Add Web backend and refactor API.

Cargo.toml

@@ -8,6 +8,7 @@ license = "MIT"
 edition = "2018"
 
 [dependencies]
+failure = "0.1"
 log = "0.4"
 
 [dev-dependencies]
@@ -15,3 +16,7 @@ env_logger = "0.6"
 
 [target.'cfg(target_os = "linux")'.dependencies]
 speech-dispatcher = "0.2"
+
+[target.wasm32-unknown-unknown.dependencies]
+wasm-bindgen = "0.2"
+web-sys = { version = "0.3", features = ["SpeechSynthesis", "SpeechSynthesisUtterance", "Window", ] }

examples/hello_world.rs

@@ -2,28 +2,29 @@ use std::u8;
 
 use tts::TTS;
 
-fn main() {
+fn main() -> Result<(), std::io::Error> {
     env_logger::init();
-    let tts: TTS = Default::default();
-    tts.speak("Hello, world.", false);
-    let original_rate = tts.get_rate();
-    tts.speak(format!("Current rate: {}", original_rate), false);
-    tts.set_rate(u8::MAX);
-    tts.speak("This is very fast.", false);
-    tts.set_rate(0);
-    tts.speak("This is very slow.", false);
-    tts.set_rate(original_rate);
-    let original_pitch = tts.get_pitch();
-    tts.set_pitch(u8::MAX);
-    tts.speak("This is high-pitch.", false);
-    tts.set_pitch(0);
-    tts.speak("This is low pitch.", false);
-    tts.set_pitch(original_pitch);
-    let original_volume = tts.get_volume();
-    tts.set_volume(u8::MAX);
-    tts.speak("This is loud!", false);
-    tts.set_volume(0);
-    tts.speak("This is quiet.", false);
-    tts.set_volume(original_volume);
-    tts.speak("Goodbye.", false);
+    let mut tts = TTS::default()?;
+    tts.speak("Hello, world.", false)?;
+    let original_rate = tts.get_rate()?;
+    tts.speak(format!("Current rate: {}", original_rate), false)?;
+    tts.set_rate(u8::MAX)?;
+    tts.speak("This is very fast.", false)?;
+    tts.set_rate(0)?;
+    tts.speak("This is very slow.", false)?;
+    tts.set_rate(original_rate)?;
+    let original_pitch = tts.get_pitch()?;
+    tts.set_pitch(u8::MAX)?;
+    tts.speak("This is high-pitch.", false)?;
+    tts.set_pitch(0)?;
+    tts.speak("This is low pitch.", false)?;
+    tts.set_pitch(original_pitch)?;
+    let original_volume = tts.get_volume()?;
+    tts.set_volume(u8::MAX)?;
+    tts.speak("This is loud!", false)?;
+    tts.set_volume(0)?;
+    tts.speak("This is quiet.", false)?;
+    tts.set_volume(original_volume)?;
+    tts.speak("Goodbye.", false)?;
+    Ok(())
 }

src/backends/mod.rs

@@ -1,5 +1,11 @@
 #[cfg(target_os = "linux")]
 mod speech_dispatcher;
 
+#[cfg(target_arch = "wasm32")]
+mod web;
+
 #[cfg(target_os = "linux")]
 pub use self::speech_dispatcher::*;
+
+#[cfg(target_arch = "wasm32")]
+pub use self::web::*;

src/backends/speech_dispatcher.rs

@@ -5,7 +5,7 @@ use std::u8;
 use log::{info, trace};
 use speech_dispatcher::*;
 
-use crate::Backend;
+use crate::{Backend, Error};
 
 pub struct SpeechDispatcher(Connection);
 
@@ -30,40 +30,45 @@ fn i32_to_u8(v: i32) -> u8 {
 }
 
 impl Backend for SpeechDispatcher {
-    fn speak(&self, text: &str, interrupt: bool) {
+    fn speak(&self, text: &str, interrupt: bool) -> Result<(), Error> {
         trace!("speak({}, {})", text, interrupt);
         if interrupt {
-            self.0.cancel();
+            self.stop()?;
         }
         self.0.say(Priority::Important, text);
+        Ok(())
     }
 
-    fn stop(&self) {
+    fn stop(&self) -> Result<(), Error> {
         trace!("stop()");
         self.0.cancel();
+        Ok(())
     }
 
-    fn get_rate(&self) -> u8 {
-        i32_to_u8(self.0.get_voice_rate())
+    fn get_rate(&self) -> Result<u8, Error> {
+        Ok(i32_to_u8(self.0.get_voice_rate()))
     }
 
