How does PHP write exif information to JPG images?

In writing a PHP to the direction of the image according to the EXIF rotation function, the function is done, but after the rotation of the picture file exif information is gone, because I use imagejpegRewrite the picture, how can I write exif back?

Post the code for the picture I rotated:

function rotateImg($img,$degrees,$bgd_color=0,$ignore_transparent=null){    $resource = imagecreatefromjpeg($img);    //$resource = imagecreatefromstring(file_get_contents($img));    if(!$resource)        return false;    $resource = imagerotate($resource, $degrees, $bgd_color,$ignore_transparent);    print_r($img);    if($resource&&imagejpeg($resource,$img)){        imagedestroy($resource);//释放内存        return true;    }    return false;}

Reply content:

In writing a PHP to the picture direction according to the function of the EXIF rotation, the function is done, but the picture file after the rotation of EXIF information is gone, because I used to imagejpeg rewrite the picture, how to write Exif back?

Post the code for the picture I rotated:

function rotateImg($img,$degrees,$bgd_color=0,$ignore_transparent=null){    $resource = imagecreatefromjpeg($img);    //$resource = imagecreatefromstring(file_get_contents($img));    if(!$resource)        return false;    $resource = imagerotate($resource, $degrees, $bgd_color,$ignore_transparent);    print_r($img);    if($resource&&imagejpeg($resource,$img)){        imagedestroy($resource);//释放内存        return true;    }    return false;}

It is easy to read/write EXIF information with Imagick.
http://php.net/manual/en/imagick.setimageproperty.php

GD is not supported for EXIF writing and can only be read.

Compared to the Gd,imagick is too advanced. Change it.

