commit 413c967aae6548031fdfb466b8ed75d3b08e70da
Author: Kuba Niegowski <kuba@niegowski.pl>
Date:   Sun Aug 19 00:44:48 2012 +0200

    first commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..24cd046
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+node_modules
+*.png
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..04d21fe
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,19 @@
+Copyright (c) 2012 Kuba Niegowski
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..5449471
--- /dev/null
+++ b/README.md
@@ -0,0 +1,10 @@
+PNG.js
+========
+
+
+Options
+--------
+- `checkCRC` - `boolean` default: `true`
+- `deflateChunkSize` - `int` default: 32 kB
+- `deflateLevel` - `int` default: 9
+- `filterType` - `int` default: -1 (auto)
diff --git a/examples/test.js b/examples/test.js
new file mode 100755
index 0000000..785f66c
--- /dev/null
+++ b/examples/test.js
@@ -0,0 +1,31 @@
+#!/usr/bin/env node
+
+var fs = require('fs'),
+    PNG = require('../lib/png').PNG;
+
+
+fs.readFile(process.argv[2], function(err, data) {
+    if (err) throw err;
+
+    var png = new PNG();
+    png.parse(data, function(err) {
+        if (err) console.log(err.stack);
+
+        for (var y = 0; y < png.height; y++) {
+            for (var x = 0; x < png.width; x++) {
+                var idx = (png.width * y + x) << 2;
+
+                // invert color
+                png.data[idx] = 255 - png.data[idx];
+                png.data[idx+1] = 255 - png.data[idx+1];
+                png.data[idx+2] = 255 - png.data[idx+2];
+
+                // and reduce opacity
+                png.data[idx+3] = png.data[idx+3] >> 1;
+            }
+        }
+
+        png.pipe(fs.createWriteStream(process.argv[3] || 'out.png'));
+        png.pack();
+    });
+});
diff --git a/examples/test2.js b/examples/test2.js
new file mode 100755
index 0000000..fe46892
--- /dev/null
+++ b/examples/test2.js
@@ -0,0 +1,33 @@
+#!/usr/bin/env node
+
+var fs = require('fs'),
+    PNG = require('../lib/png').PNG;
+
+
+var png = new PNG({
+        filterType: 4
+    }),
+    src = fs.createReadStream(process.argv[2]),
+    dst = fs.createWriteStream(process.argv[3] || 'out.png');
+
+
+png.on('parsed', function() {
+
+    for (var y = 0; y < png.height; y++) {
+        for (var x = 0; x < png.width; x++) {
+            var idx = (png.width * y + x) << 2;
+
+            // invert color
+            png.data[idx] = 255 - png.data[idx];
+            png.data[idx+1] = 255 - png.data[idx+1];
+            png.data[idx+2] = 255 - png.data[idx+2];
+
+            // and reduce opacity
+            png.data[idx+3] = png.data[idx+3] >> 1;
+        }
+    }
+
+    png.pack();
+});
+
+src.pipe(png).pipe(dst);
diff --git a/lib/compress.js b/lib/compress.js
new file mode 100644
index 0000000..f110de6
--- /dev/null
+++ b/lib/compress.js
@@ -0,0 +1,94 @@
+// Copyright (c) 2012 Kuba Niegowski
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+'use strict';
+
+var util = require('util'),
+    zlib = require('zlib'),
+    events = require('events');
+
+
+var Compress = module.exports = function(options) {
+    events.EventEmitter.call(this);
+
+    this._options = options;
+    options.deflateChunkSize = options.deflateChunkSize || 32 * 1024;
+    options.deflateLevel = options.deflateLevel || 9;
+
+    this._inflate = null;
+};
+util.inherits(Compress, events.EventEmitter);
+
+
+Compress.prototype.prepareInflate = function(type) {
+
+    if (type != 0)
+        throw new Error('Unsupported compression method');
+
+    this._inflate = zlib.createInflate();
+
+    bufferStream(this._inflate, function(data) {
+        this._inflate = null;
+        this.emit('inflated', data);
+    }.bind(this));
+
+    this._inflate.on('error', this.emit.bind(this, 'error'));
+};
+
+Compress.prototype.writeInflate = function(data) {
+    this._inflate.write(data);
+};
+
+Compress.prototype.endInflate = function() {
+    this._inflate.end();
+};
+
+Compress.prototype.deflate = function(data) {
+
+    var deflate = zlib.createDeflate({
