;
+    let mut phrase = 1;
+    loop {
+        tts.speak(format!("Phrase {}", phrase), false)?;
+        #[cfg(target_os = "macos")]
+        {
+            let run_loop: id = unsafe { NSRunLoop::currentRunLoop() };
+            unsafe {
+                let date: id = msg_send![class!(NSDate), distantFuture];
+                let _: () = msg_send![run_loop, runMode:NSDefaultRunLoopMode beforeDate:date];
+            }
+        }
+        let time = time::Duration::from_secs(5);
+        thread::sleep(time);
+        phrase += 1;
+    }
+}

examples/web/.cargo/config

@@ -0,0 +1,2 @@
+[build]
+target = "wasm32-unknown-unknown"

examples/web/.gitignore

@@ -0,0 +1 @@
+dist

examples/web/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "web"
+version = "0.1.0"
+authors = ["Nolan Darilek <nolan@thewordnerd.info>"]
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+console_log = "0.2"
+log = "0.4"
+seed = "0.9"
+tts = { path = "../.." }

examples/web/index.html

@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<html lang="en">
+
+<head>
+    <title>Example</title>
+</head>
+
+<body>
+    <div id="app"></div>
+</body>
+
+</html>

examples/web/src/main.rs

@@ -0,0 +1,157 @@
+#![allow(clippy::wildcard_imports)]
+use seed::{prelude::*, *};
+
+use tts::Tts;
+
+#[derive(Clone)]
+struct Model {
+    text: String,
+    tts: Tts,
+}
+
+#[derive(Clone)]
+enum Msg {
+    TextChanged(String),
+    RateChanged(String),
+    PitchChanged(String),
+    VolumeChanged(String),
+    VoiceChanged(String),
+    Speak,
+}
+
+fn init(_: Url, _: &mut impl Orders<Msg>) -> Model {
+    let mut tts = Tts::default().unwrap();
+    if tts.voices().unwrap().iter().len() > 0 {
+        if tts.voice().unwrap().is_none() {
+            tts.set_voice(tts.voices().unwrap().first().unwrap())
+                .expect("Failed to set voice");
+        }
+    }
+    Model {
+        text: "Hello, world. This is a test of the current text-to-speech values.".into(),
+        tts,
+    }
+}
+
+fn update(msg: Msg, model: &mut Model, _: &mut impl Orders<Msg>) {
+    use Msg::*;
+    match msg {
+        TextChanged(text) => model.text = text,
+        RateChanged(rate) => {
+            let rate = rate.parse::<f32>().unwrap();
+            model.tts.set_rate(rate).unwrap();
+        }
+        PitchChanged(pitch) => {
+            let pitch = pitch.parse::<f32>().unwrap();
+            model.tts.set_pitch(pitch).unwrap();
+        }
+        VolumeChanged(volume) => {
+            let volume = volume.parse::<f32>().unwrap();
+            model.tts.set_volume(volume).unwrap();
+        }
+        VoiceChanged(voice) => {
+            for v in model.tts.voices().unwrap() {
+                if v.id() == voice {
+                    model.tts.set_voice(&v).unwrap();
+                }
+            }
+        }
+        Speak => {
+            model.tts.speak(&model.text, false).unwrap();
+        }
+    }
+}
+
+fn view(model: &Model) -> Node<Msg> {
+    let should_show_voices = model.tts.voices().unwrap().iter().len() > 0;
+    form![
+        div![label![
+            "Text to speak",
+            input![
+                attrs! {
+                    At::Value => model.text,
+                    At::AutoFocus => AtValue::None,
+                },
+                input_ev(Ev::Input, Msg::TextChanged)
+            ],
+        ],],
+        div![label![
+            "Rate",
+            input![
+                attrs! {
+                    At::Type => "number",
+                    At::Value => model.tts.get_rate().unwrap(),
+                    At::Min => model.tts.min_rate(),
+                    At::Max => model.tts.max_rate()
+                },
+                input_ev(Ev::Input, Msg::RateChanged)
+            ],
+        ],],
+        div![label![
+            "Pitch",
+            input![
+                attrs! {
+                    At::Type => "number",
+                    At::Value => model.tts.get_pitch().unwrap(),
+                    At::Min => model.tts.min_pitch(),
+                    At::Max => model.tts.max_pitch()
+                },
+                input_ev(Ev::Input, Msg::PitchChanged)
+            ],
+        ],],
+        div![label![
+            "Volume",
+            input![
+                attrs! {
+                    At::Type => "number",
+                    At::Value => model.tts.get_volume().unwrap(),
+                    At::Min => model.tts.min_volume(),
+                    At::Max => model.tts.max_volume()
+                },
+                input_ev(Ev::Input, Msg::VolumeChanged)
+            ],
+        ],],
+        if should_show_voices {
+            div![
+                label!["Voice"],
+                select![
+                    model.tts.voices().unwrap().iter().map(|v| {
+                        let selected = if let Some(voice) = model.tts.voice().unwrap() {
+                            voice.id() == v.id()
+                        } else {
+                            false
+                        };
+                        option![
+                            attrs! {
+                                At::Value => v.id()
+                            },
+                            if selected {
+                                attrs! {
+                                    At::Selected => selected
+                                }
+                            } else {
+                                attrs! {}
+                            },
+                            v.name()
+                        ]
+                    }),
+                    input_ev(Ev::Change, Msg::VoiceChanged)
+                ]
+            ]
+        } else {
+            div!["Your browser does not seem to support selecting voices."]
+        },
+        button![
+            "Speak",
+            ev(Ev::Click, |e| {
+                e.prevent_default();
+                Msg::Speak
+            }),
+        ],
+    ]
+}
+
+fn main() {
+    console_log::init().expect("Error initializing logger");
+    App::start("app", init, update, view);
+}

