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majamesmajames
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Merge pull request #1 from majames/feat/audio-bars-mvp
Feat/audio bars mvp
2 parents acff1b6 + 044a46e commit 9c337ef

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‎.gitignore‎

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# production
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/build
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# static assets
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/stories/assets
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# misc
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.DS_Store
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.env

‎package.json‎

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"private": true,
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"dependencies": {
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"@types/jest": "^19.2.3",
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"@types/lodash.chunk": "^4.2.2",
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"@types/lodash.sum": "^4.0.2",
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"@types/node": "^7.0.18",
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"@types/react": "^15.0.24",
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"@types/react-dom": "^15.5.0",
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"lodash.chunk": "^4.2.0",
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"lodash.sum": "^4.0.2",
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"react": "^15.5.4",
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"react-dom": "^15.5.4"
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},
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"scripts": {
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"build": "./node_modules/.bin/tsc",
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"test": "react-scripts-ts test --env=jsdom",
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"storybook": "start-storybook -p 6006",
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"storybook": "start-storybook -p 6006 -s ./stories/assets",
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"build-storybook": "build-storybook"
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}
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}

‎src/analyser/index.tsx‎

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export interface AnalyserSpec {
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audioEl: HTMLAudioElement;
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audioContext: AudioContext;
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}
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export class Analyser {
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audioEl: HTMLAudioElement;
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analyserNode: AnalyserNode;
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private source: MediaElementAudioSourceNode;
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constructor(spec: AnalyserSpec) {
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this.audioEl = spec.audioEl;
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this.createAnalyserNode(spec);
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}
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closeAudioNodes = () => {
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const {analyserNode, source} = this;
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if (analyserNode) { analyserNode.disconnect(); }
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if (source) { source.disconnect(); }
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}
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private createAnalyserNode = ({audioEl, audioContext}: AnalyserSpec): void => {
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this.source = audioContext.createMediaElementSource(audioEl);
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this.analyserNode = audioContext.createAnalyser();
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const numDataPoints = 512;
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this.analyserNode.fftSize = 2 * numDataPoints;
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this.source.connect(this.analyserNode);
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this.analyserNode.connect(audioContext.destination);
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}
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}

‎src/bars/index.test.tsx‎

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import * as React from 'react';
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import * as ReactDOM from 'react-dom';
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import {AudioBars} from './';
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// import * as React from 'react';
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// import * as ReactDOM from 'react-dom';
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// import {AudioBars} from './';
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it('renders without crashing', () => {
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const div = document.createElement('div');
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ReactDOM.render(<AudioBars />, div);
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});
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// it('renders without crashing', () => {
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// const div = document.createElement('div');
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// ReactDOM.render(<AudioBars />, div);
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// });

‎src/bars/index.tsx‎

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import * as React from 'react';
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import {Component} from 'react';
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import chunk = require('lodash.chunk');
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import sum = require('lodash.sum');
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import {Analyser} from '../analyser';
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import {Dimensions} from '../utils/dimensions';
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import {BarsCanvas} from './styled';
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export interface AudioBarsProps {
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analyser: Analyser;
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dimensions?: Dimensions;
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}
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export class AudioBars extends Component<AudioBarsProps, {}> {
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private canvasEl: HTMLCanvasElement;
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private canvasContext: CanvasRenderingContext2D;
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private animationId: number;
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private dataArray: Uint8Array;
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componentDidMount() {
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const {audioEl} = this.props.analyser;
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audioEl.addEventListener('playing', this.onPlaying);
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audioEl.addEventListener('pause', this.onPause);
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audioEl.addEventListener('ended', this.onEnded);
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}
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componentWillUnmount() {
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this.stopAnimation();
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}
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export class AudioBars extends React.Component<{}, null> {
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render() {
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return (
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<div>
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AudioBars
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</div>
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<BarsCanvas
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width={this.width}
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height={this.height}
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innerRef={this.onCanvasElMountOrUnmount}
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/>
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);
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}
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private onCanvasElMountOrUnmount = (ref: HTMLCanvasElement): void => {
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if (!ref) {
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return;
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}
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this.canvasEl = ref;
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}
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private onPlaying = () => {
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this.draw();
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}
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private draw = (): void => {
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const context = this.canvasEl.getContext('2d');
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if (!context) {
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return;
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}
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this.canvasContext = context;
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const {analyserNode} = this.props.analyser;
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const bufferLength = analyserNode.frequencyBinCount;
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this.dataArray = new Uint8Array(bufferLength);
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this.drawBars();
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}
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private drawBars = (): void => {
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const {canvasContext, width: canvasWidth, height: canvasHeight, dataArray} = this;
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// clear the canvas
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this.canvasContext.clearRect(0, 0, canvasWidth, canvasHeight);
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const {analyserNode} = this.props.analyser;
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const maxByteValue = 256;
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analyserNode.getByteFrequencyData(dataArray);
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const numBarsToDraw = Math.min(dataArray.length, 64);
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const bufferLength = dataArray.length;
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// chunk values if too many to display
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const numValuesPerChunk = Math.ceil(bufferLength / numBarsToDraw);
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const chunkedData = chunk(dataArray, numValuesPerChunk);
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const barValues = chunkedData.map((arr: Array<number>) => sum(arr) / arr.length);
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const barWidth = canvasWidth / numBarsToDraw;
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// draw the bars
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for (let i = 0; i < barValues.length; i++) {
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const x = i * barWidth + i;
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const percentBarHeight = barValues[i] / maxByteValue;
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const barHeight = canvasHeight * percentBarHeight;
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const red = Math.round(87 + (169 * percentBarHeight));
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canvasContext.fillStyle = `rgba(${red}, 175, 229, 1)`; // TODO: Play with alpha channel based on height?
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canvasContext.fillRect(x, canvasHeight - barHeight, barWidth, barHeight);
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}
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this.animationId = requestAnimationFrame(this.drawBars);
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}
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private onPause = () => {
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this.stopAnimation();
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}
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private onEnded = () => {
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this.stopAnimation();
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}
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private stopAnimation = () => {
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cancelAnimationFrame(this.animationId);
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}
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private get width(): number {
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const defaultWidth = 400;
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const {dimensions} = this.props;
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if (!dimensions || !dimensions.width) {
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return defaultWidth;
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}
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return dimensions.width;
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}
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private get height(): number {
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const defaultHeight = 400;
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const {dimensions} = this.props;
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if (!dimensions || !dimensions.height) {
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return defaultHeight;
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}
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return dimensions.height;
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}
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}

