imagedestroy

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Docey
21-Oct-2006 01:59


When the script stop PHP will automatic destory ANY

resources, this goes for aswell for images, thus in the

case the use clicks the stop button, php will automatic

clear the resource.



thus imagedestroy is used to clear the memory BEFORE

the script ends. this is usefull to keep memory usage

DURING the script to an acceptable level.



hope this clear somethings up.

roland at more-pc dot nl
25-Sep-2005 09:31


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 10:25


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
05-Mar-2004 08:42


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.

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