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<ol class="chapter"><li class="affix"><a href="../introduction.html">Introduction</a></li><li class="spacer"></li><li><a href="../examples/index.html"><strong aria-hidden="true">1.</strong> Examples</a></li><li><ol class="section"><li><a href="../examples/hello-world.html"><strong aria-hidden="true">1.1.</strong> Hello, World!</a></li><li><a href="../examples/console-log.html"><strong aria-hidden="true">1.2.</strong> Using console.log</a></li><li><a href="../examples/add.html"><strong aria-hidden="true">1.3.</strong> Small wasm files</a></li><li><a href="../examples/without-a-bundler.html"><strong aria-hidden="true">1.4.</strong> Without a Bundler</a></li><li><a href="../examples/wasm2js.html"><strong aria-hidden="true">1.5.</strong> Converting WebAssembly to JS</a></li><li><a href="../examples/import-js.html"><strong aria-hidden="true">1.6.</strong> Importing functions from JS</a></li><li><a href="../examples/char.html"><strong aria-hidden="true">1.7.</strong> Working with char</a></li><li><a href="../examples/wasm-in-wasm.html"><strong aria-hidden="true">1.8.</strong> js-sys: WebAssembly in WebAssembly</a></li><li><a href="../examples/dom.html"><strong aria-hidden="true">1.9.</strong> web-sys: DOM hello world</a></li><li><a href="../examples/closures.html"><strong aria-hidden="true">1.10.</strong> web-sys: Closures</a></li><li><a href="../examples/performance.html"><strong aria-hidden="true">1.11.</strong> web-sys: performance.now</a></li><li><a href="../examples/fetch.html"><strong aria-hidden="true">1.12.</strong> web-sys: using fetch</a></li><li><a href="../examples/2d-canvas.html"><strong aria-hidden="true">1.13.</strong> web-sys: canvas hello world</a></li><li><a href="../examples/julia.html"><strong aria-hidden="true">1.14.</strong> web-sys: canvas Julia set</a></li><li><a href="../examples/web-audio.html" class="active"><strong aria-hidden="true">1.15.</strong> web-sys: WebAudio</a></li><li><a href="../examples/webgl.html"><strong aria-hidden="true">1.16.</strong> web-sys: WebGL</a></li><li><a href="../examples/websockets.html"><strong aria-hidden="true">1.17.</strong> web-sys: WebSockets</a></li><li><a href="../examples/webrtc_datachannel.html"><strong aria-hidden="true">1.18.</strong> web-sys: WebRTC DataChannel</a></li><li><a href="../examples/request-animation-frame.html"><strong aria-hidden="true">1.19.</strong> web-sys: requestAnimationFrame</a></li><li><a href="../examples/paint.html"><strong aria-hidden="true">1.20.</strong> web-sys: A Simple Paint Program</a></li><li><a href="../examples/raytrace.html"><strong aria-hidden="true">1.21.</strong> Parallel Raytracing</a></li><li><a href="../examples/todomvc.html"><strong aria-hidden="true">1.22.</strong> web-sys: A TODO MVC App</a></li></ol></li><li><a href="../reference/index.html"><strong aria-hidden="true">2.</strong> Reference</a></li><li><ol class="section"><li><a href="../reference/deployment.html"><strong aria-hidden="true">2.1.</strong> Deployment</a></li><li><a href="../reference/js-snippets.html"><strong aria-hidden="true">2.2.</strong> JS snippets</a></li><li><a href="../reference/passing-rust-closures-to-js.html"><strong aria-hidden="true">2.3.</strong> Passing Rust Closures to JS</a></li><li><a href="../reference/receiving-js-closures-in-rust.html"><strong aria-hidden="true">2.4.</strong> Receiving JS Closures in Rust</a></li><li><a href="../reference/js-promises-and-rust-futures.html"><strong aria-hidden="true">2.5.</strong> Promises and Futures</a></li><li><a href="../reference/iterating-over-js-values.html"><strong aria-hidden="true">2.6.</strong> Iterating over JS Values</a></li><li><a href="../reference/arbitrary-data-with-serde.html"><strong aria-hidden="true">2.7.</strong> Arbitrary Data with Serde</a></li><li><a href="../reference/accessing-properties-of-untyped-js-values.html"><strong aria-hidden="true">2.8.