ngryman/ribs

/*!
 * ribs
 * Copyright (c) 2013-2014 Nicolas Gryman <ngryman@gmail.com>
 * LGPL Licensed
 */

'use strict';

/**
 * Module dependencies.
 */

var Image = require('../image'),
    Pipeline = require('../pipeline'),
    utils = require('../utils'),
    check = utils.checkType,
    checkInstance = utils.checkInstance;

/**
 *
 * @param {object|[]} params
 * @param image
 * @param next
 */
function crop(params, image, next) {
    var width, height;

    // arguments type
    check('next', next, false, 'function');
    try {
        check('params', params, true, 'string', 'number', 'object', 'array');

        // early call back if params is null
        if (null == params) return next(null, image);

        // if params is a number or a string, it is assigned to width
        if ('string' == typeof params || 'number' == typeof params)
            params = { width: params };

        // array to named arguments
        else if (Array.isArray(params))
            params = utils.toParams(params, ['width', 'height', 'x', 'y', 'anchor', 'gravity']);

        check('width', params.width, true, 'number', 'string');
        check('height', params.height, true, 'number', 'string');
        check('x', params.x, true, 'number', 'string');
        check('y', params.y, true, 'number', 'string');
        check('anchor', params.anchor, true, 'string');
        check('gravity', params.gravity, true, 'string');
        check('image', image, false, 'object');
        checkInstance('image', image, Image);

        // invoke the constraints hook
        Pipeline.hook('crop', 'constraints')(params, image);

        // do nothing when specified size is the same as original one
        if (image.width == params.width && image.height == params.height) {
            next(null, image);
            return params;
        }

        // do nothing when image is empty
        if (0 === image.width && 0 === image.height) {
            next(null, image);
            return params;
        }

        image.crop(params.width, params.height, params.x, params.y, next);

        return params;
    }
    catch (err) {
        next(err, image);
        return params;
    }
}

/**
 * Register operation.
 */

Pipeline.add('crop', crop);

/**
 * Export.
 */

module.exports = crop;