<?php

/**
 * PEL: PHP Exif Library.
 * A library with support for reading and
 * writing all Exif headers in JPEG and TIFF images using PHP.
 *
 * Copyright (C) 2004, 2005, 2006 Martin Geisler.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program in the file COPYING; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA 02110-1301 USA
 */
namespace lsolesen\pel;

/**
 * Classes used to hold longs, both signed and unsigned.
 *
 * @author Martin Geisler <mgeisler@users.sourceforge.net>
 * @license http://www.gnu.org/licenses/gpl.html GNU General Public
 *          License (GPL)
 * @package PEL
 */

/**
 * Class for holding unsigned longs.
 *
 * This class can hold longs, either just a single long or an array of
 * longs. The class will be used to manipulate any of the Exif tags
 * which can have format {@link PelFormat::LONG} like in this
 * example:
 * <code>
 * $w = $ifd->getEntry(PelTag::EXIF_IMAGE_WIDTH);
 * $w->setValue($w->getValue() / 2);
 * $h = $ifd->getEntry(PelTag::EXIF_IMAGE_HEIGHT);
 * $h->setValue($h->getValue() / 2);
 * </code>
 * Here the width and height is updated to 50% of their original
 * values.
 *
 * @author Martin Geisler <mgeisler@users.sourceforge.net>
 * @package PEL
 */
class PelEntryLong extends PelEntryNumber
{

    /**
     * Make a new entry that can hold an unsigned long.
     *
     * The method accept its arguments in two forms: several integer
     * arguments or a single array argument. The {@link getValue}
     * method will always return an array except for when a single
     * integer argument is given here, or when an array with just a
     * single integer is given.
     *
     * This means that one can conveniently use objects like this:
     * <code>
     * $a = new PelEntryLong(PelTag::EXIF_IMAGE_WIDTH, 123456);
     * $b = $a->getValue() - 654321;
     * </code>
     * where the call to {@link getValue} will return an integer instead
     * of an array with one integer element, which would then have to be
     * extracted.
     *
     * @param int $tag
     *            the tag which this entry represents. This
     *            should be one of the constants defined in {@link PelTag},
     *            e.g., {@link PelTag::IMAGE_WIDTH}, or any other tag which can
     *            have format {@link PelFormat::LONG}.
     * @param int $value...
     *            the long(s) that this entry will
     *            represent or an array of longs. The argument passed must obey
     *            the same rules as the argument to {@link setValue}, namely that
     *            it should be within range of an unsigned long (32 bit), that is
     *            between 0 and 4294967295 (inclusive). If not, then a {@link
     *            PelExifOverflowException} will be thrown.
     */
    public function __construct($tag, $value = null)
    {
        $this->tag = $tag;
        $this->min = 0;
        $this->max = 4294967295;
        $this->format = PelFormat::LONG;

        $value = func_get_args();
        array_shift($value);
        $this->setValueArray($value);
    }

    /**
     * Convert a number into bytes.
     *
     * @param int $number
     *            the number that should be converted.
     * @param boolean $order
     *            one of {@link PelConvert::LITTLE_ENDIAN} and
     *            {@link PelConvert::BIG_ENDIAN}, specifying the target byte order.
     * @return string bytes representing the number given.
     */
    public function numberToBytes($number, $order)
    {
        return PelConvert::longToBytes($number, $order);
    }
}