-    fn set_rate(&self, rate: u8) {
+    fn set_rate(&mut self, rate: u8) -> Result<(), Error> {
         self.0.set_voice_rate(u8_to_i32(rate));
+        Ok(())
     }
 
-    fn get_pitch(&self) -> u8 {
-        i32_to_u8(self.0.get_voice_pitch())
+    fn get_pitch(&self) -> Result<u8, Error> {
+        Ok(i32_to_u8(self.0.get_voice_pitch()))
     }
 
-    fn set_pitch(&self, pitch: u8) {
+    fn set_pitch(&mut self, pitch: u8) -> Result<(), Error> {
         self.0.set_voice_pitch(u8_to_i32(pitch));
+        Ok(())
     }
 
-    fn get_volume(&self) -> u8 {
-        i32_to_u8(self.0.get_volume())
+    fn get_volume(&self) -> Result<u8, Error> {
+        Ok(i32_to_u8(self.0.get_volume()))
     }
 
-    fn set_volume(&self, volume: u8) {
+    fn set_volume(&mut self, volume: u8) -> Result<(), Error> {
         self.0.set_volume(u8_to_i32(volume));
+        Ok(())
     }
 }

src/backends/web.rs

@@ -0,0 +1,85 @@
+#[cfg(target_arch = "wasm32")]
+
+use std::u8;
+
+use log::{info, trace};
+use web_sys::SpeechSynthesisUtterance;
+
+use crate::{Backend, Error};
+
+pub struct Web {
+    rate: u8,
+    pitch: u8,
+    volume: u8,
+}
+
+impl Web {
+    pub fn new() -> Result<impl Backend, Error> {
+        info!("Initializing Web backend");
+        Ok(Web {
+            rate: 25,
+            pitch: 127,
+            volume: u8::MAX,
+        })
+    }
+}
+
+impl Backend for Web {
+    fn speak(&self, text: &str, interrupt: bool) -> Result<(), Error> {
+        trace!("speak({}, {})", text, interrupt);
+        let utterance = SpeechSynthesisUtterance::new_with_text(text).unwrap();
+        let mut rate: f32 = self.rate as f32;
+        rate = rate / u8::MAX as f32 * 10.;
+        utterance.set_rate(rate);
+        let mut pitch: f32 = self.pitch as f32;
+        pitch = pitch / u8::MAX as f32 * 2.;
+        utterance.set_pitch(pitch);
+        let mut volume: f32 = self.volume as f32;
+        volume = volume / u8::MAX as f32 * 1.;
+        utterance.set_volume(volume);
+        if interrupt {
+            self.stop()?;
+        }
+        if let Some(window) = web_sys::window() {
+            let speech_synthesis = window.speech_synthesis().unwrap();
+            speech_synthesis.speak(&utterance);
+        }
+        Ok(())
+    }
+
+    fn stop(&self) -> Result<(), Error> {
+        trace!("stop()");
+        if let Some(window) = web_sys::window() {
+            let speech_synthesis = window.speech_synthesis().unwrap();
+            speech_synthesis.cancel();
+        }
+        Ok(())
+    }
+
+    fn get_rate(&self) -> Result<u8, Error> {
+        Ok(self.rate)
+    }
+
+    fn set_rate(&mut self, rate: u8) -> Result<(), Error> {
+        self.rate = rate;
+        Ok(())
+    }
+
+    fn get_pitch(&self) -> Result<u8, Error> {
+        Ok(self.pitch)
+    }
+
+    fn set_pitch(&mut self, pitch: u8) -> Result<(), Error> {
+        self.pitch = pitch;
+        Ok(())
+    }
+
+    fn get_volume(&self) -> Result<u8, Error> {
+        Ok(self.volume)
+    }
+
+    fn set_volume(&mut self, volume: u8) -> Result<(), Error> {
+        self.volume = volume;
+        Ok(())
+    }
+}

src/lib.rs

@@ -4,23 +4,46 @@
 */
 
 use std::boxed::Box;
+use std::convert;
+use std::fmt;
+use std::io;
+
+use failure::Fail;
 
 mod backends;
 
 pub enum Backends {
     #[cfg(target_os = "linux")]
     SpeechDispatcher,
+    #[cfg(target_arch = "wasm32")]
+    Web,
+}
+
+#[derive(Debug, Fail)]
+pub struct Error(String);
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        write!(f, "{}", self.0)?;
+        Ok(())
+    }
+}
+
+impl convert::From<Error> for io::Error {
+    fn from(e: Error) -> io::Error {
+        io::Error::new(io::ErrorKind::Other, e.0)
+    }
 }
 
