Reading file metadata

Question

I am making a gallery implementation for PHP.

The administrator can access the download page, where he will upload and classify the image. So far so good.

The implementation will allow users to comment on photos uploaded by the administrator, so I am implementing a database table to associate comments with their respective images.

id | path .:. id | datetime | comment_title | comment_body | uid 

So far so good.

I want the administrator to be able to rename files (not necessarily through the site, but via FTP or other root access), and not interrupt the entire system.

So, I was thinking of implementing a metadata system to associate an identifier with an image. This will save me both from the first table, and it will allow me to freely manipulate the image (both move it inside folders, rename it, etc.).

The question is how to implement it? How to write metadata attached to a file, and how to read it? Google did not give real results on this.

If there is a better way to do this, I would love to hear too!

Thank any help!

Answer 1

While I myself have not used this, the XMP PHP Toolkit on sourceforge sounds like what you can look for: http://xmpphptoolkit.sourceforge.net/ That said - it is in alpha and has not been updated for a year, it appears.

The XMP Toolkit PHP Extension is a PHP module that includes the Adobe XMP Toolkit SDK. This PHP5 extension will provide classes and methods for manipulating XMP metadata from files such as jpegs, tiff, png, but also wav, mp3, avi, mpeg4, pdf, ai, eps ... Based on Adobe XMP SDK Toolkit 4.4.2. The purpose of this extension is to have php classes that can open files, extract metadata, manipulate them and put them back in a few lines of php code. This project is under the GPL v3 License.

You can also write arbitrary metadata to the image file using iptcembed. As you noted in your comment, this only works for JPEG files.

http://php.net/manual/en/function.iptcembed.php

Here is the script from the comments of the class that will receive and set the IPTC data:

 <? /************************************************************\ IPTC EASY 1.0 - IPTC data manipulator for JPEG images All reserved www.image-host-script.com Sep 15, 2008 \************************************************************/ DEFINE('IPTC_OBJECT_NAME', '005'); DEFINE('IPTC_EDIT_STATUS', '007'); DEFINE('IPTC_PRIORITY', '010'); DEFINE('IPTC_CATEGORY', '015'); DEFINE('IPTC_SUPPLEMENTAL_CATEGORY', '020'); DEFINE('IPTC_FIXTURE_IDENTIFIER', '022'); DEFINE('IPTC_KEYWORDS', '025'); DEFINE('IPTC_RELEASE_DATE', '030'); DEFINE('IPTC_RELEASE_TIME', '035'); DEFINE('IPTC_SPECIAL_INSTRUCTIONS', '040'); DEFINE('IPTC_REFERENCE_SERVICE', '045'); DEFINE('IPTC_REFERENCE_DATE', '047'); DEFINE('IPTC_REFERENCE_NUMBER', '050'); DEFINE('IPTC_CREATED_DATE', '055'); DEFINE('IPTC_CREATED_TIME', '060'); DEFINE('IPTC_ORIGINATING_PROGRAM', '065'); DEFINE('IPTC_PROGRAM_VERSION', '070'); DEFINE('IPTC_OBJECT_CYCLE', '075'); DEFINE('IPTC_BYLINE', '080'); DEFINE('IPTC_BYLINE_TITLE', '085'); DEFINE('IPTC_CITY', '090'); DEFINE('IPTC_PROVINCE_STATE', '095'); DEFINE('IPTC_COUNTRY_CODE', '100'); DEFINE('IPTC_COUNTRY', '101'); DEFINE('IPTC_ORIGINAL_TRANSMISSION_REFERENCE', '103'); DEFINE('IPTC_HEADLINE', '105'); DEFINE('IPTC_CREDIT', '110'); DEFINE('IPTC_SOURCE', '115'); DEFINE('IPTC_COPYRIGHT_STRING', '116'); DEFINE('IPTC_CAPTION', '120'); DEFINE('IPTC_LOCAL_CAPTION', '121'); class iptc { var $meta=Array(); var $hasmeta=false; var $file=false; function iptc($filename) { $size = getimagesize($filename,$info); $this->hasmeta = isset($info["APP13"]); if($this->hasmeta) $this->meta = iptcparse ($info["APP13"]); $this->file = $filename; } function set($tag, $data) { $this->meta ["2#$tag"]= Array( $data ); $this->hasmeta=true; } function get($tag) { return isset($this->meta["2#$tag"]) ? $this->meta["2#$tag"][0] : false; } function dump() { print_r($this->meta); } function binary() { $iptc_new = ''; foreach (array_keys($this->meta) as $s) { $tag = str_replace("2#", "", $s); $iptc_new .= $this->iptc_maketag(2, $tag, $this->meta[$s][0]); } return $iptc_new; } function iptc_maketag($rec,$dat,$val) { $len = strlen($val); if ($len < 0x8000) { return chr(0x1c).chr($rec).chr($dat). chr($len >> 8). chr($len & 0xff). $val; } else { return chr(0x1c).chr($rec).chr($dat). chr(0x80).chr(0x04). chr(($len >> 24) & 0xff). chr(($len >> 16) & 0xff). chr(($len >> 8 ) & 0xff). chr(($len ) & 0xff). $val; } } function write() { if(!function_exists('iptcembed')) return false; $mode = 0; $content = iptcembed($this->binary(), $this->file, $mode); $filename = $this->file; @unlink($filename); #delete if exists $fp = fopen($filename, "w"); fwrite($fp, $content); fclose($fp); } #requires GD library installed function removeAllTags() { $this->hasmeta=false; $this->meta=Array(); $img = imagecreatefromstring(implode(file($this->file))); @unlink($this->file); #delete if exists imagejpeg($img,$this->file,100); } }; ?> 

Example copyright line:

 $i = new iptc("test.jpg"); echo $i->get(IPTC_COPYRIGHT_STRING); 

Update copyright statement:

 $i = new iptc("test.jpg"); echo $i->set(IPTC_COPYRIGHT_STRING,"Here goes the new data"); $i->write();