yahoo/pngjs-image

// Copyright 2015 Yahoo! Inc.
// Copyrights licensed under the Mit License. See the accompanying LICENSE file for terms.

var intents = require('../utils/constants').intents;

/**
 * @class sRGB
 * @module PNG
 * @submodule PNGChunks
 */
module.exports = {

    /**
     * Gets the sequence
     *
     * @method getSequence
     * @return {int}
     */
    getSequence: function () {
        return 170;
    },


    /**
     * Gets the rendering intent identifier
     *
     * @method getRenderingIntent
     * @return {int}
     */
    getRenderingIntent: function () {
        return this._intent || intents.PERCEPTUAL;
    },

    /**
     * Sets the rendering intent identifier
     *
     * @method setRenderingIntent
     * @param {int} intent
     */
    setRenderingIntent: function (intent) {

        if ([intents.PERCEPTUAL, intents.RELATIVE_COLORIMETRIC, intents.SATURATION, intents.ABSOLUTE_COLORIMETRIC].indexOf(intent) === -1) {
            throw new Error('Unsupported rendering intent with identifier ' + intent + '.');
        }

        this._intent = intent;
    },


    /**
     * Is the rendering intent perceptual?
     *
     * @method isPerceptual
     * @return {boolean}
     */
    isPerceptual: function () {
        return (this.getRenderingIntent() === intents.PERCEPTUAL);
    },

    /**
     * Is the rendering intent relative colorimetric?
     *
     * @method isRelativeColorimetric
     * @return {boolean}
     */
    isRelativeColorimetric: function () {
        return (this.getRenderingIntent() === intents.RELATIVE_COLORIMETRIC);
    },

    /**
     * Is the rendering intent saturation?
     *
     * @method isSaturation
     * @return {boolean}
     */
    isSaturation: function () {
        return (this.getRenderingIntent() === intents.SATURATION);
    },

    /**
     * Is the rendering intent absolute colorimetric?
     *
     * @method isAbsoluteColorimetric
     * @return {boolean}
     */
    isAbsoluteColorimetric: function () {
        return (this.getRenderingIntent() === intents.ABSOLUTE_COLORIMETRIC);
    },


    /**
     * Parsing of chunk data
     *
     * Phase 1
     *
     * @method parse
     * @param {BufferedStream} stream Data stream
     * @param {int} length Length of chunk data
     * @param {boolean} strict Should parsing be strict?
     * @param {object} options Decoding options
     */
    parse: function (stream, length, strict, options) {

        // Validation
        if (strict && (this.getFirstChunk(this.getType(), false) !== null)) {
            throw new Error('Only one ' + this.getType() + ' is allowed in the data.');
        }

        if ((strict && (length !== 1)) || (length < 1)) {
            throw new Error('The ' + this.getType() + ' chunk should have 1 bytes, but it has ' + length + ' bytes.');
        }

        this.setRenderingIntent(stream.readUInt8());
    },

    /**
     * Gathers chunk-data from decoded chunks
     *
     * Phase 5
     *
     * @static
     * @method decodeData
     * @param {object} data Data-object that will be used to export values
     * @param {boolean} strict Should parsing be strict?
     * @param {object} options Decoding options
     */
    decodeData: function (data, strict, options) {

        var chunks = this.getChunksByType(this.getType());

        if (!chunks) {
            return ;
        }

        if (strict && (chunks.length !== 1)) {
            throw new Error('Not more than one chunk allowed for ' + this.getType() + '.');
        }

        data.volatile = data.volatile || {};
        data.volatile.renderingIntent = chunks[0].getRenderingIntent();
    },


    /**
     * Returns a list of chunks to be added to the data-stream
     *
     * Phase 1
     *
     * @static
     * @method encodeData
     * @param {Buffer} image Image data
     * @param {object} options Encoding options
     * @return {Chunk[]} List of chunks to encode
     */
    encodeData: function (image, options) {

        if (options.renderingIntent) {

            var chunk = this.createChunk(this.getType(), this.getChunks());

            chunk.setRenderingIntent(options.renderingIntent);

            return [chunk];
        } else {
            return [];
        }
    },

    /**
     * Composing of chunk data
     *
     * Phase 4
     *
     * @method compose
     * @param {BufferedStream} stream Data stream
     * @param {object} options Encoding options
     */
    compose: function (stream, options) {
        stream.writeUInt8(this.getRenderingIntent());
    }
};