@uppy/audio/lib/audio-oscilloscope/index.js

Uppy plugin that records audio using the device’s microphone.

function _classPrivateFieldLooseBase(e, t) { if (!{}.hasOwnProperty.call(e, t)) throw new TypeError("attempted to use private field on non-instance"); return e; }
var id = 0;
function _classPrivateFieldLooseKey(e) { return "__private_" + id++ + "_" + e; }
// eslint-disable-next-line @typescript-eslint/ban-types
function isFunction(v) {
  return typeof v === 'function';
}
function result(v) {
  return isFunction(v) ? v() : v;
}
var _draw = /*#__PURE__*/_classPrivateFieldLooseKey("draw");
/* Audio Oscilloscope
  https://github.com/miguelmota/audio-oscilloscope
*/
export default class AudioOscilloscope {
  // eslint-disable-next-line no-use-before-define

  constructor(canvas, options) {
    if (options === void 0) {
      options = {};
    }
    Object.defineProperty(this, _draw, {
      writable: true,
      value: () => this.draw()
    });
    const canvasOptions = options.canvas || {};
    const canvasContextOptions = options.canvasContext || {};
    this.analyser = null;
    this.bufferLength = 0;
    this.canvas = canvas;
    this.width = result(canvasOptions.width) || this.canvas.width;
    this.height = result(canvasOptions.height) || this.canvas.height;
    this.canvas.width = this.width;
    this.canvas.height = this.height;
    this.canvasContext = this.canvas.getContext('2d');
    this.canvasContext.fillStyle = result(canvasContextOptions.fillStyle) || 'rgb(255, 255, 255)';
    this.canvasContext.strokeStyle = result(canvasContextOptions.strokeStyle) || 'rgb(0, 0, 0)';
    this.canvasContext.lineWidth = result(canvasContextOptions.lineWidth) || 1;
    this.onDrawFrame = isFunction(options.onDrawFrame) ? options.onDrawFrame : () => {};
  }
  addSource(streamSource) {
    this.streamSource = streamSource;
    this.audioContext = this.streamSource.context;
    this.analyser = this.audioContext.createAnalyser();
    this.analyser.fftSize = 2048;
    this.bufferLength = this.analyser.frequencyBinCount;
    this.source = this.audioContext.createBufferSource();
    this.dataArray = new Uint8Array(this.bufferLength);
    this.analyser.getByteTimeDomainData(this.dataArray);
    this.streamSource.connect(this.analyser);
  }
  draw() {
    const {
      analyser,
      dataArray,
      bufferLength
    } = this;
    const ctx = this.canvasContext;
    const w = this.width;
    const h = this.height;
    if (analyser) {
      analyser.getByteTimeDomainData(dataArray);
    }
    ctx.fillRect(0, 0, w, h);
    ctx.beginPath();
    const sliceWidth = w * 1.0 / bufferLength;
    let x = 0;
    if (!bufferLength) {
      ctx.moveTo(0, this.height / 2);
    }
    for (let i = 0; i < bufferLength; i++) {
      const v = dataArray[i] / 128.0;
      const y = v * (h / 2);
      if (i === 0) {
        ctx.moveTo(x, y);
      } else {
        ctx.lineTo(x, y);
      }
      x += sliceWidth;
    }
    ctx.lineTo(w, h / 2);
    ctx.stroke();
    this.onDrawFrame(this);
    requestAnimationFrame(_classPrivateFieldLooseBase(this, _draw)[_draw]);
  }
}