src/backends/android.rs

@@ -0,0 +1,402 @@
+#[cfg(target_os = "android")]
+use std::{
+    collections::HashSet,
+    ffi::{CStr, CString},
+    os::raw::c_void,
+    sync::{Mutex, RwLock},
+    thread,
+    time::{Duration, Instant},
+};
+
+use jni::{
+    objects::{GlobalRef, JObject, JString},
+    sys::{jfloat, jint, JNI_VERSION_1_6},
+    JNIEnv, JavaVM,
+};
+use lazy_static::lazy_static;
+use log::{error, info};
+
+use crate::{Backend, BackendId, Error, Features, UtteranceId, Voice, CALLBACKS};
+
+lazy_static! {
+    static ref BRIDGE: Mutex<Option<GlobalRef>> = Mutex::new(None);
+    static ref NEXT_BACKEND_ID: Mutex<u64> = Mutex::new(0);
+    static ref PENDING_INITIALIZATIONS: RwLock<HashSet<u64>> = RwLock::new(HashSet::new());
+    static ref NEXT_UTTERANCE_ID: Mutex<u64> = Mutex::new(0);
+}
+
+#[allow(non_snake_case)]
+#[no_mangle]
+pub extern "system" fn JNI_OnLoad(vm: JavaVM, _: *mut c_void) -> jint {
+    let mut env = vm.get_env().expect("Cannot get reference to the JNIEnv");
+    let b = env
+        .find_class("rs/tts/Bridge")
+        .expect("Failed to find `Bridge`");
+    let b = env
+        .new_global_ref(b)
+        .expect("Failed to create `Bridge` `GlobalRef`");
+    let mut bridge = BRIDGE.lock().unwrap();
+    *bridge = Some(b);
+    JNI_VERSION_1_6
+}
+
+#[no_mangle]
+#[allow(non_snake_case)]
+pub unsafe extern "C" fn Java_rs_tts_Bridge_onInit(mut env: JNIEnv, obj: JObject, status: jint) {
+    let id = env
+        .get_field(obj, "backendId", "I")
+        .expect("Failed to get backend ID")
+        .i()
+        .expect("Failed to cast to int") as u64;
+    let mut pending = PENDING_INITIALIZATIONS.write().unwrap();
+    (*pending).remove(&id);
+    if status != 0 {
+        error!("Failed to initialize TTS engine");
+    }
+}
+
+#[no_mangle]
+#[allow(non_snake_case)]
+pub unsafe extern "C" fn Java_rs_tts_Bridge_onStart(
+    mut env: JNIEnv,
+    obj: JObject,
+    utterance_id: JString,
+) {
+    let backend_id = env
+        .get_field(obj, "backendId", "I")
+        .expect("Failed to get backend ID")
+        .i()
+        .expect("Failed to cast to int") as u64;
+    let backend_id = BackendId::Android(backend_id);
+    let utterance_id = CString::from(CStr::from_ptr(
+        env.get_string(&utterance_id).unwrap().as_ptr(),
+    ))
+    .into_string()
+    .unwrap();
+    let utterance_id = utterance_id.parse::<u64>().unwrap();
+    let utterance_id = UtteranceId::Android(utterance_id);
+    let mut callbacks = CALLBACKS.lock().unwrap();
+    let cb = callbacks.get_mut(&backend_id).unwrap();
+    if let Some(f) = cb.utterance_begin.as_mut() {
+        f(utterance_id);
+    }
+}
+
+#[no_mangle]
+#[allow(non_snake_case)]
+pub unsafe extern "C" fn Java_rs_tts_Bridge_onStop(
+    mut env: JNIEnv,
+    obj: JObject,
+    utterance_id: JString,
+) {
+    let backend_id = env
+        .get_field(obj, "backendId", "I")
+        .expect("Failed to get backend ID")
+        .i()
+        .expect("Failed to cast to int") as u64;
+    let backend_id = BackendId::Android(backend_id);
+    let utterance_id = CString::from(CStr::from_ptr(
+        env.get_string(&utterance_id).unwrap().as_ptr(),
+    ))
+    .into_string()
+    .unwrap();
+    let utterance_id = utterance_id.parse::<u64>().unwrap();
+    let utterance_id = UtteranceId::Android(utterance_id);
+    let mut callbacks = CALLBACKS.lock().unwrap();
+    let cb = callbacks.get_mut(&backend_id).unwrap();
+    if let Some(f) = cb.utterance_end.as_mut() {
+        f(utterance_id);
+    }
+}
+
+#[no_mangle]
+#[allow(non_snake_case)]
+pub unsafe extern "C" fn Java_rs_tts_Bridge_onDone(
+    mut env: JNIEnv,
+    obj: JObject,
+    utterance_id: JString,
+) {
+    let backend_id = env
+        .get_field(obj, "backendId", "I")
+        .expect("Failed to get backend ID")
+        .i()
+        .expect("Failed to cast to int") as u64;
+    let backend_id = BackendId::Android(backend_id);
+    let utterance_id = CString::from(CStr::from_ptr(
+        env.get_string(&utterance_id).unwrap().as_ptr(),
+    ))
+    .into_string()
+    .unwrap();
+    let utterance_id = utterance_id.parse::<u64>().unwrap();
+    let utterance_id = UtteranceId::Android(utterance_id);
+    let mut callbacks = CALLBACKS.lock().unwrap();
+    let cb = callbacks.get_mut(&backend_id).unwrap();
+    if let Some(f) = cb.utterance_stop.as_mut() {
+        f(utterance_id);
+    }
+}
+
+#[no_mangle]
+#[allow(non_snake_case)]
+pub unsafe extern "C" fn Java_rs_tts_Bridge_onError(
+    mut env: JNIEnv,
+    obj: JObject,
+    utterance_id: JString,
+) {
+    let backend_id = env
+        .get_field(obj, "backendId", "I")
+        .expect("Failed to get backend ID")
+        .i()
+        .expect("Failed to cast to int") as u64;
+    let backend_id = BackendId::Android(backend_id);
+    let utterance_id = CString::from(CStr::from_ptr(
+        env.get_string(&utterance_id).unwrap().as_ptr(),
+    ))
+    .into_string()
+    .unwrap();
+    let utterance_id = utterance_id.parse::<u64>().unwrap();
+    let utterance_id = UtteranceId::Android(utterance_id);
+    let mut callbacks = CALLBACKS.lock().unwrap();
+    let cb = callbacks.get_mut(&backend_id).unwrap();
+    if let Some(f) = cb.utterance_end.as_mut() {
+        f(utterance_id);
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct Android {
+    id: BackendId,
+    tts: GlobalRef,
+    rate: f32,
+    pitch: f32,
+}
+
+impl Android {
+    pub(crate) fn new() -> Result<Self, Error> {
+        info!("Initializing Android backend");
+        let mut backend_id = NEXT_BACKEND_ID.lock().unwrap();
+        let bid = *backend_id;
+        let id = BackendId::Android(bid);
+        *backend_id += 1;
+        drop(backend_id);
+        let ctx = ndk_context::android_context();
+        let vm = unsafe { jni::JavaVM::from_raw(ctx.vm().cast()) }?;
+        let context = unsafe { JObject::from_raw(ctx.context().cast()) };
+        let mut env = vm.attach_current_thread_permanently()?;
+        let bridge = BRIDGE.lock().unwrap();
+        if let Some(bridge) = &*bridge {
+            let bridge = env.new_object(bridge, "(I)V", &[(bid as jint).into()])?;
+            let tts = env.new_object(
+                "android/speech/tts/TextToSpeech",
+                "(Landroid/content/Context;Landroid/speech/tts/TextToSpeech$OnInitListener;)V",
+                &[(&context).into(), (&bridge).into()],
+            )?;
+            env.call_method(
+                &tts,
+                "setOnUtteranceProgressListener",
+                "(Landroid/speech/tts/UtteranceProgressListener;)I",
+                &[(&bridge).into()],
+            )?;
+            {
+                let mut pending = PENDING_INITIALIZATIONS.write().unwrap();
+                (*pending).insert(bid);
+            }
+            let tts = env.new_global_ref(tts)?;
+            // This hack makes my brain bleed.
+            const MAX_WAIT_TIME: Duration = Duration::from_millis(500);
+            let start = Instant::now();
+            // Wait a max of 500ms for initialization, then return an error to avoid hanging.
+            loop {
+                {
+                    let pending = PENDING_INITIALIZATIONS.read().unwrap();
+                    if !(*pending).contains(&bid) {
+                        break;
+                    }
+                    if start.elapsed() > MAX_WAIT_TIME {
+                        return Err(Error::OperationFailed);
+                    }
+                }
+                thread::sleep(Duration::from_millis(5));
+            }
+            Ok(Self {
+                id,
+                tts,
+                rate: 1.,
+                pitch: 1.,
+            })
+        } else {
+            Err(Error::NoneError)
+        }
+    }
+
+    fn vm() -> Result<JavaVM, jni::errors::Error> {
+        let ctx = ndk_context::android_context();
+        unsafe { jni::JavaVM::from_raw(ctx.vm().cast()) }
+    }
+}
+
+impl Backend for Android {
+    fn id(&self) -> Option<BackendId> {
+        Some(self.id)
+    }
+
+    fn supported_features(&self) -> Features {
+        Features {
+            stop: true,
+            rate: true,
+            pitch: true,
+            volume: false,
+            is_speaking: true,
+            utterance_callbacks: true,
+            voice: false,
+            get_voice: false,
+        }
+    }
+
+    fn speak(&mut self, text: &str, interrupt: bool) -> Result<Option<UtteranceId>, Error> {
+        let vm = Self::vm()?;
+        let mut env = vm.get_env()?;
+        let tts = self.tts.as_obj();
+        let text = env.new_string(text)?;
+        let queue_mode = if interrupt { 0 } else { 1 };
+        let mut utterance_id = NEXT_UTTERANCE_ID.lock().unwrap();
+        let uid = *utterance_id;
+        *utterance_id += 1;
+        drop(utterance_id);
+        let id = UtteranceId::Android(uid);
+        let uid = env.new_string(uid.to_string())?;
+        let rv = env.call_method(
+            tts,
+            "speak",
+            "(Ljava/lang/CharSequence;ILandroid/os/Bundle;Ljava/lang/String;)I",
+            &[
+                (&text).into(),
+                queue_mode.into(),
+                (&JObject::null()).into(),
+                (&uid).into(),
+            ],
+        )?;
+        let rv = rv.i()?;
+        if rv == 0 {
+            Ok(Some(id))
+        } else {
+            Err(Error::OperationFailed)
+        }
+    }
+
+    fn stop(&mut self) -> Result<(), Error> {
+        let vm = Self::vm()?;
+        let mut env = vm.get_env()?;
+        let tts = self.tts.as_obj();
+        let rv = env.call_method(tts, "stop", "()I", &[])?;
+        let rv = rv.i()?;
+        if rv == 0 {
+            Ok(())
+        } else {
+            Err(Error::OperationFailed)
+        }
+    }
+
+    fn min_rate(&self) -> f32 {
+        0.1
+    }
+
+    fn max_rate(&self) -> f32 {
+        10.
+    }
+
+    fn normal_rate(&self) -> f32 {
+        1.
+    }
+
+    fn get_rate(&self) -> Result<f32, Error> {
+        Ok(self.rate)
+    }
+
+    fn set_rate(&mut self, rate: f32) -> Result<(), Error> {
+        let vm = Self::vm()?;
+        let mut env = vm.get_env()?;
+        let tts = self.tts.as_obj();
+        let rate = rate as jfloat;
+        let rv = env.call_method(tts, "setSpeechRate", "(F)I", &[rate.into()])?;
+        let rv = rv.i()?;
+        if rv == 0 {
+            self.rate = rate;
+            Ok(())
+        } else {
+            Err(Error::OperationFailed)
+        }
+    }
+
+    fn min_pitch(&self) -> f32 {
+        0.1
+    }
+
+    fn max_pitch(&self) -> f32 {
+        2.
+    }
+
+    fn normal_pitch(&self) -> f32 {
+        1.
+    }
+
+    fn get_pitch(&self) -> Result<f32, Error> {
+        Ok(self.pitch)
+    }
+
+    fn set_pitch(&mut self, pitch: f32) -> Result<(), Error> {
+        let vm = Self::vm()?;
+        let mut env = vm.get_env()?;
+        let tts = self.tts.as_obj();
+        let pitch = pitch as jfloat;
+        let rv = env.call_method(tts, "setPitch", "(F)I", &[pitch.into()])?;
+        let rv = rv.i()?;
+        if rv == 0 {
+            self.pitch = pitch;
+            Ok(())
+        } else {
+            Err(Error::OperationFailed)
+        }
+    }
+
+    fn min_volume(&self) -> f32 {
+        todo!()
+    }
+
+    fn max_volume(&self) -> f32 {
+        todo!()
+    }
+
+    fn normal_volume(&self) -> f32 {
+        todo!()
+    }
+
+    fn get_volume(&self) -> Result<f32, Error> {
+        todo!()
+    }
+
+    fn set_volume(&mut self, _volume: f32) -> Result<(), Error> {
+        todo!()
+    }
+
+    fn is_speaking(&self) -> Result<bool, Error> {
+        let vm = Self::vm()?;
+        let mut env = vm.get_env()?;
+        let tts = self.tts.as_obj();
+        let rv = env.call_method(tts, "isSpeaking", "()Z", &[])?;
+        let rv = rv.z()?;
+        Ok(rv)
+    }
+
+    fn voice(&self) -> Result<Option<Voice>, Error> {
+        unimplemented!()
+    }
+
+    fn voices(&self) -> Result<Vec<Voice>, Error> {
+        unimplemented!()
+    }
+
+    fn set_voice(&mut self, _voice: &Voice) -> Result<(), Error> {
+        unimplemented!()
+    }
+}

src/backends/appkit.rs

@@ -1,5 +1,4 @@
 #[cfg(target_os = "macos")]
-#[link(name = "AppKit", kind = "framework")]
 use cocoa_foundation::base::{id, nil};
 use cocoa_foundation::foundation::NSString;
 use log::{info, trace};
@@ -7,17 +6,18 @@ use objc::declare::ClassDecl;
 use objc::runtime::*;
 use objc::*;
 
-use crate::{Backend, Error, Features};
+use crate::{Backend, BackendId, Error, Features, UtteranceId, Voice};
 
-pub struct AppKit(*mut Object, *mut Object);
+#[derive(Clone, Debug)]
+pub(crate) struct AppKit(*mut Object, *mut Object);
 
 impl AppKit {
-    pub fn new() -> Self {
+    pub(crate) fn new() -> Result<Self, Error> {
         info!("Initializing AppKit backend");
         unsafe {
             let obj: *mut Object = msg_send![class!(NSSpeechSynthesizer), new];
-            let mut decl =
-                ClassDecl::new("MyNSSpeechSynthesizerDelegate", class!(NSObject)).unwrap();
+            let mut decl = ClassDecl::new("MyNSSpeechSynthesizerDelegate", class!(NSObject))
+                .ok_or(Error::OperationFailed)?;
             decl.add_ivar::<id>("synth");
             decl.add_ivar::<id>("strings");
 
@@ -46,13 +46,15 @@ impl AppKit {
             ) {
                 unsafe {
                     let strings: id = *this.get_ivar("strings");
-                    let str: id = msg_send!(strings, firstObject);
-                    let _: () = msg_send![str, release];
-                    let _: () = msg_send!(strings, removeObjectAtIndex:0);
                     let count: u32 = msg_send![strings, count];
                     if count > 0 {
                         let str: id = msg_send!(strings, firstObject);
-                        let _: BOOL = msg_send![synth, startSpeakingString: str];
+                        let _: () = msg_send![str, release];
+                        let _: () = msg_send!(strings, removeObjectAtIndex:0);
+                        if count > 1 {
+                            let str: id = msg_send!(strings, firstObject);
+                            let _: BOOL = msg_send![synth, startSpeakingString: str];
+                        }
                     }
                 }
             }
@@ -81,27 +83,37 @@ impl AppKit {
 
             let delegate_class = decl.register();
             let delegate_obj: *mut Object = msg_send![delegate_class, new];
-            delegate_obj.as_mut().unwrap().set_ivar("synth", obj);
+            delegate_obj
+                .as_mut()
+                .ok_or(Error::OperationFailed)?
+                .set_ivar("synth", obj);
             let strings: id = msg_send![class!(NSMutableArray), new];
-            delegate_obj.as_mut().unwrap().set_ivar("strings", strings);
+            delegate_obj
+                .as_mut()
+                .ok_or(Error::OperationFailed)?
+                .set_ivar("strings", strings);
             let _: Object = msg_send![obj, setDelegate: delegate_obj];
-            AppKit(obj, delegate_obj)
+            Ok(AppKit(obj, delegate_obj))
         }
     }
 }
 
 impl Backend for AppKit {
+    fn id(&self) -> Option<BackendId> {
+        None
+    }
+
     fn supported_features(&self) -> Features {
         Features {
             stop: true,
             rate: true,
-            pitch: false,
             volume: true,
             is_speaking: true,
+            ..Default::default()
         }
     }
 
-    fn speak(&mut self, text: &str, interrupt: bool) -> Result<(), Error> {
+    fn speak(&mut self, text: &str, interrupt: bool) -> Result<Option<UtteranceId>, Error> {
         trace!("speak({}, {})", text, interrupt);
         if interrupt {
             self.stop()?;
@@ -110,7 +122,7 @@ impl Backend for AppKit {
             let str = NSString::alloc(nil).init_str(text);
             let _: () = msg_send![self.1, enqueueAndSpeak: str];
         }
-        Ok(())
+        Ok(None)
     }
 
     fn stop(&mut self) -> Result<(), Error> {
@@ -193,7 +205,19 @@ impl Backend for AppKit {
 
     fn is_speaking(&self) -> Result<bool, Error> {
         let is_speaking: i8 = unsafe { msg_send![self.0, isSpeaking] };
-        Ok(is_speaking == YES)
+        Ok(is_speaking != NO as i8)
+    }
+
+    fn voice(&self) -> Result<Option<Voice>, Error> {
+        unimplemented!()
+    }
+
+    fn voices(&self) -> Result<Vec<Voice>, Error> {
+        unimplemented!()
+    }
+
+    fn set_voice(&mut self, _voice: &Voice) -> Result<(), Error> {
+        unimplemented!()
     }
 }
 

src/backends/av_foundation.rs

@@ -1,36 +1,165 @@
 #[cfg(any(target_os = "macos", target_os = "ios"))]
-#[link(name = "AVFoundation", kind = "framework")]
-use cocoa_foundation::base::{id, nil};
+use std::sync::Mutex;
+
+use cocoa_foundation::base::{id, nil, NO};
 use cocoa_foundation::foundation::NSString;
+use core_foundation::array::CFArray;
+use core_foundation::base::TCFType;
+use core_foundation::string::CFString;
+use lazy_static::lazy_static;
 use log::{info, trace};
-use objc::runtime::*;
-use objc::*;
+use objc::runtime::{Object, Sel};
+use objc::{class, declare::ClassDecl, msg_send, sel, sel_impl};
+use oxilangtag::LanguageTag;
 