</strong> Accessing Properties of Untyped JS Values</a></li><li><a href="../reference/working-with-duck-typed-interfaces.html"><strong aria-hidden="true">2.9.</strong> Working with Duck-Typed Interfaces</a></li><li><a href="../reference/cli.html"><strong aria-hidden="true">2.10.</strong> Command Line Interface</a></li><li><a href="../reference/optimize-size.html"><strong aria-hidden="true">2.11.</strong> Optimizing for Size</a></li><li><a href="../reference/rust-targets.html"><strong aria-hidden="true">2.12.</strong> Supported Rust Targets</a></li><li><a href="../reference/browser-support.html"><strong aria-hidden="true">2.13.</strong> Supported Browsers</a></li><li><a href="../reference/types.html"><strong aria-hidden="true">2.14.</strong> Supported Types</a></li><li><ol class="section"><li><a href="../reference/types/imported-js-types.html"><strong aria-hidden="true">2.14.1.</strong> Imported JavaScript Types</a></li><li><a href="../reference/types/exported-rust-types.html"><strong aria-hidden="true">2.14.2.</strong> Exported Rust Types</a></li><li><a href="../reference/types/jsvalue.html"><strong aria-hidden="true">2.14.3.</strong> JsValue</a></li><li><a href="../reference/types/boxed-jsvalue-slice.html"><strong aria-hidden="true">2.14.4.</strong> Box<[JsValue]></a></li><li><a href="../reference/types/pointers.html"><strong aria-hidden="true">2.14.5.</strong> *const T and *mut T</a></li><li><a href="../reference/types/numbers.html"><strong aria-hidden="true">2.14.6.</strong> Numbers</a></li><li><a href="../reference/types/bool.html"><strong aria-hidden="true">2.14.7.</strong> bool</a></li><li><a href="../reference/types/char.html"><strong aria-hidden="true">2.14.8.</strong> char</a></li><li><a href="../reference/types/str.html"><strong aria-hidden="true">2.14.9.</strong> str</a></li><li><a href="../reference/types/string.html"><strong aria-hidden="true">2.14.10.</strong> String</a></li><li><a href="../reference/types/number-slices.html"><strong aria-hidden="true">2.14.11.</strong> Number Slices</a></li><li><a href="../reference/types/boxed-number-slices.html"><strong aria-hidden="true">2.14.12.</strong> Boxed Number Slices</a></li><li><a href="../reference/types/result.html"><strong aria-hidden="true">2.14.13.</strong> Result<T, JsValue></a></li></ol></li><li><a href="../reference/attributes/index.html"><strong aria-hidden="true">2.15.</strong> #[wasm_bindgen] Attributes</a></li><li><ol class="section"><li><a href="../reference/attributes/on-js-imports/index.html"><strong aria-hidden="true">2.15.1.</strong> On JavaScript Imports</a></li><li><ol class="section"><li><a href="../reference/attributes/on-js-imports/catch.html"><strong aria-hidden="true">2.15.1.1.</strong> catch</a></li><li><a href="../reference/attributes/on-js-imports/constructor.html"><strong aria-hidden="true">2.15.1.2.</strong> constructor</a></li><li><a href="../reference/attributes/on-js-imports/extends.html"><strong aria-hidden="true">2.15.1.3.</strong> extends</a></li><li><a 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class="section"><li><a href="../reference/attributes/on-rust-exports/constructor.html"><strong aria-hidden="true">2.15.2.1.</strong> constructor</a></li><li><a href="../reference/attributes/on-rust-exports/js_name.html"><strong aria-hidden="true">2.15.2.2.</strong> js_name = Blah</a></li><li><a href="../reference/attributes/on-rust-exports/readonly.html"><strong aria-hidden="true">2.15.2.3.</strong> readonly</a></li><li><a href="../reference/attributes/on-rust-exports/skip.html"><strong aria-hidden="true">2.15.2.4.</strong> skip</a></li><li><a href="../reference/attributes/on-rust-exports/start.html"><strong aria-hidden="true">2.15.2.5.</strong> start</a></li><li><a href="../reference/attributes/on-rust-exports/typescript_custom_section.html"><strong aria-hidden="true">2.15.2.6.</strong> typescript_custom_section</a></li><li><a href="../reference/attributes/on-rust-exports/getter-and-setter.html"><strong aria-hidden="true">2.15.2.7.