canvas/browser.js

/* globals document, ImageData */

const parseFont = require('./lib/parse-font')

exports.parseFont = parseFont

exports.createCanvas = function (width, height) {
  return Object.assign(document.createElement('canvas'), { width: width, height: height })
}

exports.createImageData = function (array, width, height) {
  // Browser implementation of ImageData looks at the number of arguments passed
  switch (arguments.length) {
    case 0: return new ImageData()
    case 1: return new ImageData(array)
    case 2: return new ImageData(array, width)
    default: return new ImageData(array, width, height)
  }
}

exports.loadImage = function (src, options) {
  return new Promise(function (resolve, reject) {
    const image = Object.assign(document.createElement('img'), options)

    function cleanup () {
      image.onload = null
      image.onerror = null
    }

    image.onload = function () { cleanup(); resolve(image) }
    image.onerror = function () { cleanup(); reject(new Error('Failed to load the image "' + src + '"')) }

    image.src = src
  })
}