'use strict';

var fs = require('fs');
var util = require('util');
var Stream = require('stream');
var zlib = require('zlib');
var require$$0 = require('assert');
var require$$1 = require('buffer');

function _interopDefaultLegacy (e) { return e && typeof e === 'object' && 'default' in e ? e : { 'default': e }; }

var fs__default = /*#__PURE__*/_interopDefaultLegacy(fs);
var util__default = /*#__PURE__*/_interopDefaultLegacy(util);
var Stream__default = /*#__PURE__*/_interopDefaultLegacy(Stream);
var zlib__default = /*#__PURE__*/_interopDefaultLegacy(zlib);
var require$$0__default = /*#__PURE__*/_interopDefaultLegacy(require$$0);
var require$$1__default = /*#__PURE__*/_interopDefaultLegacy(require$$1);

var pixelmatch_1 = pixelmatch;

function pixelmatch(img1, img2, output, width, height, options) {

    if (!options) options = {};

    var threshold = options.threshold === undefined ? 0.1 : options.threshold;

    // maximum acceptable square distance between two colors;
    // 35215 is the maximum possible value for the YIQ difference metric
    var maxDelta = 35215 * threshold * threshold,
        diff = 0;

    // compare each pixel of one image against the other one
    for (var y = 0; y < height; y++) {
        for (var x = 0; x < width; x++) {

            var pos = (y * width + x) * 4;

            // squared YUV distance between colors at this pixel position
            var delta = colorDelta(img1, img2, pos, pos);

            // the color difference is above the threshold
            if (delta > maxDelta) {
                // check it's a real rendering difference or just anti-aliasing
                if (!options.includeAA && (antialiased(img1, x, y, width, height, img2) ||
                                   antialiased(img2, x, y, width, height, img1))) {
                    // one of the pixels is anti-aliasing; draw as yellow and do not count as difference
                    if (output) drawPixel(output, pos, 255, 255, 0);

                } else {
                    // found substantial difference not caused by anti-aliasing; draw it as red
                    if (output) drawPixel(output, pos, 255, 0, 0);
                    diff++;
                }

            } else if (output) {
                // pixels are similar; draw background as grayscale image blended with white
                var val = blend(grayPixel(img1, pos), 0.1);
                drawPixel(output, pos, val, val, val);
            }
        }
    }

    // return the number of different pixels
    return diff;
}

// check if a pixel is likely a part of anti-aliasing;
// based on "Anti-aliased Pixel and Intensity Slope Detector" paper by V. Vysniauskas, 2009

function antialiased(img, x1, y1, width, height, img2) {
    var x0 = Math.max(x1 - 1, 0),
        y0 = Math.max(y1 - 1, 0),
        x2 = Math.min(x1 + 1, width - 1),
        y2 = Math.min(y1 + 1, height - 1),
        pos = (y1 * width + x1) * 4,
        zeroes = 0,
        positives = 0,
        negatives = 0,
        min = 0,
        max = 0,
        minX, minY, maxX, maxY;

    // go through 8 adjacent pixels
    for (var x = x0; x <= x2; x++) {
        for (var y = y0; y <= y2; y++) {
            if (x === x1 && y === y1) continue;

            // brightness delta between the center pixel and adjacent one
            var delta = colorDelta(img, img, pos, (y * width + x) * 4, true);

            // count the number of equal, darker and brighter adjacent pixels
            if (delta === 0) zeroes++;
            else if (delta < 0) negatives++;
            else if (delta > 0) positives++;

            // if found more than 2 equal siblings, it's definitely not anti-aliasing
            if (zeroes > 2) return false;

            if (!img2) continue;

            // remember the darkest pixel
            if (delta < min) {
                min = delta;
                minX = x;
                minY = y;
            }
            // remember the brightest pixel
            if (delta > max) {
                max = delta;
                maxX = x;
                maxY = y;
            }
        }
    }

    if (!img2) return true;

    // if there are no both darker and brighter pixels among siblings, it's not anti-aliasing
    if (negatives === 0 || positives === 0) return false;

    // if either the darkest or the brightest pixel has more than 2 equal siblings in both images
    // (definitely not anti-aliased), this pixel is anti-aliased
    return (!antialiased(img, minX, minY, width, height) && !antialiased(img2, minX, minY, width, height)) ||
           (!antialiased(img, maxX, maxY, width, height) && !antialiased(img2, maxX, maxY, width, height));
}

// calculate color difference according to the paper "Measuring perceived color difference
// using YIQ NTSC transmission color space in mobile applications" by Y. Kotsarenko and F. Ramos

function colorDelta(img1, img2, k, m, yOnly) {
    var a1 = img1[k + 3] / 255,
        a2 = img2[m + 3] / 255,

        r1 = blend(img1[k + 0], a1),
        g1 = blend(img1[k + 1], a1),
        b1 = blend(img1[k + 2], a1),

        r2 = blend(img2[m + 0], a2),
        g2 = blend(img2[m + 1], a2),
        b2 = blend(img2[m + 2], a2),

        y = rgb2y(r1, g1, b1) - rgb2y(r2, g2, b2);

    if (yOnly) return y; // brightness difference only

    var i = rgb2i(r1, g1, b1) - rgb2i(r2, g2, b2),
        q = rgb2q(r1, g1, b1) - rgb2q(r2, g2, b2);

    return 0.5053 * y * y + 0.299 * i * i + 0.1957 * q * q;
}

function rgb2y(r, g, b) { return r * 0.29889531 + g * 0.58662247 + b * 0.11448223; }
function rgb2i(r, g, b) { return r * 0.59597799 - g * 0.27417610 - b * 0.32180189; }
function rgb2q(r, g, b) { return r * 0.21147017 - g * 0.52261711 + b * 0.31114694; }

// blend semi-transparent color with white
function blend(c, a) {
    return 255 + (c - 255) * a;
}

function drawPixel(output, pos, r, g, b) {
    output[pos + 0] = r;
    output[pos + 1] = g;
    output[pos + 2] = b;
    output[pos + 3] = 255;
}

function grayPixel(img, i) {
    var a = img[i + 3] / 255,
        r = blend(img[i + 0], a),
        g = blend(img[i + 1], a),
        b = blend(img[i + 2], a);
    return rgb2y(r, g, b);
}

function createCommonjsModule(fn, basedir, module) {
	return module = {
		path: basedir,
		exports: {},
		require: function (path, base) {
			return commonjsRequire(path, (base === undefined || base === null) ? module.path : base);
		}
	}, fn(module, module.exports), module.exports;
}

function commonjsRequire () {
	throw new Error('Dynamic requires are not currently supported by @rollup/plugin-commonjs');
}

var chunkstream = createCommonjsModule(function (module) {






var ChunkStream = module.exports = function() {
  Stream__default['default'].call(this);

  this._buffers = [];
  this._buffered = 0;

  this._reads = [];
  this._paused = false;

  this._encoding = 'utf8';
  this.writable = true;
};
util__default['default'].inherits(ChunkStream, Stream__default['default']);


ChunkStream.prototype.read = function(length, callback) {

  this._reads.push({
    length: Math.abs(length), // if length < 0 then at most this length
    allowLess: length < 0,
    func: callback
  });

  process.nextTick(function() {
    this._process();

    // its paused and there is not enought data then ask for more
    if (this._paused && this._reads.length > 0) {
      this._paused = false;

      this.emit('drain');
    }
  }.bind(this));
};

ChunkStream.prototype.write = function(data, encoding) {

  if (!this.writable) {
    this.emit('error', new Error('Stream not writable'));
    return false;
  }

  var dataBuffer;
  if (Buffer.isBuffer(data)) {
    dataBuffer = data;
  }
  else {
    dataBuffer = new Buffer(data, encoding || this._encoding);
  }

  this._buffers.push(dataBuffer);
  this._buffered += dataBuffer.length;

  this._process();

  // ok if there are no more read requests
  if (this._reads && this._reads.length === 0) {
    this._paused = true;
  }

  return this.writable && !this._paused;
};

ChunkStream.prototype.end = function(data, encoding) {

  if (data) {
    this.write(data, encoding);
  }

  this.writable = false;

  // already destroyed
  if (!this._buffers) {
    return;
  }

  // enqueue or handle end
  if (this._buffers.length === 0) {
    this._end();
  }
  else {
    this._buffers.push(null);
    this._process();
  }
};

ChunkStream.prototype.destroySoon = ChunkStream.prototype.end;

ChunkStream.prototype._end = function() {

  if (this._reads.length > 0) {
    this.emit('error',
      new Error('Unexpected end of input')
    );
  }

  this.destroy();
};

ChunkStream.prototype.destroy = function() {

  if (!this._buffers) {
    return;
  }

  this.writable = false;
  this._reads = null;
  this._buffers = null;

  this.emit('close');
};

ChunkStream.prototype._processReadAllowingLess = function(read) {
  // ok there is any data so that we can satisfy this request
  this._reads.shift(); // == read

  // first we need to peek into first buffer
  var smallerBuf = this._buffers[0];

  // ok there is more data than we need
  if (smallerBuf.length > read.length) {

    this._buffered -= read.length;
    this._buffers[0] = smallerBuf.slice(read.length);

    read.func.call(this, smallerBuf.slice(0, read.length));

  }
  else {
    // ok this is less than maximum length so use it all
    this._buffered -= smallerBuf.length;
    this._buffers.shift(); // == smallerBuf

    read.func.call(this, smallerBuf);
  }
};

