Implemented symetric PNG.sync.write to complement PNG.sync.read

lib/packer-async.js

@@ -3,16 +3,12 @@
 var util = require('util');
 var Stream = require('stream');
 var zlib = require('zlib');
-var filter = require('./filter-pack');
-var CrcStream = require('./crc');
 var constants = require('./constants');
-var bitPacker = require('./bitpacker');
+var Packer = require('./packer');
 
 var PackerAsync = module.exports = function(options) {
   Stream.call(this);
 
-  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;
@@ -28,6 +24,13 @@ var PackerAsync = module.exports = function(options) {
     throw new Error('option bit depth:' + options.bitDepth + ' is not supported at present');
   }
 
+  this._packer = new Packer(options);
+  this._deflate = options.deflateFactory({
+    chunkSize: options.deflateChunkSize,
+    level: options.deflateLevel,
+    strategy: options.deflateStrategy
+  });
+
   this.readable = true;
 };
 util.inherits(PackerAsync, Stream);
@@ -36,79 +39,25 @@ util.inherits(PackerAsync, Stream);
 PackerAsync.prototype.pack = function(data, width, height, gamma) {
   // Signature
   this.emit('data', new Buffer(constants.PNG_SIGNATURE));
-  this.emit('data', this._packIHDR(width, height, this._options.bitDepth, this._options.colorType));
+  this.emit('data', this._packer.packIHDR(width, height));
 
   if (gamma) {
-    this.emit('data', this._packGAMA(gamma));
+    this.emit('data', this._packer.packGAMA(gamma));
   }
 
-  // convert to correct format for filtering (e.g. right bpp and bit depth)
+  var filteredData = this._packer.filterData(data, width, height);
-  var packedData = bitPacker(data, width, height, this._options);
-
-  // filter pixel data
-  var bpp = constants.COLORTYPE_TO_BPP_MAP[this._options.colorType];
-  var filteredData = filter(packedData, width, height, this._options, bpp);
 
   // compress it
-  var deflate = this._options.deflateFactory({
+  this._deflate.on('error', this.emit.bind(this, 'error'));
-    chunkSize: this._options.deflateChunkSize,
-    level: this._options.deflateLevel,
-    strategy: this._options.deflateStrategy
-  });
-  deflate.on('error', this.emit.bind(this, 'error'));
 
-  deflate.on('data', function(compressedData) {
+  this._deflate.on('data', function(compressedData) {
-    this.emit('data', this._packIDAT(compressedData));
+    this.emit('data', this._packer.packIDAT(compressedData));
   }.bind(this));
 
-  deflate.on('end', function() {
+  this._deflate.on('end', function() {
-    this.emit('data', this._packIEND());
+    this.emit('data', this._packer.packIEND());
     this.emit('end');
   }.bind(this));
 
-  deflate.end(filteredData);
+  this._deflate.end(filteredData);
-};
-
-PackerAsync.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(CrcStream.crc32(buf.slice(4, buf.length - 4)), buf.length - 4);
-  return buf;
-};
-
-PackerAsync.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);
-};
-
-PackerAsync.prototype._packIHDR = function(width, height, bitDepth, colorType) {
-
-  var buf = new Buffer(13);
-  buf.writeUInt32BE(width, 0);
-  buf.writeUInt32BE(height, 4);
-  buf[8] = bitDepth;  // Bit depth
-  buf[9] = colorType; // colorType
-  buf[10] = 0; // compression
-  buf[11] = 0; // filter
-  buf[12] = 0; // interlace
-
-  return this._packChunk(constants.TYPE_IHDR, buf);
-};
-
-PackerAsync.prototype._packIDAT = function(data) {
-  return this._packChunk(constants.TYPE_IDAT, data);
-};
-
-PackerAsync.prototype._packIEND = function() {
-  return this._packChunk(constants.TYPE_IEND, null);
 };

lib/packer-sync.js

@@ -1,5 +1,53 @@
 'use strict';
 
-module.exports = function(buffer, options) {
+var zlib = require('zlib');
-  return null;
+var constants = require('./constants');
+var Packer = require('./packer');
+
+module.exports = function(metaData, options) {
+  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.createDeflate;
+  options.bitDepth = options.bitDepth || 8;
+  options.colorType = (typeof options.colorType === 'number') ? options.colorType : constants.COLORTYPE_COLOR_ALPHA;
+
+  if (options.colorType !== constants.COLORTYPE_COLOR && options.colorType !== constants.COLORTYPE_COLOR_ALPHA) {
+    throw new Error('option color type:' + options.colorType + ' is not supported at present');
+  }
+  if (options.bitDepth !== 8) {
+    throw new Error('option bit depth:' + options.bitDepth + ' is not supported at present');
+  }
+
+  var packer = new Packer(options);
+
+  var chunks = [];
+
+  // Signature
+  chunks.push(new Buffer(constants.PNG_SIGNATURE));
+
+  // Header
+  chunks.push(packer.packIHDR(metaData.width, metaData.height));
+
+  if (metaData.gamma) {
+    chunks.push(packer.packGAMA(metaData.gamma));
+  }
+
+  var filteredData = packer.filterData(metaData.data, metaData.width, metaData.height);
+
+  // compress it
+  var compressedData = zlib.deflateSync(filteredData);
+  filteredData = null;
+
+  if (!compressedData || !compressedData.length) {
+    throw new Error('bad png - invalid compressed data response');
+  }
+  chunks.push(packer.packIDAT(compressedData));
+
+  // End
+  chunks.push(packer.packIEND());
+
+  return Buffer.concat(chunks);
 };

lib/packer.js

@@ -0,0 +1,66 @@
+/**
+ * Created by gusc on 15.3.12.
+ */
+
+var constants = require('./constants');
+var CrcStream = require('./crc');
+var bitPacker = require('./bitpacker');
+var filter = require('./filter-pack');
+
+var Packer = module.exports = function(options) {
+  this._options = options;
+};
+
+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 = filter(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(CrcStream.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);
+};