probe-image-size/lib/parse_sync/gif.js

Get image size without full download (JPG, GIF, PNG, WebP, BMP, TIFF, PSD)

'use strict'


var str2arr = require('../common').str2arr
var sliceEq = require('../common').sliceEq
var readUInt16LE = require('../common').readUInt16LE


var SIG_GIF87a = str2arr('GIF87a')
var SIG_GIF89a = str2arr('GIF89a')


module.exports = function (data) {
  if (data.length < 10) return

  if (!sliceEq(data, 0, SIG_GIF87a) && !sliceEq(data, 0, SIG_GIF89a)) return

  return {
    width: readUInt16LE(data, 6),
    height: readUInt16LE(data, 8),
    type: 'gif',
    mime: 'image/gif',
    wUnits: 'px',
    hUnits: 'px'
  }
}