-use crate::{Backend, Error, Features};
+use crate::{Backend, BackendId, Error, Features, Gender, UtteranceId, Voice, CALLBACKS};
 
-pub struct AvFoundation {
+#[derive(Clone, Debug)]
+pub(crate) struct AvFoundation {
+    id: BackendId,
+    delegate: *mut Object,
     synth: *mut Object,
     rate: f32,
     volume: f32,
     pitch: f32,
+    voice: Option<Voice>,
+}
+
+lazy_static! {
+    static ref NEXT_BACKEND_ID: Mutex<u64> = Mutex::new(0);
 }
 
 impl AvFoundation {
-    pub fn new() -> Self {
+    pub(crate) fn new() -> Result<Self, Error> {
         info!("Initializing AVFoundation backend");
+        let mut decl = ClassDecl::new("MyNSSpeechSynthesizerDelegate", class!(NSObject))
+            .ok_or(Error::OperationFailed)?;
+        decl.add_ivar::<u64>("backend_id");
+
+        extern "C" fn speech_synthesizer_did_start_speech_utterance(
+            this: &Object,
+            _: Sel,
+            _synth: *const Object,
+            utterance: id,
+        ) {
+            trace!("speech_synthesizer_did_start_speech_utterance");
+            unsafe {
+                let backend_id: u64 = *this.get_ivar("backend_id");
+                let backend_id = BackendId::AvFoundation(backend_id);
+                trace!("Locking callbacks");
+                let mut callbacks = CALLBACKS.lock().unwrap();
+                trace!("Locked");
+                let callbacks = callbacks.get_mut(&backend_id).unwrap();
+                if let Some(callback) = callbacks.utterance_begin.as_mut() {
+                    trace!("Calling utterance_begin");
+                    let utterance_id = UtteranceId::AvFoundation(utterance);
+                    callback(utterance_id);
+                    trace!("Called");
+                }
+            }
+            trace!("Done speech_synthesizer_did_start_speech_utterance");
+        }
+
+        extern "C" fn speech_synthesizer_did_finish_speech_utterance(
+            this: &Object,
+            _: Sel,
+            _synth: *const Object,
+            utterance: id,
+        ) {
+            trace!("speech_synthesizer_did_finish_speech_utterance");
+            unsafe {
+                let backend_id: u64 = *this.get_ivar("backend_id");
+                let backend_id = BackendId::AvFoundation(backend_id);
+                trace!("Locking callbacks");
+                let mut callbacks = CALLBACKS.lock().unwrap();
+                trace!("Locked");
+                let callbacks = callbacks.get_mut(&backend_id).unwrap();
+                if let Some(callback) = callbacks.utterance_end.as_mut() {
+                    trace!("Calling utterance_end");
+                    let utterance_id = UtteranceId::AvFoundation(utterance);
+                    callback(utterance_id);
+                    trace!("Called");
+                }
+            }
+            trace!("Done speech_synthesizer_did_finish_speech_utterance");
+        }
+
+        extern "C" fn speech_synthesizer_did_cancel_speech_utterance(
+            this: &Object,
+            _: Sel,
+            _synth: *const Object,
+            utterance: id,
+        ) {
+            trace!("speech_synthesizer_did_cancel_speech_utterance");
+            unsafe {
+                let backend_id: u64 = *this.get_ivar("backend_id");
+                let backend_id = BackendId::AvFoundation(backend_id);
+                trace!("Locking callbacks");
+                let mut callbacks = CALLBACKS.lock().unwrap();
+                trace!("Locked");
+                let callbacks = callbacks.get_mut(&backend_id).unwrap();
+                if let Some(callback) = callbacks.utterance_stop.as_mut() {
+                    trace!("Calling utterance_stop");
+                    let utterance_id = UtteranceId::AvFoundation(utterance);
+                    callback(utterance_id);
+                    trace!("Called");
+                }
+            }
+            trace!("Done speech_synthesizer_did_cancel_speech_utterance");
+        }
+
         unsafe {
+            decl.add_method(
+                sel!(speechSynthesizer:didStartSpeechUtterance:),
+                speech_synthesizer_did_start_speech_utterance
+                    as extern "C" fn(&Object, Sel, *const Object, id) -> (),
+            );
+            decl.add_method(
+                sel!(speechSynthesizer:didFinishSpeechUtterance:),
+                speech_synthesizer_did_finish_speech_utterance
+                    as extern "C" fn(&Object, Sel, *const Object, id) -> (),
+            );
+            decl.add_method(
+                sel!(speechSynthesizer:didCancelSpeechUtterance:),
+                speech_synthesizer_did_cancel_speech_utterance
+                    as extern "C" fn(&Object, Sel, *const Object, id) -> (),
+            );
+        }
+
+        let delegate_class = decl.register();
+        let delegate_obj: *mut Object = unsafe { msg_send![delegate_class, new] };
+        let mut backend_id = NEXT_BACKEND_ID.lock().unwrap();
+        let rv = unsafe {
+            trace!("Creating synth");
             let synth: *mut Object = msg_send![class!(AVSpeechSynthesizer), new];
+            trace!("Allocated {:?}", synth);
+            delegate_obj
+                .as_mut()
+                .unwrap()
+                .set_ivar("backend_id", *backend_id);
+            trace!("Set backend ID in delegate");
+            let _: () = msg_send![synth, setDelegate: delegate_obj];
+            trace!("Assigned delegate: {:?}", delegate_obj);
             AvFoundation {
-                synth: synth,
+                id: BackendId::AvFoundation(*backend_id),
+                delegate: delegate_obj,
+                synth,
                 rate: 0.5,
                 volume: 1.,
                 pitch: 1.,
+                voice: None,
             }
-        }
+        };
+        *backend_id += 1;
+        Ok(rv)
     }
 }
 
 impl Backend for AvFoundation {
+    fn id(&self) -> Option<BackendId> {
+        Some(self.id)
+    }
+
     fn supported_features(&self) -> Features {
         Features {
             stop: true,
@@ -38,24 +167,43 @@ impl Backend for AvFoundation {
             pitch: true,
             volume: true,
             is_speaking: true,
+            voice: true,
+            get_voice: false,
+            utterance_callbacks: true,
         }
     }
 
-    fn speak(&mut self, text: &str, interrupt: bool) -> Result<(), Error> {
+    fn speak(&mut self, text: &str, interrupt: bool) -> Result<Option<UtteranceId>, Error> {
         trace!("speak({}, {})", text, interrupt);
-        if interrupt {
+        if interrupt && self.is_speaking()? {
             self.stop()?;
         }
+        let mut utterance: id;
         unsafe {
-            let str = NSString::alloc(nil).init_str(text);
-            let utterance: id = msg_send![class!(AVSpeechUtterance), alloc];
-            let _: () = msg_send![utterance, initWithString: str];
+            trace!("Allocating utterance string");
+            let mut str = NSString::alloc(nil);
+            str = str.init_str(text);
+            trace!("Allocating utterance");
+            utterance = msg_send![class!(AVSpeechUtterance), alloc];
+            trace!("Initializing utterance");
+            utterance = msg_send![utterance, initWithString: str];
+            trace!("Setting rate to {}", self.rate);
             let _: () = msg_send![utterance, setRate: self.rate];
+            trace!("Setting volume to {}", self.volume);
             let _: () = msg_send![utterance, setVolume: self.volume];
+            trace!("Setting pitch to {}", self.pitch);
             let _: () = msg_send![utterance, setPitchMultiplier: self.pitch];
+            if let Some(voice) = &self.voice {
+                let mut vid = NSString::alloc(nil);
+                vid = vid.init_str(&voice.id());
+                let v: id = msg_send![class!(AVSpeechSynthesisVoice), voiceWithIdentifier: vid];
+                let _: () = msg_send![utterance, setVoice: v];
+            }
+            trace!("Enqueuing");
             let _: () = msg_send![self.synth, speakUtterance: utterance];
+            trace!("Done queuing");
         }
-        Ok(())
+        Ok(Some(UtteranceId::AvFoundation(utterance)))
     }
 
     fn stop(&mut self) -> Result<(), Error> {
@@ -105,6 +253,7 @@ impl Backend for AvFoundation {
     }
 
     fn set_pitch(&mut self, pitch: f32) -> Result<(), Error> {
+        trace!("set_pitch({})", pitch);
         self.pitch = pitch;
         Ok(())
     }
@@ -126,19 +275,65 @@ impl Backend for AvFoundation {
     }
 
     fn set_volume(&mut self, volume: f32) -> Result<(), Error> {
+        trace!("set_volume({})", volume);
         self.volume = volume;
         Ok(())
     }
 
     fn is_speaking(&self) -> Result<bool, Error> {
+        trace!("is_speaking()");
         let is_speaking: i8 = unsafe { msg_send![self.synth, isSpeaking] };
-        Ok(is_speaking == 1)
+        Ok(is_speaking != NO as i8)
+    }
+
+    fn voice(&self) -> Result<Option<Voice>, Error> {
+        unimplemented!()
+    }
+
+    fn voices(&self) -> Result<Vec<Voice>, Error> {
+        let voices: CFArray = unsafe {
+            CFArray::wrap_under_get_rule(msg_send![class!(AVSpeechSynthesisVoice), speechVoices])
+        };
+        let rv = voices
+            .iter()
+            .map(|v| {
+                let id: CFString = unsafe {
+                    CFString::wrap_under_get_rule(msg_send![*v as *const Object, identifier])
+                };
+                let name: CFString =
+                    unsafe { CFString::wrap_under_get_rule(msg_send![*v as *const Object, name]) };
+                let gender: i64 = unsafe { msg_send![*v as *const Object, gender] };
+                let gender = match gender {
+                    1 => Some(Gender::Male),
+                    2 => Some(Gender::Female),
+                    _ => None,
+                };
+                let language: CFString = unsafe {
+                    CFString::wrap_under_get_rule(msg_send![*v as *const Object, language])
+                };
+                let language = language.to_string();
+                let language = LanguageTag::parse(language).unwrap();
+                Voice {
+                    id: id.to_string(),
+                    name: name.to_string(),
+                    gender,
+                    language,
+                }
+            })
+            .collect();
+        Ok(rv)
+    }
+
+    fn set_voice(&mut self, voice: &Voice) -> Result<(), Error> {
+        self.voice = Some(voice.clone());
+        Ok(())
     }
 }
 
 impl Drop for AvFoundation {
     fn drop(&mut self) {
         unsafe {
+            let _: Object = msg_send![self.delegate, release];
             let _: Object = msg_send![self.synth, release];
         }
     }

src/backends/mod.rs

@@ -1,11 +1,11 @@
 #[cfg(target_os = "linux")]
 mod speech_dispatcher;
 
-#[cfg(windows)]
+#[cfg(all(windows, feature = "tolk"))]
 mod tolk;
 
 #[cfg(windows)]
-pub(crate) mod winrt;
+mod winrt;
 
 #[cfg(target_arch = "wasm32")]
 mod web;
@@ -16,17 +16,26 @@ mod appkit;
 #[cfg(any(target_os = "macos", target_os = "ios"))]
 mod av_foundation;
 
+#[cfg(target_os = "android")]
+mod android;
+
 #[cfg(target_os = "linux")]
-pub use self::speech_dispatcher::*;
+pub(crate) use self::speech_dispatcher::*;
+
+#[cfg(all(windows, feature = "tolk"))]
+pub(crate) use self::tolk::*;
 
 #[cfg(windows)]
-pub use self::tolk::*;
+pub(crate) use self::winrt::*;
 
 #[cfg(target_arch = "wasm32")]
-pub use self::web::*;
+pub(crate) use self::web::*;
 
 #[cfg(target_os = "macos")]
-pub use self::appkit::*;
+pub(crate) use self::appkit::*;
 
