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<?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
*/
/**
* Classes for dealing with Exif entries.
*
* This file defines two exception classes and the abstract class
* {@link PelEntry} which provides the basic methods that all Exif
* entries will have. All Exif entries will be represented by
* descendants of the {@link PelEntry} class --- the class itself is
* abstract and so it cannot be instantiated.
*
* @author Martin Geisler <mgeisler@users.sourceforge.net>
* @license http://www.gnu.org/licenses/gpl.html GNU General Public
* License (GPL)
* @package PEL
*/
/**
* Common ancestor class of all {@link PelIfd} entries.
*
* As this class is abstract you cannot instantiate objects from it.
* It only serves as a common ancestor to define the methods common to
* all entries. The most important methods are {@link getValue()} and
* {@link setValue()}, both of which is abstract in this class. The
* descendants will give concrete implementations for them.
*
* If you have some data coming from an image (some raw bytes), then
* the static method {@link newFromData()} is helpful --- it will look
* at the data and give you a proper decendent of {@link PelEntry}
* back.
*
* If you instead want to have an entry for some data which take the
* form of an integer, a string, a byte, or some other PHP type, then
* don't use this class. You should instead create an object of the
* right subclass ({@link PelEntryShort} for short integers, {@link
* PelEntryAscii} for strings, and so on) directly.
*
* @author Martin Geisler <mgeisler@users.sourceforge.net>
* @package PEL
*/
namespace lsolesen\pel;
abstract class PelEntry
{
/**
* Type of IFD containing this tag.
*
* This must be one of the constants defined in {@link PelIfd}:
* {@link PelIfd::IFD0} for the main image IFD, {@link PelIfd::IFD1}
* for the thumbnail image IFD, {@link PelIfd::EXIF} for the Exif
* sub-IFD, {@link PelIfd::GPS} for the GPS sub-IFD, or {@link
* PelIfd::INTEROPERABILITY} for the interoperability sub-IFD.
*
* @var int
*/
protected $ifd_type;
/**
* The bytes representing this entry.
*
* Subclasses must either override {@link getBytes()} or, if
* possible, maintain this property so that it always contains a
* true representation of the entry.
*
* @var string
*/
protected $bytes = '';
/**
* The {@link PelTag} of this entry.
*
* @var int
*/
protected $tag;
/**
* The {@link PelFormat} of this entry.
*
* @var int
*/
protected $format;
/**
* The number of components of this entry.
*
* @var int
*/
protected $components;
/**
* Return the tag of this entry.
*
* @return int the tag of this entry.
*/
public function getTag()
{
return $this->tag;
}
/**
* Return the type of IFD which holds this entry.
*
* @return int one of the constants defined in {@link PelIfd}:
* {@link PelIfd::IFD0} for the main image IFD, {@link PelIfd::IFD1}
* for the thumbnail image IFD, {@link PelIfd::EXIF} for the Exif
* sub-IFD, {@link PelIfd::GPS} for the GPS sub-IFD, or {@link
* PelIfd::INTEROPERABILITY} for the interoperability sub-IFD.
*/
public function getIfdType()
{
return $this->ifd_type;
}
/**
* Update the IFD type.
*
* @param int $type
* must be one of the constants defined in {@link
* PelIfd}: {@link PelIfd::IFD0} for the main image IFD, {@link
* PelIfd::IFD1} for the thumbnail image IFD, {@link PelIfd::EXIF}
* for the Exif sub-IFD, {@link PelIfd::GPS} for the GPS sub-IFD, or
* {@link PelIfd::INTEROPERABILITY} for the interoperability
* sub-IFD.
*/
public function setIfdType($type)
{
$this->ifd_type = $type;
}
/**
* Return the format of this entry.
*
* @return int the format of this entry.
*/
public function getFormat()
{
return $this->format;
}
/**
* Return the number of components of this entry.
*
* @return int the number of components of this entry.
*/
public function getComponents()
{
return $this->components;
}
/**
* Turn this entry into bytes.
*
* @param boolean $o
* the desired byte order, which must be either
* {@link Convert::LITTLE_ENDIAN} or {@link Convert::BIG_ENDIAN}.
* @return string bytes representing this entry.
*/
public function getBytes($o)
{
return $this->bytes;
}
/**
* Get the value of this entry as text.
*
* The value will be returned in a format suitable for presentation,
* e.g., rationals will be returned as 'x/y', ASCII strings will be
* returned as themselves etc.
*
* @param boolean $brief
* some values can be returned in a long or more
* brief form, and this parameter controls that.
* @return string the value as text.
*/
abstract public function getText($brief = false);
/**
* Get the value of this entry.
*
* The value returned will generally be the same as the one supplied
* to the constructor or with {@link setValue()}. For a formatted
* version of the value, one should use {@link getText()} instead.
*
* @return mixed the unformatted value.
*/
abstract public function getValue();
/**
* Set the value of this entry.
*
* The value should be in the same format as for the constructor.
*
* @param mixed $value
* the new value.
* @abstract
*
*/
public function setValue($value)
{
/*
* This (fake) abstract method is here to make it possible for the
* documentation to refer to PelEntry::setValue().
* It cannot declared abstract in the proper PHP way, for then PHP
* wont allow subclasses to define it with two arguments (which is
* what PelEntryCopyright does).
*/
throw new PelException('setValue() is abstract.');
}
/**
* Turn this entry into a string.
*
* @return string a string representation of this entry. This is
* mostly for debugging.
*/
public function __toString()
{
$str = Pel::fmt(" Tag: 0x%04X (%s)\n", $this->tag, PelTag::getName($this->ifd_type, $this->tag));
$str .= Pel::fmt(" Format : %d (%s)\n", $this->format, PelFormat::getName($this->format));
$str .= Pel::fmt(" Components: %d\n", $this->components);
if ($this->getTag() != PelTag::MAKER_NOTE && $this->getTag() != PelTag::PRINT_IM) {
$str .= Pel::fmt(" Value : %s\n", print_r($this->getValue(), true));
}
$str .= Pel::fmt(" Text : %s\n", $this->getText());
return $str;
}
}