ChunkStream.prototype._processRead = function(read) {
  this._reads.shift(); // == read

  var pos = 0;
  var count = 0;
  var data = new Buffer(read.length);

  // create buffer for all data
  while (pos < read.length) {

    var buf = this._buffers[count++];
    var len = Math.min(buf.length, read.length - pos);

    buf.copy(data, pos, 0, len);
    pos += len;

    // last buffer wasn't used all so just slice it and leave
    if (len !== buf.length) {
      this._buffers[--count] = buf.slice(len);
    }
  }

  // remove all used buffers
  if (count > 0) {
    this._buffers.splice(0, count);
  }

  this._buffered -= read.length;

  read.func.call(this, data);
};

ChunkStream.prototype._process = function() {

  try {
    // as long as there is any data and read requests
    while (this._buffered > 0 && this._reads && this._reads.length > 0) {

      var read = this._reads[0];

      // read any data (but no more than length)
      if (read.allowLess) {
        this._processReadAllowingLess(read);

      }
      else if (this._buffered >= read.length) {
        // ok we can meet some expectations

        this._processRead(read);
      }
      else {
        // not enought data to satisfy first request in queue
        // so we need to wait for more
        break;
      }
    }

    if (this._buffers && !this.writable) {
      this._end();
    }
  }
  catch (ex) {
    this.emit('error', ex);
  }
};
});

// Adam 7
//   0 1 2 3 4 5 6 7
// 0 x 6 4 6 x 6 4 6
// 1 7 7 7 7 7 7 7 7
// 2 5 6 5 6 5 6 5 6
// 3 7 7 7 7 7 7 7 7
// 4 3 6 4 6 3 6 4 6
// 5 7 7 7 7 7 7 7 7
// 6 5 6 5 6 5 6 5 6
// 7 7 7 7 7 7 7 7 7


var imagePasses = [
  { // pass 1 - 1px
    x: [0],
    y: [0]
  },
  { // pass 2 - 1px
    x: [4],
    y: [0]
  },
  { // pass 3 - 2px
    x: [0, 4],
    y: [4]
  },
  { // pass 4 - 4px
    x: [2, 6],
    y: [0, 4]
  },
  { // pass 5 - 8px
    x: [0, 2, 4, 6],
    y: [2, 6]
  },
  { // pass 6 - 16px
    x: [1, 3, 5, 7],
    y: [0, 2, 4, 6]
  },
  { // pass 7 - 32px
    x: [0, 1, 2, 3, 4, 5, 6, 7],
    y: [1, 3, 5, 7]
  }
];

var getImagePasses = function(width, height) {
  var images = [];
  var xLeftOver = width % 8;
  var yLeftOver = height % 8;
  var xRepeats = (width - xLeftOver) / 8;
  var yRepeats = (height - yLeftOver) / 8;
  for (var i = 0; i < imagePasses.length; i++) {
    var pass = imagePasses[i];
    var passWidth = xRepeats * pass.x.length;
    var passHeight = yRepeats * pass.y.length;
    for (var j = 0; j < pass.x.length; j++) {
      if (pass.x[j] < xLeftOver) {
        passWidth++;
      }
      else {
        break;
      }
    }
    for (j = 0; j < pass.y.length; j++) {
      if (pass.y[j] < yLeftOver) {
        passHeight++;
      }
      else {
        break;
      }
    }
    if (passWidth > 0 && passHeight > 0) {
      images.push({ width: passWidth, height: passHeight, index: i });
    }
  }
  return images;
};

var getInterlaceIterator = function(width) {
  return function(x, y, pass) {
    var outerXLeftOver = x % imagePasses[pass].x.length;
    var outerX = (((x - outerXLeftOver) / imagePasses[pass].x.length) * 8) + imagePasses[pass].x[outerXLeftOver];
    var outerYLeftOver = y % imagePasses[pass].y.length;
    var outerY = (((y - outerYLeftOver) / imagePasses[pass].y.length) * 8) + imagePasses[pass].y[outerYLeftOver];
    return (outerX * 4) + (outerY * width * 4);
  };
};

var interlace = {
	getImagePasses: getImagePasses,
	getInterlaceIterator: getInterlaceIterator
};

var paethPredictor = function paethPredictor(left, above, upLeft) {

  var paeth = left + above - upLeft;
  var pLeft = Math.abs(paeth - left);
  var pAbove = Math.abs(paeth - above);
  var pUpLeft = Math.abs(paeth - upLeft);

  if (pLeft <= pAbove && pLeft <= pUpLeft) {
    return left;
  }
  if (pAbove <= pUpLeft) {
    return above;
  }
  return upLeft;
};

var filterParse = createCommonjsModule(function (module) {




function getByteWidth(width, bpp, depth) {
  var byteWidth = width * bpp;
  if (depth !== 8) {
    byteWidth = Math.ceil(byteWidth / (8 / depth));
  }
  return byteWidth;
}

var Filter = module.exports = function(bitmapInfo, dependencies) {

  var width = bitmapInfo.width;
  var height = bitmapInfo.height;
  var interlace$1 = bitmapInfo.interlace;
  var bpp = bitmapInfo.bpp;
  var depth = bitmapInfo.depth;

  this.read = dependencies.read;
  this.write = dependencies.write;
  this.complete = dependencies.complete;

  this._imageIndex = 0;
  this._images = [];
  if (interlace$1) {
    var passes = interlace.getImagePasses(width, height);
    for (var i = 0; i < passes.length; i++) {
      this._images.push({
        byteWidth: getByteWidth(passes[i].width, bpp, depth),
        height: passes[i].height,
        lineIndex: 0
      });
    }
  }
  else {
    this._images.push({
      byteWidth: getByteWidth(width, bpp, depth),
      height: height,
      lineIndex: 0
    });
  }

  // when filtering the line we look at the pixel to the left
  // the spec also says it is done on a byte level regardless of the number of pixels
  // so if the depth is byte compatible (8 or 16) we subtract the bpp in order to compare back
  // a pixel rather than just a different byte part. However if we are sub byte, we ignore.
  if (depth === 8) {
    this._xComparison = bpp;
  }
  else if (depth === 16) {
    this._xComparison = bpp * 2;
  }
  else {
    this._xComparison = 1;
  }
};

Filter.prototype.start = function() {
  this.read(this._images[this._imageIndex].byteWidth + 1, this._reverseFilterLine.bind(this));
};

Filter.prototype._unFilterType1 = function(rawData, unfilteredLine, byteWidth) {

  var xComparison = this._xComparison;
  var xBiggerThan = xComparison - 1;

  for (var x = 0; x < byteWidth; x++) {
    var rawByte = rawData[1 + x];
    var f1Left = x > xBiggerThan ? unfilteredLine[x - xComparison] : 0;
    unfilteredLine[x] = rawByte + f1Left;
  }
};

Filter.prototype._unFilterType2 = function(rawData, unfilteredLine, byteWidth) {

  var lastLine = this._lastLine;

  for (var x = 0; x < byteWidth; x++) {
    var rawByte = rawData[1 + x];
    var f2Up = lastLine ? lastLine[x] : 0;
    unfilteredLine[x] = rawByte + f2Up;
  }
};

Filter.prototype._unFilterType3 = function(rawData, unfilteredLine, byteWidth) {

  var xComparison = this._xComparison;
  var xBiggerThan = xComparison - 1;
  var lastLine = this._lastLine;

  for (var x = 0; x < byteWidth; x++) {
    var rawByte = rawData[1 + x];
    var f3Up = lastLine ? lastLine[x] : 0;
    var f3Left = x > xBiggerThan ? unfilteredLine[x - xComparison] : 0;
    var f3Add = Math.floor((f3Left + f3Up) / 2);
    unfilteredLine[x] = rawByte + f3Add;
  }
};

Filter.prototype._unFilterType4 = function(rawData, unfilteredLine, byteWidth) {

  var xComparison = this._xComparison;
  var xBiggerThan = xComparison - 1;
  var lastLine = this._lastLine;

  for (var x = 0; x < byteWidth; x++) {
    var rawByte = rawData[1 + x];
    var f4Up = lastLine ? lastLine[x] : 0;
    var f4Left = x > xBiggerThan ? unfilteredLine[x - xComparison] : 0;
    var f4UpLeft = x > xBiggerThan && lastLine ? lastLine[x - xComparison] : 0;
    var f4Add = paethPredictor(f4Left, f4Up, f4UpLeft);
    unfilteredLine[x] = rawByte + f4Add;
  }
};

