在php中写入exif数据 [英] writing exif data in php
问题描述
我正在尝试创建一个网站，可以在其中添加和修改JPEG文件中的元数据.
有没有一种方法可以以相当简单的方式写入exif数据.
我看过一个或两个例子，但是它们太复杂了，无法在我给出的时间范围内掌握.
我知道IPTC，我知道可以将元数据添加到JPEG文件中.但是这样做的正确方法是什么?
如果有人可以提供有关如何使用EXIF或IPTC或PHP的任何其他库或功能将元数据添加到JPEG的帮助，那我将非常感激.
更新:
首先感谢 dbers 的回复. /p>
我仔细阅读了代码.我设法将默认标签添加到JPG中.
我对代码的小部分含义还是有些困惑.
例如，在php函数中写入exif数据:
function iptc_make_tag($rec, $data, $value)
{
$length = strlen($value);
$retval = chr(0x1C) . chr($rec) . chr($data);
...
}
我没有遇到函数变量，如果未定义$rec，$data和$value，如何引用它们.还是取自iptc_make_tag?
我回显了$rec和$value，但是我没有在屏幕上得到任何值.
if(isset($info['APP13']))
我不确定APP13的含义，当我尝试回显$info时，当我在表中回显$info时，只会得到以下内容.
'2#120' => 'Test image', '2#116' => 'Copyright 2008-2009, The PHP Group'
我知道您找到了解决方案，但这可能会帮助正在寻找同一事物的其他人！
所有对IPTC标签的引用都可以从 PDF
现在是代码(PHP> = 5.4):
<?
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 = [];
var $file = null;
function __construct($filename)
{
$info = null;
$size = getimagesize($filename, $info);
if(isset($info["APP13"])) $this->meta = iptcparse($info["APP13"]);
$this->file = $filename;
}
function getValue($tag)
{
return isset($this->meta["2#$tag"]) ? $this->meta["2#$tag"][0] : "";
}
function setValue($tag, $data)
{
$this->meta["2#$tag"] = [$data];
$this->write();
}
private function write()
{
$mode = 0;
$content = iptcembed($this->binary(), $this->file, $mode);
$filename = $this->file;
if(file_exists($this->file)) unlink($this->file);
$fp = fopen($this->file, "w");
fwrite($fp, $content);
fclose($fp);
}
private function binary()
{
$data = "";
foreach(array_keys($this->meta) as $key)
{
$tag = str_replace("2#", "", $key);
$data .= $this->iptc_maketag(2, $tag, $this->meta[$key][0]);
}
return $data;
}
function iptc_maketag($rec, $data, $value)
{
$length = strlen($value);
$retval = chr(0x1C) . chr($rec) . chr($data);
if($length < 0x8000)
{
$retval .= chr($length >> 8) . chr($length & 0xFF);
}
else
{
$retval .= chr(0x80) .
chr(0x04) .
chr(($length >> 24) & 0xFF) .
chr(($length >> 16) & 0xFF) .
chr(($length >> 8) & 0xFF) .
chr($length & 0xFF);
}
return $retval . $value;
}
function dump()
{
echo "<pre>";
print_r($this->meta);
echo "</pre>";
}
#requires GD library installed
function removeAllTags()
{
$this->meta = [];
$img = imagecreatefromstring(implode(file($this->file)));
if(file_exists($this->file)) unlink($this->file);
imagejpeg($img, $this->file, 100);
}
}
$file = "photo.jpg";
$objIPTC = new IPTC($file);
//set title
$objIPTC->setValue(IPTC_HEADLINE, "A title for this picture");
//set description
$objIPTC->setValue(IPTC_CAPTION, "Some words describing what can be seen in this picture.");
echo $objIPTC->getValue(IPTC_HEADLINE);
?>
I'm trying to create a website where I can add and modify metadata within a JPEG file.
Is there a way in which I can write the exif data in a fairly easy way.
I have seen one or two examples, but they are they too complex to grasp in the timeframe I have been given.
I am aware of IPTC and I know metadata can be added to the JPEG file. But what would be the correct way of doing this?
If someone could provide some help on how to add metadata to JPEG using EXIF or IPTC or any other library or feature of PHP then I'd be highly appreciative.
Update:
First of all thanks for the reply by dbers.
I've looked through the code. I've managed to get it to add the default tags into the JPG.
I am still a bit confused as to what small portions of the code mean.
For example writing exif data in the php function:
function iptc_make_tag($rec, $data, $value)
{
$length = strlen($value);
$retval = chr(0x1C) . chr($rec) . chr($data);
...
}
I haven't come across a function variable, and how are $rec, $data and $value being referenced if they havent been defined. Or are they taken from iptc_make_tag?
I echoed out $rec and $value but I dont get a value back on screen.
if(isset($info['APP13']))
I'm not sure what APP13 means and when I try to echo out $info, I just get the following when I echo out $info in a table.
'2#120' => 'Test image', '2#116' => 'Copyright 2008-2009, The PHP Group'
I know you found the solution, but this might help anyone else that s looking for the same thing!
I modified a class that I found here (thanks debers).
And all the references to IPTC tags can be readed from this PDF
And now the code (PHP >= 5.4):
<?
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 = [];
var $file = null;
function __construct($filename)
{
$info = null;
$size = getimagesize($filename, $info);
if(isset($info["APP13"])) $this->meta = iptcparse($info["APP13"]);
$this->file = $filename;
}
function getValue($tag)
{
return isset($this->meta["2#$tag"]) ? $this->meta["2#$tag"][0] : "";
}
function setValue($tag, $data)
{
$this->meta["2#$tag"] = [$data];
$this->write();
}
private function write()
{
$mode = 0;
$content = iptcembed($this->binary(), $this->file, $mode);
$filename = $this->file;
if(file_exists($this->file)) unlink($this->file);
$fp = fopen($this->file, "w");
fwrite($fp, $content);
fclose($fp);
}
private function binary()
{
$data = "";
foreach(array_keys($this->meta) as $key)
{
$tag = str_replace("2#", "", $key);
$data .= $this->iptc_maketag(2, $tag, $this->meta[$key][0]);
}
return $data;
}
function iptc_maketag($rec, $data, $value)
{
$length = strlen($value);
$retval = chr(0x1C) . chr($rec) . chr($data);
if($length < 0x8000)
{
$retval .= chr($length >> 8) . chr($length & 0xFF);
}
else
{
$retval .= chr(0x80) .
chr(0x04) .
chr(($length >> 24) & 0xFF) .
chr(($length >> 16) & 0xFF) .
chr(($length >> 8) & 0xFF) .
chr($length & 0xFF);
}
return $retval . $value;
}
function dump()
{
echo "<pre>";
print_r($this->meta);
echo "</pre>";
}
#requires GD library installed
function removeAllTags()
{
$this->meta = [];
$img = imagecreatefromstring(implode(file($this->file)));
if(file_exists($this->file)) unlink($this->file);
imagejpeg($img, $this->file, 100);
}
}
$file = "photo.jpg";
$objIPTC = new IPTC($file);
//set title
$objIPTC->setValue(IPTC_HEADLINE, "A title for this picture");
//set description
$objIPTC->setValue(IPTC_CAPTION, "Some words describing what can be seen in this picture.");
echo $objIPTC->getValue(IPTC_HEADLINE);
?>
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