 #[cfg(any(target_os = "macos", target_os = "ios"))]
-pub use self::av_foundation::*;
+pub(crate) use self::av_foundation::*;
+
+#[cfg(target_os = "android")]
+pub(crate) use self::android::*;

src/backends/speech_dispatcher.rs

@@ -1,49 +1,116 @@
 #[cfg(target_os = "linux")]
+use std::{collections::HashMap, sync::Mutex};
+
+use lazy_static::*;
 use log::{info, trace};
+use oxilangtag::LanguageTag;
 use speech_dispatcher::*;
 
-use crate::{Backend, Error, Features};
+use crate::{Backend, BackendId, Error, Features, UtteranceId, Voice, CALLBACKS};
 
-pub struct SpeechDispatcher(Connection);
+#[derive(Clone, Debug)]
+pub(crate) struct SpeechDispatcher(Connection);
+
+lazy_static! {
+    static ref SPEAKING: Mutex<HashMap<usize, bool>> = {
+        let m: HashMap<usize, bool> = HashMap::new();
+        Mutex::new(m)
+    };
+}
 
 impl SpeechDispatcher {
-    pub fn new() -> Self {
+    pub(crate) fn new() -> std::result::Result<Self, Error> {
         info!("Initializing SpeechDispatcher backend");
-        let connection = speech_dispatcher::Connection::open("tts", "tts", "tts", Mode::Single);
-        SpeechDispatcher(connection)
+        let connection = speech_dispatcher::Connection::open("tts", "tts", "tts", Mode::Threaded)?;
+        let sd = SpeechDispatcher(connection);
+        let mut speaking = SPEAKING.lock().unwrap();
+        speaking.insert(sd.0.client_id(), false);
+        sd.0.on_begin(Some(Box::new(|msg_id, client_id| {
+            let mut speaking = SPEAKING.lock().unwrap();
+            speaking.insert(client_id, true);
+            let mut callbacks = CALLBACKS.lock().unwrap();
+            let backend_id = BackendId::SpeechDispatcher(client_id);
+            let cb = callbacks.get_mut(&backend_id).unwrap();
+            let utterance_id = UtteranceId::SpeechDispatcher(msg_id as u64);
+            if let Some(f) = cb.utterance_begin.as_mut() {
+                f(utterance_id);
+            }
+        })));
+        sd.0.on_end(Some(Box::new(|msg_id, client_id| {
+            let mut speaking = SPEAKING.lock().unwrap();
+            speaking.insert(client_id, false);
+            let mut callbacks = CALLBACKS.lock().unwrap();
+            let backend_id = BackendId::SpeechDispatcher(client_id);
+            let cb = callbacks.get_mut(&backend_id).unwrap();
+            let utterance_id = UtteranceId::SpeechDispatcher(msg_id as u64);
+            if let Some(f) = cb.utterance_end.as_mut() {
+                f(utterance_id);
+            }
+        })));
+        sd.0.on_cancel(Some(Box::new(|msg_id, client_id| {
+            let mut speaking = SPEAKING.lock().unwrap();
+            speaking.insert(client_id, false);
+            let mut callbacks = CALLBACKS.lock().unwrap();
+            let backend_id = BackendId::SpeechDispatcher(client_id);
+            let cb = callbacks.get_mut(&backend_id).unwrap();
+            let utterance_id = UtteranceId::SpeechDispatcher(msg_id as u64);
+            if let Some(f) = cb.utterance_stop.as_mut() {
+                f(utterance_id);
+            }
+        })));
+        sd.0.on_pause(Some(Box::new(|_msg_id, client_id| {
+            let mut speaking = SPEAKING.lock().unwrap();
+            speaking.insert(client_id, false);
+        })));
+        sd.0.on_resume(Some(Box::new(|_msg_id, client_id| {
+            let mut speaking = SPEAKING.lock().unwrap();
+            speaking.insert(client_id, true);
+        })));
+        Ok(sd)
     }
 }
 
 impl Backend for SpeechDispatcher {
+    fn id(&self) -> Option<BackendId> {
+        Some(BackendId::SpeechDispatcher(self.0.client_id()))
+    }
+
     fn supported_features(&self) -> Features {
         Features {
             stop: true,
             rate: true,
             pitch: true,
             volume: true,
-            is_speaking: false,
+            is_speaking: true,
+            voice: true,
+            get_voice: false,
+            utterance_callbacks: true,
         }
     }
 
-    fn speak(&mut self, text: &str, interrupt: bool) -> Result<(), Error> {
+    fn speak(&mut self, text: &str, interrupt: bool) -> Result<Option<UtteranceId>, Error> {
         trace!("speak({}, {})", text, interrupt);
         if interrupt {
             self.stop()?;
         }
         let single_char = text.to_string().capacity() == 1;
         if single_char {
-            self.0.set_punctuation(Punctuation::All);
+            self.0.set_punctuation(Punctuation::All)?;
         }
-        self.0.say(Priority::Important, text);
+        let id = self.0.say(Priority::Important, text);
         if single_char {
-            self.0.set_punctuation(Punctuation::None);
+            self.0.set_punctuation(Punctuation::None)?;
+        }
+        if let Some(id) = id {
+            Ok(Some(UtteranceId::SpeechDispatcher(id)))
+        } else {
+            Err(Error::NoneError)
         }
-        Ok(())
     }
 
     fn stop(&mut self) -> Result<(), Error> {
         trace!("stop()");
-        self.0.cancel();
+        self.0.cancel()?;
         Ok(())
     }
 
@@ -64,7 +131,7 @@ impl Backend for SpeechDispatcher {
     }
 
     fn set_rate(&mut self, rate: f32) -> Result<(), Error> {
-        self.0.set_voice_rate(rate as i32);
+        self.0.set_voice_rate(rate as i32)?;
         Ok(())
     }
 
@@ -85,7 +152,7 @@ impl Backend for SpeechDispatcher {
     }
 
     fn set_pitch(&mut self, pitch: f32) -> Result<(), Error> {
-        self.0.set_voice_pitch(pitch as i32);
+        self.0.set_voice_pitch(pitch as i32)?;
         Ok(())
     }
 
@@ -106,11 +173,50 @@ impl Backend for SpeechDispatcher {
     }
 
     fn set_volume(&mut self, volume: f32) -> Result<(), Error> {
-        self.0.set_volume(volume as i32);
+        self.0.set_volume(volume as i32)?;
         Ok(())
     }
 
     fn is_speaking(&self) -> Result<bool, Error> {
+        let speaking = SPEAKING.lock().unwrap();
+        let is_speaking = speaking.get(&self.0.client_id()).unwrap();
+        Ok(*is_speaking)
+    }
+
+    fn voices(&self) -> Result<Vec<Voice>, Error> {
+        let rv = self
+            .0
+            .list_synthesis_voices()?
+            .iter()
+            .filter(|v| LanguageTag::parse(v.language.clone()).is_ok())
+            .map(|v| Voice {
+                id: v.name.clone(),
+                name: v.name.clone(),
+                gender: None,
+                language: LanguageTag::parse(v.language.clone()).unwrap(),
+            })
+            .collect::<Vec<Voice>>();
+        Ok(rv)
+    }
+
+    fn voice(&self) -> Result<Option<Voice>, Error> {
         unimplemented!()
     }
+
+    fn set_voice(&mut self, voice: &Voice) -> Result<(), Error> {
+        for v in self.0.list_synthesis_voices()? {
+            if v.name == voice.name {
+                self.0.set_synthesis_voice(&v)?;
+                return Ok(());
+            }
+        }
+        Err(Error::OperationFailed)
+    }
+}
+
+impl Drop for SpeechDispatcher {
+    fn drop(&mut self) {
+        let mut speaking = SPEAKING.lock().unwrap();
+        speaking.remove(&self.0.client_id());
+    }
 }

src/backends/tolk.rs

@@ -1,13 +1,16 @@
-#[cfg(windows)]
+#[cfg(all(windows, feature = "tolk"))]
+use std::sync::Arc;
+
 use log::{info, trace};
 use tolk::Tolk as TolkPtr;
 
-use crate::{Backend, Error, Features};
+use crate::{Backend, BackendId, Error, Features, UtteranceId, Voice};
 
-pub struct Tolk(TolkPtr);
+#[derive(Clone, Debug)]
+pub(crate) struct Tolk(Arc<TolkPtr>);
 
 impl Tolk {
-    pub fn new() -> Option<Self> {
+    pub(crate) fn new() -> Option<Self> {
         info!("Initializing Tolk backend");
         let tolk = TolkPtr::new();
         if tolk.detect_screen_reader().is_some() {
@@ -19,20 +22,21 @@ impl Tolk {
 }
 
 impl Backend for Tolk {
+    fn id(&self) -> Option<BackendId> {
+        None
+    }
+
     fn supported_features(&self) -> Features {
         Features {
             stop: true,
-            rate: false,
-            pitch: false,
-            volume: false,
-            is_speaking: false,
+            ..Default::default()
         }
     }
 
-    fn speak(&mut self, text: &str, interrupt: bool) -> Result<(), Error> {
+    fn speak(&mut self, text: &str, interrupt: bool) -> Result<Option<UtteranceId>, Error> {
         trace!("speak({}, {})", text, interrupt);
         self.0.speak(text, interrupt);
-        Ok(())
+        Ok(None)
     }
 
     fn stop(&mut self) -> Result<(), Error> {
@@ -104,4 +108,16 @@ impl Backend for Tolk {
     fn is_speaking(&self) -> Result<bool, Error> {
         unimplemented!()
     }
+
+    fn voice(&self) -> Result<Option<Voice>, Error> {
+        unimplemented!()
+    }
+
+    fn voices(&self) -> Result<Vec<Voice>, Error> {
+        unimplemented!()
+    }
+
+    fn set_voice(&mut self, _voice: &Voice) -> Result<(), Error> {
+        unimplemented!()
+    }
 }

src/backends/web.rs

@@ -1,27 +1,54 @@
 #[cfg(target_arch = "wasm32")]
+use std::sync::Mutex;
+
+use lazy_static::lazy_static;
 use log::{info, trace};
-use web_sys::SpeechSynthesisUtterance;
+use oxilangtag::LanguageTag;
+use wasm_bindgen::prelude::*;
+use wasm_bindgen::JsCast;
+use web_sys::{
+    SpeechSynthesisErrorCode, SpeechSynthesisErrorEvent, SpeechSynthesisEvent,
+    SpeechSynthesisUtterance, SpeechSynthesisVoice,
+};
 
-use crate::{Backend, Error, Features};
+use crate::{Backend, BackendId, Error, Features, UtteranceId, Voice, CALLBACKS};
 
+#[derive(Clone, Debug)]
 pub struct Web {
+    id: BackendId,
     rate: f32,
     pitch: f32,
     volume: f32,
+    voice: Option<SpeechSynthesisVoice>,
+}
+
+lazy_static! {
+    static ref NEXT_BACKEND_ID: Mutex<u64> = Mutex::new(0);
+    static ref UTTERANCE_MAPPINGS: Mutex<Vec<(BackendId, UtteranceId)>> = Mutex::new(Vec::new());
+    static ref NEXT_UTTERANCE_ID: Mutex<u64> = Mutex::new(0);
 }
 
 impl Web {
     pub fn new() -> Result<Self, Error> {
         info!("Initializing Web backend");
-        Ok(Web {
+        let mut backend_id = NEXT_BACKEND_ID.lock().unwrap();
+        let rv = Web {
+            id: BackendId::Web(*backend_id),
             rate: 1.,
             pitch: 1.,
             volume: 1.,
-        })
+            voice: None,
+        };
+        *backend_id += 1;
+        Ok(rv)
     }
 }
 
 impl Backend for Web {
+    fn id(&self) -> Option<BackendId> {
+        Some(self.id)
+    }
+
     fn supported_features(&self) -> Features {
         Features {
             stop: true,
@@ -29,23 +56,69 @@ impl Backend for Web {
             pitch: true,
             volume: true,
             is_speaking: true,
+            voice: true,
+            get_voice: true,
+            utterance_callbacks: true,
         }
     }
 