+            chunkSize: this._options.deflateChunkSize,
+            level: this._options.deflateLevel
+        });
+
+    bufferStream(deflate, function(data) {
+        this.emit('deflated', data);
+    }.bind(this));
+
+    deflate.on('error', this.emit.bind(this, 'error'));
+
+    deflate.end(data);
+};
+
+function bufferStream(stream, callback) {
+
+    var buffers = [],
+        length = 0;
+
+    stream.on('data', function(data) {
+        buffers.push(data);
+        length += data.length;
+    });
+
+    stream.on('end', function() {
+        callback(Buffer.concat(buffers, length));
+    });
+
+    return stream;
+};
diff --git a/lib/filter.js b/lib/filter.js
new file mode 100644
index 0000000..379a65f
--- /dev/null
+++ b/lib/filter.js
@@ -0,0 +1,254 @@
+// Copyright (c) 2012 Kuba Niegowski
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+'use strict';
+
+var util = require('util'),
+    zlib = require('zlib'),
+    events = require('events');
+
+
+var Filter = module.exports = function(options) {
+    events.EventEmitter.call(this);
+
+    this._options = options;
+    options.filterType = 'filterType' in options ? options.filterType : -1;
+
+    this._width = 0;
+    this._height = 0;
+
+    this._filters = {
+        0: this._filterNone.bind(this),
+        1: this._filterSub.bind(this),
+        2: this._filterUp.bind(this),
+        3: this._filterAvg.bind(this),
+        4: this._filterPaeth.bind(this)
+    };
+
+};
+util.inherits(Filter, events.EventEmitter);
+
+
+Filter.prototype.prepare = function(width, height, type) {
+
+    if (type != 0)
+        throw new Error('Unsupported filter method');
+
+    this.width = width;
+    this.height = height;
+};
+
+Filter.prototype.unfilter = function(rawData) {
+
+    var pxLineLength = this.width << 2,
+        rawLineLength = pxLineLength + 1,
+        pxData = new Buffer(pxLineLength * this.height);
+
+    for (var y = 0; y < this.height; y++) {
+
+        var rawRowPos = rawLineLength * y + 1,
+            pxRowPos = y * pxLineLength,
+            pxUpRowPos = pxRowPos - pxLineLength,
+            filter = rawData[rawRowPos - 1];
+
+        if (filter == 0) {
+            rawData.copy(pxData, pxRowPos, rawRowPos, rawRowPos + pxLineLength);
+
+        } else if (filter == 1) {
+            for (var x = 0; x < pxLineLength; x++) {
+
+                var left = x >= 4 ? pxData[pxRowPos + x - 4] : 0;
+                pxData[pxRowPos + x] = rawData[rawRowPos + x] + left;
+            }
+
+        } else if (filter == 2) {
+            for (var x = 0; x < pxLineLength; x++) {
+
+                var up = y > 0 ? pxData[pxUpRowPos + x] : 0;
+                pxData[pxRowPos + x] = rawData[rawRowPos + x] + up;
+            }
+
+        } else if (filter == 3) {
+            for (var x = 0; x < pxLineLength; x++) {
+
+                var left = x >= 4 ? pxData[pxRowPos + x - 4] : 0,
+                    up = y > 0 ? pxData[pxUpRowPos + x] : 0;
+
+                pxData[pxRowPos + x] = rawData[rawRowPos + x]
+                    + Math.floor((left + up) / 2);
+            }
+
+        } else if (filter == 4) {
+            for (var x = 0; x < pxLineLength; x++) {
+
+                var left = x >= 4 ? pxData[pxRowPos + x - 4] : 0,
+                    up = y > 0 ? pxData[pxUpRowPos + x] : 0,
+                    upLeft = x >= 4 && y > 0 ? pxData[pxUpRowPos + x - 4] : 0;
+
+                pxData[pxRowPos + x] = rawData[rawRowPos + x]
+                    + PaethPredictor(left, up, upLeft)
+            }
+        }
+    }
+    return pxData;
+};
+
+
+Filter.prototype.filter = function(pxData, width, height) {
+
+    var rawData = new Buffer(((width << 2) + 1) * height);
+
+    for (var y = 0; y < height; y++) {
+
+        // find best filter for this line (with lowest sum of values)
+        if (this._options.filterType == -1) {
+            var min = Infinity,
+                sel = 0;
+
+            for (var f in this._filters) {
+                var sum = this._filters[f](pxData, y, width, height, null);
