<?php //================================================================================================
//================================================================================================
//================================================================================================
/*
	Exifer
	Extracts EXIF information from digital photos.

	Copyright © 2003 Jake Olefsky
	http://www.offsky.com/software/exif/index.php
	jake@olefsky.com

	Please see exif.php for the complete information about this software.

	------------

	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. http://www.gnu.org/copyleft/gpl.html
*/
//================================================================================================
//================================================================================================
//================================================================================================

//=================
// Looks up the name of the tag
//====================================================================
function lookup_GPS_tag($tag) {

	switch($tag) {
		case "0000": $tag = "Version"; break;
		case "0001": $tag = "Latitude Reference"; break;			//north or south
		case "0002": $tag = "Latitude"; break;							//dd mm.mm or dd mm ss
		case "0003": $tag = "Longitude Reference"; break;			//east or west
		case "0004": $tag = "Longitude"; break;						//dd mm.mm or dd mm ss
		case "0005": $tag = "Altitude Reference"; break;			//sea level or below sea level
		case "0006": $tag = "Altitude"; break;							//positive rational number
		case "0007": $tag = "Time"; break;								//three positive rational numbers
		case "0008": $tag = "Satellite"; break;							//text string up to 999 bytes long
		case "0009": $tag = "ReceiveStatus"; break;					//in progress or interop
		case "000a": $tag = "MeasurementMode"; break;			//2D or 3D
		case "000b": $tag = "MeasurementPrecision"; break;		//positive rational number
		case "000c": $tag = "SpeedUnit"; break;						//KPH, MPH, knots
		case "000d": $tag = "ReceiverSpeed"; break;				//positive rational number
		case "000e": $tag = "MovementDirectionRef"; break;		//true or magnetic north
		case "000f": $tag = "MovementDirection"; break;			//positive rational number
		case "0010": $tag = "ImageDirectionRef"; break;			//true or magnetic north
		case "0011": $tag = "ImageDirection"; break;				//positive rational number
		case "0012": $tag = "GeodeticSurveyData"; break;			//text string up to 999 bytes long
		case "0013": $tag = "DestLatitudeRef"; break;				//north or south
		case "0014": $tag = "DestinationLatitude"; break;			//three positive rational numbers
		case "0015": $tag = "DestLongitudeRef"; break;				//east or west
		case "0016": $tag = "DestinationLongitude"; break;		//three positive rational numbers
		case "0017": $tag = "DestBearingRef"; break;				//true or magnetic north
		case "0018": $tag = "DestinationBearing"; break;			//positive rational number
		case "0019": $tag = "DestDistanceRef"; break;				//km, miles, knots
		case "001a": $tag = "DestinationDistance"; break;			//positive rational number
		case "001b": $tag = "ProcessingMethod"; break;
		case "001c": $tag = "AreaInformation"; break;
		case "001d": $tag = "Datestamp"; break;						//text string 10 bytes long
		case "001e": $tag = "DifferentialCorrection"; break;		//integer in range 0-65535

		default: $tag = "unknown:".$tag; break;
	}

	return $tag;
}

//=================
// Formats a rational number
//====================================================================
function GPSRational($data, $intel) {

	if($intel==1) $top = hexdec(substr($data, 8, 8)); 	//intel stores them bottom-top
	else $top = hexdec(substr($data, 0, 8));				//motorola stores them top-bottom

	if($intel==1) $bottom = hexdec(substr($data,0,8));	//intel stores them bottom-top
	else $bottom = hexdec(substr($data, 8, 8));				//motorola stores them top-bottom

	if($bottom!=0) $data=$top/$bottom;
	else if($top==0) $data = 0;
	else $data=$top."/".$bottom;

	return $data;
}
//=================
// Formats Data for the data type
//====================================================================
function formatGPSData($type,$tag,$intel,$data) {

	if($type=="ASCII") {
		if($tag=="0001" || $tag=="0003") { // Latitude Reference, Longitude Reference
			$data = ($data{1} == $data{2} && $data{1} == $data{3}) ? $data{0} : $data;
		}

	} else if($type=="URATIONAL" || $type=="SRATIONAL") {
		$data = bin2hex($data);
		if($intel==1) $data = intel2Moto($data);

		if($intel==1) $top = hexdec(substr($data, 8, 8)); 	//intel stores them bottom-top
		else $top = hexdec(substr($data, 0, 8));				//motorola stores them top-bottom

		if($intel==1) $bottom = hexdec(substr($data, 0, 8));	//intel stores them bottom-top
		else $bottom = hexdec(substr($data, 8, 8));				//motorola stores them top-bottom

		if($type=="SRATIONAL" && $top>2147483647) $top = $top - 4294967296; //this makes the number signed instead of unsigned

		if($tag=="0002" || $tag=="0004") { //Latitude, Longitude

			if($intel==1) {
				$seconds = GPSRational(substr($data, 0, 16),$intel);
				$hour = GPSRational(substr($data, 32, 16),$intel); 
			} else {
				$hour= GPSRational(substr($data, 0, 16),$intel);
				$seconds = GPSRational(substr($data, 32, 16),$intel);
			}
			$minutes = GPSRational(substr($data, 16, 16),$intel);