-    fn speak(&mut self, text: &str, interrupt: bool) -> Result<(), Error> {
+    fn speak(&mut self, text: &str, interrupt: bool) -> Result<Option<UtteranceId>, Error> {
         trace!("speak({}, {})", text, interrupt);
         let utterance = SpeechSynthesisUtterance::new_with_text(text).unwrap();
         utterance.set_rate(self.rate);
         utterance.set_pitch(self.pitch);
         utterance.set_volume(self.volume);
+        if self.voice.is_some() {
+            utterance.set_voice(self.voice.as_ref());
+        }
+        let id = self.id().unwrap();
+        let mut uid = NEXT_UTTERANCE_ID.lock().unwrap();
+        let utterance_id = UtteranceId::Web(*uid);
+        *uid += 1;
+        drop(uid);
+        let mut mappings = UTTERANCE_MAPPINGS.lock().unwrap();
+        mappings.push((self.id, utterance_id));
+        drop(mappings);
+        let callback = Closure::wrap(Box::new(move |_evt: SpeechSynthesisEvent| {
+            let mut callbacks = CALLBACKS.lock().unwrap();
+            let callback = callbacks.get_mut(&id).unwrap();
+            if let Some(f) = callback.utterance_begin.as_mut() {
+                f(utterance_id);
+            }
+        }) as Box<dyn Fn(_)>);
+        utterance.set_onstart(Some(callback.as_ref().unchecked_ref()));
+        let callback = Closure::wrap(Box::new(move |_evt: SpeechSynthesisEvent| {
+            let mut callbacks = CALLBACKS.lock().unwrap();
+            let callback = callbacks.get_mut(&id).unwrap();
+            if let Some(f) = callback.utterance_end.as_mut() {
+                f(utterance_id);
+            }
+            let mut mappings = UTTERANCE_MAPPINGS.lock().unwrap();
+            mappings.retain(|v| v.1 != utterance_id);
+        }) as Box<dyn Fn(_)>);
+        utterance.set_onend(Some(callback.as_ref().unchecked_ref()));
+        let callback = Closure::wrap(Box::new(move |evt: SpeechSynthesisErrorEvent| {
+            if evt.error() == SpeechSynthesisErrorCode::Canceled {
+                let mut callbacks = CALLBACKS.lock().unwrap();
+                let callback = callbacks.get_mut(&id).unwrap();
+                if let Some(f) = callback.utterance_stop.as_mut() {
+                    f(utterance_id);
+                }
+            }
+            let mut mappings = UTTERANCE_MAPPINGS.lock().unwrap();
+            mappings.retain(|v| v.1 != utterance_id);
+        }) as Box<dyn Fn(_)>);
+        utterance.set_onerror(Some(callback.as_ref().unchecked_ref()));
         if interrupt {
             self.stop()?;
         }
         if let Some(window) = web_sys::window() {
             let speech_synthesis = window.speech_synthesis().unwrap();
             speech_synthesis.speak(&utterance);
+            Ok(Some(utterance_id))
+        } else {
+            Err(Error::NoneError)
         }
-        Ok(())
     }
 
     fn stop(&mut self) -> Result<(), Error> {
@@ -131,4 +204,72 @@ impl Backend for Web {
             Err(Error::NoneError)
         }
     }
+
+    fn voice(&self) -> Result<Option<Voice>, Error> {
+        if let Some(voice) = &self.voice {
+            Ok(Some(voice.clone().into()))
+        } else {
+            if let Some(window) = web_sys::window() {
+                let speech_synthesis = window.speech_synthesis().unwrap();
+                for voice in speech_synthesis.get_voices().iter() {
+                    let voice: SpeechSynthesisVoice = voice.into();
+                    if voice.default() {
+                        return Ok(Some(voice.into()));
+                    }
+                }
+            } else {
+                return Err(Error::NoneError);
+            }
+            Ok(None)
+        }
+    }
+
+    fn voices(&self) -> Result<Vec<Voice>, Error> {
+        if let Some(window) = web_sys::window() {
+            let speech_synthesis = window.speech_synthesis().unwrap();
+            let mut rv: Vec<Voice> = vec![];
+            for v in speech_synthesis.get_voices().iter() {
+                let v: SpeechSynthesisVoice = v.into();
+                rv.push(v.into());
+            }
+            Ok(rv)
+        } else {
+            Err(Error::NoneError)
+        }
+    }
+
+    fn set_voice(&mut self, voice: &Voice) -> Result<(), Error> {
+        if let Some(window) = web_sys::window() {
+            let speech_synthesis = window.speech_synthesis().unwrap();
+            for v in speech_synthesis.get_voices().iter() {
+                let v: SpeechSynthesisVoice = v.into();
+                if v.voice_uri() == voice.id {
+                    self.voice = Some(v);
+                    return Ok(());
+                }
+            }
+            Err(Error::OperationFailed)
+        } else {
+            Err(Error::NoneError)
+        }
+    }
+}
+
+impl Drop for Web {
+    fn drop(&mut self) {
+        let mut mappings = UTTERANCE_MAPPINGS.lock().unwrap();
+        mappings.retain(|v| v.0 != self.id);
+    }
+}
+
+impl From<SpeechSynthesisVoice> for Voice {
+    fn from(other: SpeechSynthesisVoice) -> Self {
+        let language = LanguageTag::parse(other.lang()).unwrap();
+        Voice {
+            id: other.voice_uri(),
+            name: other.name(),
+            gender: None,
+            language,
+        }
+    }
 }

src/backends/winrt.rs

@@ -1,50 +1,150 @@
 #[cfg(windows)]
-use log::{info, trace};
-
-use tts_winrt_bindings::windows::media::core::MediaSource;
-use tts_winrt_bindings::windows::media::playback::{
-    MediaPlaybackItem, MediaPlaybackList, MediaPlaybackState, MediaPlayer,
+use std::{
+    collections::{HashMap, VecDeque},
+    sync::Mutex,
 };
-use tts_winrt_bindings::windows::media::speech_synthesis::SpeechSynthesizer;
 
-use crate::{Backend, Error, Features};
+use lazy_static::lazy_static;
+use log::{info, trace};
+use oxilangtag::LanguageTag;
+use windows::{
+    Foundation::TypedEventHandler,
+    Media::{
+        Core::MediaSource,
+        Playback::{MediaPlayer, MediaPlayerAudioCategory},
+        SpeechSynthesis::{SpeechSynthesizer, VoiceGender, VoiceInformation},
+    },
+};
 
-impl From<winrt::Error> for Error {
-    fn from(e: winrt::Error) -> Self {
-        Error::WinRT(e)
+use crate::{Backend, BackendId, Error, Features, Gender, UtteranceId, Voice, CALLBACKS};
+
+impl From<windows::core::Error> for Error {
+    fn from(e: windows::core::Error) -> Self {
+        Error::WinRt(e)
     }
 }
 
-pub struct WinRT {
+#[derive(Clone)]
+pub struct WinRt {
+    id: BackendId,
     synth: SpeechSynthesizer,
     player: MediaPlayer,
-    playback_list: MediaPlaybackList,
+    rate: f32,
+    pitch: f32,
+    volume: f32,
+    voice: VoiceInformation,
 }
 
-impl WinRT {
+struct Utterance {
+    id: UtteranceId,
+    text: String,
+    rate: f32,
+    pitch: f32,
+    volume: f32,
+    voice: VoiceInformation,
+}
+
+lazy_static! {
+    static ref NEXT_BACKEND_ID: Mutex<u64> = Mutex::new(0);
+    static ref NEXT_UTTERANCE_ID: Mutex<u64> = Mutex::new(0);
+    static ref BACKEND_TO_SPEECH_SYNTHESIZER: Mutex<HashMap<BackendId, SpeechSynthesizer>> = {
+        let v: HashMap<BackendId, SpeechSynthesizer> = HashMap::new();
+        Mutex::new(v)
+    };
+    static ref BACKEND_TO_MEDIA_PLAYER: Mutex<HashMap<BackendId, MediaPlayer>> = {
+        let v: HashMap<BackendId, MediaPlayer> = HashMap::new();
+        Mutex::new(v)
+    };
+    static ref UTTERANCES: Mutex<HashMap<BackendId, VecDeque<Utterance>>> = {
+        let utterances: HashMap<BackendId, VecDeque<Utterance>> = HashMap::new();
+        Mutex::new(utterances)
+    };
+}
+
+impl WinRt {
     pub fn new() -> std::result::Result<Self, Error> {
         info!("Initializing WinRT backend");
-        let playback_list = MediaPlaybackList::new()?;
+        let synth = SpeechSynthesizer::new()?;
         let player = MediaPlayer::new()?;
-        player.set_auto_play(true)?;
-        player.set_source(&playback_list)?;
+        player.SetRealTimePlayback(true)?;
+        player.SetAudioCategory(MediaPlayerAudioCategory::Speech)?;
+        let mut backend_id = NEXT_BACKEND_ID.lock().unwrap();
+        let bid = BackendId::WinRt(*backend_id);
+        *backend_id += 1;
+        drop(backend_id);
+        {
+            let mut utterances = UTTERANCES.lock().unwrap();
+            utterances.insert(bid, VecDeque::new());
+        }
+        let mut backend_to_media_player = BACKEND_TO_MEDIA_PLAYER.lock().unwrap();
+        backend_to_media_player.insert(bid, player.clone());
+        drop(backend_to_media_player);
+        let mut backend_to_speech_synthesizer = BACKEND_TO_SPEECH_SYNTHESIZER.lock().unwrap();
+        backend_to_speech_synthesizer.insert(bid, synth.clone());
+        drop(backend_to_speech_synthesizer);
+        let bid_clone = bid;
+        player.MediaEnded(&TypedEventHandler::new(
+            move |sender: &Option<MediaPlayer>, _args| {
+                if let Some(sender) = sender {
+                    let backend_to_media_player = BACKEND_TO_MEDIA_PLAYER.lock().unwrap();
+                    let id = backend_to_media_player.iter().find(|v| v.1 == sender);
+                    if let Some((id, _)) = id {
+                        let mut utterances = UTTERANCES.lock().unwrap();
+                        if let Some(utterances) = utterances.get_mut(id) {
+                            if let Some(utterance) = utterances.pop_front() {
+                                let mut callbacks = CALLBACKS.lock().unwrap();
+                                let callbacks = callbacks.get_mut(id).unwrap();
+                                if let Some(callback) = callbacks.utterance_end.as_mut() {
+                                    callback(utterance.id);
+                                }
+                                if let Some(utterance) = utterances.front() {
+                                    let backend_to_speech_synthesizer =
+                                        BACKEND_TO_SPEECH_SYNTHESIZER.lock().unwrap();
+                                    let id = backend_to_speech_synthesizer
+                                        .iter()
+                                        .find(|v| *v.0 == bid_clone);
+                                    if let Some((_, tts)) = id {
+                                        tts.Options()?.SetSpeakingRate(utterance.rate.into())?;
+                                        tts.Options()?.SetAudioPitch(utterance.pitch.into())?;
+                                        tts.Options()?.SetAudioVolume(utterance.volume.into())?;
+                                        tts.SetVoice(&utterance.voice)?;
+                                        let text = &utterance.text;
+                                        let stream =
+                                            tts.SynthesizeTextToStreamAsync(&text.into())?.get()?;
+                                        let content_type = stream.ContentType()?;
+                                        let source =
+                                            MediaSource::CreateFromStream(&stream, &content_type)?;
+                                        sender.SetSource(&source)?;
+                                        sender.Play()?;
+                                        if let Some(callback) = callbacks.utterance_begin.as_mut() {
+                                            callback(utterance.id);
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+                Ok(())
+            },
+        ))?;
         Ok(Self {
-            synth: SpeechSynthesizer::new()?,
-            player: player,
-            playback_list: playback_list,
+            id: bid,
+            synth,
+            player,
+            rate: 1.,
+            pitch: 1.,
+            volume: 1.,
+            voice: SpeechSynthesizer::DefaultVoice()?,
         })
     }
-
-    fn reinit_player(&mut self) -> std::result::Result<(), Error> {
-        self.playback_list = MediaPlaybackList::new()?;
-        self.player = MediaPlayer::new()?;
-        self.player.set_auto_play(true)?;
-        self.player.set_source(&self.playback_list)?;
-        Ok(())
-    }
 }
 
-impl Backend for WinRT {
+impl Backend for WinRt {
+    fn id(&self) -> Option<BackendId> {
+        Some(self.id)
+    }
+
     fn supported_features(&self) -> Features {
         Features {
             stop: true,
@@ -52,36 +152,83 @@ impl Backend for WinRT {
             pitch: true,
             volume: true,
             is_speaking: true,
+            voice: true,
+            get_voice: true,
+            utterance_callbacks: true,
         }
     }
 
