[wip] convert Filter to .ts (#503)

* Convert filter.js to typescript

* remove unneeded imports in tests

Tone/component/filter/Filter.test.ts

@@ -0,0 +1,126 @@
+import { expect } from "chai";
+import { BasicTests } from "test/helper/Basic";
+import { connectFrom, connectTo } from "test/helper/Connect";
+import { Filter }  from "./Filter";
+import { Offline } from "test/helper/Offline";
+import { PassAudio } from "test/helper/PassAudio";
+import { Oscillator } from '../../source/oscillator/Oscillator'
+
+describe("Filter", () => {
+
+	BasicTests(Filter);
+
+	context("Filtering", () => {
+
+		it("handles input and output connections", () => {
+			var filter = new Filter();
+            connectFrom().connect(filter);
+			filter.dispose();
+		});
+
+		it("can be constructed with a arguments", () => {
+			var filter = new Filter(200, "highpass");
+			expect(filter.frequency.value).to.be.closeTo(200, 0.001);
+			expect(filter.type).to.equal("highpass");
+			filter.dispose();
+		});
+
+		it("can be constructed with an object", () => {
+			var filter = new Filter({
+				"frequency" : 340,
+				"type" : "bandpass"
+			});
+			expect(filter.frequency.value).to.be.closeTo(340, 0.001);
+			expect(filter.type).to.equal("bandpass");
+			filter.dispose();
+		});
+
+		it("can set/get values as an Object", () => {
+			var filter = new Filter();
+			var values = {
+				type : "highpass",
+				frequency : 440,
+				rolloff : -24,
+				Q : 2,
+				gain : -6,
+            };
+			filter.set(values);
+			expect(filter.get()).to.have.keys(["type", "frequency", "rolloff", "Q", "gain"]);
+			expect(filter.type).to.equal(values.type);
+			expect(filter.frequency.value).to.equal(values.frequency);
+			expect(filter.rolloff).to.equal(values.rolloff);
+			expect(filter.Q.value).to.equal(values.Q);
+			expect(filter.gain.value).to.be.closeTo(values.gain, 0.04);
+			filter.dispose();
+		});
+
+		it("can get the frequency response curve", () => {
+			var filter = new Filter();
+			var curve = filter.getFrequencyResponse(32);
+			expect(curve.length).to.equal(32);
+			expect(curve[0]).be.closeTo(1, 0.01);
+			expect(curve[5]).be.closeTo(0.5, 0.1);
+			expect(curve[15]).be.closeTo(0, 0.01);
+			expect(curve[31]).be.closeTo(0, 0.01);
+			filter.dispose();
+		});
+
+		it("passes the incoming signal through", () => {
+			return PassAudio(function(input){
+				var filter = new Filter().toMaster();
+				input.connect(filter);
+			});
+		});
+
+		it.skip("passes the incoming stereo signal through", () => {
+			// return PassAudioStereo(function(input){
+			// 	var filter = new Filter().toMaster();
+			// 	input.connect(filter);
+			// });
+		});
+
+		it("only accepts filter values -12, -24, -48 and -96", () => {
+			var filter = new Filter();
+			filter.rolloff = -12;
+			expect(filter.rolloff).to.equal(-12);
+			filter.rolloff = "-24";
+			expect(filter.rolloff).to.equal(-24);
+			filter.rolloff = -48;
+			expect(filter.rolloff).to.equal(-48);
+			filter.rolloff = -96;
+			expect(filter.rolloff).to.equal(-96);
+			expect(() =>{
+                // @ts-ignore
+				filter.rolloff = -95;
+			}).to.throw(Error);
+			filter.dispose();
+		});
+
+		it("can set the basic filter types", () => {
+			var filter = new Filter();
+			var types = ["lowpass", "highpass", "bandpass", "lowshelf", "highshelf", "notch", "allpass", "peaking"];
+			for (var i = 0; i < types.length; i++){
+				filter.type = types[i];
+				expect(filter.type).to.equal(types[i]);
+			}
+			expect(() => {
+				filter.type = "nontype";
+			}).to.throw(Error);
+			filter.dispose();
+		});
+
+		it("attenuates the incoming signal", () => {
+			return Offline(() => {
+				var filter = new Filter(700, "lowpass").toMaster();
+				filter.Q.value = 0;
+				var osc = new Oscillator(880).connect(filter);
+				osc.start(0);
+			}, 0.2).then(function(buffer){
+				expect(buffer.getRmsAtTime(0.05)).to.be.within(0.37, 0.53);
+				expect(buffer.getRmsAtTime(0.1)).to.be.within(0.37, 0.53);
+			});
+		});
+		
+	});
+});
+

