PHP: imagedestroy

imagedestroy

(PHP 3, PHP 4, PHP 5)

imagedestroy -- Destroy an image

Description

bool imagedestroy ( resource image )

imagedestroy() frees any memory associated with image image. image is the image identifier returned by one of the image create functions, such as imagecreatetruecolor().

imagedestroy

roland at more-pc dot nl
24-Sep-2005 06:31


As Andrew states below, it's IMPERATIVE that you use the imagedestroy() function. But your script may abort before it reaches the call to imagedestroy() (for example the user may click the browsers 'stop' button). In this case the default PHP behaviour is to abort the script, never reaching your call to imagedestroy().

One way of doing it (the one which works very well for me) is with register_shutdown_function():

<?

function shutdown_func() {

    global $img;

    if($img)

        imagedestroy($img);

}

register_shutdown_function("shutdown_func");

$img = imagecreate...(...);

... // manipulate image

// normally I'd need the following line, but now it's handled by shutdown_func()

// imagedestroy($img);

?>

Andrew Hoffmann - ahoffmann at wisc dot edu
23-Jun-2005 07:25


When working with a lot of high-resolution images, it's IMPERATIVE that you use the imagedestroy() function.



In my scenario, I was taking two high resolution desktop wallpapers and shrinking them down into successively smaller ones (preventing the user from having to upload a dozen files).



At first, my script would run, then just stop.  I realized later that I had not destroyed the source image and the newly resized image in memory after I had finished writing the file out to disk.  Thus, I quickly reached the memory limit that my hosting provider placed in their php.ini file.



Reusing an image variable does NOT clear the old data out of memory!  You must use imagedestroy() to clear the data out.  (I don't know if unset() works as well).



Also note that the image data in memory is raw, so don't base how much memory you are using based on the original filesize of the compressed image (such as jpeg or png).

dan at mlodecki dot net
04-Mar-2004 04:42


I have noticed that gd drawing functions can behave oddly if there is a previous image which has not been imagedestroy()'ed.  You should always imagedestroy when you are done with an image object.