+                if (sum < min) {
+                    sel = f;
+                    min = sum;
+                }
+            }
+
+        } else {
+            sel = this._options.filterType;
+        }
+        this._filters[sel](pxData, y, width, height, rawData);
+    }
+    return rawData;
+};
+
+Filter.prototype._filterNone = function(pxData, y, width, height, rawData) {
+
+    var pxRowLength = width << 2,
+        rawRowLength = pxRowLength + 1,
+        sum = 0;
+
+    if (!rawData) {
+        for (var x = 0; x < pxRowLength; x++)
+            sum += pxData[y * pxRowLength + x];
+
+    } else {
+        rawData[y * rawRowLength] = 0;
+        pxData.copy(rawData, rawRowLength * y + 1, pxRowLength * y, pxRowLength * (y + 1));
+    }
+
+    return sum;
+};
+
+Filter.prototype._filterSub = function(pxData, y, width, height, rawData) {
+
+    var pxRowLength = width << 2,
+        rawRowLength = pxRowLength + 1,
+        sum = 0;
+
+    if (rawData)
+        rawData[y * rawRowLength] = 1;
+
+    for (var x = 0; x < pxRowLength; x++) {
+
+        var left = x >= 4 ? pxData[y * pxRowLength + x - 4] : 0,
+            val = pxData[y * pxRowLength + x] - left;
+
+        if (!rawData) sum += val;
+        else rawData[y * rawRowLength + 1 + x] = val;
+    }
+    return sum;
+};
+
+Filter.prototype._filterUp = function(pxData, y, width, height, rawData) {
+
+    var pxRowLength = width << 2,
+        rawRowLength = pxRowLength + 1,
+        sum = 0;
+
+    if (rawData)
+        rawData[y * rawRowLength] = 2;
+
+    for (var x = 0; x < pxRowLength; x++) {
+
+        var up = y > 0 ? pxData[(y - 1) * pxRowLength + x] : 0,
+            val = pxData[y * pxRowLength + x] - up;
+
+        if (!rawData) sum += val;
+        else rawData[y * rawRowLength + 1 + x] = val;
+    }
+    return sum;
+};
+
+Filter.prototype._filterAvg = function(pxData, y, width, height, rawData) {
+
+    var pxRowLength = width << 2,
+        rawRowLength = pxRowLength + 1,
+        sum = 0;
+
+    if (rawData)
+        rawData[y * rawRowLength] = 3;
+
+    for (var x = 0; x < pxRowLength; x++) {
+
+        var left = x >= 4 ? pxData[y * pxRowLength + x - 4] : 0,
+            up = y > 0 ? pxData[(y - 1) * pxRowLength + x] : 0,
+            val = pxData[y * pxRowLength + x] - ((left + up) >> 1);
+
+        if (!rawData) sum += val;
+        else rawData[y * rawRowLength + 1 + x] = val;
+    }
+    return sum;
+};
+
+Filter.prototype._filterPaeth = function(pxData, y, width, height, rawData) {
+
+    var pxRowLength = width << 2,
+        rawRowLength = pxRowLength + 1,
+        sum = 0;
+
+    if (rawData)
+        rawData[y * rawRowLength] = 4;
+
+    for (var x = 0; x < pxRowLength; x++) {
+
+        var left = x >= 4 ? pxData[y * pxRowLength + x - 4] : 0,
+            up = y > 0 ? pxData[(y - 1) * pxRowLength + x] : 0,
+            upLeft = x >= 4 && y > 0 ? pxData[(y - 1) * pxRowLength + x - 4] : 0,
+            val = pxData[y * pxRowLength + x] - PaethPredictor(left, up, upLeft);
+
+        if (!rawData) sum += val;
+        else rawData[y * rawRowLength + 1 + x] = val;
+    }
+    return sum;
+};
+
+
+
+var PaethPredictor = function(left, above, upLeft) {
+
+    var p = left + above - upLeft,
+        pLeft = Math.abs(p - left),
+        pAbove = Math.abs(p - above),
+        pUpLeft = Math.abs(p - upLeft);
+
+    if (pLeft <= pAbove && pLeft <= pUpLeft) return left;
+    else if (pAbove <= pUpLeft) return above;
+    else return upLeft;
+};
diff --git a/lib/parser.js b/lib/parser.js
new file mode 100644
index 0000000..ed7b3bf
--- /dev/null
+++ b/lib/parser.js
@@ -0,0 +1,272 @@
+// Copyright (c) 2012 Kuba Niegowski
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+'use strict';
+
+
+var util = require('util'),
+    Stream = require('stream'),
+    Compress = require('./compress'),
+    Filter = require('./filter');
+
+
+var signature = [0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a];
+
+var TYPE_IHDR = 0x49484452;
+var TYPE_IEND = 0x49454e44;
+var TYPE_IDAT = 0x49444154;
+
+