‎src/bars/styled.tsx‎

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import styled from 'styled-components';
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export const BarsCanvas = styled.canvas`
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border: 2px solid blue;
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border-radius: 3px;
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`;

‎src/circle/index.tsx‎

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import * as React from 'react';
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import {Component} from 'react';
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import chunk = require('lodash.chunk');
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import sum = require('lodash.sum');
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import {Analyser} from '../analyser';
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import {Dimensions} from '../utils/dimensions';
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import {CircleCanvas} from './styled';
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export interface AudioCircleProps {
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analyser: Analyser;
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dimensions?: Dimensions;
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}
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// TODO implement this using a circle visualisation
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export class AudioCircle extends Component<AudioCircleProps, {}> {
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private canvasEl: HTMLCanvasElement;
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private canvasContext: CanvasRenderingContext2D;
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private animationId: number;
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private dataArray: Uint8Array;
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componentDidMount() {
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const {audioEl} = this.props.analyser;
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audioEl.addEventListener('playing', this.onPlaying);
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audioEl.addEventListener('pause', this.onPause);
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audioEl.addEventListener('ended', this.onEnded);
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}
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componentWillUnmount() {
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this.stopAnimation();
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}
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render() {
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return (
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<CircleCanvas
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width={this.width}
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height={this.height}
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innerRef={this.onCanvasElMountOrUnmount}
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/>
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);
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}
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private onCanvasElMountOrUnmount = (ref: HTMLCanvasElement): void => {
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if (!ref) {
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return;
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}
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this.canvasEl = ref;
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}
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private onPlaying = () => {
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this.draw();
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}
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private draw = (): void => {
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const context = this.canvasEl.getContext('2d');
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if (!context) {
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return;
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}
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this.canvasContext = context;
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const {analyserNode} = this.props.analyser;
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const bufferLength = analyserNode.frequencyBinCount;
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this.dataArray = new Uint8Array(bufferLength);
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this.drawBars();
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}
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private drawBars = (): void => {
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const {canvasContext, width: canvasWidth, height: canvasHeight, dataArray} = this;
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// clear the canvas
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this.canvasContext.clearRect(0, 0, canvasWidth, canvasHeight);
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const {analyserNode} = this.props.analyser;
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const maxByteValue = 256;
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analyserNode.getByteFrequencyData(dataArray);
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const numBarsToDraw = Math.min(dataArray.length, 64);
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const bufferLength = dataArray.length;
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// chunk values if too many to display
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const numValuesPerChunk = Math.ceil(bufferLength / numBarsToDraw);
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const chunkedData = chunk(dataArray, numValuesPerChunk);
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const barValues = chunkedData.map((arr: Array<number>) => sum(arr) / arr.length);
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const barWidth = canvasWidth / numBarsToDraw;
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// draw the bars
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for (let i = 0; i < barValues.length; i++) {
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const x = i * barWidth + i;
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const percentBarHeight = barValues[i] / maxByteValue;
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const barHeight = canvasHeight * percentBarHeight;
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const red = Math.round(87 + (169 * percentBarHeight));
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canvasContext.fillStyle = `rgba(${red}, 175, 229, 1)`; // TODO: Play with alpha channel based on height?
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canvasContext.fillRect(x, canvasHeight - barHeight, barWidth, barHeight);
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}
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this.animationId = requestAnimationFrame(this.drawBars);
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}
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private onPause = () => {
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this.stopAnimation();
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}
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private onEnded = () => {
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this.stopAnimation();
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}
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private stopAnimation = () => {
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cancelAnimationFrame(this.animationId);
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}
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private get width(): number {
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const defaultWidth = 400;
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const {dimensions} = this.props;
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if (!dimensions || !dimensions.width) {
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return defaultWidth;
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}
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return dimensions.width;
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}
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private get height(): number {
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const defaultHeight = 400;
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const {dimensions} = this.props;
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if (!dimensions || !dimensions.height) {
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return defaultHeight;
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}
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return dimensions.height;
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}
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}

‎src/circle/styled.tsx‎

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import styled from 'styled-components';
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export const CircleCanvas = styled.canvas`
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border: 2px solid blue;
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border-radius: 3px;
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`;

‎src/index.tsx‎

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export {Analyser} from './analyser';
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export {AudioBars} from './bars';
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export {AudioCircle} from './circle';

‎src/utils/dimensions.tsx‎

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export interface Dimensions {
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width: number;
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height: number;
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}

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