AudioContext construction

components/script/dom/audiocontext.rs

@@ -21,14 +21,36 @@ use std::rc::Rc;
 #[dom_struct]
 pub struct AudioContext {
     context: BaseAudioContext,
+    latency_hint: AudioContextLatencyCategory,
+    /// https://webaudio.github.io/web-audio-api/#dom-audiocontext-baselatency
     base_latency: f64,
+    /// https://webaudio.github.io/web-audio-api/#dom-audiocontext-outputlatency
     output_latency: f64,
 }
 
 impl AudioContext {
+    #[allow(unrooted_must_root)]
+    // https://webaudio.github.io/web-audio-api/#AudioContext-constructors
     fn new_inherited(global: &GlobalScope, options: &AudioContextOptions) -> AudioContext {
+        // Steps 1-3.
+        let context = BaseAudioContext::new_inherited(global, BaseAudioContextOptions::AudioContext(options.into()));
+
+        // Step 4.1.
+        let latency_hint = options.latencyHint;
+
+        // Step 4.2. The sample rate is set during the creation of the BaseAudioContext.
+        // servo-media takes care of setting the default sample rate of the output device
+        // and of resampling the audio output if needed.
+
+        // Step 5.
+        if context.is_allowed_to_start() {
+            // Step 6.
+            context.resume();
+        }
+
         AudioContext {
-            context: BaseAudioContext::new_inherited(global, BaseAudioContextOptions::AudioContext(options.into())),
+            context,
+            latency_hint,
             base_latency: 0., // TODO
             output_latency: 0., // TODO
         }
@@ -44,6 +66,7 @@ impl AudioContext {
         reflect_dom_object(Box::new(context), global, AudioContextBinding::Wrap)
     }
 
+    // https://webaudio.github.io/web-audio-api/#AudioContext-constructors
     pub fn Constructor(window: &Window,
                        options: &AudioContextOptions) -> Fallible<DomRoot<AudioContext>> {
         let global = window.upcast::<GlobalScope>();

components/script/dom/baseaudiocontext.rs

@@ -3,24 +3,30 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::audiodestinationnode::AudioDestinationNode;
+use dom::bindings::cell::DomRefCell;
 use dom::bindings::codegen::Bindings::AudioNodeBinding::AudioNodeOptions;
 use dom::bindings::codegen::Bindings::AudioNodeBinding::{ChannelCountMode, ChannelInterpretation};
 use dom::bindings::codegen::Bindings::BaseAudioContextBinding::BaseAudioContextMethods;
 use dom::bindings::codegen::Bindings::BaseAudioContextBinding::AudioContextState;
 use dom::bindings::codegen::Bindings::OscillatorNodeBinding::OscillatorOptions;
+use dom::bindings::inheritance::Castable;
 use dom::bindings::num::Finite;
+use dom::bindings::refcounted::Trusted;
 use dom::bindings::reflector::{DomObject, Reflector};
 use dom::bindings::root::DomRoot;
 use dom::globalscope::GlobalScope;
-use dom::promise::Promise;
 use dom::oscillatornode::OscillatorNode;
+use dom::promise::Promise;
+use dom::window::Window;
 use dom_struct::dom_struct;
 use servo_media::ServoMedia;
 use servo_media::audio::graph::AudioGraph;
 use servo_media::audio::graph::{OfflineAudioGraphOptions, RealTimeAudioGraphOptions};
 use servo_media::audio::graph_impl::NodeId;
 use servo_media::audio::node::AudioNodeType;
+use std::cell::Cell;
 use std::rc::Rc;
+use task_source::TaskSource;
 
 pub enum BaseAudioContextOptions {
     AudioContext(RealTimeAudioGraphOptions),
@@ -32,10 +38,17 @@ pub struct BaseAudioContext {
     reflector_: Reflector,
     #[ignore_malloc_size_of = "servo_media"]
     audio_graph: AudioGraph,
+    /// https://webaudio.github.io/web-audio-api/#dom-baseaudiocontext-destination
     destination: Option<DomRoot<AudioDestinationNode>>,
+    /// https://webaudio.github.io/web-audio-api/#dom-baseaudiocontext-samplerate
     sample_rate: f32,
+    /// https://webaudio.github.io/web-audio-api/#dom-baseaudiocontext-currenttime
     current_time: f64,
-    state: AudioContextState,
+    /// https://webaudio.github.io/web-audio-api/#dom-baseaudiocontext-state
+    state: Cell<AudioContextState>,
+    /// https://webaudio.github.io/web-audio-api/#pendingresumepromises
+    #[ignore_malloc_size_of = "promises are hard"]
+    pending_resume_promises: DomRefCell<Vec<Rc<Promise>>>,
 }
 
 impl BaseAudioContext {
@@ -58,7 +71,8 @@ impl BaseAudioContext {
             destination: None,
             current_time: 0.,
             sample_rate,
-            state: AudioContextState::Suspended,
+            state: Cell::new(AudioContextState::Suspended),
+            pending_resume_promises: Default::default(),
         };
 
         let mut options = unsafe { AudioNodeOptions::empty(global.get_cx()) };
@@ -74,6 +88,30 @@ impl BaseAudioContext {
     pub fn create_node_engine(&self, node_type: AudioNodeType) -> NodeId {
         self.audio_graph.create_node(node_type)
     }
+
+    // https://webaudio.github.io/web-audio-api/#allowed-to-start
+    pub fn is_allowed_to_start(&self) -> bool {
+        self.state.get() == AudioContextState::Suspended
+    }
+
+    pub fn resume(&self) {
+        let window = DomRoot::downcast::<Window>(self.global()).unwrap();
+        let task_source = window.dom_manipulation_task_source();
+
+        // Set the state attribute to `running`.
+        let this = Trusted::new(self);
+        task_source.queue(task!(set_state: move || {
+            let this = this.root();
+            this.state.set(AudioContextState::Running);
+        }), window.upcast()).unwrap();
+
+        // Queue a task to fire a simple event named `statechange` at the AudioContext.
+        task_source.queue_simple_event(
+            self.upcast(),
+            atom!("statechange"),
+            &window,
+            );
+    }
 }
 
 impl BaseAudioContextMethods for BaseAudioContext {
@@ -89,7 +127,7 @@ impl BaseAudioContextMethods for BaseAudioContext {
 
     // https://webaudio.github.io/web-audio-api/#dom-baseaudiocontext-state
     fn State(&self) -> AudioContextState {
-        self.state
+        self.state.get()
     }
 
     // https://webaudio.github.io/web-audio-api/#dom-baseaudiocontext-resume