320 lines
12 KiB
PHP
320 lines
12 KiB
PHP
<?php
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/**
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* PEL: PHP Exif Library.
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* A library with support for reading and
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* writing all Exif headers in JPEG and TIFF images using PHP.
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*
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* Copyright (C) 2004, 2005, 2006, 2007 Martin Geisler.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program in the file COPYING; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301 USA
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*/
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/**
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* Class for holding a date and time.
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*
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* This class can hold a timestamp, and it will be used as
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* in this example where the time is advanced by one week:
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* <code>
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* $entry = $ifd->getEntry(PelTag::DATE_TIME_ORIGINAL);
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* $time = $entry->getValue();
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* print('The image was taken on the ' . date('jS', $time));
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* $entry->setValue($time + 7 * 24 * 3600);
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* </code>
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*
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* The example used a standard UNIX timestamp, which is the default
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* for this class.
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*
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* But the Exif format defines dates outside the range of a UNIX
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* timestamp (about 1970 to 2038) and so you can also get access to
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* the timestamp in two other formats: a simple string or a Julian Day
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* Count. Please see the Calendar extension in the PHP Manual for more
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* information about the Julian Day Count.
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*
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* @author Martin Geisler <mgeisler@users.sourceforge.net>
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* @package PEL
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*/
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namespace lsolesen\pel;
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class PelEntryTime extends PelEntryAscii
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{
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/**
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* Constant denoting a UNIX timestamp.
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*/
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const UNIX_TIMESTAMP = 1;
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/**
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* Constant denoting a Exif string.
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*/
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const EXIF_STRING = 2;
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/**
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* Constant denoting a Julian Day Count.
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*/
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const JULIAN_DAY_COUNT = 3;
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/**
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* The Julian Day Count of the timestamp held by this entry.
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*
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* This is an integer counting the number of whole days since
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* January 1st, 4713 B.C. The fractional part of the timestamp held
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* by this entry is stored in {@link $seconds}.
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*
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* @var int
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*/
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private $day_count;
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/**
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* The number of seconds into the day of the timestamp held by this
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* entry.
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*
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* The number of whole days is stored in {@link $day_count} and the
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* number of seconds left-over is stored here.
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*
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* @var int
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*/
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private $seconds;
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/**
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* Make a new entry for holding a timestamp.
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*
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* @param integer $tag
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* the Exif tag which this entry represents. There are
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* only three standard tags which hold timestamp, so this should be
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* one of the constants {@link PelTag::DATE_TIME}, {@link
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* PelTag::DATE_TIME_ORIGINAL}, or {@link
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* PelTag::DATE_TIME_DIGITIZED}.
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* @param integer|string|double $timestamp
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* the timestamp held by this entry in the correct form
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* as indicated by the third argument. For {@link UNIX_TIMESTAMP}
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* this is an integer counting the number of seconds since January
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* 1st 1970, for {@link EXIF_STRING} this is a string of the form
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* 'YYYY:MM:DD hh:mm:ss', and for {@link JULIAN_DAY_COUNT} this is a
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* floating point number where the integer part denotes the day
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* count and the fractional part denotes the time of day (0.25 means
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* 6:00, 0.75 means 18:00).
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* @param integer $type
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* the type of the timestamp. This must be one of
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* {@link UNIX_TIMESTAMP}, {@link EXIF_STRING}, or
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* {@link JULIAN_DAY_COUNT}.
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*/
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public function __construct($tag, $timestamp, $type = self::UNIX_TIMESTAMP)
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{
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$this->tag = $tag;
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$this->format = PelFormat::ASCII;
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$this->setValue($timestamp, $type);
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}
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/**
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* Return the timestamp of the entry.
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*
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* The timestamp held by this entry is returned in one of three
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* formats: as a standard UNIX timestamp (default), as a fractional
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* Julian Day Count, or as a string.
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*
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* @param integer $type
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* the type of the timestamp. This must be one of
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* {@link UNIX_TIMESTAMP}, {@link EXIF_STRING}, or
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* {@link JULIAN_DAY_COUNT}.
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* @return integer|string|false the timestamp held by this entry in the correct form
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* as indicated by the type argument. For {@link UNIX_TIMESTAMP}
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* this is an integer counting the number of seconds since January
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* 1st 1970, for {@link EXIF_STRING} this is a string of the form
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* 'YYYY:MM:DD hh:mm:ss', and for {@link JULIAN_DAY_COUNT} this is a
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* floating point number where the integer part denotes the day
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* count and the fractional part denotes the time of day (0.25 means
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* 6:00, 0.75 means 18:00).
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*/
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public function getValue($type = self::UNIX_TIMESTAMP)
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{
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switch ($type) {
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case self::UNIX_TIMESTAMP:
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$seconds = $this->convertJdToUnix($this->day_count);
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if ($seconds === false) {
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/*
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* We get false if the Julian Day Count is outside the range
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* of a UNIX timestamp.
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*/
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return false;
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} else {
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return $seconds + $this->seconds;
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}
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break;
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case self::EXIF_STRING:
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list ($year, $month, $day) = $this->convertJdToGregorian($this->day_count);
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$hours = (int) ($this->seconds / 3600);
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$minutes = (int) ($this->seconds % 3600 / 60);
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$seconds = $this->seconds % 60;
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return sprintf('%04d:%02d:%02d %02d:%02d:%02d', $year, $month, $day, $hours, $minutes, $seconds);
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case self::JULIAN_DAY_COUNT:
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return $this->day_count + $this->seconds / 86400;
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default:
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throw new PelInvalidArgumentException('Expected UNIX_TIMESTAMP (%d), ' . 'EXIF_STRING (%d), or ' . 'JULIAN_DAY_COUNT (%d) for $type, got %d.', self::UNIX_TIMESTAMP, self::EXIF_STRING, self::JULIAN_DAY_COUNT, $type);
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}
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}
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/**
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* Update the timestamp held by this entry.