			$data = $hour+$minutes/60+$seconds/3600;
		} else if($tag=="0007") { //Time
			$seconds = GPSRational(substr($data, 0, 16),$intel);
			$minutes = GPSRational(substr($data, 16, 16),$intel);
			$hour = GPSRational(substr($data, 32, 16),$intel);

			$data = $hour.":".$minutes.":".$seconds;
		} else {
			if($bottom!=0) $data=$top/$bottom;
			else if($top==0) $data = 0;
			else $data=$top."/".$bottom;

			if($tag=="0006") {
				$data .= 'm';
			}
		}
	} else if($type=="USHORT" || $type=="SSHORT" || $type=="ULONG" || $type=="SLONG" || $type=="FLOAT" || $type=="DOUBLE") {
		$data = bin2hex($data);
		if($intel==1) $data = intel2Moto($data);
		$data=hexdec($data);

	} else if($type=="UNDEFINED") {

	} else if($type=="UBYTE") {
		$data = bin2hex($data);
		if($intel==1) $num = intel2Moto($data);

		if($tag=="0000") { // VersionID
			$data =  hexdec(substr($data, 0, 2)) .
					".". hexdec(substr($data, 2, 2)) .
					".". hexdec(substr($data, 4, 2)) .
					".". hexdec(substr($data, 6, 2));

			} else if($tag=="0005") { // Altitude Reference
				if($data == "00000000") { $data = plog_tr('Above Sea Level'); }
			else if($data == "01000000") { $data = plog_tr('Below Sea Level'); }
			}

	} else {
		$data = bin2hex($data);
		if($intel==1) $data = intel2Moto($data);
	}

	return $data;
}

//=================
// GPS Special data section
// Useful websites
// http://drewnoakes.com/code/exif/sampleOutput.html
// http://www.geosnapper.com
//====================================================================
function parseGPS($block, &$result, $offset, $seek, $globalOffset) {

	if($result['Endien']=="Intel") $intel=1;
	else $intel=0;

	$v = fseek($seek, $globalOffset+$offset); //offsets are from TIFF header which is 12 bytes from the start of the file
	if($v==-1) {
		$result['Errors'] = $result['Errors']++;
	}

	$num = bin2hex(fread( $seek, 2 ));
	if($intel==1) $num = intel2Moto($num);
	$num=hexdec($num);
	$result['GPS']['NumTags'] = $num;

	if ($num == 0) {
		return;
	}

	$block = fread( $seek, $num*12 );
	$place = 0;

	//loop thru all tags  Each field is 12 bytes
	for($i=0;$i<$num;$i++) {
		//2 byte tag
		$tag = bin2hex(substr($block, $place, 2)); $place+=2;
		if($intel==1) $tag = intel2Moto($tag);
		$tag_name = lookup_GPS_tag($tag);

		//2 byte datatype
		$type = bin2hex(substr($block, $place, 2)); $place+=2;
		if($intel==1) $type = intel2Moto($type);
		lookup_type($type,$size);

		//4 byte number of elements
		$count = bin2hex(substr($block, $place, 4)); $place+=4;
		if($intel==1) $count = intel2Moto($count);
		$bytesofdata = $size*hexdec($count);

		//4 byte value or pointer to value if larger than 4 bytes
		$value = substr($block, $place, 4); $place+=4;

		if($bytesofdata<=4) {
			$data = $value;
		} else {
			$value = bin2hex($value);
			if($intel==1) $value = intel2Moto($value);

			$v = fseek($seek,$globalOffset+hexdec($value)); //offsets are from TIFF header which is 12 bytes from the start of the file
			if($v==0) {
				$data = fread($seek, $bytesofdata);
			} else if($v==-1) {
				$result['Errors'] = $result['Errors']++;
			}
		}

		if($result['VerboseOutput']==1) {
			$result['GPS'][$tag_name] = formatGPSData($type,$tag,$intel,$data);
			$result['GPS'][$tag_name."_Verbose"]['RawData'] = bin2hex($data);
			$result['GPS'][$tag_name."_Verbose"]['Type'] = $type;
			$result['GPS'][$tag_name."_Verbose"]['Bytes'] = $bytesofdata;
		} else {
			$result['GPS'][$tag_name] = formatGPSData($type,$tag,$intel,$data);
		}
	}
}

?>