| 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112 |
1
1
336
336
336
336
336
336
1
1
322
322
322
322
322
322
322
644
322
322
322
322
1
1288
1288
1288
1288
1288
1288
1
322
322
322
322
322
322
322
322
322
1
644
1
322
| // 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'),
zlib = require('zlib'),
Filter = require('./filter'),
CrcStream = require('./crc'),
constants = require('./constants');
var Packer = 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;
this.readable = true;
};
util.inherits(Packer, Stream);
Packer.prototype.pack = function(data, width, height) {
// Signature
this.emit('data', new Buffer(constants.PNG_SIGNATURE));
this.emit('data', this._packIHDR(width, height));
// filter pixel data
//TODO {}
var filter = new Filter(width, height, 4, 8, false, this._options, {});
var data = filter.filter(data);
// compress it
var deflate = zlib.createDeflate({
chunkSize: this._options.deflateChunkSize,
level: this._options.deflateLevel,
strategy: this._options.deflateStrategy
});
deflate.on('error', this.emit.bind(this, 'error'));
deflate.on('data', function(data) {
this.emit('data', this._packIDAT(data));
}.bind(this));
deflate.on('end', function() {
this.emit('data', this._packIEND());
this.emit('end');
}.bind(this));
deflate.end(data);
};
Packer.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(CrcStream.crc32(buf.slice(4, buf.length - 4)), buf.length - 4);
return buf;
};
Packer.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(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);
};
|