</strong> getter and setter</a></li><li><a href="../reference/attributes/on-rust-exports/inspectable.html"><strong aria-hidden="true">2.15.2.8.</strong> inspectable</a></li><li><a href="../reference/attributes/on-rust-exports/skip_typescript.html"><strong aria-hidden="true">2.15.2.9.</strong> skip_typescript</a></li><li><a href="../reference/attributes/on-rust-exports/typescript_type.html"><strong aria-hidden="true">2.15.2.10.</strong> typescript_type</a></li></ol></li></ol></li></ol></li><li><a href="../web-sys/index.html"><strong aria-hidden="true">3.</strong> web-sys</a></li><li><ol class="section"><li><a href="../web-sys/using-web-sys.html"><strong aria-hidden="true">3.1.</strong> Using web-sys</a></li><li><a href="../web-sys/cargo-features.html"><strong aria-hidden="true">3.2.</strong> Cargo Features</a></li><li><a href="../web-sys/function-overloads.html"><strong aria-hidden="true">3.3.</strong> Function Overloads</a></li><li><a href="../web-sys/type-translations.html"><strong aria-hidden="true">3.4.</strong> Type Translations</a></li><li><a href="../web-sys/inheritance.html"><strong aria-hidden="true">3.5.</strong> Inheritance</a></li><li><a href="../web-sys/unstable-apis.html"><strong aria-hidden="true">3.6.</strong> Unstable APIs</a></li></ol></li><li><a href="../wasm-bindgen-test/index.html"><strong aria-hidden="true">4.</strong> Testing with wasm-bindgen-test</a></li><li><ol class="section"><li><a href="../wasm-bindgen-test/usage.html"><strong aria-hidden="true">4.1.</strong> Usage</a></li><li><a href="../wasm-bindgen-test/asynchronous-tests.html"><strong aria-hidden="true">4.2.</strong> Writing Asynchronous Tests</a></li><li><a href="../wasm-bindgen-test/browsers.html"><strong aria-hidden="true">4.3.</strong> Testing in Headless Browsers</a></li><li><a href="../wasm-bindgen-test/continuous-integration.html"><strong aria-hidden="true">4.4.</strong> Continuous Integration</a></li></ol></li><li><a href="../contributing/index.html"><strong aria-hidden="true">5.</strong> Contributing to wasm-bindgen</a></li><li><ol class="section"><li><a href="../contributing/testing.html"><strong aria-hidden="true">5.1.</strong> Testing</a></li><li><a href="../contributing/design/index.html"><strong aria-hidden="true">5.2.</strong> Internal Design</a></li><li><ol class="section"><li><a href="../contributing/design/js-objects-in-rust.html"><strong aria-hidden="true">5.2.1.</strong> JS Objects in Rust</a></li><li><a href="../contributing/design/exporting-rust.html"><strong aria-hidden="true">5.2.2.</strong> Exporting a function to JS</a></li><li><a href="../contributing/design/exporting-rust-struct.html"><strong aria-hidden="true">5.2.3.</strong> Exporting a struct to JS</a></li><li><a href="../contributing/design/importing-js.html"><strong aria-hidden="true">5.2.4.</strong> Importing a function from JS</a></li><li><a href="../contributing/design/importing-js-struct.html"><strong aria-hidden="true">5.2.5.</strong> Importing a class from JS</a></li><li><a href="../contributing/design/rust-type-conversions.html"><strong aria-hidden="true">5.2.6.</strong> Rust Type conversions</a></li><li><a href="../contributing/design/describe.html"><strong aria-hidden="true">5.2.7.</strong> Types in wasm-bindgen</a></li></ol></li><li><a href="../contributing/js-sys/index.html"><strong aria-hidden="true">5.3.</strong> js-sys</a></li><li><ol class="section"><li><a href="../contributing/js-sys/testing.html"><strong aria-hidden="true">5.3.1.</strong> Testing</a></li><li><a href="../contributing/js-sys/adding-more-apis.html"><strong aria-hidden="true">5.3.2.</strong> Adding More APIs</a></li></ol></li><li><a href="../contributing/web-sys/index.html"><strong aria-hidden="true">5.4.</strong> web-sys</a></li><li><ol class="section"><li><a href="../contributing/web-sys/overview.html"><strong aria-hidden="true">5.4.1.</strong> Overview</a></li><li><a href="../contributing/web-sys/testing.html"><strong aria-hidden="true">5.4.2.</strong> Testing</a></li><li><a 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<div id="content" class="content">