+var Parser = module.exports = function(options) {
+    Stream.call(this);
+
+    this._options = options;
+    options.checkCRC = options.checkCRC !== false;
+
+    this._hasIHDR = false;
+    this._hasIEND = false;
+
+    this._chunks = {};
+    this._chunks[TYPE_IHDR] = this._parseIHDR.bind(this);
+    this._chunks[TYPE_IEND] = this._parseIEND.bind(this);
+    this._chunks[TYPE_IDAT] = this._parseIDAT.bind(this);
+
+    this._compress = new Compress(options);
+    this._filter = new Filter(options);
+
+    this._initCompress();
+};
+util.inherits(Parser, Stream);
+
+Parser.prototype._initCompress = function() {
+
+    this._compress.on('error', this.emit.bind(this, 'error'));
+
+    this._compress.on('deflated', this._packData.bind(this));
+    this._compress.on('inflated', function(data) {
+        this.emit('parsed', this._filter.unfilter(data));
+    }.bind(this));
+};
+
+Parser.prototype._parse = function(data) {
+
+    var idx = 0;
+
+    try {
+        // check PNG file signature
+        while (idx < signature.length) {
+            if (data[idx] != signature[idx]) {
+                throw new Error('Invalid file signature');
+            }
+            idx++;
+        }
+        //console.log('Signature is ok');
+
+        // iterate chunks
+        while (idx < data.length) {
+            idx = this._parseChunk(data, idx);
+        }
+    }
+    catch(err) {
+        this.emit('error', err);
+    }
+};
+
+Parser.prototype._pack = function(width, height, data) {
+
+    // Signature
+    this.emit('data', new Buffer(signature));
+    this.emit('data', this._packIHDR(width, height));
+
+    // filter pixel data
+    var data = this._filter.filter(data, width, height);
+
+    // compress it
+    this._compress.deflate(data);
+};
+
+Parser.prototype._packData = function(data) {
+
+    // console.log('deflate', data.length);
+
+    this.emit('data', this._packIDAT(data));
+    this.emit('data', this._packIEND());
+    this.emit('end');
+};
+
+Parser.prototype._parseChunk = function(data, idx) {
+
+    if (this._hasIEND)
+        throw new Error('Not expected chunk after IEND');
+
+    // chunk size (only content)
+    var length = data.readUInt32BE(idx);
+    idx += 4;
+
+    // chunk type
+    var type = data.readUInt32BE(idx),
+        ancillary = !!(data[idx] & 0x20),  // or critical
+        priv = !!(data[idx+1] & 0x20),  // or public
+        safeToCopy = !!(data[idx+3] & 0x20),  // or unsafe
+        name = '';
+    for (var i = 0; i < 4; i++)
+        name += String.fromCharCode(data[idx+i]);
+    idx += 4;
+
+    // console.log('chunk ', name, length);
+
+    // calc CRC (of chunk type and content)
+    var calcCrc = crc32(data.slice(idx - 4, idx + length)),
+        content = data.slice(idx, idx + length);
+    idx += length;
+
+    // read CRC
+    var fileCrc = data.readInt32BE(idx);
+    idx += 4;
+
+    // and check CRC
+    if (this._options.checkCRC && calcCrc != fileCrc)
+        throw new Error('Crc error');
+
+
+    if (!this._hasIHDR && type != TYPE_IHDR)
+        throw new Error('Expected IHDR on beggining');
+
+    if (this._chunks[type]) {
+        this._chunks[type](content);
+
+    } else if (!ancillary)
+        throw new Error('Unsupported critical chunk type ' + name);
+
+    return idx;
+};
+
+Parser.prototype._packChunk = function(type, data) {
+
+    var len = (data ? data.length : 0),
+        buf = new Buffer(len + 12);
+
+    buf.writeUInt32BE(len, 0);
+    buf.writeUInt32BE(type, 4);
+
+    if (data) data.copy(buf, 8);
+
+    buf.writeInt32BE(crc32(buf.slice(4, buf.length - 4)), buf.length - 4);
+    return buf;
+};
+
+
+Parser.prototype._parseIHDR = function(data) {
+
+    var width = data.readUInt32BE(0),
+        height = data.readUInt32BE(4),
+        depth = data[8],
+        colorType = data[9], // 1 palette, 2 color, 4 alpha
+        compr = data[10],
+        filter = data[11],
+        interlace = data[12];
+
+    // console.log('    width', width, 'height', height,
+    //     'depth', depth, 'colorType', colorType,
