get-pixels-buffer/node-pixels.js at master · und3fin3/get-pixels-buffer · GitHub

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'use strict'

var ndarray       = require('ndarray')
var PNG           = require('pngjs').PNG
var jpeg          = require('jpeg-js')
var pack          = require('ndarray-pack')
var GifReader     = require('omggif').GifReader
var Bitmap        = require('node-bitmap')

function handlePNG(data, cb) {
  var png = new PNG();
  png.parse(data, function(err, img_data) {
    if(err) {
      cb(err)
      return
    }
    cb(null, ndarray(new Uint8Array(img_data.data),
      [img_data.width|0, img_data.height|0, 4],
      [4, 4*img_data.width|0, 1],
      0))
  })
}

function handleJPEG(data, cb) {
  var jpegData
  try {
    jpegData = jpeg.decode(data)
  }
  catch(e) {
    cb(e)
    return
  }
  if(!jpegData) {
    cb(new Error("Error decoding jpeg"))
    return
  }
  var nshape = [ jpegData.height, jpegData.width, 4 ]
  var result = ndarray(jpegData.data, nshape)
  cb(null, result.transpose(1,0))
}

function handleGIF(data, cb) {
  var reader, nshape, ndata, result
  try {
    reader = new GifReader(data)
  } catch(err) {
    cb(err)
    return
  }
  if(reader.numFrames() > 0) {
    nshape = [reader.numFrames(), reader.height, reader.width, 4]
    ndata = new Uint8Array(nshape[0] * nshape[1] * nshape[2] * nshape[3])
    result = ndarray(ndata, nshape)
    try {
      for(var i=0; i<reader.numFrames(); ++i) {
        reader.decodeAndBlitFrameRGBA(i, ndata.subarray(
          result.index(i, 0, 0, 0),
          result.index(i+1, 0, 0, 0)))
      }
    } catch(err) {
      cb(err)
      return
    }
    cb(null, result.transpose(0,2,1))
  } else {
    nshape = [reader.height, reader.width, 4]
    ndata = new Uint8Array(nshape[0] * nshape[1] * nshape[2])
    result = ndarray(ndata, nshape)
    try {
      reader.decodeAndBlitFrameRGBA(0, ndata)
    } catch(err) {
      cb(err)
      return
    }
    cb(null, result.transpose(1,0))
  }
}

function handleBMP(data, cb) {
  var bmp = new Bitmap(data)
  try {
    bmp.init()
  } catch(e) {
    cb(e)
    return
  }
  var bmpData = bmp.getData()
  var nshape = [ bmpData.getHeight(), bmpData.getWidth(), 4 ]
  var ndata = new Uint8Array(nshape[0] * nshape[1] * nshape[2])
  var result = ndarray(ndata, nshape)
  pack(bmpData, result)
  cb(null, result.transpose(1,0))
}


function doParse(type, data, cb) {
  switch(type) {
    case 'png':
      handlePNG(data, cb)
    break

    case 'jpg':
    case 'jpeg':
      handleJPEG(data, cb)
    break

    case 'gif':
      handleGIF(data, cb)
    break

    case 'bmp':
      handleBMP(data, cb)
    break

    default:
      cb(new Error("Unsupported file type: " + type))
  }
}

module.exports = function getPixels(buf) {
  function compare(a, b) {
    for(let i in a) {
      if (a[i] !== b[i]) return false;
    }
    return true;
  }

  return new Promise( (resolve, reject) => {
    var type;
    if(compare([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a], buf))
      type = 'png';
    else if(compare([0xff, 0xe0], buf) && compare([0x4a, 0x46, 0x49, 0x46, 0x00], buf.slice(6)))
      type = 'jpg';
    else if(compare([0x47, 0x49, 0x46, 0x38]))
      type = 'gif';
    else if(compare([0x42, 0x4d], buf))
      type = 'bmp';
    else
      return reject(new Error('Unknown file type'));

    doParse(type, buf, (err, d) => err ? reject(err) : resolve(d));
  })
}