mirror of
https://github.com/danbulant/pngjs
synced 2026-05-27 05:41:47 +00:00
110 lines
3.3 KiB
JavaScript
Executable file
110 lines
3.3 KiB
JavaScript
Executable file
// 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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zlib = require('zlib'),
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Filter = require('./filter'),
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CrcStream = require('./crc'),
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constants = require('./constants');
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var Packer = module.exports = function(options) {
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Stream.call(this);
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this._options = options;
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options.deflateChunkSize = options.deflateChunkSize || 32 * 1024;
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options.deflateLevel = options.deflateLevel || 9;
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options.deflateStrategy = options.deflateStrategy || 3;
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this.readable = true;
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};
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util.inherits(Packer, Stream);
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Packer.prototype.pack = function(data, width, height) {
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// Signature
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this.emit('data', new Buffer(constants.PNG_SIGNATURE));
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this.emit('data', this._packIHDR(width, height));
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// filter pixel data
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var filter = new Filter(width, height, 4, data, this._options);
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var data = filter.filter();
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// compress it
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var deflate = zlib.createDeflate({
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chunkSize: this._options.deflateChunkSize,
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level: this._options.deflateLevel,
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strategy: this._options.deflateStrategy
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});
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deflate.on('error', this.emit.bind(this, 'error'));
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deflate.on('data', function(data) {
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this.emit('data', this._packIDAT(data));
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}.bind(this));
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deflate.on('end', function() {
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this.emit('data', this._packIEND());
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this.emit('end');
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}.bind(this));
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deflate.end(data);
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};
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Packer.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(CrcStream.crc32(buf.slice(4, buf.length - 4)), buf.length - 4);
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return buf;
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};
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Packer.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(constants.TYPE_IHDR, buf);
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};
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Packer.prototype._packIDAT = function(data) {
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return this._packChunk(constants.TYPE_IDAT, data);
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};
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Packer.prototype._packIEND = function() {
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return this._packChunk(constants.TYPE_IEND, null);
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};
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