Filter.prototype._reverseFilterLine = function(rawData) {

  var filter = rawData[0];
  var unfilteredLine;
  var currentImage = this._images[this._imageIndex];
  var byteWidth = currentImage.byteWidth;

  if (filter === 0) {
    unfilteredLine = rawData.slice(1, byteWidth + 1);
  }
  else {

    unfilteredLine = new Buffer(byteWidth);

    switch (filter) {
      case 1:
        this._unFilterType1(rawData, unfilteredLine, byteWidth);
        break;
      case 2:
        this._unFilterType2(rawData, unfilteredLine, byteWidth);
        break;
      case 3:
        this._unFilterType3(rawData, unfilteredLine, byteWidth);
        break;
      case 4:
        this._unFilterType4(rawData, unfilteredLine, byteWidth);
        break;
      default:
        throw new Error('Unrecognised filter type - ' + filter);
    }
  }

  this.write(unfilteredLine);

  currentImage.lineIndex++;
  if (currentImage.lineIndex >= currentImage.height) {
    this._lastLine = null;
    this._imageIndex++;
    currentImage = this._images[this._imageIndex];
  }
  else {
    this._lastLine = unfilteredLine;
  }

  if (currentImage) {
    // read, using the byte width that may be from the new current image
    this.read(currentImage.byteWidth + 1, this._reverseFilterLine.bind(this));
  }
  else {
    this._lastLine = null;
    this.complete();
  }
};
});

var filterParseAsync = createCommonjsModule(function (module) {






var FilterAsync = module.exports = function(bitmapInfo) {
  chunkstream.call(this);

  var buffers = [];
  var that = this;
  this._filter = new filterParse(bitmapInfo, {
    read: this.read.bind(this),
    write: function(buffer) {
      buffers.push(buffer);
    },
    complete: function() {
      that.emit('complete', Buffer.concat(buffers));
    }
  });

  this._filter.start();
};
util__default['default'].inherits(FilterAsync, chunkstream);
});

var constants = {

  PNG_SIGNATURE: [0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a],

  TYPE_IHDR: 0x49484452,
  TYPE_IEND: 0x49454e44,
  TYPE_IDAT: 0x49444154,
  TYPE_PLTE: 0x504c5445,
  TYPE_tRNS: 0x74524e53, // eslint-disable-line camelcase
  TYPE_gAMA: 0x67414d41, // eslint-disable-line camelcase

  // color-type bits
  COLORTYPE_GRAYSCALE: 0,
  COLORTYPE_PALETTE: 1,
  COLORTYPE_COLOR: 2,
  COLORTYPE_ALPHA: 4, // e.g. grayscale and alpha

  // color-type combinations
  COLORTYPE_PALETTE_COLOR: 3,
  COLORTYPE_COLOR_ALPHA: 6,

  COLORTYPE_TO_BPP_MAP: {
    0: 1,
    2: 3,
    3: 1,
    4: 2,
    6: 4
  },

  GAMMA_DIVISION: 100000
};

var crc = createCommonjsModule(function (module) {

var crcTable = [];

(function() {
  for (var i = 0; i < 256; i++) {
    var currentCrc = i;
    for (var j = 0; j < 8; j++) {
      if (currentCrc & 1) {
        currentCrc = 0xedb88320 ^ (currentCrc >>> 1);
      }
      else {
        currentCrc = currentCrc >>> 1;
      }
    }
    crcTable[i] = currentCrc;
  }
}());

var CrcCalculator = module.exports = function() {
  this._crc = -1;
};

CrcCalculator.prototype.write = function(data) {

  for (var i = 0; i < data.length; i++) {
    this._crc = crcTable[(this._crc ^ data[i]) & 0xff] ^ (this._crc >>> 8);
  }
  return true;
};

CrcCalculator.prototype.crc32 = function() {
  return this._crc ^ -1;
};


CrcCalculator.crc32 = function(buf) {

  var crc = -1;
  for (var i = 0; i < buf.length; i++) {
    crc = crcTable[(crc ^ buf[i]) & 0xff] ^ (crc >>> 8);
  }
  return crc ^ -1;
};
});

var parser = createCommonjsModule(function (module) {





var Parser = module.exports = function(options, dependencies) {

  this._options = options;
  options.checkCRC = options.checkCRC !== false;

  this._hasIHDR = false;
  this._hasIEND = false;
  this._emittedHeadersFinished = false;

  // input flags/metadata
  this._palette = [];
  this._colorType = 0;

  this._chunks = {};
  this._chunks[constants.TYPE_IHDR] = this._handleIHDR.bind(this);
  this._chunks[constants.TYPE_IEND] = this._handleIEND.bind(this);
  this._chunks[constants.TYPE_IDAT] = this._handleIDAT.bind(this);
  this._chunks[constants.TYPE_PLTE] = this._handlePLTE.bind(this);
  this._chunks[constants.TYPE_tRNS] = this._handleTRNS.bind(this);
  this._chunks[constants.TYPE_gAMA] = this._handleGAMA.bind(this);

  this.read = dependencies.read;
  this.error = dependencies.error;
  this.metadata = dependencies.metadata;
  this.gamma = dependencies.gamma;
  this.transColor = dependencies.transColor;
  this.palette = dependencies.palette;
  this.parsed = dependencies.parsed;
  this.inflateData = dependencies.inflateData;
  this.finished = dependencies.finished;
  this.simpleTransparency = dependencies.simpleTransparency;
  this.headersFinished = dependencies.headersFinished || function() {};
};

Parser.prototype.start = function() {
  this.read(constants.PNG_SIGNATURE.length,
    this._parseSignature.bind(this)
  );
};

Parser.prototype._parseSignature = function(data) {

  var signature = constants.PNG_SIGNATURE;

  for (var i = 0; i < signature.length; i++) {
    if (data[i] !== signature[i]) {
      this.error(new Error('Invalid file signature'));
      return;
    }
  }
  this.read(8, this._parseChunkBegin.bind(this));
};

Parser.prototype._parseChunkBegin = function(data) {

  // chunk content length
  var length = data.readUInt32BE(0);

  // chunk type
  var type = data.readUInt32BE(4);
  var name = '';
  for (var i = 4; i < 8; i++) {
    name += String.fromCharCode(data[i]);
  }

  //console.log('chunk ', name, length);

  // chunk flags
  var ancillary = Boolean(data[4] & 0x20); // or critical
  //    priv = Boolean(data[5] & 0x20), // or public
  //    safeToCopy = Boolean(data[7] & 0x20); // or unsafe

  if (!this._hasIHDR && type !== constants.TYPE_IHDR) {
    this.error(new Error('Expected IHDR on beggining'));
    return;
  }

  this._crc = new crc();
  this._crc.write(new Buffer(name));

  if (this._chunks[type]) {
    return this._chunks[type](length);
  }

  if (!ancillary) {
    this.error(new Error('Unsupported critical chunk type ' + name));
    return;
  }

  this.read(length + 4, this._skipChunk.bind(this));
};

Parser.prototype._skipChunk = function(/*data*/) {
  this.read(8, this._parseChunkBegin.bind(this));
};

Parser.prototype._handleChunkEnd = function() {
  this.read(4, this._parseChunkEnd.bind(this));
};

Parser.prototype._parseChunkEnd = function(data) {

  var fileCrc = data.readInt32BE(0);
  var calcCrc = this._crc.crc32();

  // check CRC
  if (this._options.checkCRC && calcCrc !== fileCrc) {
    this.error(new Error('Crc error - ' + fileCrc + ' - ' + calcCrc));
    return;
  }

  if (!this._hasIEND) {
    this.read(8, this._parseChunkBegin.bind(this));
  }
};

Parser.prototype._handleIHDR = function(length) {
  this.read(length, this._parseIHDR.bind(this));
};
Parser.prototype._parseIHDR = function(data) {

  this._crc.write(data);

  var width = data.readUInt32BE(0);
  var height = data.readUInt32BE(4);
  var depth = data[8];
  var colorType = data[9]; // bits: 1 palette, 2 color, 4 alpha
  var compr = data[10];
  var filter = data[11];
  var interlace = data[12];

  // console.log('    width', width, 'height', height,
  //     'depth', depth, 'colorType', colorType,
  //     'compr', compr, 'filter', filter, 'interlace', interlace
  // );

  if (depth !== 8 && depth !== 4 && depth !== 2 && depth !== 1 && depth !== 16) {
    this.error(new Error('Unsupported bit depth ' + depth));
    return;
  }
  if (!(colorType in constants.COLORTYPE_TO_BPP_MAP)) {
    this.error(new Error('Unsupported color type'));
    return;
  }
  if (compr !== 0) {
    this.error(new Error('Unsupported compression method'));
    return;
  }
  if (filter !== 0) {
    this.error(new Error('Unsupported filter method'));
    return;
  }
  if (interlace !== 0 && interlace !== 1) {
    this.error(new Error('Unsupported interlace method'));
    return;
  }

  this._colorType = colorType;

  var bpp = constants.COLORTYPE_TO_BPP_MAP[this._colorType];

  this._hasIHDR = true;

  this.metadata({
    width: width,
    height: height,
    depth: depth,
    interlace: Boolean(interlace),
    palette: Boolean(colorType & constants.COLORTYPE_PALETTE),
    color: Boolean(colorType & constants.COLORTYPE_COLOR),
    alpha: Boolean(colorType & constants.COLORTYPE_ALPHA),
    bpp: bpp,
    colorType: colorType
  });

  this._handleChunkEnd();
};


Parser.prototype._handlePLTE = function(length) {
  this.read(length, this._parsePLTE.bind(this));
};
Parser.prototype._parsePLTE = function(data) {

  this._crc.write(data);

  var entries = Math.floor(data.length / 3);
  // console.log('Palette:', entries);

  for (var i = 0; i < entries; i++) {
    this._palette.push([
      data[i * 3],
      data[i * 3 + 1],
      data[i * 3 + 2],
      0xff
    ]);
  }

  this.palette(this._palette);

  this._handleChunkEnd();
};

Parser.prototype._handleTRNS = function(length) {
  this.simpleTransparency();
  this.read(length, this._parseTRNS.bind(this));
};
Parser.prototype._parseTRNS = function(data) {

  this._crc.write(data);

