playcanvas/build/playcanvas/src/platform/audio/channel.js

PlayCanvas WebGL game engine

import { math } from '../../core/math/math.js';
import { hasAudioContext } from './capabilities.js';

class Channel {
		getVolume() {
				return this.volume;
		}
		getLoop() {
				return this.loop;
		}
		setLoop(loop) {
				this.loop = loop;
				if (this.source) {
						this.source.loop = loop;
				}
		}
		getPitch() {
				return this.pitch;
		}
		onManagerVolumeChange() {
				this.setVolume(this.getVolume());
		}
		onManagerSuspend() {
				if (this.isPlaying() && !this.suspended) {
						this.suspended = true;
						this.pause();
				}
		}
		onManagerResume() {
				if (this.suspended) {
						this.suspended = false;
						this.unpause();
				}
		}
		play() {
				if (this.source) {
						throw new Error('Call stop() before calling play()');
				}
				this._createSource();
				if (!this.source) {
						return;
				}
				this.startTime = this.manager.context.currentTime;
				this.source.start(0, this.startOffset % this.source.buffer.duration);
				this.setVolume(this.volume);
				this.setLoop(this.loop);
				this.setPitch(this.pitch);
				this.manager.on('volumechange', this.onManagerVolumeChange, this);
				this.manager.on('suspend', this.onManagerSuspend, this);
				this.manager.on('resume', this.onManagerResume, this);
				if (this.manager.suspended) {
						this.onManagerSuspend();
				}
		}
		pause() {
				if (this.source) {
						this.paused = true;
						this.startOffset += this.manager.context.currentTime - this.startTime;
						this.source.stop(0);
						this.source = null;
				}
		}
		unpause() {
				if (this.source || !this.paused) {
						console.warn('Call pause() before unpausing.');
						return;
				}
				this._createSource();
				if (!this.source) {
						return;
				}
				this.startTime = this.manager.context.currentTime;
				this.source.start(0, this.startOffset % this.source.buffer.duration);
				this.setVolume(this.volume);
				this.setLoop(this.loop);
				this.setPitch(this.pitch);
				this.paused = false;
		}
		stop() {
				if (this.source) {
						this.source.stop(0);
						this.source = null;
				}
				this.manager.off('volumechange', this.onManagerVolumeChange, this);
				this.manager.off('suspend', this.onManagerSuspend, this);
				this.manager.off('resume', this.onManagerResume, this);
		}
		setVolume(volume) {
				volume = math.clamp(volume, 0, 1);
				this.volume = volume;
				if (this.gain) {
						this.gain.gain.value = volume * this.manager.volume;
				}
		}
		setPitch(pitch) {
				this.pitch = pitch;
				if (this.source) {
						this.source.playbackRate.value = pitch;
				}
		}
		isPlaying() {
				return !this.paused && this.source.playbackState === this.source.PLAYING_STATE;
		}
		getDuration() {
				return this.source ? this.source.buffer.duration : 0;
		}
		_createSource() {
				var context = this.manager.context;
				if (this.sound.buffer) {
						this.source = context.createBufferSource();
						this.source.buffer = this.sound.buffer;
						this.source.connect(this.gain);
						this.gain.connect(context.destination);
						if (!this.loop) {
								this.source.onended = this.pause.bind(this);
						}
				}
		}
		constructor(manager, sound, options = {}){
				var _options_volume;
				this.volume = (_options_volume = options.volume) != null ? _options_volume : 1;
				var _options_loop;
				this.loop = (_options_loop = options.loop) != null ? _options_loop : false;
				var _options_pitch;
				this.pitch = (_options_pitch = options.pitch) != null ? _options_pitch : 1;
				this.sound = sound;
				this.paused = false;
				this.suspended = false;
				this.manager = manager;
				this.source = null;
				if (hasAudioContext()) {
						this.startTime = 0;
						this.startOffset = 0;
						var context = manager.context;
						this.gain = context.createGain();
				} else if (sound.audio) {
						this.source = sound.audio.cloneNode(false);
						this.source.pause();
				}
		}
}
if (!hasAudioContext()) {
		Object.assign(Channel.prototype, {
				play: function play() {
						if (this.source) {
								this.paused = false;
								this.setVolume(this.volume);
								this.setLoop(this.loop);
								this.setPitch(this.pitch);
								this.source.play();
						}
						this.manager.on('volumechange', this.onManagerVolumeChange, this);
						this.manager.on('suspend', this.onManagerSuspend, this);
						this.manager.on('resume', this.onManagerResume, this);
						if (this.manager.suspended) {
								this.onManagerSuspend();
						}
				},
				pause: function pause() {
						if (this.source) {
								this.paused = true;
								this.source.pause();
						}
				},
				unpause: function unpause() {
						if (this.source) {
								this.paused = false;
								this.source.play();
						}
				},
				stop: function stop() {
						if (this.source) {
								this.source.pause();
						}
						this.manager.off('volumechange', this.onManagerVolumeChange, this);
						this.manager.off('suspend', this.onManagerSuspend, this);
						this.manager.off('resume', this.onManagerResume, this);
				},
				setVolume: function setVolume(volume) {
						volume = math.clamp(volume, 0, 1);
						this.volume = volume;
						if (this.source) {
								this.source.volume = volume * this.manager.volume;
						}
				},
				setPitch: function setPitch(pitch) {
						this.pitch = pitch;
						if (this.source) {
								this.source.playbackRate = pitch;
						}
				},
				getDuration: function getDuration() {
						return this.source && !isNaN(this.source.duration) ? this.source.duration : 0;
				},
				isPlaying: function isPlaying() {
						return !this.source.paused;
				}
		});
}

export { Channel };