LibWeb: Implement BaseAudioContext.createGain

Author: https://github.com/shannonbooth
Commit: 6466fca20a
Pull-request: https://github.com/SerenityOS/serenity/pull/24471

Userland/Libraries/LibWeb/WebAudio/BaseAudioContext.cpp

@@ -11,6 +11,7 @@
 #include <LibWeb/WebAudio/AudioBuffer.h>
 #include <LibWeb/WebAudio/BaseAudioContext.h>
 #include <LibWeb/WebAudio/DynamicsCompressorNode.h>
+#include <LibWeb/WebAudio/GainNode.h>
 #include <LibWeb/WebAudio/OscillatorNode.h>
 
 namespace Web::WebAudio {
@@ -61,6 +62,13 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<DynamicsCompressorNode>> BaseAudioContext::
     return DynamicsCompressorNode::create(realm(), *this);
 }
 
+// https://webaudio.github.io/web-audio-api/#dom-baseaudiocontext-creategain
+JS::NonnullGCPtr<GainNode> BaseAudioContext::create_gain()
+{
+    // Factory method for GainNode.
+    return GainNode::create(realm(), *this);
+}
+
 // https://webaudio.github.io/web-audio-api/#dom-baseaudiocontext-createbuffer
 WebIDL::ExceptionOr<void> BaseAudioContext::verify_audio_options_inside_nominal_range(JS::Realm& realm, WebIDL::UnsignedLong number_of_channels, WebIDL::UnsignedLong length, float sample_rate)
 {

Userland/Libraries/LibWeb/WebAudio/BaseAudioContext.h

@@ -50,6 +50,7 @@ public:
     WebIDL::ExceptionOr<JS::NonnullGCPtr<AudioBuffer>> create_buffer(WebIDL::UnsignedLong number_of_channels, WebIDL::UnsignedLong length, float sample_rate);
     WebIDL::ExceptionOr<JS::NonnullGCPtr<OscillatorNode>> create_oscillator();
     WebIDL::ExceptionOr<JS::NonnullGCPtr<DynamicsCompressorNode>> create_dynamics_compressor();
+    JS::NonnullGCPtr<GainNode> create_gain();
 
 protected:
     explicit BaseAudioContext(JS::Realm&, float m_sample_rate = 0);

Userland/Libraries/LibWeb/WebAudio/BaseAudioContext.idl

@@ -2,6 +2,7 @@
 #import <DOM/EventHandler.idl>
 #import <WebAudio/AudioBuffer.idl>
 #import <WebAudio/DynamicsCompressorNode.idl>
+#import <WebAudio/GainNode.idl>
 #import <WebAudio/OscillatorNode.idl>
 
 // https://www.w3.org/TR/webaudio/#enumdef-audiocontextstate
@@ -33,7 +34,7 @@ interface BaseAudioContext : EventTarget {
     [FIXME] ConvolverNode createConvolver ();
     [FIXME] DelayNode createDelay (optional double maxDelayTime = 1.0);
     DynamicsCompressorNode createDynamicsCompressor();
-    [FIXME] GainNode createGain ();
+    GainNode createGain();
     [FIXME] IIRFilterNode createIIRFilter (sequence<double> feedforward, sequence<double> feedback);
     OscillatorNode createOscillator();
     [FIXME] PannerNode createPanner ();