  // palette
  if (this._colorType === constants.COLORTYPE_PALETTE_COLOR) {
    if (this._palette.length === 0) {
      this.error(new Error('Transparency chunk must be after palette'));
      return;
    }
    if (data.length > this._palette.length) {
      this.error(new Error('More transparent colors than palette size'));
      return;
    }
    for (var i = 0; i < data.length; i++) {
      this._palette[i][3] = data[i];
    }
    this.palette(this._palette);
  }

  // for colorType 0 (grayscale) and 2 (rgb)
  // there might be one gray/color defined as transparent
  if (this._colorType === constants.COLORTYPE_GRAYSCALE) {
    // grey, 2 bytes
    this.transColor([data.readUInt16BE(0)]);
  }
  if (this._colorType === constants.COLORTYPE_COLOR) {
    this.transColor([data.readUInt16BE(0), data.readUInt16BE(2), data.readUInt16BE(4)]);
  }

  this._handleChunkEnd();
};

Parser.prototype._handleGAMA = function(length) {
  this.read(length, this._parseGAMA.bind(this));
};
Parser.prototype._parseGAMA = function(data) {

  this._crc.write(data);
  this.gamma(data.readUInt32BE(0) / constants.GAMMA_DIVISION);

  this._handleChunkEnd();
};

Parser.prototype._handleIDAT = function(length) {
  if (!this._emittedHeadersFinished) {
    this._emittedHeadersFinished = true;
    this.headersFinished();
  }
  this.read(-length, this._parseIDAT.bind(this, length));
};
Parser.prototype._parseIDAT = function(length, data) {

  this._crc.write(data);

  if (this._colorType === constants.COLORTYPE_PALETTE_COLOR && this._palette.length === 0) {
    throw new Error('Expected palette not found');
  }

  this.inflateData(data);
  var leftOverLength = length - data.length;

  if (leftOverLength > 0) {
    this._handleIDAT(leftOverLength);
  }
  else {
    this._handleChunkEnd();
  }
};

Parser.prototype._handleIEND = function(length) {
  this.read(length, this._parseIEND.bind(this));
};
Parser.prototype._parseIEND = function(data) {

  this._crc.write(data);

  this._hasIEND = true;
  this._handleChunkEnd();

  if (this.finished) {
    this.finished();
  }
};
});

var pixelBppMapper = [
  // 0 - dummy entry
  function() {},

  // 1 - L
  // 0: 0, 1: 0, 2: 0, 3: 0xff
  function(pxData, data, pxPos, rawPos) {
    if (rawPos === data.length) {
      throw new Error('Ran out of data');
    }

    var pixel = data[rawPos];
    pxData[pxPos] = pixel;
    pxData[pxPos + 1] = pixel;
    pxData[pxPos + 2] = pixel;
    pxData[pxPos + 3] = 0xff;
  },

  // 2 - LA
  // 0: 0, 1: 0, 2: 0, 3: 1
  function(pxData, data, pxPos, rawPos) {
    if (rawPos + 1 >= data.length) {
      throw new Error('Ran out of data');
    }

    var pixel = data[rawPos];
    pxData[pxPos] = pixel;
    pxData[pxPos + 1] = pixel;
    pxData[pxPos + 2] = pixel;
    pxData[pxPos + 3] = data[rawPos + 1];
  },

  // 3 - RGB
  // 0: 0, 1: 1, 2: 2, 3: 0xff
  function(pxData, data, pxPos, rawPos) {
    if (rawPos + 2 >= data.length) {
      throw new Error('Ran out of data');
    }

    pxData[pxPos] = data[rawPos];
    pxData[pxPos + 1] = data[rawPos + 1];
    pxData[pxPos + 2] = data[rawPos + 2];
    pxData[pxPos + 3] = 0xff;
  },

  // 4 - RGBA
  // 0: 0, 1: 1, 2: 2, 3: 3
  function(pxData, data, pxPos, rawPos) {
    if (rawPos + 3 >= data.length) {
      throw new Error('Ran out of data');
    }

    pxData[pxPos] = data[rawPos];
    pxData[pxPos + 1] = data[rawPos + 1];
    pxData[pxPos + 2] = data[rawPos + 2];
    pxData[pxPos + 3] = data[rawPos + 3];
  }
];

var pixelBppCustomMapper = [
  // 0 - dummy entry
  function() {},

  // 1 - L
  // 0: 0, 1: 0, 2: 0, 3: 0xff
  function(pxData, pixelData, pxPos, maxBit) {
    var pixel = pixelData[0];
    pxData[pxPos] = pixel;
    pxData[pxPos + 1] = pixel;
    pxData[pxPos + 2] = pixel;
    pxData[pxPos + 3] = maxBit;
  },

  // 2 - LA
  // 0: 0, 1: 0, 2: 0, 3: 1
  function(pxData, pixelData, pxPos) {
    var pixel = pixelData[0];
    pxData[pxPos] = pixel;
    pxData[pxPos + 1] = pixel;
    pxData[pxPos + 2] = pixel;
    pxData[pxPos + 3] = pixelData[1];
  },

  // 3 - RGB
  // 0: 0, 1: 1, 2: 2, 3: 0xff
  function(pxData, pixelData, pxPos, maxBit) {
    pxData[pxPos] = pixelData[0];
    pxData[pxPos + 1] = pixelData[1];
    pxData[pxPos + 2] = pixelData[2];
    pxData[pxPos + 3] = maxBit;
  },

  // 4 - RGBA
  // 0: 0, 1: 1, 2: 2, 3: 3
  function(pxData, pixelData, pxPos) {
    pxData[pxPos] = pixelData[0];
    pxData[pxPos + 1] = pixelData[1];
    pxData[pxPos + 2] = pixelData[2];
    pxData[pxPos + 3] = pixelData[3];
  }
];

function bitRetriever(data, depth) {

  var leftOver = [];
  var i = 0;

  function split() {
    if (i === data.length) {
      throw new Error('Ran out of data');
    }
    var byte = data[i];
    i++;
    var byte8, byte7, byte6, byte5, byte4, byte3, byte2, byte1;
    switch (depth) {
      default:
        throw new Error('unrecognised depth');
      case 16:
        byte2 = data[i];
        i++;
        leftOver.push(((byte << 8) + byte2));
        break;
      case 4:
        byte2 = byte & 0x0f;
        byte1 = byte >> 4;
        leftOver.push(byte1, byte2);
        break;
      case 2:
        byte4 = byte & 3;
        byte3 = byte >> 2 & 3;
        byte2 = byte >> 4 & 3;
        byte1 = byte >> 6 & 3;
        leftOver.push(byte1, byte2, byte3, byte4);
        break;
      case 1:
        byte8 = byte & 1;
        byte7 = byte >> 1 & 1;
        byte6 = byte >> 2 & 1;
        byte5 = byte >> 3 & 1;
        byte4 = byte >> 4 & 1;
        byte3 = byte >> 5 & 1;
        byte2 = byte >> 6 & 1;
        byte1 = byte >> 7 & 1;
        leftOver.push(byte1, byte2, byte3, byte4, byte5, byte6, byte7, byte8);
        break;
    }
  }

  return {
    get: function(count) {
      while (leftOver.length < count) {
        split();
      }
      var returner = leftOver.slice(0, count);
      leftOver = leftOver.slice(count);
      return returner;
    },
    resetAfterLine: function() {
      leftOver.length = 0;
    },
    end: function() {
      if (i !== data.length) {
        throw new Error('extra data found');
      }
    }
  };
}

function mapImage8Bit(image, pxData, getPxPos, bpp, data, rawPos) { // eslint-disable-line max-params
  var imageWidth = image.width;
  var imageHeight = image.height;
  var imagePass = image.index;
  for (var y = 0; y < imageHeight; y++) {
    for (var x = 0; x < imageWidth; x++) {
      var pxPos = getPxPos(x, y, imagePass);
      pixelBppMapper[bpp](pxData, data, pxPos, rawPos);
      rawPos += bpp; //eslint-disable-line no-param-reassign
    }
  }
  return rawPos;
}

function mapImageCustomBit(image, pxData, getPxPos, bpp, bits, maxBit) { // eslint-disable-line max-params
  var imageWidth = image.width;
  var imageHeight = image.height;
  var imagePass = image.index;
  for (var y = 0; y < imageHeight; y++) {
    for (var x = 0; x < imageWidth; x++) {
      var pixelData = bits.get(bpp);
      var pxPos = getPxPos(x, y, imagePass);
      pixelBppCustomMapper[bpp](pxData, pixelData, pxPos, maxBit);
    }
    bits.resetAfterLine();
  }
}

var dataToBitMap = function(data, bitmapInfo) {

  var width = bitmapInfo.width;
  var height = bitmapInfo.height;
  var depth = bitmapInfo.depth;
  var bpp = bitmapInfo.bpp;
  var interlace$1 = bitmapInfo.interlace;

  if (depth !== 8) {
    var bits = bitRetriever(data, depth);
  }
  var pxData;
  if (depth <= 8) {
    pxData = new Buffer(width * height * 4);
  }
  else {
    pxData = new Uint16Array(width * height * 4);
  }
  var maxBit = Math.pow(2, depth) - 1;
  var rawPos = 0;
  var images;
  var getPxPos;

