# Code coverage report for lib\packer.js

## Statements: 100% (44 / 44) Branches: 80% (8 / 10) Functions: 100% (8 / 8) Lines: 100% (43 / 43) Ignored: none

All files » lib/ » packer.js

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     // 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);
    };