Tone.js/Tone/effect/FeedbackDelay.ts

import { Delay } from "../core/context/Delay";
import { Param } from "../core/context/Param";
import { optionsFromArguments } from "../core/util/Defaults";
import { readOnly } from "../core/util/Interface";
import { FeedbackEffect,  FeedbackEffectOptions } from "./FeedbackEffect";

interface FeedbackDelayOptions extends FeedbackEffectOptions {
	delayTime: Time;
	maxDelay: Time;
}

/**
 * FeedbackDelay is a DelayNode in which part of output signal is fed back into the delay.
 *
 * @param delayTime The delay applied to the incoming signal.
 * @param feedback The amount of the effected signal which is fed back through the delay.
 * @example
 * var feedbackDelay = new FeedbackDelay("8n", 0.5).toDestination();
 * var tom = new Tone.MembraneSynth({
 * 	"octaves" : 4,
 * 	"pitchDecay" : 0.1
 * }).connect(feedbackDelay);
 * tom.triggerAttackRelease("A2","32n");
 */
export class FeedbackDelay extends FeedbackEffect<FeedbackDelayOptions> {

	/**
	 *  the delay node
	 */
	private _delayNode: Delay;

	/**
	 *  The delayTime of the FeedbackDelay.
	 */
	readonly delayTime: Param<Time>;

	constructor(delayTime?: Time, feedback?: NormalRange);
	constructor(options?: Partial<FeedbackDelayOptions>);
	constructor() {

		super(optionsFromArguments(FeedbackDelay.getDefaults(), arguments, ["delayTime", "feedback"]));
		const options = optionsFromArguments(FeedbackDelay.getDefaults(), arguments, ["delayTime", "feedback"]);

		this._delayNode = new Delay({
			context: this.context,
			delayTime: options.delayTime,
			maxDelay: options.maxDelay,
		});
		this.delayTime = this._delayNode.delayTime;
		this._internalChannels.push(this._delayNode);

		// connect it up
		this.connectEffect(this._delayNode);
		readOnly(this, "delayTime");
	}

	static getDefaults(): FeedbackDelayOptions {
		return Object.assign(FeedbackEffect.getDefaults(), {
			delayTime: 0.25,
			maxDelay: 1,
		});
	}

	dispose(): this {
		super.dispose();
		this._delayNode.dispose();
		this.delayTime.dispose();
		return this;
	}
}