  if (interlace$1) {
    images = interlace.getImagePasses(width, height);
    getPxPos = interlace.getInterlaceIterator(width, height);
  }
  else {
    var nonInterlacedPxPos = 0;
    getPxPos = function() {
      var returner = nonInterlacedPxPos;
      nonInterlacedPxPos += 4;
      return returner;
    };
    images = [{ width: width, height: height }];
  }

  for (var imageIndex = 0; imageIndex < images.length; imageIndex++) {
    if (depth === 8) {
      rawPos = mapImage8Bit(images[imageIndex], pxData, getPxPos, bpp, data, rawPos);
    }
    else {
      mapImageCustomBit(images[imageIndex], pxData, getPxPos, bpp, bits, maxBit);
    }
  }
  if (depth === 8) {
    if (rawPos !== data.length) {
      throw new Error('extra data found');
    }
  }
  else {
    bits.end();
  }

  return pxData;
};

var bitmapper = {
	dataToBitMap: dataToBitMap
};

function dePalette(indata, outdata, width, height, palette) {
  var pxPos = 0;
  // use values from palette
  for (var y = 0; y < height; y++) {
    for (var x = 0; x < width; x++) {
      var color = palette[indata[pxPos]];

      if (!color) {
        throw new Error('index ' + indata[pxPos] + ' not in palette');
      }

      for (var i = 0; i < 4; i++) {
        outdata[pxPos + i] = color[i];
      }
      pxPos += 4;
    }
  }
}

function replaceTransparentColor(indata, outdata, width, height, transColor) {
  var pxPos = 0;
  for (var y = 0; y < height; y++) {
    for (var x = 0; x < width; x++) {
      var makeTrans = false;

      if (transColor.length === 1) {
        if (transColor[0] === indata[pxPos]) {
          makeTrans = true;
        }
      }
      else if (transColor[0] === indata[pxPos] && transColor[1] === indata[pxPos + 1] && transColor[2] === indata[pxPos + 2]) {
        makeTrans = true;
      }
      if (makeTrans) {
        for (var i = 0; i < 4; i++) {
          outdata[pxPos + i] = 0;
        }
      }
      pxPos += 4;
    }
  }
}

function scaleDepth(indata, outdata, width, height, depth) {
  var maxOutSample = 255;
  var maxInSample = Math.pow(2, depth) - 1;
  var pxPos = 0;

  for (var y = 0; y < height; y++) {
    for (var x = 0; x < width; x++) {
      for (var i = 0; i < 4; i++) {
        outdata[pxPos + i] = Math.floor((indata[pxPos + i] * maxOutSample) / maxInSample + 0.5);
      }
      pxPos += 4;
    }
  }
}

var formatNormaliser = function(indata, imageData) {

  var depth = imageData.depth;
  var width = imageData.width;
  var height = imageData.height;
  var colorType = imageData.colorType;
  var transColor = imageData.transColor;
  var palette = imageData.palette;

  var outdata = indata; // only different for 16 bits

  if (colorType === 3) { // paletted
    dePalette(indata, outdata, width, height, palette);
  }
  else {
    if (transColor) {
      replaceTransparentColor(indata, outdata, width, height, transColor);
    }
    // if it needs scaling
    if (depth !== 8) {
      // if we need to change the buffer size
      if (depth === 16) {
        outdata = new Buffer(width * height * 4);
      }
      scaleDepth(indata, outdata, width, height, depth);
    }
  }
  return outdata;
};

var parserAsync = createCommonjsModule(function (module) {









var ParserAsync = module.exports = function(options) {
  chunkstream.call(this);

  this._parser = new parser(options, {
    read: this.read.bind(this),
    error: this._handleError.bind(this),
    metadata: this._handleMetaData.bind(this),
    gamma: this.emit.bind(this, 'gamma'),
    palette: this._handlePalette.bind(this),
    transColor: this._handleTransColor.bind(this),
    finished: this._finished.bind(this),
    inflateData: this._inflateData.bind(this),
    simpleTransparency: this._simpleTransparency.bind(this),
    headersFinished: this._headersFinished.bind(this)
  });
  this._options = options;
  this.writable = true;

  this._parser.start();
};
util__default['default'].inherits(ParserAsync, chunkstream);


ParserAsync.prototype._handleError = function(err) {

  this.emit('error', err);

  this.writable = false;

  this.destroy();

  if (this._inflate && this._inflate.destroy) {
    this._inflate.destroy();
  }

  if (this._filter) {
    this._filter.destroy();
    // For backward compatibility with Node 7 and below.
    // Suppress errors due to _inflate calling write() even after
    // it's destroy()'ed.
    this._filter.on('error', function() {});
  }

  this.errord = true;
};

ParserAsync.prototype._inflateData = function(data) {
  if (!this._inflate) {
    if (this._bitmapInfo.interlace) {
      this._inflate = zlib__default['default'].createInflate();

      this._inflate.on('error', this.emit.bind(this, 'error'));
      this._filter.on('complete', this._complete.bind(this));

      this._inflate.pipe(this._filter);
    }
    else {
      var rowSize = ((this._bitmapInfo.width * this._bitmapInfo.bpp * this._bitmapInfo.depth + 7) >> 3) + 1;
      var imageSize = rowSize * this._bitmapInfo.height;
      var chunkSize = Math.max(imageSize, zlib__default['default'].Z_MIN_CHUNK);

      this._inflate = zlib__default['default'].createInflate({ chunkSize: chunkSize });
      var leftToInflate = imageSize;

      var emitError = this.emit.bind(this, 'error');
      this._inflate.on('error', function(err) {
        if (!leftToInflate) {
          return;
        }

        emitError(err);
      });
      this._filter.on('complete', this._complete.bind(this));

      var filterWrite = this._filter.write.bind(this._filter);
      this._inflate.on('data', function(chunk) {
        if (!leftToInflate) {
          return;
        }

        if (chunk.length > leftToInflate) {
          chunk = chunk.slice(0, leftToInflate);
        }

        leftToInflate -= chunk.length;

        filterWrite(chunk);
      });

      this._inflate.on('end', this._filter.end.bind(this._filter));
    }
  }
  this._inflate.write(data);
};

ParserAsync.prototype._handleMetaData = function(metaData) {
  this._metaData = metaData;
  this._bitmapInfo = Object.create(metaData);

  this._filter = new filterParseAsync(this._bitmapInfo);
};

ParserAsync.prototype._handleTransColor = function(transColor) {
  this._bitmapInfo.transColor = transColor;
};

ParserAsync.prototype._handlePalette = function(palette) {
  this._bitmapInfo.palette = palette;
};

ParserAsync.prototype._simpleTransparency = function() {
  this._metaData.alpha = true;
};

ParserAsync.prototype._headersFinished = function() {
  // Up until this point, we don't know if we have a tRNS chunk (alpha)
  // so we can't emit metadata any earlier
  this.emit('metadata', this._metaData);
};

ParserAsync.prototype._finished = function() {
  if (this.errord) {
    return;
  }

  if (!this._inflate) {
    this.emit('error', 'No Inflate block');
  }
  else {
    // no more data to inflate
    this._inflate.end();
  }
  this.destroySoon();
};

ParserAsync.prototype._complete = function(filteredData) {

  if (this.errord) {
    return;
  }

  try {
    var bitmapData = bitmapper.dataToBitMap(filteredData, this._bitmapInfo);

    var normalisedBitmapData = formatNormaliser(bitmapData, this._bitmapInfo);
    bitmapData = null;
  }
  catch (ex) {
    this._handleError(ex);
    return;
  }

  this.emit('parsed', normalisedBitmapData);
};
});

var bitpacker = function(dataIn, width, height, options) {
  var outHasAlpha = [constants.COLORTYPE_COLOR_ALPHA, constants.COLORTYPE_ALPHA].indexOf(options.colorType) !== -1;
  if (options.colorType === options.inputColorType) {
    var bigEndian = (function() {
      var buffer = new ArrayBuffer(2);
      new DataView(buffer).setInt16(0, 256, true /* littleEndian */);
      // Int16Array uses the platform's endianness.
      return new Int16Array(buffer)[0] !== 256;
    })();
    // If no need to convert to grayscale and alpha is present/absent in both, take a fast route
    if (options.bitDepth === 8 || (options.bitDepth === 16 && bigEndian)) {
      return dataIn;
    }
  }

