commit c1673f7b40363f33fe7a1247fa1777b5049da973
Author: Rob Watson <rob@rfwatson.net>
Date:   Sun Jun 9 10:59:40 2019 +0200

    WIP 1: closure inside struct method, borrow checking issues. About to refactor to use modules.

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..53eaa21
--- /dev/null
+++ b/.gitignore
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diff --git a/Cargo.lock b/Cargo.lock
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diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..fe48286
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,13 @@
+[package]
+name = "audio-test"
+version = "0.1.0"
+authors = ["Rob Watson <rob@rfwatson.net>"]
+edition = "2018"
+
+[dependencies]
+cpal = "0.8.2"
+sample = "0.10.0"
+
+[dependencies.gtk]
+version = "0.5.0"
+features = ["v3_10"]
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..2cc0c03
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,117 @@
+extern crate cpal;
+extern crate gtk;
+
+use std::thread;
+use std::iter::Iterator;
+use cpal::{EventLoop, StreamData, UnknownTypeInputBuffer, Sample};
+use gtk::prelude::*;
+use gtk::{Button, Window, WindowType};
+
+pub struct Gui {
+    window: gtk::Window
+}
+
+impl Gui {
+    pub fn new() -> Self {
+        let window = Window::new(WindowType::Toplevel);
+        window.set_title("Hello GTK");
+        window.set_default_size(350, 70);
+
+        let button = Button::new_with_label("Click me now");
+        window.add(&button);
+        window.show_all();
+
+        window.connect_delete_event(|_, _| {
+            println!("Bye");
+            gtk::main_quit();
+            Inhibit(false)
+        });
+
+        button.connect_clicked(|_| {
+            println!("Clicked!");
+        });
+
+        Self {
+            window: window
+        }
+    }
+}
+
+struct AudioEngine {
+    event_loop: EventLoop,
+    max_value: i16,
+}
+
+impl AudioEngine {
+    pub fn new() -> Self {
+        AudioEngine {
+            event_loop: EventLoop::new(),
+            max_value: 0
+        }
+    }
+
+    pub fn init(&mut self) -> Result<(), String> {
+        let device = cpal::default_input_device()
+            .ok_or("Could not find a default input device")?;
+        let mut supported_formats_range = device.supported_input_formats()
+            .map_err(|_| "Could not get supported input formats")?;
+        let format = supported_formats_range
+            .next()
+            .ok_or("Could not get supported formats range")?
+            .with_max_sample_rate();
+
+        let stream_id = self.event_loop.build_input_stream(&device, &format)
+            .map_err(|_| "Could not build input stream")?;
+        self.event_loop.play_stream(stream_id);
+
+        Ok(())
+    }
+
+    pub fn run(&mut self) {
+        self.event_loop.run(|_stream_id, stream_data| {
+            match stream_data {
+                StreamData::Input { buffer: UnknownTypeInputBuffer::I16(buffer) } =>
+                    self.process_audio(buffer),
+               StreamData::Input { buffer: UnknownTypeInputBuffer::U16(buffer) } =>
+                    self.process_audio(buffer),
+                StreamData::Input { buffer: UnknownTypeInputBuffer::F32(buffer) } =>
+                    self.process_audio(buffer),
+                _ => unreachable!()
+            }
+        });
+    }
+
+    fn process_audio<T>(&mut self, buffer: cpal::InputBuffer<T>) where T: cpal::Sample {
+        let max = buffer
+            .iter()
+            .map(Sample::to_i16)
+            .max()
+            .unwrap_or(0)
+            .abs();
+
+        if max > self.max_value {
+            println!("new max: {}", max);
+            self.max_value = max;
+        }
+    }
+}
+
+fn main() {
+    // Audio:
+    thread::spawn(move || {
+        let mut audio_engine = AudioEngine::new();
+        audio_engine.init().unwrap_or_else(|err| {
+            panic!("Could not start audio engine: {}", err);
+        });
+
+        audio_engine.run();
+    });
+
+    // GUI
+    if gtk::init().is_err() {
+        panic!("Failed to initialize GTK.");
+    }
+    let _gui = Gui::new();
+
+    gtk::main();
+}