-    fn speak(&mut self, text: &str, interrupt: bool) -> std::result::Result<(), Error> {
-        trace!("speak({}, {})", text, interrupt);
-        if interrupt {
+    fn speak(
+        &mut self,
+        text: &str,
+        interrupt: bool,
+    ) -> std::result::Result<Option<UtteranceId>, Error> {
+        if interrupt && self.is_speaking()? {
             self.stop()?;
         }
-        let stream = self.synth.synthesize_text_to_stream_async(text)?.get()?;
-        let content_type = stream.content_type()?;
-        let source = MediaSource::create_from_stream(stream, content_type)?;
-        let item = MediaPlaybackItem::create(source)?;
-        let state = self.player.playback_session()?.playback_state()?;
-        if state == MediaPlaybackState::Paused {
-            let index = self.playback_list.current_item_index()?;
-            let total = self.playback_list.items()?.size()?;
-            if total != 0 && index == total - 1 {
-                self.reinit_player()?;
+        let utterance_id = {
+            let mut uid = NEXT_UTTERANCE_ID.lock().unwrap();
+            let utterance_id = UtteranceId::WinRt(*uid);
+            *uid += 1;
+            utterance_id
+        };
+        let mut no_utterances = false;
+        {
+            let mut utterances = UTTERANCES.lock().unwrap();
+            if let Some(utterances) = utterances.get_mut(&self.id) {
+                no_utterances = utterances.is_empty();
+                let utterance = Utterance {
+                    id: utterance_id,
+                    text: text.into(),
+                    rate: self.rate,
+                    pitch: self.pitch,
+                    volume: self.volume,
+                    voice: self.voice.clone(),
+                };
+                utterances.push_back(utterance);
             }
         }
-        self.playback_list.items()?.append(item)?;
-        if !self.is_speaking()? {
-            self.player.play()?;
+        if no_utterances {
+            self.synth.Options()?.SetSpeakingRate(self.rate.into())?;
+            self.synth.Options()?.SetAudioPitch(self.pitch.into())?;
+            self.synth.Options()?.SetAudioVolume(self.volume.into())?;
+            self.synth.SetVoice(&self.voice)?;
+            let stream = self
+                .synth
+                .SynthesizeTextToStreamAsync(&text.into())?
+                .get()?;
+            let content_type = stream.ContentType()?;
+            let source = MediaSource::CreateFromStream(&stream, &content_type)?;
+            self.player.SetSource(&source)?;
+            self.player.Play()?;
+            let mut callbacks = CALLBACKS.lock().unwrap();
+            let callbacks = callbacks.get_mut(&self.id).unwrap();
+            if let Some(callback) = callbacks.utterance_begin.as_mut() {
+                callback(utterance_id);
+            }
         }
-        Ok(())
+        Ok(Some(utterance_id))
     }
 
     fn stop(&mut self) -> std::result::Result<(), Error> {
         trace!("stop()");
-        self.reinit_player()?;
+        if !self.is_speaking()? {
+            return Ok(());
+        }
+        let mut utterances = UTTERANCES.lock().unwrap();
+        if let Some(utterances) = utterances.get(&self.id) {
+            let mut callbacks = CALLBACKS.lock().unwrap();
+            let callbacks = callbacks.get_mut(&self.id).unwrap();
+            if let Some(callback) = callbacks.utterance_stop.as_mut() {
+                for utterance in utterances {
+                    callback(utterance.id);
+                }
+            }
+        }
+        if let Some(utterances) = utterances.get_mut(&self.id) {
+            utterances.clear();
+        }
+        self.player.Pause()?;
         Ok(())
     }
 
@@ -98,12 +245,12 @@ impl Backend for WinRT {
     }
 
     fn get_rate(&self) -> std::result::Result<f32, Error> {
-        let rate = self.synth.options()?.speaking_rate()?;
+        let rate = self.synth.Options()?.SpeakingRate()?;
         Ok(rate as f32)
     }
 
     fn set_rate(&mut self, rate: f32) -> std::result::Result<(), Error> {
-        self.synth.options()?.set_speaking_rate(rate.into())?;
+        self.rate = rate;
         Ok(())
     }
 
@@ -120,12 +267,12 @@ impl Backend for WinRT {
     }
 
     fn get_pitch(&self) -> std::result::Result<f32, Error> {
-        let pitch = self.synth.options()?.audio_pitch()?;
+        let pitch = self.synth.Options()?.AudioPitch()?;
         Ok(pitch as f32)
     }
 
     fn set_pitch(&mut self, pitch: f32) -> std::result::Result<(), Error> {
-        self.synth.options()?.set_audio_pitch(pitch.into())?;
+        self.pitch = pitch;
         Ok(())
     }
 
@@ -142,18 +289,76 @@ impl Backend for WinRT {
     }
 
     fn get_volume(&self) -> std::result::Result<f32, Error> {
-        let volume = self.synth.options()?.audio_volume()?;
+        let volume = self.synth.Options()?.AudioVolume()?;
         Ok(volume as f32)
     }
 
     fn set_volume(&mut self, volume: f32) -> std::result::Result<(), Error> {
-        self.synth.options()?.set_audio_volume(volume.into())?;
+        self.volume = volume;
         Ok(())
     }
 
     fn is_speaking(&self) -> std::result::Result<bool, Error> {
-        let state = self.player.playback_session()?.playback_state()?;
-        let playing = state == MediaPlaybackState::Opening || state == MediaPlaybackState::Playing;
-        Ok(playing)
+        let utterances = UTTERANCES.lock().unwrap();
+        let utterances = utterances.get(&self.id).unwrap();
+        Ok(!utterances.is_empty())
+    }
+
+    fn voice(&self) -> Result<Option<Voice>, Error> {
+        let voice = self.synth.Voice()?;
+        let voice = voice.try_into()?;
+        Ok(Some(voice))
+    }
+
+    fn voices(&self) -> Result<Vec<Voice>, Error> {
+        let mut rv: Vec<Voice> = vec![];
+        for voice in SpeechSynthesizer::AllVoices()? {
+            rv.push(voice.try_into()?);
+        }
+        Ok(rv)
+    }
+
+    fn set_voice(&mut self, voice: &Voice) -> Result<(), Error> {
+        for v in SpeechSynthesizer::AllVoices()? {
+            let vid: String = v.Id()?.try_into()?;
+            if vid == voice.id {
+                self.voice = v;
+                return Ok(());
+            }
+        }
+        Err(Error::OperationFailed)
+    }
+}
+
+impl Drop for WinRt {
+    fn drop(&mut self) {
+        let id = self.id;
+        let mut backend_to_media_player = BACKEND_TO_MEDIA_PLAYER.lock().unwrap();
+        backend_to_media_player.remove(&id);
+        let mut backend_to_speech_synthesizer = BACKEND_TO_SPEECH_SYNTHESIZER.lock().unwrap();
+        backend_to_speech_synthesizer.remove(&id);
+        let mut utterances = UTTERANCES.lock().unwrap();
+        utterances.remove(&id);
+    }
+}
+
+impl TryInto<Voice> for VoiceInformation {
+    type Error = Error;
+
+    fn try_into(self) -> Result<Voice, Self::Error> {
+        let gender = self.Gender()?;
+        let gender = if gender == VoiceGender::Male {
+            Gender::Male
+        } else {
+            Gender::Female
+        };
+        let language: String = self.Language()?.try_into()?;
+        let language = LanguageTag::parse(language).unwrap();
+        Ok(Voice {
+            id: self.Id()?.try_into()?,
+            name: self.DisplayName()?.try_into()?,
+            gender: Some(gender),
+            language,
+        })
     }
 }

src/lib.rs

@@ -1,74 +1,223 @@
-/*!
- * a Text-To-Speech (TTS) library providing high-level interfaces to a variety of backends.
- * Currently supported backends are:
- * * Windows
- *   * Screen readers/SAPI via Tolk
- *   * WinRT
- * * Linux via [Speech Dispatcher](https://freebsoft.org/speechd)
- * * MacOS
- *   * AppKit on MacOS 10.13 and below
- *   * AVFoundation on MacOS 10.14 and above, and iOS
- * * WebAssembly
- */
+//! * a Text-To-Speech (TTS) library providing high-level interfaces to a variety of backends.
+//!  * Currently supported backends are:
+//!  * * Windows
+//!  *   * Screen readers/SAPI via Tolk (requires `tolk` Cargo feature)
+//!  *   * WinRT
+//!  * * Linux via [Speech Dispatcher](https://freebsoft.org/speechd)
+//!  * * MacOS/iOS
+//!  *   * AppKit on MacOS 10.13 and below
+//!  *   * AVFoundation on MacOS 10.14 and above, and iOS
+//!  * * Android
+//!  * * WebAssembly
 
-use std::boxed::Box;
+use std::collections::HashMap;
 #[cfg(target_os = "macos")]
 use std::ffi::CStr;
+use std::fmt;
+use std::rc::Rc;
+#[cfg(windows)]
+use std::string::FromUtf16Error;
+use std::sync::Mutex;
+use std::{boxed::Box, sync::RwLock};
 
-#[cfg(target_os = "macos")]
+#[cfg(any(target_os = "macos", target_os = "ios"))]
 use cocoa_foundation::base::id;
+use dyn_clonable::*;
+use lazy_static::lazy_static;
 #[cfg(target_os = "macos")]
 use libc::c_char;
 #[cfg(target_os = "macos")]
 use objc::{class, msg_send, sel, sel_impl};
+pub use oxilangtag::LanguageTag;
+#[cfg(target_os = "linux")]
+use speech_dispatcher::Error as SpeechDispatcherError;
 use thiserror::Error;
+#[cfg(all(windows, feature = "tolk"))]
+use tolk::Tolk;
 
 mod backends;
 
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub enum Backends {
-    #[cfg(target_os = "linux")]
-    SpeechDispatcher,
-    #[cfg(target_arch = "wasm32")]
-    Web,
-    #[cfg(windows)]
-    Tolk,
-    #[cfg(windows)]
-    WinRT,
+    #[cfg(target_os = "android")]
+    Android,
     #[cfg(target_os = "macos")]
     AppKit,
     #[cfg(any(target_os = "macos", target_os = "ios"))]
     AvFoundation,
+    #[cfg(target_os = "linux")]
+    SpeechDispatcher,
+    #[cfg(all(windows, feature = "tolk"))]
+    Tolk,
+    #[cfg(target_arch = "wasm32")]
+    Web,
+    #[cfg(windows)]
+    WinRt,
 }
 
