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| Current File : //proc/self/root/home/saurabh/.npm/_npx/249ca9fcd30c476a/node_modules/pngjs/lib/packer.js |
'use strict';
var constants = require('./constants');
var CrcStream = require('./crc');
var bitPacker = require('./bitpacker');
var filter = require('./filter-pack');
var zlib = require('zlib');
var Packer = module.exports = function(options) {
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;
options.inputHasAlpha = options.inputHasAlpha != null ? options.inputHasAlpha : true;
options.deflateFactory = options.deflateFactory || zlib.createDeflate;
options.bitDepth = options.bitDepth || 8;
// This is outputColorType
options.colorType = (typeof options.colorType === 'number') ? options.colorType : constants.COLORTYPE_COLOR_ALPHA;
options.inputColorType = (typeof options.inputColorType === 'number') ? options.inputColorType : constants.COLORTYPE_COLOR_ALPHA;
if ([
constants.COLORTYPE_GRAYSCALE,
constants.COLORTYPE_COLOR,
constants.COLORTYPE_COLOR_ALPHA,
constants.COLORTYPE_ALPHA
].indexOf(options.colorType) === -1) {
throw new Error('option color type:' + options.colorType + ' is not supported at present');
}
if ([
constants.COLORTYPE_GRAYSCALE,
constants.COLORTYPE_COLOR,
constants.COLORTYPE_COLOR_ALPHA,
constants.COLORTYPE_ALPHA
].indexOf(options.inputColorType) === -1) {
throw new Error('option input color type:' + options.inputColorType + ' is not supported at present');
}
if (options.bitDepth !== 8 && options.bitDepth !== 16) {
throw new Error('option bit depth:' + options.bitDepth + ' is not supported at present');
}
};
Packer.prototype.getDeflateOptions = function() {
return {
chunkSize: this._options.deflateChunkSize,
level: this._options.deflateLevel,
strategy: this._options.deflateStrategy
};
};
Packer.prototype.createDeflate = function() {
return this._options.deflateFactory(this.getDeflateOptions());
};
Packer.prototype.filterData = function(data, width, height) {
// convert to correct format for filtering (e.g. right bpp and bit depth)
var packedData = bitPacker(data, width, height, this._options);
// filter pixel data
var bpp = constants.COLORTYPE_TO_BPP_MAP[this._options.colorType];
var filteredData = filter(packedData, width, height, this._options, bpp);
return filteredData;
};
Packer.prototype._packChunk = function(type, data) {
var len = (data ? data.length : 0);
var 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.packGAMA = function(gamma) {
var buf = new Buffer(4);
buf.writeUInt32BE(Math.floor(gamma * constants.GAMMA_DIVISION), 0);
return this._packChunk(constants.TYPE_gAMA, buf);
};
Packer.prototype.packIHDR = function(width, height) {
var buf = new Buffer(13);
buf.writeUInt32BE(width, 0);
buf.writeUInt32BE(height, 4);
buf[8] = this._options.bitDepth; // Bit depth
buf[9] = this._options.colorType; // 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);
};
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