Auto merge of #23919 - tdelacour:ISSUE-21803, r=jdm

ISSUE-21803: Implement ConstantSourceNode audionode

<!-- Please describe your changes on the following line: -->
More or less followed the steps outlined in `components/script/dom/mod.rs` (and also used the [previous PR](https://github.com/servo/servo/pull/23152) on this issue as reference). Updated `wpt` tests as well.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #21803 (GitHub issue number if applicable)

<!-- Either: -->
- [X] There are tests for these changes OR
- [ ] These changes do not require tests because ___

<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/23919)
<!-- Reviewable:end -->

components/script/dom/baseaudiocontext.rs

@@ -24,6 +24,7 @@ use crate::dom::bindings::codegen::Bindings::BaseAudioContextBinding::DecodeSucc
 use crate::dom::bindings::codegen::Bindings::BiquadFilterNodeBinding::BiquadFilterOptions;
 use crate::dom::bindings::codegen::Bindings::ChannelMergerNodeBinding::ChannelMergerOptions;
 use crate::dom::bindings::codegen::Bindings::ChannelSplitterNodeBinding::ChannelSplitterOptions;
+use crate::dom::bindings::codegen::Bindings::ConstantSourceNodeBinding::ConstantSourceOptions;
 use crate::dom::bindings::codegen::Bindings::GainNodeBinding::GainOptions;
 use crate::dom::bindings::codegen::Bindings::OscillatorNodeBinding::OscillatorOptions;
 use crate::dom::bindings::codegen::Bindings::PannerNodeBinding::PannerOptions;
@@ -37,6 +38,7 @@ use crate::dom::bindings::root::{DomRoot, MutNullableDom};
 use crate::dom::biquadfilternode::BiquadFilterNode;
 use crate::dom::channelmergernode::ChannelMergerNode;
 use crate::dom::channelsplitternode::ChannelSplitterNode;
+use crate::dom::constantsourcenode::ConstantSourceNode;
 use crate::dom::domexception::{DOMErrorName, DOMException};
 use crate::dom::eventtarget::EventTarget;
 use crate::dom::gainnode::GainNode;
@@ -378,6 +380,15 @@ impl BaseAudioContextMethods for BaseAudioContext {
         )
     }
 
+    /// https://webaudio.github.io/web-audio-api/#dom-baseaudiocontext-createconstantsource
+    fn CreateConstantSource(&self) -> Fallible<DomRoot<ConstantSourceNode>> {
+        ConstantSourceNode::new(
+            &self.global().as_window(),
+            &self,
+            &ConstantSourceOptions::empty(),
+        )
+    }
+
     /// https://webaudio.github.io/web-audio-api/#dom-baseaudiocontext-createchannelmerger
     fn CreateChannelMerger(&self, count: u32) -> Fallible<DomRoot<ChannelMergerNode>> {
         let mut opts = ChannelMergerOptions::empty();