 trait Backend {
-    fn speak(&self, text: &str, interrupt: bool);
-    fn stop(&self);
-    fn get_rate(&self) -> u8;
-    fn set_rate(&self, rate: u8);
-    fn get_pitch(&self) -> u8;
-    fn set_pitch(&self, pitch: u8);
-    fn get_volume(&self) -> u8;
-    fn set_volume(&self, volume: u8);
+    fn speak(&self, text: &str, interrupt: bool) -> Result<(), Error>;
+    fn stop(&self) -> Result<(), Error>;
+    fn get_rate(&self) -> Result<u8, Error>;
+    fn set_rate(&mut self, rate: u8) -> Result<(), Error>;
+    fn get_pitch(&self) -> Result<u8, Error>;
+    fn set_pitch(&mut self, pitch: u8) -> Result<(), Error>;
+    fn get_volume(&self) -> Result<u8, Error>;
+    fn set_volume(&mut self, volume: u8) -> Result<(), Error>;
 }
 
 pub struct TTS(Box<Backend>);
@@ -30,78 +53,84 @@ impl TTS {
     /**
      * Create a new `TTS` instance with the specified backend.
     */
-    pub fn new(backend: Backends) -> TTS {
+    pub fn new(backend: Backends) -> Result<TTS, Error> {
         match backend {
             #[cfg(target_os = "linux")]
-            Backends::SpeechDispatcher => TTS(Box::new(backends::SpeechDispatcher::new())),
+            Backends::SpeechDispatcher => Ok(TTS(Box::new(backends::SpeechDispatcher::new()))),
+            #[cfg(target_arch = "wasm32")]
+            Backends::Web => {
+                let tts = backends::Web::new()?;
+                Ok(TTS(Box::new(tts)))
+            },
         }
     }
 
+    pub fn default() -> Result<TTS, Error> {
+        #[cfg(target_os = "linux")]
+        let tts = TTS::new(Backends::SpeechDispatcher);
+        #[cfg(target_arch = "wasm32")]
+        let tts = TTS::new(Backends::Web);
+        tts
+    }
+
     /**
      * Speaks the specified text, optionally interrupting current speech.
     */
-    pub fn speak<S: Into<String>>(&self, text: S, interrupt: bool) -> &Self {
-        self.0.speak(text.into().as_str(), interrupt);
-        self
+    pub fn speak<S: Into<String>>(&self, text: S, interrupt: bool) -> Result<&Self, Error> {
+        self.0.speak(text.into().as_str(), interrupt)?;
+        Ok(self)
     }
 
     /**
      * Stops current speech.
     */
-    pub fn stop(&self) -> &Self {
-        self.0.stop();
-        self
+    pub fn stop(&self) -> Result<&Self, Error> {
+        self.0.stop()?;
+        Ok(self)
     }
 
     /**
      * Gets the current speech rate.
     */
-    pub fn get_rate(&self) -> u8 {
+    pub fn get_rate(&self) -> Result<u8, Error> {
         self.0.get_rate()
     }
 
     /**
      * Sets the desired speech rate.
     */
-    pub fn set_rate(&self, rate: u8) -> &Self {
-        self.0.set_rate(rate);
-        self
+    pub fn set_rate(&mut self, rate: u8) -> Result<&Self, Error> {
+        self.0.set_rate(rate)?;
+        Ok(self)
     }
 
     /**
      * Gets the current speech pitch.
     */
-    pub fn get_pitch(&self) -> u8 {
+    pub fn get_pitch(&self) -> Result<u8, Error> {
         self.0.get_pitch()
     }
 
     /**
      * Sets the desired speech pitch.
     */
-    pub fn set_pitch(&self, pitch: u8) -> &Self {
-        self.0.set_pitch(pitch);
-        self
+    pub fn set_pitch(&mut self, pitch: u8) -> Result<&Self, Error> {
+        self.0.set_pitch(pitch)?;
+        Ok(self)
     }
 
     /**
      * Gets the current speech volume.
     */
-    pub fn get_volume(&self) -> u8 {
+    pub fn get_volume(&self) -> Result<u8, Error> {
         self.0.get_volume()
     }
 
     /**
      * Sets the desired speech volume.
     */
-    pub fn set_volume(&self, volume: u8) -> &Self {
-        self.0.set_volume(volume);
-        self
-    }
-}
-
-impl Default for TTS {
-    fn default() -> TTS {
-        #[cfg(target_os = "linux")]
-        TTS::new(Backends::SpeechDispatcher)
+    pub fn set_volume(&mut self, volume: u8) -> Result<&Self, Error> {
+        self.0.set_volume(volume)?;
+        Ok(self)
     }
 }