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<main>
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<h1><a class="header" href="#webaudio" id="webaudio">WebAudio</a></h1>
|
|
<p><a href="https://github.com/rustwasm/wasm-bindgen/tree/master/examples/webaudio">View full source code</a> or <a href="https://rustwasm.github.io/wasm-bindgen/exbuild/webaudio/">view the compiled example online</a></p>
|
|
<p>This example creates an <a href="https://en.wikipedia.org/wiki/Frequency_modulation_synthesis">FM
|
|
oscillator</a> using
|
|
the <a href="https://developer.mozilla.org/en-US/docs/Web/API/Web_Audio_API">WebAudio
|
|
API</a> and
|
|
<code>web-sys</code>.</p>
|
|
<h2><a class="header" href="#cargotoml" id="cargotoml"><code>Cargo.toml</code></a></h2>
|
|
<p>The <code>Cargo.toml</code> enables the types needed to use the relevant bits of the
|
|
WebAudio API.</p>
|
|
<pre><code class="language-toml">[package]
|
|
name = "webaudio"
|
|
version = "0.1.0"
|
|
authors = ["The wasm-bindgen Developers"]
|
|
edition = "2018"
|
|
|
|
[lib]
|
|
crate-type = ["cdylib"]
|
|
|
|
[dependencies]
|
|
wasm-bindgen = "0.2.63"
|
|
|
|
[dependencies.web-sys]
|
|
version = "0.3.4"
|
|
features = [
|
|
'AudioContext',
|
|
'AudioDestinationNode',
|
|
'AudioNode',
|
|
'AudioParam',
|
|
'GainNode',
|
|
'OscillatorNode',
|
|
'OscillatorType',
|
|
]
|
|
|
|
</code></pre>
|
|
<h2><a class="header" href="#srclibrs" id="srclibrs"><code>src/lib.rs</code></a></h2>
|
|
<p>The Rust code implements the FM oscillator.</p>
|
|
<pre><pre class="playpen"><code class="language-rust">
|
|
# #![allow(unused_variables)]
|
|
#fn main() {
|
|
use wasm_bindgen::prelude::*;
|
|
use web_sys::{AudioContext, OscillatorType};
|
|
|
|
/// Converts a midi note to frequency
|
|
///
|
|
/// A midi note is an integer, generally in the range of 21 to 108
|
|
pub fn midi_to_freq(note: u8) -> f32 {
|
|
27.5 * 2f32.powf((note as f32 - 21.0) / 12.0)
|
|
}
|
|
|
|
#[wasm_bindgen]
|
|
pub struct FmOsc {
|
|
ctx: AudioContext,
|
|
/// The primary oscillator. This will be the fundamental frequency
|
|
primary: web_sys::OscillatorNode,
|
|
|
|
/// Overall gain (volume) control
|
|
gain: web_sys::GainNode,
|
|
|
|
/// Amount of frequency modulation
|
|
fm_gain: web_sys::GainNode,
|
|
|
|
/// The oscillator that will modulate the primary oscillator's frequency
|
|
fm_osc: web_sys::OscillatorNode,
|
|
|
|
/// The ratio between the primary frequency and the fm_osc frequency.
|
|
///
|
|
/// Generally fractional values like 1/2 or 1/4 sound best
|
|
fm_freq_ratio: f32,
|
|
|
|
fm_gain_ratio: f32,
|
|
}
|
|
|
|
impl Drop for FmOsc {
|
|
fn drop(&mut self) {
|
|
let _ = self.ctx.close();
|
|
}
|
|
}
|
|
|
|
#[wasm_bindgen]
|
|
impl FmOsc {
|
|
#[wasm_bindgen(constructor)]
|
|
pub fn new() -> Result<FmOsc, JsValue> {
|
|
let ctx = web_sys::AudioContext::new()?;
|
|
|
|
// Create our web audio objects.
|
|
let primary = ctx.create_oscillator()?;
|
|
let fm_osc = ctx.create_oscillator()?;
|
|
let gain = ctx.create_gain()?;
|
|
let fm_gain = ctx.create_gain()?;
|
|
|
|
// Some initial settings:
|
|
primary.set_type(OscillatorType::Sine);
|
|
primary.frequency().set_value(440.0); // A4 note
|
|
gain.gain().set_value(0.0); // starts muted
|
|
fm_gain.gain().set_value(0.0); // no initial frequency modulation
|
|
fm_osc.set_type(OscillatorType::Sine);
|
|
fm_osc.frequency().set_value(0.0);
|
|
|
|
// Connect the nodes up!
|
|
|
|
// The primary oscillator is routed through the gain node, so that
|
|
// it can control the overall output volume.
|
|
primary.connect_with_audio_node(&gain)?;
|
|
|
|
// Then connect the gain node to the AudioContext destination (aka
|
|
// your speakers).