+impl fmt::Display for Backends {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        match self {
+            #[cfg(target_os = "android")]
+            Backends::Android => writeln!(f, "Android"),
+            #[cfg(target_os = "macos")]
+            Backends::AppKit => writeln!(f, "AppKit"),
+            #[cfg(any(target_os = "macos", target_os = "ios"))]
+            Backends::AvFoundation => writeln!(f, "AVFoundation"),
+            #[cfg(target_os = "linux")]
+            Backends::SpeechDispatcher => writeln!(f, "Speech Dispatcher"),
+            #[cfg(all(windows, feature = "tolk"))]
+            Backends::Tolk => writeln!(f, "Tolk"),
+            #[cfg(target_arch = "wasm32")]
+            Backends::Web => writeln!(f, "Web"),
+            #[cfg(windows)]
+            Backends::WinRt => writeln!(f, "Windows Runtime"),
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+pub enum BackendId {
+    #[cfg(target_os = "android")]
+    Android(u64),
+    #[cfg(any(target_os = "macos", target_os = "ios"))]
+    AvFoundation(u64),
+    #[cfg(target_os = "linux")]
+    SpeechDispatcher(usize),
+    #[cfg(target_arch = "wasm32")]
+    Web(u64),
+    #[cfg(windows)]
+    WinRt(u64),
+}
+
+impl fmt::Display for BackendId {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        match self {
+            #[cfg(target_os = "android")]
+            BackendId::Android(id) => writeln!(f, "Android({id})"),
+            #[cfg(any(target_os = "macos", target_os = "ios"))]
+            BackendId::AvFoundation(id) => writeln!(f, "AvFoundation({id})"),
+            #[cfg(target_os = "linux")]
+            BackendId::SpeechDispatcher(id) => writeln!(f, "SpeechDispatcher({id})"),
+            #[cfg(target_arch = "wasm32")]
+            BackendId::Web(id) => writeln!(f, "Web({id})"),
+            #[cfg(windows)]
+            BackendId::WinRt(id) => writeln!(f, "WinRT({id})"),
+        }
+    }
+}
+
+// # Note
+//
+// Most trait implementations are blocked by cocoa_foundation::base::id;
+// which is a type alias for objc::runtime::Object, which only implements Debug.
+#[derive(Debug)]
+#[cfg_attr(
+    not(any(target_os = "macos", target_os = "ios")),
+    derive(Clone, Copy, Eq, Hash, PartialEq, PartialOrd, Ord)
+)]
+#[cfg_attr(
+    all(feature = "serde", not(any(target_os = "macos", target_os = "ios"))),
+    derive(serde::Serialize, serde::Deserialize)
+)]
+pub enum UtteranceId {
+    #[cfg(target_os = "android")]
+    Android(u64),
+    #[cfg(any(target_os = "macos", target_os = "ios"))]
+    AvFoundation(id),
+    #[cfg(target_os = "linux")]
+    SpeechDispatcher(u64),
+    #[cfg(target_arch = "wasm32")]
+    Web(u64),
+    #[cfg(windows)]
+    WinRt(u64),
+}
+
+// # Note
+//
+// Display is not implemented by cocoa_foundation::base::id;
+// which is a type alias for objc::runtime::Object, which only implements Debug.
+#[cfg(not(any(target_os = "macos", target_os = "ios")))]
+impl fmt::Display for UtteranceId {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        match self {
+            #[cfg(target_os = "android")]
+            UtteranceId::Android(id) => writeln!(f, "Android({id})"),
+            #[cfg(target_os = "linux")]
+            UtteranceId::SpeechDispatcher(id) => writeln!(f, "SpeechDispatcher({id})"),
+            #[cfg(target_arch = "wasm32")]
+            UtteranceId::Web(id) => writeln!(f, "Web({})", id),
+            #[cfg(windows)]
+            UtteranceId::WinRt(id) => writeln!(f, "WinRt({id})"),
+        }
+    }
+}
+
+unsafe impl Send for UtteranceId {}
+
+unsafe impl Sync for UtteranceId {}
+
+#[derive(Clone, Copy, Debug, Default, Eq, Hash, PartialEq, PartialOrd, Ord)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct Features {
-    pub stop: bool,
-    pub rate: bool,
-    pub pitch: bool,
-    pub volume: bool,
     pub is_speaking: bool,
+    pub pitch: bool,
+    pub rate: bool,
+    pub stop: bool,
+    pub utterance_callbacks: bool,
+    pub voice: bool,
+    pub get_voice: bool,
+    pub volume: bool,
+}
+
+impl fmt::Display for Features {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        writeln!(f, "{self:#?}")
+    }
+}
+
+impl Features {
+    pub fn new() -> Self {
+        Self::default()
+    }
 }
 
 #[derive(Debug, Error)]
 pub enum Error {
     #[error("IO error: {0}")]
-    IO(#[from] std::io::Error),
+    Io(#[from] std::io::Error),
     #[error("Value not received")]
     NoneError,
+    #[error("Operation failed")]
+    OperationFailed,
     #[cfg(target_arch = "wasm32")]
-    #[error("JavaScript error: [0])]")]
+    #[error("JavaScript error: [0]")]
     JavaScriptError(wasm_bindgen::JsValue),
+    #[cfg(target_os = "linux")]
+    #[error("Speech Dispatcher error: {0}")]
+    SpeechDispatcher(#[from] SpeechDispatcherError),
     #[cfg(windows)]
     #[error("WinRT error")]
-    WinRT(winrt::Error),
+    WinRt(windows::core::Error),
+    #[cfg(windows)]
+    #[error("UTF string conversion failed")]
+    UtfStringConversionFailed(#[from] FromUtf16Error),
     #[error("Unsupported feature")]
     UnsupportedFeature,
     #[error("Out of range")]
     OutOfRange,
+    #[cfg(target_os = "android")]
+    #[error("JNI error: [0])]")]
+    JNI(#[from] jni::errors::Error),
 }
 
-pub trait Backend {
+#[clonable]
+pub trait Backend: Clone {
+    fn id(&self) -> Option<BackendId>;
     fn supported_features(&self) -> Features;
-    fn speak(&mut self, text: &str, interrupt: bool) -> Result<(), Error>;
+    fn speak(&mut self, text: &str, interrupt: bool) -> Result<Option<UtteranceId>, Error>;
     fn stop(&mut self) -> Result<(), Error>;
     fn min_rate(&self) -> f32;
     fn max_rate(&self) -> f32;
@@ -86,59 +235,103 @@ pub trait Backend {
     fn get_volume(&self) -> Result<f32, Error>;
     fn set_volume(&mut self, volume: f32) -> Result<(), Error>;
     fn is_speaking(&self) -> Result<bool, Error>;
+    fn voices(&self) -> Result<Vec<Voice>, Error>;
+    fn voice(&self) -> Result<Option<Voice>, Error>;
+    fn set_voice(&mut self, voice: &Voice) -> Result<(), Error>;
 }
 
-pub struct TTS(Box<dyn Backend>);
+#[derive(Default)]
+struct Callbacks {
+    utterance_begin: Option<Box<dyn FnMut(UtteranceId)>>,
+    utterance_end: Option<Box<dyn FnMut(UtteranceId)>>,
+    utterance_stop: Option<Box<dyn FnMut(UtteranceId)>>,
+}
 
-unsafe impl std::marker::Send for TTS {}
+unsafe impl Send for Callbacks {}
 
-unsafe impl std::marker::Sync for TTS {}
+unsafe impl Sync for Callbacks {}
 
-impl TTS {
-    /**
-     * Create a new `TTS` instance with the specified backend.
-     */
-    pub fn new(backend: Backends) -> Result<TTS, Error> {
-        match backend {
+lazy_static! {
+    static ref CALLBACKS: Mutex<HashMap<BackendId, Callbacks>> = {
+        let m: HashMap<BackendId, Callbacks> = HashMap::new();
+        Mutex::new(m)
+    };
+}
+
+#[derive(Clone)]
+pub struct Tts(Rc<RwLock<Box<dyn Backend>>>);
+
+unsafe impl Send for Tts {}
+
+unsafe impl Sync for Tts {}
+
+impl Tts {
+    /// Create a new `TTS` instance with the specified backend.
+    pub fn new(backend: Backends) -> Result<Tts, Error> {
+        let backend = match backend {
             #[cfg(target_os = "linux")]
-            Backends::SpeechDispatcher => Ok(TTS(Box::new(backends::SpeechDispatcher::new()))),
+            Backends::SpeechDispatcher => {
+                let tts = backends::SpeechDispatcher::new()?;
+                Ok(Tts(Rc::new(RwLock::new(Box::new(tts)))))
+            }
             #[cfg(target_arch = "wasm32")]
             Backends::Web => {
                 let tts = backends::Web::new()?;
-                Ok(TTS(Box::new(tts)))
+                Ok(Tts(Rc::new(RwLock::new(Box::new(tts)))))
             }
-            #[cfg(windows)]
+            #[cfg(all(windows, feature = "tolk"))]
             Backends::Tolk => {
                 let tts = backends::Tolk::new();
                 if let Some(tts) = tts {
-                    Ok(TTS(Box::new(tts)))
+                    Ok(Tts(Rc::new(RwLock::new(Box::new(tts)))))
                 } else {
                     Err(Error::NoneError)
                 }
             }
             #[cfg(windows)]
-            Backends::WinRT => {
-                let tts = backends::winrt::WinRT::new()?;
-                Ok(TTS(Box::new(tts)))
+            Backends::WinRt => {
+                let tts = backends::WinRt::new()?;
+                Ok(Tts(Rc::new(RwLock::new(Box::new(tts)))))
             }
             #[cfg(target_os = "macos")]
-            Backends::AppKit => Ok(TTS(Box::new(backends::AppKit::new()))),
+            Backends::AppKit => Ok(Tts(Rc::new(RwLock::new(
+                Box::new(backends::AppKit::new()?),
+            )))),
             #[cfg(any(target_os = "macos", target_os = "ios"))]
-            Backends::AvFoundation => Ok(TTS(Box::new(backends::AvFoundation::new()))),
+            Backends::AvFoundation => Ok(Tts(Rc::new(RwLock::new(Box::new(
+                backends::AvFoundation::new()?,
+            ))))),
+            #[cfg(target_os = "android")]
+            Backends::Android => {
+                let tts = backends::Android::new()?;
+                Ok(Tts(Rc::new(RwLock::new(Box::new(tts)))))
+            }
+        };
+        if let Ok(backend) = backend {
+            if let Some(id) = backend.0.read().unwrap().id() {
+                let mut callbacks = CALLBACKS.lock().unwrap();
+                callbacks.insert(id, Callbacks::default());
+            }
+            Ok(backend)
+        } else {
+            backend
         }
     }
 
-    pub fn default() -> Result<TTS, Error> {
+    #[allow(clippy::should_implement_trait)]
+    pub fn default() -> Result<Tts, Error> {
         #[cfg(target_os = "linux")]
-        let tts = TTS::new(Backends::SpeechDispatcher);
-        #[cfg(windows)]
-        let tts = if let Some(tts) = TTS::new(Backends::Tolk).ok() {
+        let tts = Tts::new(Backends::SpeechDispatcher);
+        #[cfg(all(windows, feature = "tolk"))]
+        let tts = if let Ok(tts) = Tts::new(Backends::Tolk) {
             Ok(tts)
         } else {
-            TTS::new(Backends::WinRT)
+            Tts::new(Backends::WinRt)
         };
+        #[cfg(all(windows, not(feature = "tolk")))]
+        let tts = Tts::new(Backends::WinRt);
         #[cfg(target_arch = "wasm32")]
-        let tts = TTS::new(Backends::Web);
+        let tts = Tts::new(Backends::Web);
         #[cfg(target_os = "macos")]
         let tts = unsafe {
             // Needed because the Rust NSProcessInfo structs report bogus values, and I don't want to pull in a full bindgen stack.
@@ -147,94 +340,88 @@ impl TTS {
             let str: *const c_char = msg_send![version, UTF8String];
             let str = CStr::from_ptr(str);
             let str = str.to_string_lossy();
-            let version: Vec<&str> = str.split(" ").collect();
+            let version: Vec<&str> = str.split(' ').collect();
             let version = version[1];
-            let version_parts: Vec<&str> = version.split(".").collect();
+            let version_parts: Vec<&str> = version.split('.').collect();
+            let major_version: i8 = version_parts[0].parse().unwrap();
             let minor_version: i8 = version_parts[1].parse().unwrap();
-            if minor_version >= 14 {
-                TTS::new(Backends::AvFoundation)
+            if major_version >= 11 || minor_version >= 14 {
+                Tts::new(Backends::AvFoundation)
             } else {
-                TTS::new(Backends::AppKit)
+                Tts::new(Backends::AppKit)
             }
         };
         #[cfg(target_os = "ios")]
-        let tts = TTS::new(Backends::AvFoundation);
+        let tts = Tts::new(Backends::AvFoundation);
+        #[cfg(target_os = "android")]
+        let tts = Tts::new(Backends::Android);
         tts
     }
 
-    /**
-     * Returns the features supported by this TTS engine
-     */
+    /// Returns the features supported by this TTS engine
     pub fn supported_features(&self) -> Features {
-        self.0.supported_features()
+        self.0.read().unwrap().supported_features()
     }
 
-    /**
-     * Speaks the specified text, optionally interrupting current speech.
-     */
-    pub fn speak<S: Into<String>>(&mut self, text: S, interrupt: bool) -> Result<&Self, Error> {
-        self.0.speak(text.into().as_str(), interrupt)?;
-        Ok(self)
+    /// Speaks the specified text, optionally interrupting current speech.
+    pub fn speak<S: Into<String>>(
+        &mut self,
+        text: S,
+        interrupt: bool,
+    ) -> Result<Option<UtteranceId>, Error> {
+        self.0
+            .write()
+            .unwrap()
+            .speak(text.into().as_str(), interrupt)
     }
 