+    //     'compr', compr, 'filter', filter, 'interlace', interlace
+    // );
+
+    if (depth != 8)
+        throw new Error('Unsupported bit depth');
+    if (colorType != 6)
+        throw new Error('Unsupported color type');
+    if (interlace != 0)
+        throw new Error('Unsupported interlace method');
+
+    this._compress.prepareInflate(compr);
+    this._filter.prepare(width, height, filter);
+
+    this._hasIHDR = true;
+
+    this.emit('metadata', width, height);
+};
+
+Parser.prototype._packIHDR = function(width, height) {
+
+    var buf = new Buffer(13);
+    buf.writeUInt32BE(width, 0);
+    buf.writeUInt32BE(height, 4);
+    buf[8] = 8;
+    buf[9] = 6; // colorType
+    buf[10] = 0; // compression
+    buf[11] = 0; // filter
+    buf[12] = 0; // interlace
+
+    return this._packChunk(TYPE_IHDR, buf);
+};
+
+
+Parser.prototype._parseIDAT = function(data) {
+    this._compress.writeInflate(data);
+};
+
+Parser.prototype._packIDAT = function(data) {
+    return this._packChunk(TYPE_IDAT, data);
+};
+
+
+Parser.prototype._parseIEND = function(data) {
+
+    // no more data to inflate
+    this._compress.endInflate();
+
+    this._hasIEND = true;
+};
+
+Parser.prototype._packIEND = function() {
+    return this._packChunk(TYPE_IEND, null);
+};
+
+
+
+
+
+
+
+
+// prepare crc table as in PNG Specification
+var crcTable = [];
+
+for (var i = 0; i < 256; i++) {
+    var c = i;
+    for (var j = 0; j < 8; j++) {
+        if (c & 1) {
+            c = 0xedb88320 ^ (c >>> 1);
+        } else {
+            c = c >>> 1;
+        }
+    }
+    crcTable[i] = c;
+}
+
+function crc32(buf) {
+
+    var crc = -1;
+    for (var i = 0; i < buf.length; i++) {
+        crc = crcTable[(crc ^ buf[i]) & 0xff] ^ (crc >>> 8);
+    }
+    return crc ^ -1;
+}
+
diff --git a/lib/png.js b/lib/png.js
new file mode 100644
index 0000000..0d1e624
--- /dev/null
+++ b/lib/png.js
@@ -0,0 +1,94 @@
+// Copyright (c) 2012 Kuba Niegowski
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+'use strict';
+
+
+var util = require('util'),
+    Parser = require('./parser');
+
+
+var PNG = exports.PNG = function(options) {
+    Parser.call(this, options);
+
+    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;
+
+    this.on('metadata', this._metadata.bind(this));
+
+    this.readable = this.writable = true;
+    this._buffers = [];
+    this._buffLen = 0;
+
+    this.on('parsed', function(data) {
+        this.data = data;
+    }.bind(this));
+};
+util.inherits(PNG, Parser);
+
+
+PNG.prototype.pack = function() {
+    this._pack(this.width, this.height, this.data);
+};
+
+
+PNG.prototype.parse = function(data, callback) {
+
+    if (callback) {
+        var onParsed = null, onError = null;
+
+        this.once('parsed', onParsed = function(data) {
+            this.removeListener('error', onError);
+
+            this.data = data;
+            callback(null, this);
+
+        }.bind(this));
+
+        this.once('error', onError = function(err) {
+            this.removeListener('parsed', onParsed);
+
+            callback(err, null);
+        }.bind(this));
+    }
+
+    this._parse(data);
+};
+
+PNG.prototype.write = function(data) {
+    this._buffers.push(data);
+    this._buffLen += data.length;
+};
+
+PNG.prototype.end = function(data) {
+    if (data) this.write(data);
+    this._parse(Buffer.concat(this._buffers, this._buffLen));
+    this._buffers = [];
+    this._buffLen = 0;
+};
+
+PNG.prototype._metadata = function(width, height) {
+    this.width = width;
+    this.height = height;
+    this.data = null;
+};
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..0e33ee4
--- /dev/null
+++ b/package.json
@@ -0,0 +1,15 @@
+{
+    "name": "pngjs",
+    "version": "0.1.0-alpha",
+    "description": "Simple PNG encoder/decoder",
+    "author": "Kuba Niegowski",
+    "contributors": [],
+    "homepage": "https://github.com/niegowski/node-pngjs/",
+    "keywords" : [
+        "png"
+    ],
+    "engines": {
+        "node": "0.8.x"
+    },
+    "main": "./lib/png.js"
+}