|
|
gain.connect_with_audio_node(&ctx.destination())?;
|
|
|
|
// The FM oscillator is connected to its own gain node, so it can
|
|
// control the amount of modulation.
|
|
fm_osc.connect_with_audio_node(&fm_gain)?;
|
|
|
|
// Connect the FM oscillator to the frequency parameter of the main
|
|
// oscillator, so that the FM node can modulate its frequency.
|
|
fm_gain.connect_with_audio_param(&primary.frequency())?;
|
|
|
|
// Start the oscillators!
|
|
primary.start()?;
|
|
fm_osc.start()?;
|
|
|
|
Ok(FmOsc {
|
|
ctx,
|
|
primary,
|
|
gain,
|
|
fm_gain,
|
|
fm_osc,
|
|
fm_freq_ratio: 0.0,
|
|
fm_gain_ratio: 0.0,
|
|
})
|
|
}
|
|
|
|
/// Sets the gain for this oscillator, between 0.0 and 1.0.
|
|
#[wasm_bindgen]
|
|
pub fn set_gain(&self, mut gain: f32) {
|
|
if gain > 1.0 {
|
|
gain = 1.0;
|
|
}
|
|
if gain < 0.0 {
|
|
gain = 0.0;
|
|
}
|
|
self.gain.gain().set_value(gain);
|
|
}
|
|
|
|
#[wasm_bindgen]
|
|
pub fn set_primary_frequency(&self, freq: f32) {
|
|
self.primary.frequency().set_value(freq);
|
|
|
|
// The frequency of the FM oscillator depends on the frequency of the
|
|
// primary oscillator, so we update the frequency of both in this method.
|
|
self.fm_osc.frequency().set_value(self.fm_freq_ratio * freq);
|
|
self.fm_gain.gain().set_value(self.fm_gain_ratio * freq);
|
|
}
|
|
|
|
#[wasm_bindgen]
|
|
pub fn set_note(&self, note: u8) {
|
|
let freq = midi_to_freq(note);
|
|
self.set_primary_frequency(freq);
|
|
}
|
|
|
|
/// This should be between 0 and 1, though higher values are accepted.
|
|
#[wasm_bindgen]
|
|
pub fn set_fm_amount(&mut self, amt: f32) {
|
|
self.fm_gain_ratio = amt;
|
|
|
|
self.fm_gain
|
|
.gain()
|
|
.set_value(self.fm_gain_ratio * self.primary.frequency().value());
|
|
}
|
|
|
|
/// This should be between 0 and 1, though higher values are accepted.
|
|
#[wasm_bindgen]
|
|
pub fn set_fm_frequency(&mut self, amt: f32) {
|
|
self.fm_freq_ratio = amt;
|
|
self.fm_osc
|
|
.frequency()
|
|
.set_value(self.fm_freq_ratio * self.primary.frequency().value());
|
|
}
|
|
}
|
|
|
|
#}</code></pre></pre>
|
|
<h2><a class="header" href="#indexjs" id="indexjs"><code>index.js</code></a></h2>
|
|
<p>A small bit of JavaScript glues the rust module to input widgets and translates
|
|
events into calls into wasm code.</p>
|
|
<pre><code class="language-js">import('./pkg')
|
|
.then(rust_module => {
|
|
let fm = null;
|
|
|
|
const play_button = document.getElementById("play");
|
|
play_button.addEventListener("click", event => {
|
|
if (fm === null) {
|
|
fm = new rust_module.FmOsc();
|
|
fm.set_note(50);
|
|
fm.set_fm_frequency(0);
|
|
fm.set_fm_amount(0);
|
|
fm.set_gain(0.8);
|
|
} else {
|
|
fm.free();
|
|
fm = null;
|
|
}
|
|
});
|
|
|
|
const primary_slider = document.getElementById("primary_input");
|
|
primary_slider.addEventListener("input", event => {
|
|
if (fm) {
|
|
fm.set_note(parseInt(event.target.value));
|
|
}
|
|
});
|
|
|
|
const fm_freq = document.getElementById("fm_freq");
|
|
fm_freq.addEventListener("input", event => {
|
|
if (fm) {
|
|
fm.set_fm_frequency(parseFloat(event.target.value));
|
|
}
|
|
});
|
|
|
|
const fm_amount = document.getElementById("fm_amount");
|
|
fm_amount.addEventListener("input", event => {
|
|
if (fm) {
|
|
fm.set_fm_amount(parseFloat(event.target.value));
|
|
}
|
|
});
|
|
})
|
|
.catch(console.error);
|
|
|
|
</code></pre>
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