3 var util = require('util');
4 var Stream = require('stream');
5 var constants = require('./constants');
6 var Packer = require('./packer');
8 var PackerAsync = module.exports = function(opt) {
11 var options = opt || {};
13 this._packer = new Packer(options);
14 this._deflate = this._packer.createDeflate();
18 util.inherits(PackerAsync, Stream);
21 PackerAsync.prototype.pack = function(data, width, height, gamma) {
23 this.emit('data', new Buffer(constants.PNG_SIGNATURE));
24 this.emit('data', this._packer.packIHDR(width, height));
27 this.emit('data', this._packer.packGAMA(gamma));
30 var filteredData = this._packer.filterData(data, width, height);
33 this._deflate.on('error', this.emit.bind(this, 'error'));
35 this._deflate.on('data', function(compressedData) {
36 this.emit('data', this._packer.packIDAT(compressedData));
39 this._deflate.on('end', function() {
40 this.emit('data', this._packer.packIEND());
44 this._deflate.end(filteredData);