components/script/dom/constantsourcenode.rs

@@ -0,0 +1,98 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use crate::dom::audioparam::AudioParam;
+use crate::dom::audioscheduledsourcenode::AudioScheduledSourceNode;
+use crate::dom::baseaudiocontext::BaseAudioContext;
+use crate::dom::bindings::codegen::Bindings::AudioParamBinding::AutomationRate;
+use crate::dom::bindings::codegen::Bindings::ConstantSourceNodeBinding::ConstantSourceNodeMethods;
+use crate::dom::bindings::codegen::Bindings::ConstantSourceNodeBinding::{
+    self, ConstantSourceOptions,
+};
+use crate::dom::bindings::error::Fallible;
+use crate::dom::bindings::reflector::reflect_dom_object;
+use crate::dom::bindings::root::{Dom, DomRoot};
+use crate::dom::window::Window;
+use dom_struct::dom_struct;
+use servo_media::audio::constant_source_node::ConstantSourceNodeOptions as ServoMediaConstantSourceOptions;
+use servo_media::audio::node::AudioNodeInit;
+use servo_media::audio::param::ParamType;
+use std::f32;
+
+#[dom_struct]
+pub struct ConstantSourceNode {
+    source_node: AudioScheduledSourceNode,
+    offset: Dom<AudioParam>,
+}
+
+impl ConstantSourceNode {
+    #[allow(unrooted_must_root)]
+    fn new_inherited(
+        window: &Window,
+        context: &BaseAudioContext,
+        options: &ConstantSourceOptions,
+    ) -> Fallible<ConstantSourceNode> {
+        let node_options = Default::default();
+        let source_node = AudioScheduledSourceNode::new_inherited(
+            AudioNodeInit::ConstantSourceNode(options.into()),
+            context,
+            node_options, /* 2, MAX, Speakers */
+            0,            /* inputs */
+            1,            /* outputs */
+        )?;
+        let node_id = source_node.node().node_id();
+        let offset = AudioParam::new(
+            window,
+            context,
+            node_id,
+            ParamType::Offset,
+            AutomationRate::A_rate,
+            *options.offset,
+            f32::MIN,
+            f32::MAX,
+        );
+
+        Ok(ConstantSourceNode {
+            source_node,
+            offset: Dom::from_ref(&offset),
+        })
+    }
+
+    #[allow(unrooted_must_root)]
+    pub fn new(
+        window: &Window,
+        context: &BaseAudioContext,
+        options: &ConstantSourceOptions,
+    ) -> Fallible<DomRoot<ConstantSourceNode>> {
+        let node = ConstantSourceNode::new_inherited(window, context, options)?;
+        Ok(reflect_dom_object(
+            Box::new(node),
+            window,
+            ConstantSourceNodeBinding::Wrap,
+        ))
+    }
+
+    pub fn Constructor(
+        window: &Window,
+        context: &BaseAudioContext,
+        options: &ConstantSourceOptions,
+    ) -> Fallible<DomRoot<ConstantSourceNode>> {
+        ConstantSourceNode::new(window, context, options)
+    }
+}
+
+impl ConstantSourceNodeMethods for ConstantSourceNode {
+    // https://webaudio.github.io/web-audio-api/#dom-constantsourcenode-offset
+    fn Offset(&self) -> DomRoot<AudioParam> {
+        DomRoot::from_ref(&self.offset)
+    }
+}
+
+impl<'a> From<&'a ConstantSourceOptions> for ServoMediaConstantSourceOptions {
+    fn from(options: &'a ConstantSourceOptions) -> Self {
+        Self {
+            offset: *options.offset,
+        }
+    }
+}

components/script/dom/mod.rs

@@ -254,6 +254,7 @@ pub mod closeevent;
 pub mod comment;
 pub mod compositionevent;
 pub mod console;
+pub mod constantsourcenode;
 mod create;
 pub mod crypto;
 pub mod css;

components/script/dom/webidls/BaseAudioContext.webidl

@@ -31,7 +31,7 @@ interface BaseAudioContext : EventTarget {
                                        optional DecodeSuccessCallback successCallback,
                                        optional DecodeErrorCallback errorCallback);
   [Throws] AudioBufferSourceNode createBufferSource();
-  // ConstantSourceNode createConstantSource();
+  [Throws] ConstantSourceNode createConstantSource();
   // ScriptProcessorNode createScriptProcessor(optional unsigned long bufferSize = 0,
   //                                           optional unsigned long numberOfInputChannels = 2,
   //                                           optional unsigned long numberOfOutputChannels = 2);

components/script/dom/webidls/ConstantSourceNode.webidl

@@ -0,0 +1,17 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+/*
+ * The origin of this IDL file is
+ * https://webaudio.github.io/web-audio-api/#ConstantSourceNode
+ */
+
+dictionary ConstantSourceOptions: AudioNodeOptions {
+  float offset = 1;
+};
+
+[Exposed=Window,
+ Constructor (BaseAudioContext context, optional ConstantSourceOptions options = {})]
+interface ConstantSourceNode : AudioScheduledSourceNode {
+  readonly attribute AudioParam offset;
+};