Tone.js/Tone/effect/Effect.ts

import { CrossFade } from "../component/channel/CrossFade";
import { Gain } from "../core/context/Gain";
import { ToneAudioNode, ToneAudioNodeOptions } from "../core/context/ToneAudioNode";
import { NormalRange } from "../core/type/Units";
import { readOnly } from "../core/util/Interface";
import { Signal } from "../signal/Signal";

export interface EffectOptions extends ToneAudioNodeOptions {
	wet: NormalRange;
}
/**
 * Effect is the base class for effects. Connect the effect between
 * the effectSend and effectReturn GainNodes, then control the amount of
 * effect which goes to the output using the wet control.
 */
export abstract class Effect<Options extends EffectOptions>
	extends ToneAudioNode<Options> {

	readonly name: string = "Effect";

	/**
	 * the drywet knob to control the amount of effect
	 */
	private _dryWet: CrossFade = new CrossFade({ context: this.context });

	/**
	 * The wet control is how much of the effected
	 * will pass through to the output. 1 = 100% effected
	 * signal, 0 = 100% dry signal.
	 */
	wet: Signal<"normalRange"> = this._dryWet.fade;

	/**
	 * connect the effectSend to the input of hte effect
	 */
	protected effectSend: Gain = new Gain({ context: this.context });

	/**
	 * connect the output of the effect to the effectReturn
	 */
	protected effectReturn: Gain = new Gain({ context: this.context });

	/**
	 * The effect input node
	 */
	input: Gain = new Gain({ context: this.context });

	/**
	 * The effect output
	 */
	output = this._dryWet;

	constructor(options: EffectOptions) {
		super(options);

		// connections
		this.input.fan(this._dryWet.a, this.effectSend);
		this.effectReturn.connect(this._dryWet.b);
		this.wet.setValueAtTime(options.wet, 0);
		this._internalChannels = [this.effectReturn, this.effectSend];
		readOnly(this, "wet");
	}

	static getDefaults(): EffectOptions {
		return Object.assign(ToneAudioNode.getDefaults(), {
			wet: 1,
		});
	}

	/**
	 * chains the effect in between the effectSend and effectReturn
	 */
	protected connectEffect(effect: ToneAudioNode | AudioNode): this {
		// add it to the internal channels
		this._internalChannels.push(effect);
		this.effectSend.chain(effect, this.effectReturn);
		return this;
	}

	dispose(): this {
		super.dispose();
		this._dryWet.dispose();
		this.effectSend.dispose();
		this.effectReturn.dispose();
		this.wet.dispose();
		return this;
	}
}