3 var constants = require('./constants');
4 var CrcStream = require('./crc');
5 var bitPacker = require('./bitpacker');
6 var filter = require('./filter-pack');
7 var zlib = require('zlib');
9 var Packer = module.exports = function(options) {
10 this._options = options;
12 options.deflateChunkSize = options.deflateChunkSize || 32 * 1024;
13 options.deflateLevel = options.deflateLevel != null ? options.deflateLevel : 9;
14 options.deflateStrategy = options.deflateStrategy != null ? options.deflateStrategy : 3;
15 options.inputHasAlpha = options.inputHasAlpha != null ? options.inputHasAlpha : true;
16 options.deflateFactory = options.deflateFactory || zlib.createDeflate;
17 options.bitDepth = options.bitDepth || 8;
18 // This is outputColorType
19 options.colorType = (typeof options.colorType === 'number') ? options.colorType : constants.COLORTYPE_COLOR_ALPHA;
20 options.inputColorType = (typeof options.inputColorType === 'number') ? options.inputColorType : constants.COLORTYPE_COLOR_ALPHA;
23 constants.COLORTYPE_GRAYSCALE,
24 constants.COLORTYPE_COLOR,
25 constants.COLORTYPE_COLOR_ALPHA,
26 constants.COLORTYPE_ALPHA
27 ].indexOf(options.colorType) === -1) {
28 throw new Error('option color type:' + options.colorType + ' is not supported at present');
31 constants.COLORTYPE_GRAYSCALE,
32 constants.COLORTYPE_COLOR,
33 constants.COLORTYPE_COLOR_ALPHA,
34 constants.COLORTYPE_ALPHA
35 ].indexOf(options.inputColorType) === -1) {
36 throw new Error('option input color type:' + options.inputColorType + ' is not supported at present');
38 if (options.bitDepth !== 8 && options.bitDepth !== 16) {
39 throw new Error('option bit depth:' + options.bitDepth + ' is not supported at present');
43 Packer.prototype.getDeflateOptions = function() {
45 chunkSize: this._options.deflateChunkSize,
46 level: this._options.deflateLevel,
47 strategy: this._options.deflateStrategy
51 Packer.prototype.createDeflate = function() {
52 return this._options.deflateFactory(this.getDeflateOptions());
55 Packer.prototype.filterData = function(data, width, height) {
56 // convert to correct format for filtering (e.g. right bpp and bit depth)
57 var packedData = bitPacker(data, width, height, this._options);
60 var bpp = constants.COLORTYPE_TO_BPP_MAP[this._options.colorType];
61 var filteredData = filter(packedData, width, height, this._options, bpp);
65 Packer.prototype._packChunk = function(type, data) {
67 var len = (data ? data.length : 0);
68 var buf = new Buffer(len + 12);
70 buf.writeUInt32BE(len, 0);
71 buf.writeUInt32BE(type, 4);
77 buf.writeInt32BE(CrcStream.crc32(buf.slice(4, buf.length - 4)), buf.length - 4);
81 Packer.prototype.packGAMA = function(gamma) {
82 var buf = new Buffer(4);
83 buf.writeUInt32BE(Math.floor(gamma * constants.GAMMA_DIVISION), 0);
84 return this._packChunk(constants.TYPE_gAMA, buf);
87 Packer.prototype.packIHDR = function(width, height) {
89 var buf = new Buffer(13);
90 buf.writeUInt32BE(width, 0);
91 buf.writeUInt32BE(height, 4);
92 buf[8] = this._options.bitDepth; // Bit depth
93 buf[9] = this._options.colorType; // colorType
94 buf[10] = 0; // compression
95 buf[11] = 0; // filter
96 buf[12] = 0; // interlace
98 return this._packChunk(constants.TYPE_IHDR, buf);
101 Packer.prototype.packIDAT = function(data) {
102 return this._packChunk(constants.TYPE_IDAT, data);
105 Packer.prototype.packIEND = function() {
106 return this._packChunk(constants.TYPE_IEND, null);