note 103258 deleted from function.imagecreatefromjpeg by danbrown

Note Submitter: petrhk at volny dot cz ---- A memory limit causes a problem with an image resizing. Function imagecopyresampled() does not report an error for too large image. Because a server hosting usually prohibits to set memory limit, it is better to approximate a greatest size before starting work with an image. //Class for a calculation supposed limit of an image - depend on a memory_limit //Returns area in count of pixels (width * height) or true for an adjustable memory limit class calcMemForImage{ function getApproxSize(){ $IMGCONST=24;//for jpg - usual mime type $SECURECONST=1.5;//It's minimum, it is necessary to calculate with memory for PHP script. //See http://www.php.net/manual/en/function.imagecreatefromjpeg.php#64155 - $TWEAKFACTOR. // PHP_VERSION_ID is available as of PHP 5.2.7, if our // version is lower than that, then emulate it //http://php.net/manual/en/function.phpversion.php if (!defined('PHP_VERSION_ID')) { $version=explode('-',phpversion()); $version = explode('.', $version[0]); define('PHP_VERSION_ID', ($version[0] * 10000 + $version[1] * 100 + $version[2])); } //there is default limit 16 MB for PHP 5.2.0 and later and 8MB for previous versions $memdef=(PHP_VERSION_ID>=50200)?16:8; if(ini_get('memory_limit')){ //try to set memory limit if(!ini_set( 'memory_limit', ceil(1.1*self::return_bytes(ini_get('memory_limit'))/1048576) .'M')){ //if a limit is not adjustable return ceil((self::return_bytes( ini_get('memory_limit')) - 65536)/$IMGCONST/$SECURECONST); }else { //if a limit is adjustable back to the original limit ini_set( 'memory_limit', ini_get('memory_limit')); return true;//if memory limit is adjustable } }//if ini_get('memory_limit') does not work else return ceil(($memdef*1048576-65536)/$IMGCONST / $SECURECONST); } //http://www.php.net/manual/en/function.ini-get.php#96996 function return_bytes ($size_str){ switch (substr ($size_str, -1)){ case 'M': case 'm': return (int)$size_str * 1048576; case 'K': case 'k': return (int)$size_str * 1024; case 'G': case 'g': return (int)$size_str * 1073741824; default: return $size_str; } } } //example $w=new calcMemForImage(); echo $w->getApproxSize();