-    /**
-     * Stops current speech.
-     */
+    /// Stops current speech.
     pub fn stop(&mut self) -> Result<&Self, Error> {
         let Features { stop, .. } = self.supported_features();
         if stop {
-            self.0.stop()?;
+            self.0.write().unwrap().stop()?;
             Ok(self)
         } else {
             Err(Error::UnsupportedFeature)
         }
     }
 
-    /**
-     * Returns the minimum rate for this speech synthesizer.
-     */
+    /// Returns the minimum rate for this speech synthesizer.
     pub fn min_rate(&self) -> f32 {
-        self.0.min_rate()
+        self.0.read().unwrap().min_rate()
     }
 
-    /**
-     * Returns the maximum rate for this speech synthesizer.
-     */
+    /// Returns the maximum rate for this speech synthesizer.
     pub fn max_rate(&self) -> f32 {
-        self.0.max_rate()
+        self.0.read().unwrap().max_rate()
     }
 
-    /**
-     * Returns the normal rate for this speech synthesizer.
-     */
+    /// Returns the normal rate for this speech synthesizer.
     pub fn normal_rate(&self) -> f32 {
-        self.0.normal_rate()
+        self.0.read().unwrap().normal_rate()
     }
 
-    /**
-     * Gets the current speech rate.
-     */
+    /// Gets the current speech rate.
     pub fn get_rate(&self) -> Result<f32, Error> {
         let Features { rate, .. } = self.supported_features();
         if rate {
-            self.0.get_rate()
+            self.0.read().unwrap().get_rate()
         } else {
             Err(Error::UnsupportedFeature)
         }
     }
 
-    /**
-     * Sets the desired speech rate.
-     */
+    /// Sets the desired speech rate.
     pub fn set_rate(&mut self, rate: f32) -> Result<&Self, Error> {
         let Features {
             rate: rate_feature, ..
         } = self.supported_features();
         if rate_feature {
-            if rate < self.0.min_rate() || rate > self.0.max_rate() {
+            let mut backend = self.0.write().unwrap();
+            if rate < backend.min_rate() || rate > backend.max_rate() {
                 Err(Error::OutOfRange)
             } else {
-                self.0.set_rate(rate)?;
+                backend.set_rate(rate)?;
                 Ok(self)
             }
         } else {
@@ -242,52 +429,43 @@ impl TTS {
         }
     }
 
-    /**
-     * Returns the minimum pitch for this speech synthesizer.
-     */
+    /// Returns the minimum pitch for this speech synthesizer.
     pub fn min_pitch(&self) -> f32 {
-        self.0.min_pitch()
+        self.0.read().unwrap().min_pitch()
     }
 
-    /**
-     * Returns the maximum pitch for this speech synthesizer.
-     */
+    /// Returns the maximum pitch for this speech synthesizer.
     pub fn max_pitch(&self) -> f32 {
-        self.0.max_pitch()
+        self.0.read().unwrap().max_pitch()
     }
 
-    /**
-     * Returns the normal pitch for this speech synthesizer.
-     */
+    /// Returns the normal pitch for this speech synthesizer.
     pub fn normal_pitch(&self) -> f32 {
-        self.0.normal_pitch()
+        self.0.read().unwrap().normal_pitch()
     }
 
-    /**
-     * Gets the current speech pitch.
-     */
+    /// Gets the current speech pitch.
     pub fn get_pitch(&self) -> Result<f32, Error> {
         let Features { pitch, .. } = self.supported_features();
         if pitch {
-            self.0.get_pitch()
+            self.0.read().unwrap().get_pitch()
         } else {
             Err(Error::UnsupportedFeature)
         }
     }
 
-    /**
-     * Sets the desired speech pitch.
-     */
+    /// Sets the desired speech pitch.
     pub fn set_pitch(&mut self, pitch: f32) -> Result<&Self, Error> {
         let Features {
             pitch: pitch_feature,
             ..
         } = self.supported_features();
         if pitch_feature {
-            if pitch < self.0.min_pitch() || pitch > self.0.max_pitch() {
+            let mut backend = self.0.write().unwrap();
+            if pitch < backend.min_pitch() || pitch > backend.max_pitch() {
                 Err(Error::OutOfRange)
             } else {
-                self.0.set_pitch(pitch)?;
+                backend.set_pitch(pitch)?;
                 Ok(self)
             }
         } else {
@@ -295,52 +473,43 @@ impl TTS {
         }
     }
 
-    /**
-     * Returns the minimum volume for this speech synthesizer.
-     */
+    /// Returns the minimum volume for this speech synthesizer.
     pub fn min_volume(&self) -> f32 {
-        self.0.min_volume()
+        self.0.read().unwrap().min_volume()
     }
 
-    /**
-     * Returns the maximum volume for this speech synthesizer.
-     */
+    /// Returns the maximum volume for this speech synthesizer.
     pub fn max_volume(&self) -> f32 {
-        self.0.max_volume()
+        self.0.read().unwrap().max_volume()
     }
 
-    /**
-     * Returns the normal volume for this speech synthesizer.
-     */
+    /// Returns the normal volume for this speech synthesizer.
     pub fn normal_volume(&self) -> f32 {
-        self.0.normal_volume()
+        self.0.read().unwrap().normal_volume()
     }
 
-    /**
-     * Gets the current speech volume.
-     */
+    /// Gets the current speech volume.
     pub fn get_volume(&self) -> Result<f32, Error> {
         let Features { volume, .. } = self.supported_features();
         if volume {
-            self.0.get_volume()
+            self.0.read().unwrap().get_volume()
         } else {
             Err(Error::UnsupportedFeature)
         }
     }
 
-    /**
-     * Sets the desired speech volume.
-     */
+    /// Sets the desired speech volume.
     pub fn set_volume(&mut self, volume: f32) -> Result<&Self, Error> {
         let Features {
             volume: volume_feature,
             ..
         } = self.supported_features();
         if volume_feature {
-            if volume < self.0.min_volume() || volume > self.0.max_volume() {
+            let mut backend = self.0.write().unwrap();
+            if volume < backend.min_volume() || volume > backend.max_volume() {
                 Err(Error::OutOfRange)
             } else {
-                self.0.set_volume(volume)?;
+                backend.set_volume(volume)?;
                 Ok(self)
             }
         } else {
@@ -348,15 +517,167 @@ impl TTS {
         }
     }
 
-    /**
-     * Returns whether this speech synthesizer is speaking.
-     */
+    /// Returns whether this speech synthesizer is speaking.
     pub fn is_speaking(&self) -> Result<bool, Error> {
         let Features { is_speaking, .. } = self.supported_features();
         if is_speaking {
-            self.0.is_speaking()
+            self.0.read().unwrap().is_speaking()
         } else {
             Err(Error::UnsupportedFeature)
         }
     }
+
+    /// Returns list of available voices.
+    pub fn voices(&self) -> Result<Vec<Voice>, Error> {
+        let Features { voice, .. } = self.supported_features();
+        if voice {
+            self.0.read().unwrap().voices()
+        } else {
+            Err(Error::UnsupportedFeature)
+        }
+    }
+
+    /// Return the current speaking voice.
+    pub fn voice(&self) -> Result<Option<Voice>, Error> {
+        let Features { get_voice, .. } = self.supported_features();
+        if get_voice {
+            self.0.read().unwrap().voice()
+        } else {
+            Err(Error::UnsupportedFeature)
+        }
+    }
+
+    /// Set speaking voice.
+    pub fn set_voice(&mut self, voice: &Voice) -> Result<(), Error> {
+        let Features {
+            voice: voice_feature,
+            ..
+        } = self.supported_features();
+        if voice_feature {
+            self.0.write().unwrap().set_voice(voice)
+        } else {
+            Err(Error::UnsupportedFeature)
+        }
+    }
+
+    /// Called when this speech synthesizer begins speaking an utterance.
+    pub fn on_utterance_begin(
+        &self,
+        callback: Option<Box<dyn FnMut(UtteranceId)>>,
+    ) -> Result<(), Error> {
+        let Features {
+            utterance_callbacks,
+            ..
+        } = self.supported_features();
+        if utterance_callbacks {
+            let mut callbacks = CALLBACKS.lock().unwrap();
+            let id = self.0.read().unwrap().id().unwrap();
+            let callbacks = callbacks.get_mut(&id).unwrap();
+            callbacks.utterance_begin = callback;
+            Ok(())
+        } else {
+            Err(Error::UnsupportedFeature)
+        }
+    }
+
+    /// Called when this speech synthesizer finishes speaking an utterance.
+    pub fn on_utterance_end(
+        &self,
+        callback: Option<Box<dyn FnMut(UtteranceId)>>,
+    ) -> Result<(), Error> {
+        let Features {
+            utterance_callbacks,
+            ..
+        } = self.supported_features();
+        if utterance_callbacks {
+            let mut callbacks = CALLBACKS.lock().unwrap();
+            let id = self.0.read().unwrap().id().unwrap();
+            let callbacks = callbacks.get_mut(&id).unwrap();
+            callbacks.utterance_end = callback;
+            Ok(())
+        } else {
+            Err(Error::UnsupportedFeature)
+        }
+    }
+
+    /// Called when this speech synthesizer is stopped and still has utterances in its queue.
+    pub fn on_utterance_stop(
+        &self,
+        callback: Option<Box<dyn FnMut(UtteranceId)>>,
+    ) -> Result<(), Error> {
+        let Features {
+            utterance_callbacks,
+            ..
+        } = self.supported_features();
+        if utterance_callbacks {
+            let mut callbacks = CALLBACKS.lock().unwrap();
+            let id = self.0.read().unwrap().id().unwrap();
+            let callbacks = callbacks.get_mut(&id).unwrap();
+            callbacks.utterance_stop = callback;
+            Ok(())
+        } else {
+            Err(Error::UnsupportedFeature)
+        }
+    }
+
+    /*
+     * Returns `true` if a screen reader is available to provide speech.
+     */
+    #[allow(unreachable_code)]
+    pub fn screen_reader_available() -> bool {
+        #[cfg(target_os = "windows")]
+        {
+            #[cfg(feature = "tolk")]
+            {
+                let tolk = Tolk::new();
+                return tolk.detect_screen_reader().is_some();
+            }
+            #[cfg(not(feature = "tolk"))]
+            return false;
+        }
+        false
+    }
+}
+
+impl Drop for Tts {
+    fn drop(&mut self) {
+        if Rc::strong_count(&self.0) <= 1 {
+            if let Some(id) = self.0.read().unwrap().id() {
+                let mut callbacks = CALLBACKS.lock().unwrap();
+                callbacks.remove(&id);
+            }
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum Gender {
+    Male,
+    Female,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Voice {
+    pub(crate) id: String,
+    pub(crate) name: String,
+    pub(crate) gender: Option<Gender>,
+    pub(crate) language: LanguageTag<String>,
+}
+
+impl Voice {
+    pub fn id(&self) -> String {
+        self.id.clone()
+    }
+
+    pub fn name(&self) -> String {
+        self.name.clone()
+    }
+
+    pub fn gender(&self) -> Option<Gender> {
+        self.gender
+    }
+
+    pub fn language(&self) -> LanguageTag<String> {
+        self.language.clone()
+    }
 }

winrt_bindings/Cargo.toml

@@ -1,13 +0,0 @@
-[package]
-name = "tts_winrt_bindings"
-version = "0.1.0"
-authors = ["Nolan Darilek <nolan@thewordnerd.info>"]
-description = "Internal crate used by `tts`"
-license = "MIT"
-edition = "2018"
-
-[dependencies]
-winrt = "0.7"
-
-[build-dependencies]
-winrt = "0.7"

winrt_bindings/build.rs

@@ -1,12 +0,0 @@
-winrt::build!(
-    dependencies
-        os
-    types
-        windows::media::core::MediaSource
-        windows::media::playback::{MediaPlaybackItem, MediaPlaybackList, MediaPlaybackState, MediaPlayer}
-        windows::media::speech_synthesis::SpeechSynthesizer
-);
-
-fn main() {
-    build();
-}

winrt_bindings/src/lib.rs

@@ -1 +0,0 @@
-include!(concat!(env!("OUT_DIR"), "/winrt.rs"));