mirror of
https://github.com/danbulant/pngjs
synced 2026-05-27 05:41:47 +00:00
98 lines
2.9 KiB
JavaScript
98 lines
2.9 KiB
JavaScript
// Copyright (c) 2012 Kuba Niegowski
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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'use strict';
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var util = require('util'),
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Stream = require('stream'),
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Compress = require('./compress'),
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Filter = require('./filter');
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var Parser = module.exports = function(options) {
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Stream.call(this);
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this._options = options;
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// this._compress = new Compress(options);
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// this._compress.on('error', this.emit.bind(this, 'error'));
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// this._compress.on('deflated', this._packData.bind(this));
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};
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util.inherits(Parser, Stream);
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Parser.prototype._pack = function(width, height, data) {
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// Signature
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this.emit('data', new Buffer(signature));
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this.emit('data', this._packIHDR(width, height));
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// filter pixel data
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var data = this._filter.filter(data, width, height);
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// compress it
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this._compress.deflate(data);
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};
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Parser.prototype._packData = function(data) {
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// console.log('deflate', data.length);
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this.emit('data', this._packIDAT(data));
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this.emit('data', this._packIEND());
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this.emit('end');
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};
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Parser.prototype._packChunk = function(type, data) {
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var len = (data ? data.length : 0),
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buf = new Buffer(len + 12);
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buf.writeUInt32BE(len, 0);
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buf.writeUInt32BE(type, 4);
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if (data) data.copy(buf, 8);
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buf.writeInt32BE(crc32(buf.slice(4, buf.length - 4)), buf.length - 4);
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return buf;
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};
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Parser.prototype._packIHDR = function(width, height) {
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var buf = new Buffer(13);
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buf.writeUInt32BE(width, 0);
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buf.writeUInt32BE(height, 4);
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buf[8] = 8;
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buf[9] = 6; // colorType
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buf[10] = 0; // compression
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buf[11] = 0; // filter
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buf[12] = 0; // interlace
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return this._packChunk(TYPE_IHDR, buf);
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};
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Parser.prototype._packIDAT = function(data) {
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return this._packChunk(TYPE_IDAT, data);
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};
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Parser.prototype._packIEND = function() {
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return this._packChunk(TYPE_IEND, null);
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};
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