Tone/component/filter/Filter.ts

@@ -0,0 +1,200 @@
+import {ToneAudioNode, ToneAudioNodeOptions, InputNode, OutputNode} from '../../core/context/ToneAudioNode';
+import { optionsFromArguments } from "Tone/core/util/Defaults";
+import { Signal } from 'Tone/signal/Signal';
+import { readOnly, writable } from 'Tone/core/util/Interface';
+
+type FilterType = "lowpass" | "highpass" | "bandpass" | "lowshelf" | "highshelf" | "peaking" | "notch" | "allpass";
+type RolloffType = "-12" | "-24" | "-48" | "-96";
+
+interface FilterOptions extends ToneAudioNodeOptions {
+	type: FilterType;
+	frequency: number;
+	rolloff: RolloffType;
+	Q: number;
+	gain: number
+}
+
+/**
+ *  @class  Tone.Filter is a filter which allows for all of the same native methods
+ *          as the [BiquadFilterNode](http://webaudio.github.io/web-audio-api/#the-biquadfilternode-interface).
+ *          Tone.Filter has the added ability to set the filter rolloff at -12
+ *          (default), -24 and -48.
+ *
+ *  @constructor
+ *  @extends {Tone.AudioNode}
+ *  @param {Frequency|Object} [frequency] The cutoff frequency of the filter.
+ *  @param {string=} type The type of filter.
+ *  @param {number=} rolloff The drop in decibels per octave after the cutoff frequency.
+ *                            3 choices: -12, -24, and -48
+ *  @example
+ *  var filter = new Tone.Filter(200, "highpass");
+ */
+export class Filter extends ToneAudioNode<FilterOptions> {
+
+	readonly name = "Filter";
+
+	readonly input = this.context.createBiquadFilter();
+	readonly output = this.context.createBiquadFilter();
+	private _filters: BiquadFilterNode[];
+
+
+	/**
+	 * The internal channels for channel routing changes
+	 */
+	protected _internalChannels = [this.output];
+
+	/**
+	 *  the rolloff value of the filter
+	 *  @type {number}
+	 *  @private
+	 */
+	private _rolloff: number;
+	private _type: FilterType;
+
+	readonly Q: Signal;
+
+	/**
+	 *  The cutoff frequency of the filter.
+	 *  @type {Frequency}
+	 *  @signal
+	 */
+	readonly frequency: Signal;
+
+	/**
+	 *  The detune parameter
+	 *  @type {Cents}
+	 *  @signal
+	 */
+	readonly detune = new Signal(0, "cents");
+
+	/**
+	 *  The gain of the filter, only used in certain filter types
+	 *  @type {Number}
+	 *  @signal
+	 */
+	readonly gain: Signal;
+
+	constructor(frequency?: number, type?: FilterType, rolloff?: RolloffType);
+	constructor(Q?: number, gain?: number, frequency?: number, type?: FilterType, rolloff?: RolloffType);
+	constructor(options?: Partial<FilterOptions>);
+	constructor() {
+		super(optionsFromArguments(Filter.getDefaults(), arguments, ["frequency", "type", "rolloff", "Q", "gain"]));
+		const options = optionsFromArguments(Filter.getDefaults(), arguments, ["frequency", "type", "rolloff", "Q", "gain"]);
+
+		this._filters = [];
+
+		this._rolloff = parseInt(options.rolloff);
+		this.rolloff = options.rolloff;
+		this.Q = new Signal(options.Q);
+		this.frequency = new Signal(options.frequency, "frequency");
+		this.gain = new Signal(options.gain, "decibels");
+		this._type = options.type;
+
+		readOnly(this, ["detune", "frequency", "gain", "Q"]);