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*
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* @param integer|float|string $timestamp
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* the timestamp held by this entry in the correct form
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* as indicated by the third argument. For {@link UNIX_TIMESTAMP}
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* this is an integer counting the number of seconds since January
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* 1st 1970, for {@link EXIF_STRING} this is a string of the form
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* 'YYYY:MM:DD hh:mm:ss', and for {@link JULIAN_DAY_COUNT} this is a
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* floating point number where the integer part denotes the day
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* count and the fractional part denotes the time of day (0.25 means
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* 6:00, 0.75 means 18:00).
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* @param integer $type
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* the type of the timestamp. This must be one of
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* {@link UNIX_TIMESTAMP}, {@link EXIF_STRING}, or
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* {@link JULIAN_DAY_COUNT}.
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* @throws PelInvalidArgumentException
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*/
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public function setValue($timestamp, $type = self::UNIX_TIMESTAMP)
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{
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if ($type === self::UNIX_TIMESTAMP) {
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if (is_int($timestamp) || is_float($timestamp)) {
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$this->day_count = $this->convertUnixToJd($timestamp);
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$this->seconds = $timestamp % 86400;
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} else {
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throw new PelInvalidArgumentException('Expected integer value for $type, got %s', gettype($timestamp));
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}
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} elseif ($type === self::EXIF_STRING) {
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/*
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* Clean the timestamp: some timestamps are broken other
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* separators than ':' and ' '.
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*/
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$d = preg_split('/[^0-9]+/', $timestamp);
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for ($i = 0; $i < 6; $i ++) {
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if (empty($d[$i])) {
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$d[$i] = 0;
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}
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}
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$this->day_count = $this->convertGregorianToJd($d[0], $d[1], $d[2]);
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$this->seconds = $d[3] * 3600 + $d[4] * 60 + $d[5];
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} elseif ($type === self::JULIAN_DAY_COUNT) {
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if (is_int($timestamp) || is_float($timestamp)) {
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$this->day_count = (int) floor($timestamp);
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$this->seconds = (int) (86400 * ($timestamp - floor($timestamp)));
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} else {
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throw new PelInvalidArgumentException('Expected integer value for $type, got %s', gettype($timestamp));
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}
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} else {
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throw new PelInvalidArgumentException('Expected UNIX_TIMESTAMP (%d), ' . 'EXIF_STRING (%d), or ' . 'JULIAN_DAY_COUNT (%d) for $type, got %d.', self::UNIX_TIMESTAMP, self::EXIF_STRING, self::JULIAN_DAY_COUNT, $type);
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}
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// finally update the string which will be used when this is turned into bytes.
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parent::setValue($this->getValue(self::EXIF_STRING));
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}
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// The following four functions are used for converting back and
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// forth between the date formats. They are used in preference to
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// the ones from the PHP calendar extension to avoid having to
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// fiddle with timezones and to avoid depending on the extension.
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//
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// See http://www.hermetic.ch/cal_stud/jdn.htm#comp for a reference.
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/**
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* Converts a date in year/month/day format to a Julian Day count.
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*
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* @param integer $year
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* the year.
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* @param integer $month
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* the month, 1 to 12.
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* @param integer $day
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* the day in the month.
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* @return integer the Julian Day count.
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*/
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public function convertGregorianToJd($year, $month, $day)
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{
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// Special case mapping 0/0/0 -> 0
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if ($year == 0 || $month == 0 || $day == 0) {
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return 0;
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}
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$m1412 = ($month <= 2) ? - 1 : 0;
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return floor((1461 * ($year + 4800 + $m1412)) / 4) + floor((367 * ($month - 2 - 12 * $m1412)) / 12) - floor((3 * floor(($year + 4900 + $m1412) / 100)) / 4) + $day - 32075;
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}
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/**
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* Converts a Julian Day count to a year/month/day triple.
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*
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* @param int $jd
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* the Julian Day count.
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* @return array an array with three entries: year, month, day.
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*/
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public function convertJdToGregorian($jd)
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{
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// Special case mapping 0 -> 0/0/0
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if ($jd == 0) {
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return [
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0,
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0,
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0
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];
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}
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$l = $jd + 68569;
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$n = floor((4 * $l) / 146097);
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$l = $l - floor((146097 * $n + 3) / 4);
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$i = floor((4000 * ($l + 1)) / 1461001);
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$l = $l - floor((1461 * $i) / 4) + 31;
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$j = floor((80 * $l) / 2447);
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$d = $l - floor((2447 * $j) / 80);
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$l = floor($j / 11);
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$m = $j + 2 - (12 * $l);
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$y = 100 * ($n - 49) + $i + $l;
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return [
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$y,
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$m,
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$d
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];
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}
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/**
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* Converts a UNIX timestamp to a Julian Day count.
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*
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* @param integer|float $timestamp
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* the timestamp.
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* @return float the Julian Day count.
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*/
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public function convertUnixToJd($timestamp)
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{
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return floor($timestamp / 86400) + 2440588;
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}
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/**
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* Converts a Julian Day count to a UNIX timestamp.
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*
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* @param integer|float $jd
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* the Julian Day count.
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* @return mixed $timestamp the integer timestamp or false if the
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* day count cannot be represented as a UNIX timestamp.
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*/
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public function convertJdToUnix($jd)
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{
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if ($jd > 0) {
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$timestamp = ($jd - 2440588) * 86400;
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if ($timestamp >= 0) {
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return $timestamp;
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}
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}
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return false;
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}
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}
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