Add voices feature

Implemented for AVFoundation backend but set_voice has no effect for now
Warning: does not build on Linux or windows for now

Cargo.toml

@@ -29,6 +29,7 @@ speech-dispatcher = "0.6"
 
 [target.'cfg(any(target_os = "macos", target_os = "ios"))'.dependencies]
 cocoa-foundation = "0.1"
+core-foundation = "0.9"
 libc = "0.2"
 objc = "0.2"
 

src/backends/appkit.rs

@@ -195,6 +195,18 @@ impl Backend for AppKit {
         let is_speaking: i8 = unsafe { msg_send![self.0, isSpeaking] };
         Ok(is_speaking == YES)
     }
+
+    fn voice(&self) -> Result<String,Error> {
+        unimplemented!()
+    }
+
+    fn list_voices(&self) -> Vec<String> {
+        unimplemented!()
+    }
+
+    fn set_voice(&self, voice: String) -> Result<(),Error> {
+        unimplemented!()
+    }
 }
 
 impl Drop for AppKit {

src/backends/av_foundation.rs

@@ -8,11 +8,15 @@ use objc::*;
 
 use crate::{Backend, Error, Features};
 
+mod voices;
+use voices::AVSpeechSynthesisVoice;
+
 pub struct AvFoundation {
     synth: *mut Object,
     rate: f32,
     volume: f32,
     pitch: f32,
+    voice: AVSpeechSynthesisVoice,
 }
 
 impl AvFoundation {
@@ -25,6 +29,7 @@ impl AvFoundation {
                 rate: 0.5,
                 volume: 1.,
                 pitch: 1.,
+                voice: AVSpeechSynthesisVoice::new(),
             }
         }
     }
@@ -38,6 +43,7 @@ impl Backend for AvFoundation {
             pitch: true,
             volume: true,
             is_speaking: true,
+            voices: true,
         }
     }
 
@@ -134,6 +140,18 @@ impl Backend for AvFoundation {
         let is_speaking: i8 = unsafe { msg_send![self.synth, isSpeaking] };
         Ok(is_speaking == 1)
     }
+
+    fn voice(&self) -> Result<String,Error> {
+        Ok(self.voice.identifier())
+    }
+
+    fn list_voices(&self) -> Vec<String> {
+        AVSpeechSynthesisVoice::list().iter().map(|v| {v.identifier()}).collect()
+    }
+
+    fn set_voice(&self, voice: String) -> Result<(),Error> {
+        Ok(())
+    }
 }
 
 impl Drop for AvFoundation {

src/backends/av_foundation/voices.rs

@@ -0,0 +1,31 @@
+
+use objc::runtime::*;
+use objc::*;
+use core_foundation::array::CFArray;
+use core_foundation::string::CFString;
+
+#[derive(Copy,Clone)]
+pub struct AVSpeechSynthesisVoice(*const Object);
+
+impl AVSpeechSynthesisVoice {
+    pub fn new() -> Self {
+        Self::list()[0]
+    }
+
+    pub fn list() -> Vec<Self> {
+        let voices: CFArray = unsafe{msg_send![class!(AVSpeechSynthesisVoice), speechVoices]};
+        voices.iter().map(|v| {
+            AVSpeechSynthesisVoice{0: *v as *mut Object}
+        }).collect()
+    }
+
+    pub fn name(self) -> String {
+        let name: CFString = unsafe{msg_send![self.0, name]};
+        name.to_string()
+    }
+
+    pub fn identifier(self) -> String {
+        let identifier: CFString = unsafe{msg_send![self.0, identifier]};
+        identifier.to_string()
+    }
+}

src/lib.rs

@@ -46,6 +46,7 @@ pub struct Features {
     pub pitch: bool,
     pub volume: bool,
     pub is_speaking: bool,
+    pub voices: bool,
 }
 
 impl Default for Features {
@@ -56,6 +57,7 @@ impl Default for Features {
             pitch: false,
             volume: false,
             is_speaking: false,
+            voices: false,
         }
     }
 }
@@ -98,6 +100,9 @@ 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 voice(&self) -> Result<String, Error>;
+    fn list_voices(&self) -> Vec<String>;
+    fn set_voice(&self, voice: String) -> Result<(),Error>;
 }
 
 pub struct TTS(Box<dyn Backend>);
@@ -371,4 +376,38 @@ impl TTS {
             Err(Error::UnsupportedFeature)
         }
     }
+
+    /**
+     * Returns list of available voices.
+     */
+    pub fn list_voices(&self) -> Vec<String> {
+        self.0.list_voices()
+    }
+
+    /**
+     * Return the current speaking voice. 
+     */
+    pub fn voice(&self) -> Result<String,Error> {
+        let Features { voices, .. } = self.supported_features();
+        if voices {
+            self.0.voice()
+        } else {
+            Err(Error::UnsupportedFeature)
+        }
+    }
+
+    /**
+     * Set speaking voice.
+     */
+    pub fn set_voice(&self, voice: String) -> Result<(),Error> {
+        let Features {
+            voices: voices_feature,
+            ..
+        } = self.0.supported_features();
+        if voices_feature {
+            self.0.set_voice(voice)
+        } else {
+            Err(Error::UnsupportedFeature)
+        }
+    }
 }