File Content: PelEntryTime.php <?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, 2007 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 */ /** * Class for holding a date and time. * * This class can hold a timestamp, and it will be used as * in this example where the time is advanced by one week: * <code> * $entry = $ifd->getEntry(PelTag::DATE_TIME_ORIGINAL); * $time = $entry->getValue(); * print('The image was taken on the ' . date('jS', $time)); * $entry->setValue($time + 7 * 24 * 3600); * </code> * * The example used a standard UNIX timestamp, which is the default * for this class. * * But the Exif format defines dates outside the range of a UNIX * timestamp (about 1970 to 2038) and so you can also get access to * the timestamp in two other formats: a simple string or a Julian Day * Count. Please see the Calendar extension in the PHP Manual for more * information about the Julian Day Count. * * @author Martin Geisler <mgeisler@users.sourceforge.net> * @package PEL */ namespace lsolesen\pel; class PelEntryTime extends PelEntryAscii { /** * Constant denoting a UNIX timestamp. */ const UNIX_TIMESTAMP = 1; /** * Constant denoting a Exif string. */ const EXIF_STRING = 2; /** * Constant denoting a Julian Day Count. */ const JULIAN_DAY_COUNT = 3; /** * The Julian Day Count of the timestamp held by this entry. * * This is an integer counting the number of whole days since * January 1st, 4713 B.C. The fractional part of the timestamp held * by this entry is stored in {@link $seconds}. * * @var int */ private $day_count; /** * The number of seconds into the day of the timestamp held by this * entry. * * The number of whole days is stored in {@link $day_count} and the * number of seconds left-over is stored here. * * @var int */ private $seconds; /** * Make a new entry for holding a timestamp. * * @param integer $tag * the Exif tag which this entry represents. There are * only three standard tags which hold timestamp, so this should be * one of the constants {@link PelTag::DATE_TIME}, {@link * PelTag::DATE_TIME_ORIGINAL}, or {@link * PelTag::DATE_TIME_DIGITIZED}. * @param integer|string|double $timestamp * the timestamp held by this entry in the correct form * as indicated by the third argument. For {@link UNIX_TIMESTAMP} * this is an integer counting the number of seconds since January * 1st 1970, for {@link EXIF_STRING} this is a string of the form * 'YYYY:MM:DD hh:mm:ss', and for {@link JULIAN_DAY_COUNT} this is a * floating point number where the integer part denotes the day * count and the fractional part denotes the time of day (0.25 means * 6:00, 0.75 means 18:00). * @param integer $type * the type of the timestamp. This must be one of * {@link UNIX_TIMESTAMP}, {@link EXIF_STRING}, or * {@link JULIAN_DAY_COUNT}. */ public function __construct($tag, $timestamp, $type = self::UNIX_TIMESTAMP) { $this->tag = $tag; $this->format = PelFormat::ASCII; $this->setValue($timestamp, $type); } /** * Return the timestamp of the entry. * * The timestamp held by this entry is returned in one of three * formats: as a standard UNIX timestamp (default), as a fractional * Julian Day Count, or as a string. * * @param integer $type * the type of the timestamp. This must be one of * {@link UNIX_TIMESTAMP}, {@link EXIF_STRING}, or * {@link JULIAN_DAY_COUNT}. * @return integer|string|false the timestamp held by this entry in the correct form * as indicated by the type argument. For {@link UNIX_TIMESTAMP} * this is an integer counting the number of seconds since January * 1st 1970, for {@link EXIF_STRING} this is a string of the form * 'YYYY:MM:DD hh:mm:ss', and for {@link JULIAN_DAY_COUNT} this is a * floating point number where the integer part denotes the day * count and the fractional part denotes the time of day (0.25 means * 6:00, 0.75 means 18:00). */ public function getValue($type = self::UNIX_TIMESTAMP) { switch ($type) { case self::UNIX_TIMESTAMP: $seconds = $this->convertJdToUnix($this->day_count); if ($seconds === false) { /* * We get false if the Julian Day Count is outside the range * of a UNIX timestamp. */ return false; } else { return $seconds + $this->seconds; } case self::EXIF_STRING: list ($year, $month, $day) = $this->convertJdToGregorian($this->day_count); $hours = (int) ($this->seconds / 3600); $minutes = (int) ($this->seconds % 3600 / 60); $seconds = $this->seconds % 60; return sprintf('%04d:%02d:%02d %02d:%02d:%02d', $year, $month, $day, $hours, $minutes, $seconds); case self::JULIAN_DAY_COUNT: return $this->day_count + $this->seconds / 86400; default: 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); } } /** * Update the timestamp held by this entry. * * @param integer|float|string $timestamp * the timestamp held by this entry in the correct form * as indicated by the third argument. For {@link UNIX_TIMESTAMP} * this is an integer counting the number of seconds since January * 1st 1970, for {@link EXIF_STRING} this is a string of the form * 'YYYY:MM:DD hh:mm:ss', and for {@link JULIAN_DAY_COUNT} this is a * floating point number where the integer part denotes the day * count and the fractional part denotes the time of day (0.25 means * 6:00, 0.75 means 18:00). * @param integer $type * the type of the timestamp. This must be one of * {@link UNIX_TIMESTAMP}, {@link EXIF_STRING}, or * {@link JULIAN_DAY_COUNT}. * @throws PelInvalidArgumentException */ public function setValue($timestamp, $type = self::UNIX_TIMESTAMP) { if ($type === self::UNIX_TIMESTAMP) { if (is_int($timestamp) || is_float($timestamp)) { $this->day_count = (int) $this->convertUnixToJd($timestamp); $this->seconds = $timestamp % 86400; } else { throw new PelInvalidArgumentException('Expected integer value for $type, got %s', gettype($timestamp)); } } elseif ($type === self::EXIF_STRING) { /* * Clean the timestamp: some timestamps are broken other * separators than ':' and ' '. */ $d = preg_split('/[^0-9]+/', $timestamp); for ($i = 0; $i < 6; $i ++) { if (empty($d[$i])) { $d[$i] = 0; } } $this->day_count = $this->convertGregorianToJd($d[0], $d[1], $d[2]); $this->seconds = $d[3] * 3600 + $d[4] * 60 + $d[5]; } elseif ($type === self::JULIAN_DAY_COUNT) { if (is_int($timestamp) || is_float($timestamp)) { $this->day_count = (int) floor($timestamp); $this->seconds = (int) (86400 * ($timestamp - floor($timestamp))); } else { throw new PelInvalidArgumentException('Expected integer value for $type, got %s', gettype($timestamp)); } } else { 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, $type); } // finally update the string which will be used when this is turned into bytes. parent::setValue($this->getValue(self::EXIF_STRING)); } // The following four functions are used for converting back and // forth between the date formats. They are used in preference to // the ones from the PHP calendar extension to avoid having to // fiddle with timezones and to avoid depending on the extension. // // See http://www.hermetic.ch/cal_stud/jdn.htm#comp for a reference. /** * Converts a date in year/month/day format to a Julian Day count. * * @param integer $year * the year. * @param integer $month * the month, 1 to 12. * @param integer $day * the day in the month. * @return integer the Julian Day count. */ public function convertGregorianToJd($year, $month, $day) { // Special case mapping 0/0/0 -> 0 if ($year == 0 || $month == 0 || $day == 0) { return 0; } $m1412 = ($month <= 2) ? - 1 : 0; return (int) (floor((1461 * ($year + 4800 + $m1412)) / 4) + floor((367 * ($month - 2 - 12 * $m1412)) / 12) - floor((3 * floor(($year + 4900 + $m1412) / 100)) / 4) + $day - 32075); } /** * Converts a Julian Day count to a year/month/day triple. * * @param int $jd * the Julian Day count. * @return array an array with three entries: year, month, day. */ public function convertJdToGregorian($jd) { // Special case mapping 0 -> 0/0/0 if ($jd == 0) { return [ 0, 0, 0 ]; } $l = $jd + 68569; $n = floor((4 * $l) / 146097); $l = $l - floor((146097 * $n + 3) / 4); $i = floor((4000 * ($l + 1)) / 1461001); $l = $l - floor((1461 * $i) / 4) + 31; $j = floor((80 * $l) / 2447); $d = $l - floor((2447 * $j) / 80); $l = floor($j / 11); $m = $j + 2 - (12 * $l); $y = 100 * ($n - 49) + $i + $l; return [ $y, $m, $d ]; } /** * Converts a UNIX timestamp to a Julian Day count. * * @param integer|float $timestamp * the timestamp. * @return float the Julian Day count. */ public function convertUnixToJd($timestamp) { return floor($timestamp / 86400) + 2440588; } /** * Converts a Julian Day count to a UNIX timestamp. * * @param integer|float $jd * the Julian Day count. * @return mixed $timestamp the integer timestamp or false if the * day count cannot be represented as a UNIX timestamp. */ public function convertJdToUnix($jd) { if ($jd > 0) { $timestamp = ($jd - 2440588) * 86400; if ($timestamp >= 0) { return $timestamp; } } return false; } } Submit