  // map to a UInt16 array if data is 16bit, fix endianness below
  var data = options.bitDepth !== 16 ? dataIn : new Uint16Array(dataIn.buffer);

  var maxValue = 255;
  var inBpp = constants.COLORTYPE_TO_BPP_MAP[options.inputColorType];
  if (inBpp === 4 && !options.inputHasAlpha) {
    inBpp = 3;
  }
  var outBpp = constants.COLORTYPE_TO_BPP_MAP[options.colorType];
  if (options.bitDepth === 16) {
    maxValue = 65535;
    outBpp *= 2;
  }
  var outData = new Buffer(width * height * outBpp);

  var inIndex = 0;
  var outIndex = 0;

  var bgColor = options.bgColor || {};
  if (bgColor.red === undefined) {
    bgColor.red = maxValue;
  }
  if (bgColor.green === undefined) {
    bgColor.green = maxValue;
  }
  if (bgColor.blue === undefined) {
    bgColor.blue = maxValue;
  }

  function getRGBA() {
    var red;
    var green;
    var blue;
    var alpha = maxValue;
    switch (options.inputColorType) {
      case constants.COLORTYPE_COLOR_ALPHA:
        alpha = data[inIndex + 3];
        red = data[inIndex];
        green = data[inIndex + 1];
        blue = data[inIndex + 2];
        break;
      case constants.COLORTYPE_COLOR:
        red = data[inIndex];
        green = data[inIndex + 1];
        blue = data[inIndex + 2];
        break;
      case constants.COLORTYPE_ALPHA:
        alpha = data[inIndex + 1];
        red = data[inIndex];
        green = red;
        blue = red;
        break;
      case constants.COLORTYPE_GRAYSCALE:
        red = data[inIndex];
        green = red;
        blue = red;
        break;
      default:
        throw new Error('input color type:' + options.inputColorType + ' is not supported at present');
    }

    if (options.inputHasAlpha) {
      if (!outHasAlpha) {
        alpha /= maxValue;
        red = Math.min(Math.max(Math.round((1 - alpha) * bgColor.red + alpha * red), 0), maxValue);
        green = Math.min(Math.max(Math.round((1 - alpha) * bgColor.green + alpha * green), 0), maxValue);
        blue = Math.min(Math.max(Math.round((1 - alpha) * bgColor.blue + alpha * blue), 0), maxValue);
      }
    }
    return { red: red, green: green, blue: blue, alpha: alpha };
  }

  for (var y = 0; y < height; y++) {
    for (var x = 0; x < width; x++) {
      var rgba = getRGBA();

      switch (options.colorType) {
        case constants.COLORTYPE_COLOR_ALPHA:
        case constants.COLORTYPE_COLOR:
          if (options.bitDepth === 8) {
            outData[outIndex] = rgba.red;
            outData[outIndex + 1] = rgba.green;
            outData[outIndex + 2] = rgba.blue;
            if (outHasAlpha) {
              outData[outIndex + 3] = rgba.alpha;
            }
          }
          else {
            outData.writeUInt16BE(rgba.red, outIndex);
            outData.writeUInt16BE(rgba.green, outIndex + 2);
            outData.writeUInt16BE(rgba.blue, outIndex + 4);
            if (outHasAlpha) {
              outData.writeUInt16BE(rgba.alpha, outIndex + 6);
            }
          }
          break;
        case constants.COLORTYPE_ALPHA:
        case constants.COLORTYPE_GRAYSCALE:
          // Convert to grayscale and alpha
          var grayscale = (rgba.red + rgba.green + rgba.blue) / 3;
          if (options.bitDepth === 8) {
            outData[outIndex] = grayscale;
            if (outHasAlpha) {
              outData[outIndex + 1] = rgba.alpha;
            }
          }
          else {
            outData.writeUInt16BE(grayscale, outIndex);
            if (outHasAlpha) {
              outData.writeUInt16BE(rgba.alpha, outIndex + 2);
            }
          }
          break;
        default:
          throw new Error('unrecognised color Type ' + options.colorType);
      }

      inIndex += inBpp;
      outIndex += outBpp;
    }
  }

  return outData;
};

function filterNone(pxData, pxPos, byteWidth, rawData, rawPos) {

  for (var x = 0; x < byteWidth; x++) {
    rawData[rawPos + x] = pxData[pxPos + x];
  }
}

function filterSumNone(pxData, pxPos, byteWidth) {

  var sum = 0;
  var length = pxPos + byteWidth;

  for (var i = pxPos; i < length; i++) {
    sum += Math.abs(pxData[i]);
  }
  return sum;
}

function filterSub(pxData, pxPos, byteWidth, rawData, rawPos, bpp) {

  for (var x = 0; x < byteWidth; x++) {

    var left = x >= bpp ? pxData[pxPos + x - bpp] : 0;
    var val = pxData[pxPos + x] - left;

    rawData[rawPos + x] = val;
  }
}

function filterSumSub(pxData, pxPos, byteWidth, bpp) {

  var sum = 0;
  for (var x = 0; x < byteWidth; x++) {

    var left = x >= bpp ? pxData[pxPos + x - bpp] : 0;
    var val = pxData[pxPos + x] - left;

    sum += Math.abs(val);
  }

  return sum;
}

function filterUp(pxData, pxPos, byteWidth, rawData, rawPos) {

  for (var x = 0; x < byteWidth; x++) {

    var up = pxPos > 0 ? pxData[pxPos + x - byteWidth] : 0;
    var val = pxData[pxPos + x] - up;

    rawData[rawPos + x] = val;
  }
}

function filterSumUp(pxData, pxPos, byteWidth) {

  var sum = 0;
  var length = pxPos + byteWidth;
  for (var x = pxPos; x < length; x++) {

    var up = pxPos > 0 ? pxData[x - byteWidth] : 0;
    var val = pxData[x] - up;

    sum += Math.abs(val);
  }

  return sum;
}

function filterAvg(pxData, pxPos, byteWidth, rawData, rawPos, bpp) {

  for (var x = 0; x < byteWidth; x++) {

    var left = x >= bpp ? pxData[pxPos + x - bpp] : 0;
    var up = pxPos > 0 ? pxData[pxPos + x - byteWidth] : 0;
    var val = pxData[pxPos + x] - ((left + up) >> 1);

    rawData[rawPos + x] = val;
  }
}

function filterSumAvg(pxData, pxPos, byteWidth, bpp) {

  var sum = 0;
  for (var x = 0; x < byteWidth; x++) {

    var left = x >= bpp ? pxData[pxPos + x - bpp] : 0;
    var up = pxPos > 0 ? pxData[pxPos + x - byteWidth] : 0;
    var val = pxData[pxPos + x] - ((left + up) >> 1);

    sum += Math.abs(val);
  }

  return sum;
}

function filterPaeth(pxData, pxPos, byteWidth, rawData, rawPos, bpp) {

  for (var x = 0; x < byteWidth; x++) {

    var left = x >= bpp ? pxData[pxPos + x - bpp] : 0;
    var up = pxPos > 0 ? pxData[pxPos + x - byteWidth] : 0;
    var upleft = pxPos > 0 && x >= bpp ? pxData[pxPos + x - (byteWidth + bpp)] : 0;
    var val = pxData[pxPos + x] - paethPredictor(left, up, upleft);

    rawData[rawPos + x] = val;
  }
}

function filterSumPaeth(pxData, pxPos, byteWidth, bpp) {
  var sum = 0;
  for (var x = 0; x < byteWidth; x++) {

    var left = x >= bpp ? pxData[pxPos + x - bpp] : 0;
    var up = pxPos > 0 ? pxData[pxPos + x - byteWidth] : 0;
    var upleft = pxPos > 0 && x >= bpp ? pxData[pxPos + x - (byteWidth + bpp)] : 0;
    var val = pxData[pxPos + x] - paethPredictor(left, up, upleft);

    sum += Math.abs(val);
  }

  return sum;
}

var filters = {
  0: filterNone,
  1: filterSub,
  2: filterUp,
  3: filterAvg,
  4: filterPaeth
};

var filterSums = {
  0: filterSumNone,
  1: filterSumSub,
  2: filterSumUp,
  3: filterSumAvg,
  4: filterSumPaeth
};

var filterPack = function(pxData, width, height, options, bpp) {

  var filterTypes;
  if (!('filterType' in options) || options.filterType === -1) {
    filterTypes = [0, 1, 2, 3, 4];
  }
  else if (typeof options.filterType === 'number') {
    filterTypes = [options.filterType];
  }
  else {
    throw new Error('unrecognised filter types');
  }

  if (options.bitDepth === 16) {
    bpp *= 2;
  }
  var byteWidth = width * bpp;
  var rawPos = 0;
  var pxPos = 0;
  var rawData = new Buffer((byteWidth + 1) * height);

  var sel = filterTypes[0];

  for (var y = 0; y < height; y++) {

    if (filterTypes.length > 1) {
      // find best filter for this line (with lowest sum of values)
      var min = Infinity;

      for (var i = 0; i < filterTypes.length; i++) {
        var sum = filterSums[filterTypes[i]](pxData, pxPos, byteWidth, bpp);
        if (sum < min) {
          sel = filterTypes[i];
          min = sum;
        }
      }
    }

    rawData[rawPos] = sel;
    rawPos++;
    filters[sel](pxData, pxPos, byteWidth, rawData, rawPos, bpp);
    rawPos += byteWidth;
    pxPos += byteWidth;
  }
  return rawData;
};

var packer = createCommonjsModule(function (module) {







var Packer = module.exports = function(options) {
  this._options = options;

  options.deflateChunkSize = options.deflateChunkSize || 32 * 1024;
  options.deflateLevel = options.deflateLevel != null ? options.deflateLevel : 9;
  options.deflateStrategy = options.deflateStrategy != null ? options.deflateStrategy : 3;
  options.inputHasAlpha = options.inputHasAlpha != null ? options.inputHasAlpha : true;
  options.deflateFactory = options.deflateFactory || zlib__default['default'].createDeflate;
  options.bitDepth = options.bitDepth || 8;
  // This is outputColorType
  options.colorType = (typeof options.colorType === 'number') ? options.colorType : constants.COLORTYPE_COLOR_ALPHA;
  options.inputColorType = (typeof options.inputColorType === 'number') ? options.inputColorType : constants.COLORTYPE_COLOR_ALPHA;

  if ([
    constants.COLORTYPE_GRAYSCALE,
    constants.COLORTYPE_COLOR,
    constants.COLORTYPE_COLOR_ALPHA,
    constants.COLORTYPE_ALPHA
  ].indexOf(options.colorType) === -1) {
    throw new Error('option color type:' + options.colorType + ' is not supported at present');
  }
  if ([
    constants.COLORTYPE_GRAYSCALE,
    constants.COLORTYPE_COLOR,
    constants.COLORTYPE_COLOR_ALPHA,
    constants.COLORTYPE_ALPHA
  ].indexOf(options.inputColorType) === -1) {
    throw new Error('option input color type:' + options.inputColorType + ' is not supported at present');
  }
  if (options.bitDepth !== 8 && options.bitDepth !== 16) {
    throw new Error('option bit depth:' + options.bitDepth + ' is not supported at present');
  }
};

