Create an Audio Visualizer with React and Canvas: Part 2 of 3

Create an Audio Visualizer with React and Canvas: Part 2 of 3

You’ve made it to part 2 of this tutorial — nice job! If you’ve stumbled here from the wild see Part 1 of this tutorial to get started with your own audio visualizer.

Let’s get started.Step1: AudioContext and Frequency Array

Define componentDidMount and create an AudioContext which provide us a method to interface with the audio.

What we have done is programmatically create an audio source node. The goal here is a frequency array, and now we have a way to capture the output of our soundFile. We need to analyze it to capture frequency data of a stream while it plays. Fortunate for us we are modern web developers and we have the power of HTML5 — yessssssss!

Simply take the context and call its method createAnalyser()….this.analyser = this.context.createAnalyser();…

Now we have an AnalyserNode!

Time to get analyzing. Take the audio source and connect it to our AnalyserNode. On the next line let’s connect the analyzer to our audio destination….this.source.connect(this.analyser);this.analyser.connect(this.context.destination);…

Finally we are ready to instantiate our frequency array 😊. Your component method should look like the example below.

Now we are ready create a canvas node and with a little math, wrapped in magic, our visualizer will come to be.Brief Introduction to the Power of Canvas API

Canvas is an HTML API for drawing animation, game graphics, data visualization, photo manipulation, and real-time video processing with Javascript. Its functionality is provided to us with the canvas HTML tag and the following could be used inside a react component or directly on an html file.<canvas id=”myCanvas” width=”500″ height=”200″></canvas>

To learn more about the basic usage of canvas outside of react click here.

This tutorial will focus on using canvas within a React application. Let’s return to our application’s file Canvas.js.Step 2: Creating a React Reference to Canvas

Inside the constructor of your component create a react reference, createRef(), to access Canvas’ api after componentDidMount….constructor(props){this.audio = new Audio(songFile);this.canvas = React.createRef()}…

Add the canvas element to the render function and pass it to our ref….<canvas ref={this.canvas} />…Step 3: Animation Loop and Draw Bar Functions

The image at the very start of this tutorial is a circle with a radius of zero and five hundred and fifty five lines, with a width of one, that wrap around its circumference. We want our visualizer to fill as much of the window’s dimensions as possible.

Contect us : Vector Magic crack

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