From e6cbba66fed669c9c6808584a4f1551cfdb5de30 Mon Sep 17 00:00:00 2001
From: Justin Worthe <justin.worthe@gmail.com>
Date: Thu, 13 Oct 2016 18:07:21 +0200
Subject: Function to start listening on microphone

Messy. To clean up once I've seen if it works.
---
 src/audio.rs | 90 ++++++++++++++++++++++++++++++++++++++----------------------
 src/gui.rs   |  3 +-
 2 files changed, 59 insertions(+), 34 deletions(-)

diff --git a/src/audio.rs b/src/audio.rs
index 526a227..cdeb88a 100644
--- a/src/audio.rs
+++ b/src/audio.rs
@@ -1,58 +1,86 @@
 extern crate portaudio;
 use portaudio as pa;
 
+use std::sync::mpsc::*;
+
 const SAMPLE_RATE: f64 = 44100.0;
 const FRAMES: usize = 512;
 
-pub fn get_device_list() -> Result<Vec<(u32, String)>, pa::Error> {
-    let pa = try!(pa::PortAudio::new());
-    let default_host = try!(pa.default_host_api());
-    println!("Using default host: {:#?}", default_host);
+pub fn init() -> Result<pa::PortAudio, pa::Error> {
+    pa::PortAudio::new()
+}
 
-    let mut list = Vec::new();
-    let devices = try!(pa.devices());
-    for device in devices {
-        let (pa::DeviceIndex(idx), info) = try!(device);
-        if info.max_input_channels == 0 {
-            continue;
-        }
-        list.push((idx, info.name.to_string()));
-    }
+pub fn get_device_list(pa: &pa::PortAudio) -> Result<Vec<(u32, String)>, pa::Error> {
+    // This pa.devices gives a Result of devices, each of which is
+    // also a Result. So a Result<Collection<Result<Device>>>. We
+    // mould it into devices: a Vec<(index, DeviceInfo)>.
+    let devices = try!(try!(pa.devices()).map(|device| {
+        device.map(|(pa::DeviceIndex(idx), info)| (idx, info))
+    }).collect::<Result<Vec<_>, _>>());
+    
+    let list = devices.iter().filter(|&&(_, ref info)| info.max_input_channels > 0)
+        .map(|&(idx, ref info)| (idx, info.name.to_string()))
+        .collect();
     Ok(list)
 }
 
-pub fn run(device_index: u32) -> Result<(), pa::Error> {
-    let pa = try!(pa::PortAudio::new());
+#[test]
+fn get_device_list_returns_devices() {
+    let pa = init().expect("Could not init portaudio");
+    let devices = get_device_list(&pa).expect("Getting devices had an error");
+
+    // all machines should have at least one input stream, even if
+    // that's just a virtual stream with a name like "default".
+    assert!(devices.len() > 0);
+}
+
+
+pub struct OpenRecordingChannel<'a> {
+    receiver: Receiver<Vec<f64>>,
+    //pa: &'a portaudio::PortAudio,
+    stream: pa::Stream<'a, pa::NonBlocking, pa::Input<f32>>
+}
 
-    let input_info = try!(pa.device_info(pa::DeviceIndex(device_index)));
-    println!("Using {} for input", input_info.name);
+pub fn start_listening<'a>(pa: &'a pa::PortAudio, device_index: u32) -> Result<OpenRecordingChannel<'a>, pa::Error> {
+    //let pa = try!(pa::PortAudio::new());
+    let device_info = try!(pa.device_info(pa::DeviceIndex(device_index)));
+    let latency = device_info.default_low_input_latency;
 
     // Construct the input stream parameters.
-    let latency = input_info.default_low_input_latency;
+
     let input_params = pa::StreamParameters::<f32>::new(pa::DeviceIndex(device_index), 1, true, latency);
 
     // Check that the stream format is supported.
     try!(pa.is_input_format_supported(input_params, SAMPLE_RATE));
 
-    // Construct the settings with which we'll open our duplex stream.
-    let settings = pa::InputStreamSettings::new(input_params, SAMPLE_RATE, FRAMES as u32);
+    // Construct the settings with which we'll open our stream.
+    let stream_settings = pa::InputStreamSettings::new(input_params, SAMPLE_RATE, FRAMES as u32);
 
-    // We'll use this channel to send the count_down to the main thread for fun.
-    let (sender, receiver) = ::std::sync::mpsc::channel();
+    // This channel will let us read from and control the audio stream
+    let (sender, receiver) = channel();
 
-    // A callback to pass to the non-blocking stream.
+    // This callback A callback to pass to the non-blocking stream.
     let callback = move |pa::InputStreamCallbackArgs { buffer, .. }| {
         sender.send(buffer.iter().map(|x| *x as f64).collect()).ok();
         pa::Continue
     };
 
-    // Construct a stream with input and output sample types of f32.
-    let mut stream = try!(pa.open_non_blocking_stream(settings, callback));
-
+    let mut stream = try!(pa.open_non_blocking_stream(stream_settings, callback));
     try!(stream.start());
+    
+
+    //How do I call this? try!(stream.stop());
+
+    Ok(OpenRecordingChannel {
+        receiver: receiver,
+//        pa: &pa,
+        stream: stream
+    })
+}
 
-    let mut samples_index = 0;
-    // Do some stuff!
+
+/*
+   let mut samples_index = 0;
     while let Ok(samples) = receiver.recv() {
         samples_index += 1;
         if samples_index % 100 != 0 {
@@ -67,8 +95,4 @@ pub fn run(device_index: u32) -> Result<(), pa::Error> {
             ).unwrap().max_freq;
         println!("{}Hz", max_frequency.floor());
     }
-
-    try!(stream.stop());
-
-    Ok(())
-}
+*/
diff --git a/src/gui.rs b/src/gui.rs
index 66ae1f7..de8a322 100644
--- a/src/gui.rs
+++ b/src/gui.rs
@@ -8,7 +8,8 @@ pub fn start_gui() -> Result<(), String> {
     let window = gtk::Window::new(gtk::WindowType::Toplevel);
     window.set_title("Musician Training");
 
-    let audio_devices = try!(::audio::get_device_list().map_err(|e| e.to_string()));
+    let pa = ::audio::init().expect("Could not init portaudio");
+    let audio_devices = try!(::audio::get_device_list(&pa).map_err(|e| e.to_string()));
     let dropdown = gtk::ComboBoxText::new();
     for (index, name) in audio_devices {
         dropdown.append(Some(format!("{}", index).as_ref()), name.as_ref());
-- 
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