Packer.prototype.getDeflateOptions = function() {
  return {
    chunkSize: this._options.deflateChunkSize,
    level: this._options.deflateLevel,
    strategy: this._options.deflateStrategy
  };
};

Packer.prototype.createDeflate = function() {
  return this._options.deflateFactory(this.getDeflateOptions());
};

Packer.prototype.filterData = function(data, width, height) {
  // convert to correct format for filtering (e.g. right bpp and bit depth)
  var packedData = bitpacker(data, width, height, this._options);

  // filter pixel data
  var bpp = constants.COLORTYPE_TO_BPP_MAP[this._options.colorType];
  var filteredData = filterPack(packedData, width, height, this._options, bpp);
  return filteredData;
};

Packer.prototype._packChunk = function(type, data) {

  var len = (data ? data.length : 0);
  var buf = new Buffer(len + 12);

  buf.writeUInt32BE(len, 0);
  buf.writeUInt32BE(type, 4);

  if (data) {
    data.copy(buf, 8);
  }

  buf.writeInt32BE(crc.crc32(buf.slice(4, buf.length - 4)), buf.length - 4);
  return buf;
};

Packer.prototype.packGAMA = function(gamma) {
  var buf = new Buffer(4);
  buf.writeUInt32BE(Math.floor(gamma * constants.GAMMA_DIVISION), 0);
  return this._packChunk(constants.TYPE_gAMA, buf);
};

Packer.prototype.packIHDR = function(width, height) {

  var buf = new Buffer(13);
  buf.writeUInt32BE(width, 0);
  buf.writeUInt32BE(height, 4);
  buf[8] = this._options.bitDepth; // Bit depth
  buf[9] = this._options.colorType; // colorType
  buf[10] = 0; // compression
  buf[11] = 0; // filter
  buf[12] = 0; // interlace

  return this._packChunk(constants.TYPE_IHDR, buf);
};

Packer.prototype.packIDAT = function(data) {
  return this._packChunk(constants.TYPE_IDAT, data);
};

Packer.prototype.packIEND = function() {
  return this._packChunk(constants.TYPE_IEND, null);
};
});

var packerAsync = createCommonjsModule(function (module) {






var PackerAsync = module.exports = function(opt) {
  Stream__default['default'].call(this);

  var options = opt || {};

  this._packer = new packer(options);
  this._deflate = this._packer.createDeflate();

  this.readable = true;
};
util__default['default'].inherits(PackerAsync, Stream__default['default']);


PackerAsync.prototype.pack = function(data, width, height, gamma) {
  // Signature
  this.emit('data', new Buffer(constants.PNG_SIGNATURE));
  this.emit('data', this._packer.packIHDR(width, height));

  if (gamma) {
    this.emit('data', this._packer.packGAMA(gamma));
  }

  var filteredData = this._packer.filterData(data, width, height);

  // compress it
  this._deflate.on('error', this.emit.bind(this, 'error'));

  this._deflate.on('data', function(compressedData) {
    this.emit('data', this._packer.packIDAT(compressedData));
  }.bind(this));

  this._deflate.on('end', function() {
    this.emit('data', this._packer.packIEND());
    this.emit('end');
  }.bind(this));

  this._deflate.end(filteredData);
};
});

var syncInflate = createCommonjsModule(function (module, exports) {

var assert = require$$0__default['default'].ok;



var kMaxLength = require$$1__default['default'].kMaxLength;

function Inflate(opts) {
  if (!(this instanceof Inflate)) {
    return new Inflate(opts);
  }

  if (opts && opts.chunkSize < zlib__default['default'].Z_MIN_CHUNK) {
    opts.chunkSize = zlib__default['default'].Z_MIN_CHUNK;
  }

  zlib__default['default'].Inflate.call(this, opts);

  // Node 8 --> 9 compatibility check
  this._offset = this._offset === undefined ? this._outOffset : this._offset;
  this._buffer = this._buffer || this._outBuffer;

  if (opts && opts.maxLength != null) {
    this._maxLength = opts.maxLength;
  }
}

function createInflate(opts) {
  return new Inflate(opts);
}

function _close(engine, callback) {
  if (callback) {
    process.nextTick(callback);
  }

  // Caller may invoke .close after a zlib error (which will null _handle).
  if (!engine._handle) {
    return;
  }

  engine._handle.close();
  engine._handle = null;
}

Inflate.prototype._processChunk = function(chunk, flushFlag, asyncCb) {
  if (typeof asyncCb === 'function') {
    return zlib__default['default'].Inflate._processChunk.call(this, chunk, flushFlag, asyncCb);
  }

  var self = this;

  var availInBefore = chunk && chunk.length;
  var availOutBefore = this._chunkSize - this._offset;
  var leftToInflate = this._maxLength;
  var inOff = 0;

  var buffers = [];
  var nread = 0;

  var error;
  this.on('error', function(err) {
    error = err;
  });

  function handleChunk(availInAfter, availOutAfter) {
    if (self._hadError) {
      return;
    }

    var have = availOutBefore - availOutAfter;
    assert(have >= 0, 'have should not go down');

    if (have > 0) {
      var out = self._buffer.slice(self._offset, self._offset + have);
      self._offset += have;

      if (out.length > leftToInflate) {
        out = out.slice(0, leftToInflate);
      }

      buffers.push(out);
      nread += out.length;
      leftToInflate -= out.length;

      if (leftToInflate === 0) {
        return false;
      }
    }

    if (availOutAfter === 0 || self._offset >= self._chunkSize) {
      availOutBefore = self._chunkSize;
      self._offset = 0;
      self._buffer = Buffer.allocUnsafe(self._chunkSize);
    }

    if (availOutAfter === 0) {
      inOff += (availInBefore - availInAfter);
      availInBefore = availInAfter;

      return true;
    }

    return false;
  }

  assert(this._handle, 'zlib binding closed');
  do {
    var res = this._handle.writeSync(flushFlag,
      chunk, // in
      inOff, // in_off
      availInBefore, // in_len
      this._buffer, // out
      this._offset, //out_off
      availOutBefore); // out_len
    // Node 8 --> 9 compatibility check
    res = res || this._writeState;
  } while (!this._hadError && handleChunk(res[0], res[1]));

  if (this._hadError) {
    throw error;
  }

  if (nread >= kMaxLength) {
    _close(this);
    throw new RangeError('Cannot create final Buffer. It would be larger than 0x' + kMaxLength.toString(16) + ' bytes');
  }

  var buf = Buffer.concat(buffers, nread);
  _close(this);

  return buf;
};

util__default['default'].inherits(Inflate, zlib__default['default'].Inflate);

function zlibBufferSync(engine, buffer) {
  if (typeof buffer === 'string') {
    buffer = Buffer.from(buffer);
  }
  if (!(buffer instanceof Buffer)) {
    throw new TypeError('Not a string or buffer');
  }

  var flushFlag = engine._finishFlushFlag;
  if (flushFlag == null) {
    flushFlag = zlib__default['default'].Z_FINISH;
  }

  return engine._processChunk(buffer, flushFlag);
}

function inflateSync(buffer, opts) {
  return zlibBufferSync(new Inflate(opts), buffer);
}

module.exports = exports = inflateSync;
exports.Inflate = Inflate;
exports.createInflate = createInflate;
exports.inflateSync = inflateSync;
});

var syncReader = createCommonjsModule(function (module) {

var SyncReader = module.exports = function(buffer) {

  this._buffer = buffer;
  this._reads = [];
};

SyncReader.prototype.read = function(length, callback) {

  this._reads.push({
    length: Math.abs(length), // if length < 0 then at most this length
    allowLess: length < 0,
    func: callback
  });
};

SyncReader.prototype.process = function() {

  // as long as there is any data and read requests
  while (this._reads.length > 0 && this._buffer.length) {

    var read = this._reads[0];

    if (this._buffer.length && (this._buffer.length >= read.length || read.allowLess)) {

      // ok there is any data so that we can satisfy this request
      this._reads.shift(); // == read

      var buf = this._buffer;

      this._buffer = buf.slice(read.length);

      read.func.call(this, buf.slice(0, read.length));

    }
    else {
      break;
    }

  }

  if (this._reads.length > 0) {
    return new Error('There are some read requests waitng on finished stream');
  }

  if (this._buffer.length > 0) {
    return new Error('unrecognised content at end of stream');
  }

