<?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  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
 */

/* $Id$ */


/**
 * Namespace for functions operating on Exif formats.
 *
 * @author Martin Geisler <mgeisler@users.sourceforge.net>
 * @version $Revision$
 * @date $Date$
 * @license http://www.gnu.org/licenses/gpl.html GNU General Public
 * License (GPL)
 * @package PEL
 */

/**
 * Namespace for functions operating on Exif formats.
 *
 * This class defines the constants that are to be used whenever one
 * has to refer to the format of an Exif tag.  They will be
 * collectively denoted by the pseudo-type PelFormat throughout the
 * documentation.
 *
 * All the methods defined here are static, and they all operate on a
 * single argument which should be one of the class constants.
 *
 * @author Martin Geisler <mgeisler@users.sourceforge.net>
 * @package PEL
 */
class PelFormat {

    /**
     * Unsigned byte.
     *
     * Each component will be an unsigned 8-bit integer with a value
     * between 0 and 255.
     *
     * Modelled with the {@link PelEntryByte} class.
     */
    const BYTE       =  1;

    /**
     * ASCII string.
     *
     * Each component will be an ASCII character.
     *
     * Modelled with the {@link PelEntryAscii} class.
     */
    const ASCII      =  2;

    /**
     * Unsigned short.
     *
     * Each component will be an unsigned 16-bit integer with a value
     * between 0 and 65535.
     *
     * Modelled with the {@link PelEntryShort} class.
     */
    const SHORT      =  3;

    /**
     * Unsigned long.
     *
     * Each component will be an unsigned 32-bit integer with a value
     * between 0 and 4294967295.
     *
     * Modelled with the {@link PelEntryLong} class.
     */
    const LONG       =  4;

    /**
     * Unsigned rational number.
     *
     * Each component will consist of two unsigned 32-bit integers
     * denoting the enumerator and denominator.  Each integer will have
     * a value between 0 and 4294967295.
     *
     * Modelled with the {@link PelEntryRational} class.
     */
    const RATIONAL   =  5;

    /**
     * Signed byte.
     *
     * Each component will be a signed 8-bit integer with a value
     * between -128 and 127.
     *
     * Modelled with the {@link PelEntrySByte} class.
     */
    const SBYTE      =  6;

    /**
     * Undefined byte.
     *
     * Each component will be a byte with no associated interpretation.
     *
     * Modelled with the {@link PelEntryUndefined} class.
     */
    const UNDEFINED  =  7;

    /**
     * Signed short.
     *
     * Each component will be a signed 16-bit integer with a value
     * between -32768 and 32767.
     *
     * Modelled with the {@link PelEntrySShort} class.
     */
    const SSHORT     =  8;

    /**
     * Signed long.
     *
     * Each component will be a signed 32-bit integer with a value
     * between -2147483648 and 2147483647.
     *
     * Modelled with the {@link PelEntrySLong} class.
     */
    const SLONG      =  9;

    /**
     * Signed rational number.
     *
     * Each component will consist of two signed 32-bit integers
     * denoting the enumerator and denominator.  Each integer will have
     * a value between -2147483648 and 2147483647.
     *
     * Modelled with the {@link PelEntrySRational} class.
     */
    const SRATIONAL  = 10;

    /**
     * Floating point number.
     *
     * Entries with this format are not currently implemented.
     */
    const FLOAT      = 11;

    /**
     * Double precision floating point number.
     *
     * Entries with this format are not currently implemented.
     */
    const DOUBLE     = 12;


    /**
     * Returns the name of a format.
     *
     * @param PelFormat the format.
     *
     * @return string the name of the format, e.g., 'Ascii' for the
     * {@link ASCII} format etc.
     */
    static function getName($type) {
        switch ($type) {
            case self::ASCII:     return 'Ascii';
            case self::BYTE:      return 'Byte';
            case self::SHORT:     return 'Short';
            case self::LONG:      return 'Long';
            case self::RATIONAL:  return 'Rational';
            case self::SBYTE:     return 'SByte';
            case self::SSHORT:    return 'SShort';
            case self::SLONG:     return 'SLong';
            case self::SRATIONAL: return 'SRational';
            case self::FLOAT:     return 'Float';
            case self::DOUBLE:    return 'Double';
            case self::UNDEFINED: return 'Undefined';
            default:
                return Pel::fmt('Unknown format: 0x%X', $type);
        }
    }


    /**
     * Return the size of components in a given format.
     *
     * @param PelFormat the format.
     *
     * @return the size in bytes needed to store one component with the
     * given format.
     */
    static function getSize($type) {
        switch ($type) {
            case self::ASCII:     return 1;
            case self::BYTE:      return 1;
            case self::SHORT:     return 2;
            case self::LONG:      return 4;
            case self::RATIONAL:  return 8;
            case self::SBYTE:     return 1;
            case self::SSHORT:    return 2;
            case self::SLONG:     return 4;
            case self::SRATIONAL: return 8;
            case self::FLOAT:     return 4;
            case self::DOUBLE:    return 8;
            case self::UNDEFINED: return 1;
            default:
                return Pel::fmt('Unknown format: 0x%X', $type);
        }
    }

}