+	}
+
+	static getDefaults(): FilterOptions {
+		return Object.assign(ToneAudioNode.getDefaults(), {
+			type: "lowpass" as FilterType,
+			frequency: 200,
+			rolloff: "-12" as RolloffType,
+			Q: 1,
+			gain: 0
+		});
+	}
+
+	get type(): FilterType {
+		return this.type;
+	}
+	set type(type: FilterType) {
+		var types: FilterType[] = ["lowpass", "highpass", "bandpass", "lowshelf", "highshelf", "notch", "allpass", "peaking"];
+		if (types.indexOf(type)=== -1){
+			throw new TypeError("Tone.Filter: invalid type "+type);
+		}
+		this._filters.forEach(filter => filter.type = type);
+	}
+
+	get rolloff(): RolloffType {
+		return this.rolloff;
+	}
+
+	set rolloff(rolloff: RolloffType) {
+		const rolloffNum = parseInt(rolloff, 10);
+		const possibilities = [-12, -24, -48, -96];
+
+		const cascadingCount = possibilities.indexOf(rolloffNum);
+		//check the rolloff is valid
+		if (cascadingCount === -1){
+			throw new RangeError("Tone.Filter: rolloff can only be -12, -24, -48 or -96");
+		}
+
+		this._rolloff = rolloffNum;
+
+		this.input.disconnect();
+
+		this._filters.forEach(filter => {
+			filter.disconnect();
+		});
+
+		this._filters = new Array(cascadingCount);
+		for (let count = 0; count < cascadingCount; count++){
+			let filter = this.context.createBiquadFilter();
+			filter.type = this._type;
+			this.frequency.connect(filter.frequency);
+			this.detune.connect(filter.detune);
+			this.Q.connect(filter.Q);
+			this.gain.connect(filter.gain);
+			this._filters[count] = filter;
+		}
+	}
+
+	/**
+	 * Get the frequency response curve. This curve represets how the filter
+	 * responses to frequencies between 20hz-20khz. 
+	 * @param  {Number} [len=128] The number of values to return
+	 * @return {Float32Array}     The frequency response curve between 20-20k
+	 */
+	getFrequencyResponse(len: number): Float32Array {
+		// len = Tone.defaultArg(len, 128); Is this still needed?	
+
+		//start with all 1s
+		const totalResponse = new Float32Array(len).map(() => 1);
+		const freqValues = new Float32Array(len);
+		for (let i = 0; i < len; i++){
+			const norm = Math.pow(i / len, 2);
+			const freq = norm * (20000 - 20) + 20;
+			freqValues[i] = freq;
+		}
+		const magValues = new Float32Array(len);
+		const phaseValues = new Float32Array(len);
+		this._filters.forEach(() => {
+			const filterClone = this.context.createBiquadFilter();
+			filterClone.type = this._type;
+			filterClone.Q.value = this.Q.value;
+			filterClone.frequency.value = this.frequency.value;
+			filterClone.gain.value = this.gain.value;
+			filterClone.getFrequencyResponse(freqValues, magValues, phaseValues);
+			magValues.forEach((val, i) =>{
+				totalResponse[i] *= val;
+			});
+		});
+		return totalResponse;
+	}
+
+	/**
+	 *  Clean up.
+	 *  @return {Tone.Filter} this
+	 */
+    dispose(): this {
+		super.dispose();
+		this._filters.forEach(filter => {
+			filter.disconnect();
+		});
+		writable(this, ["detune", "frequency", "gain", "Q"]);
+		this.frequency.dispose();
+		this.Q.dispose();
+		this.detune.dispose();
+		this.gain.dispose();
+		return this;
+	}
+}