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use std::{
sync::{atomic::AtomicBool, Arc},
use rodio::{Decoder, SpatialSink};
use smallvec::SmallVec;
use amethyst_core::ecs::{prelude::Component, storage::BTreeStorage};
use crate::{source::Source, DecoderError};
/// An audio source, add this component to anything that emits sound.
/// TODO: This should get a proper Debug impl parsing the sinks and sound queue
pub struct AudioEmitter {
pub(crate) sinks: SmallVec<[(SpatialSink, Arc<AtomicBool>); 4]>,
pub(crate) sound_queue: SmallVec<[Decoder<Cursor<Source>>; 4]>,
pub(crate) picker: Option<Box<dyn FnMut(&mut AudioEmitter) -> bool + Send + Sync>>,
impl AudioEmitter {
/// Creates a new AudioEmitter component initialized to the given positions.
/// These positions will stay synced with Transform if the Transform component is available
/// on this entity.
pub fn new() -> AudioEmitter {
/// Plays an audio source from this emitter.
pub fn play(&mut self, source: &Source) -> Result<(), DecoderError> {
.push(Decoder::new(Cursor::new(source.clone())).map_err(|_| DecoderError)?);
/// An emitter's picker will be called by the AudioSystem whenever the emitter runs out of
/// sounds to play.
/// During callback the picker is separated from the emitter in order to avoid multiple
/// aliasing.
/// After the callback is complete, if the picker returned true then the
/// picker that just finished will be reattached.
pub fn set_picker(&mut self, picker: Box<dyn FnMut(&mut AudioEmitter) -> bool + Send + Sync>) {
self.picker = Some(picker);
/// Clears the previously set picker.
pub fn clear_picker(&mut self) {
self.picker = None;
impl Component for AudioEmitter {
type Storage = BTreeStorage<Self>;
mod tests {
use std::{fs::File, io::Read, vec::Vec};
use amethyst_utils::app_root_dir::application_root_dir;
use crate::{AudioEmitter, Source};
// test_play tests the AudioEmitter's play function
fn test_play(file_name: &str, should_pass: bool) {
// Get the full file path
let app_root = application_root_dir().unwrap();
let audio_path = app_root.join(file_name);
// Convert the file contents into a byte vec
let mut f = File::open(audio_path).unwrap();
let mut buffer = Vec::new();
f.read_to_end(&mut buffer).unwrap();
// Create a Source and AudioEmitter from those bytes
let src = Source { bytes: buffer };
let mut emitter = AudioEmitter::default();
// Call play
match {
Ok(_pass) => assert!(
"Expected `play` result to be Err(..), but was Ok(..)"
Err(fail) => assert!(
"Expected `play` result to be `Ok(..)`, but was {:?}",
fn test_play_wav() {
test_play("tests/sound_test.wav", true);
fn test_play_mp3() {
test_play("tests/sound_test.mp3", true);
fn test_play_flac() {
test_play("tests/sound_test.flac", true);
fn test_play_ogg() {
test_play("tests/sound_test.ogg", true);
fn test_play_fake() {
test_play("tests/sound_test.fake", false);
// test_picker tests the set and clear picker functions
fn test_picker() {
// Create the input variables
let mut emitter_main = AudioEmitter::default();
let box_picker: Box<dyn FnMut(&mut AudioEmitter) -> bool + Send + Sync> =
// Test set_picker and assert that it is not empty
// Test clear_picker and assert it is empty
// use_audio_emitter is a fake test function to play an AudioEmitter
fn use_audio_emitter(_emitter: &mut AudioEmitter) -> bool {
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