};
});

var process_1 = function(inBuffer, bitmapInfo) {

  var outBuffers = [];
  var reader = new syncReader(inBuffer);
  var filter = new filterParse(bitmapInfo, {
    read: reader.read.bind(reader),
    write: function(bufferPart) {
      outBuffers.push(bufferPart);
    },
    complete: function() {
    }
  });

  filter.start();
  reader.process();

  return Buffer.concat(outBuffers);
};

var filterParseSync = {
	process: process_1
};

var hasSyncZlib$1 = true;


if (!zlib__default['default'].deflateSync) {
  hasSyncZlib$1 = false;
}







var parserSync = function(buffer, options) {

  if (!hasSyncZlib$1) {
    throw new Error('To use the sync capability of this library in old node versions, please pin pngjs to v2.3.0');
  }

  var err;
  function handleError(_err_) {
    err = _err_;
  }

  var metaData;
  function handleMetaData(_metaData_) {
    metaData = _metaData_;
  }

  function handleTransColor(transColor) {
    metaData.transColor = transColor;
  }

  function handlePalette(palette) {
    metaData.palette = palette;
  }

  function handleSimpleTransparency() {
    metaData.alpha = true;
  }

  var gamma;
  function handleGamma(_gamma_) {
    gamma = _gamma_;
  }

  var inflateDataList = [];
  function handleInflateData(inflatedData) {
    inflateDataList.push(inflatedData);
  }

  var reader = new syncReader(buffer);

  var parser$1 = new parser(options, {
    read: reader.read.bind(reader),
    error: handleError,
    metadata: handleMetaData,
    gamma: handleGamma,
    palette: handlePalette,
    transColor: handleTransColor,
    inflateData: handleInflateData,
    simpleTransparency: handleSimpleTransparency
  });

  parser$1.start();
  reader.process();

  if (err) {
    throw err;
  }

  //join together the inflate datas
  var inflateData = Buffer.concat(inflateDataList);
  inflateDataList.length = 0;

  var inflatedData;
  if (metaData.interlace) {
    inflatedData = zlib__default['default'].inflateSync(inflateData);
  }
  else {
    var rowSize = ((metaData.width * metaData.bpp * metaData.depth + 7) >> 3) + 1;
    var imageSize = rowSize * metaData.height;
    inflatedData = syncInflate(inflateData, { chunkSize: imageSize, maxLength: imageSize });
  }
  inflateData = null;

  if (!inflatedData || !inflatedData.length) {
    throw new Error('bad png - invalid inflate data response');
  }

  var unfilteredData = filterParseSync.process(inflatedData, metaData);
  inflateData = null;

  var bitmapData = bitmapper.dataToBitMap(unfilteredData, metaData);
  unfilteredData = null;

  var normalisedBitmapData = formatNormaliser(bitmapData, metaData);

  metaData.data = normalisedBitmapData;
  metaData.gamma = gamma || 0;

  return metaData;
};

var hasSyncZlib = true;

if (!zlib__default['default'].deflateSync) {
  hasSyncZlib = false;
}



var packerSync = function(metaData, opt) {

  if (!hasSyncZlib) {
    throw new Error('To use the sync capability of this library in old node versions, please pin pngjs to v2.3.0');
  }

  var options = opt || {};

  var packer$1 = new packer(options);

  var chunks = [];

  // Signature
  chunks.push(new Buffer(constants.PNG_SIGNATURE));

  // Header
  chunks.push(packer$1.packIHDR(metaData.width, metaData.height));

  if (metaData.gamma) {
    chunks.push(packer$1.packGAMA(metaData.gamma));
  }

  var filteredData = packer$1.filterData(metaData.data, metaData.width, metaData.height);

  // compress it
  var compressedData = zlib__default['default'].deflateSync(filteredData, packer$1.getDeflateOptions());
  filteredData = null;

  if (!compressedData || !compressedData.length) {
    throw new Error('bad png - invalid compressed data response');
  }
  chunks.push(packer$1.packIDAT(compressedData));

  // End
  chunks.push(packer$1.packIEND());

  return Buffer.concat(chunks);
};

var read = function(buffer, options) {

  return parserSync(buffer, options || {});
};

var write = function(png, options) {

  return packerSync(png, options);
};

var pngSync = {
	read: read,
	write: write
};

var png = createCommonjsModule(function (module, exports) {








var PNG = exports.PNG = function(options) {
  Stream__default['default'].call(this);

  options = options || {}; // eslint-disable-line no-param-reassign

  // coerce pixel dimensions to integers (also coerces undefined -> 0):
  this.width = options.width | 0;
  this.height = options.height | 0;

  this.data = this.width > 0 && this.height > 0 ?
    new Buffer(4 * this.width * this.height) : null;

  if (options.fill && this.data) {
    this.data.fill(0);
  }

  this.gamma = 0;
  this.readable = this.writable = true;

  this._parser = new parserAsync(options);

  this._parser.on('error', this.emit.bind(this, 'error'));
  this._parser.on('close', this._handleClose.bind(this));
  this._parser.on('metadata', this._metadata.bind(this));
  this._parser.on('gamma', this._gamma.bind(this));
  this._parser.on('parsed', function(data) {
    this.data = data;
    this.emit('parsed', data);
  }.bind(this));

  this._packer = new packerAsync(options);
  this._packer.on('data', this.emit.bind(this, 'data'));
  this._packer.on('end', this.emit.bind(this, 'end'));
  this._parser.on('close', this._handleClose.bind(this));
  this._packer.on('error', this.emit.bind(this, 'error'));

};
util__default['default'].inherits(PNG, Stream__default['default']);

PNG.sync = pngSync;

PNG.prototype.pack = function() {

  if (!this.data || !this.data.length) {
    this.emit('error', 'No data provided');
    return this;
  }

  process.nextTick(function() {
    this._packer.pack(this.data, this.width, this.height, this.gamma);
  }.bind(this));

  return this;
};


PNG.prototype.parse = function(data, callback) {

  if (callback) {
    var onParsed, onError;

    onParsed = function(parsedData) {
      this.removeListener('error', onError);

      this.data = parsedData;
      callback(null, this);
    }.bind(this);

    onError = function(err) {
      this.removeListener('parsed', onParsed);

      callback(err, null);
    }.bind(this);

    this.once('parsed', onParsed);
    this.once('error', onError);
  }

  this.end(data);
  return this;
};

PNG.prototype.write = function(data) {
  this._parser.write(data);
  return true;
};

PNG.prototype.end = function(data) {
  this._parser.end(data);
};

PNG.prototype._metadata = function(metadata) {
  this.width = metadata.width;
  this.height = metadata.height;

  this.emit('metadata', metadata);
};

PNG.prototype._gamma = function(gamma) {
  this.gamma = gamma;
};

PNG.prototype._handleClose = function() {
  if (!this._parser.writable && !this._packer.readable) {
    this.emit('close');
  }
};


PNG.bitblt = function(src, dst, srcX, srcY, width, height, deltaX, deltaY) { // eslint-disable-line max-params
  // coerce pixel dimensions to integers (also coerces undefined -> 0):
  /* eslint-disable no-param-reassign */
  srcX |= 0;
  srcY |= 0;
  width |= 0;
  height |= 0;
  deltaX |= 0;
  deltaY |= 0;
  /* eslint-enable no-param-reassign */

  if (srcX > src.width || srcY > src.height || srcX + width > src.width || srcY + height > src.height) {
    throw new Error('bitblt reading outside image');
  }

  if (deltaX > dst.width || deltaY > dst.height || deltaX + width > dst.width || deltaY + height > dst.height) {
    throw new Error('bitblt writing outside image');
  }

  for (var y = 0; y < height; y++) {
    src.data.copy(dst.data,
      ((deltaY + y) * dst.width + deltaX) << 2,
      ((srcY + y) * src.width + srcX) << 2,
      ((srcY + y) * src.width + srcX + width) << 2
    );
  }
};


PNG.prototype.bitblt = function(dst, srcX, srcY, width, height, deltaX, deltaY) { // eslint-disable-line max-params

  PNG.bitblt(this, dst, srcX, srcY, width, height, deltaX, deltaY);
  return this;
};

PNG.adjustGamma = function(src) {
  if (src.gamma) {
    for (var y = 0; y < src.height; y++) {
      for (var x = 0; x < src.width; x++) {
        var idx = (src.width * y + x) << 2;

        for (var i = 0; i < 3; i++) {
          var sample = src.data[idx + i] / 255;
          sample = Math.pow(sample, 1 / 2.2 / src.gamma);
          src.data[idx + i] = Math.round(sample * 255);
        }
      }
    }
    src.gamma = 0;
  }
};

PNG.prototype.adjustGamma = function() {
  PNG.adjustGamma(this);
};
});

function getMismatchedPixels(pixelMatchInput) {
    const imgA = fs__default['default'].createReadStream(pixelMatchInput.imageAPath).pipe(new png.PNG()).on('parsed', doneReading);
    const imgB = fs__default['default'].createReadStream(pixelMatchInput.imageBPath).pipe(new png.PNG()).on('parsed', doneReading);
    let filesRead = 0;
    function doneReading() {
        if (++filesRead < 2)
            return;
        const mismatchedPixels = pixelmatch_1(imgA.data, imgB.data, null, pixelMatchInput.width, pixelMatchInput.height, {
            threshold: pixelMatchInput.pixelmatchThreshold,
            includeAA: false,
        });
        process.send(mismatchedPixels);
    }
}
process.on('message', getMismatchedPixels);