Add initial Android stubs.

Cargo.toml

@@ -39,3 +39,6 @@ objc = "0.2"
 [target.wasm32-unknown-unknown.dependencies]
 wasm-bindgen = "0.2"
 web-sys = { version = "0.3", features = ["EventTarget", "SpeechSynthesis", "SpeechSynthesisErrorCode", "SpeechSynthesisErrorEvent", "SpeechSynthesisEvent", "SpeechSynthesisUtterance", "Window", ] }
+
+[target.'cfg(target_os="android")'.dependencies]
+jni = "0.18"

src/backends/android.rs

@@ -0,0 +1,114 @@
+#[cfg(target_os = "android")]
+use std::sync::Mutex;
+
+use lazy_static::lazy_static;
+use log::info;
+
+use crate::{Backend, BackendId, Error, Features, UtteranceId, CALLBACKS};
+
+lazy_static! {
+    static ref NEXT_BACKEND_ID: Mutex<u64> = Mutex::new(0);
+}
+
+#[derive(Clone, Debug)]
+pub(crate) struct Android(BackendId);
+
+impl Android {
+    pub(crate) fn new() -> Self {
+        info!("Initializing Android backend");
+        let mut backend_id = NEXT_BACKEND_ID.lock().unwrap();
+        let bid = BackendId::Android(*backend_id);
+        *backend_id += 1;
+        Self(bid)
+    }
+}
+
+impl Backend for Android {
+    fn id(&self) -> Option<BackendId> {
+        Some(self.0)
+    }
+
+    fn supported_features(&self) -> Features {
+        Features {
+            stop: false,
+            rate: false,
+            pitch: false,
+            volume: false,
+            is_speaking: false,
+            utterance_callbacks: false,
+        }
+    }
+
+    fn speak(&mut self, text: &str, interrupt: bool) -> Result<Option<UtteranceId>, Error> {
+        println!("Speaking {}, {:?}", text, interrupt);
+        Ok(None)
+    }
+
+    fn stop(&mut self) -> Result<(), Error> {
+        todo!()
+    }
+
+    fn min_rate(&self) -> f32 {
+        todo!()
+    }
+
+    fn max_rate(&self) -> f32 {
+        todo!()
+    }
+
+    fn normal_rate(&self) -> f32 {
+        todo!()
+    }
+
+    fn get_rate(&self) -> Result<f32, Error> {
+        todo!()
+    }
+
+    fn set_rate(&mut self, rate: f32) -> Result<(), Error> {
+        todo!()
+    }
+
+    fn min_pitch(&self) -> f32 {
+        todo!()
+    }
+
+    fn max_pitch(&self) -> f32 {
+        todo!()
+    }
+
+    fn normal_pitch(&self) -> f32 {
+        todo!()
+    }
+
+    fn get_pitch(&self) -> Result<f32, Error> {
+        todo!()
+    }
+
+    fn set_pitch(&mut self, pitch: f32) -> Result<(), Error> {
+        todo!()
+    }
+
+    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> {
+        todo!()
+    }
+}

src/backends/mod.rs

@@ -16,6 +16,9 @@ mod appkit;
 #[cfg(any(target_os = "macos", target_os = "ios"))]
 mod av_foundation;
 
+#[cfg(target_os = "android")]
+mod android;
+
 #[cfg(target_os = "linux")]
 pub(crate) use self::speech_dispatcher::*;
 
@@ -30,3 +33,6 @@ pub(crate) use self::appkit::*;
 
 #[cfg(any(target_os = "macos", target_os = "ios"))]
 pub(crate) use self::av_foundation::*;
+
+#[cfg(target_os = "android")]
+pub(crate) use self::android::*;

src/lib.rs

@@ -43,6 +43,8 @@ pub enum Backends {
     AppKit,
     #[cfg(any(target_os = "macos", target_os = "ios"))]
     AvFoundation,
+    #[cfg(target_os = "android")]
+    Android,
 }
 
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
@@ -55,6 +57,8 @@ pub enum BackendId {
     WinRT(u64),
     #[cfg(any(target_os = "macos", target_os = "ios"))]
     AvFoundation(u64),
+    #[cfg(target_os = "android")]
+    Android(u64),
 }
 
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
@@ -193,6 +197,8 @@ impl TTS {
             Backends::AppKit => Ok(TTS(Box::new(backends::AppKit::new()))),
             #[cfg(any(target_os = "macos", target_os = "ios"))]
             Backends::AvFoundation => Ok(TTS(Box::new(backends::AvFoundation::new()))),
+            #[cfg(target_os = "android")]
+            Backends::Android => Ok(TTS(Box::new(backends::Android::new()))),
         };
         if let Ok(backend) = backend {
             if let Some(id) = backend.0.id() {
@@ -239,6 +245,8 @@ impl TTS {
         };
         #[cfg(target_os = "ios")]
         let tts = TTS::new(Backends::AvFoundation);
+        #[cfg(target_os = "android")]
+        let tts = TTS::new(Backends::Android);
         tts
     }