A lot of Drupal sites use ImageCache and ImageAPI to automatically
scale and process images for display. Most of them (the vast majority, unless
I miss my guess) will be using the GD toolkit and running with mod_php
embedded in Apache. This is fine in most cases, but sometimes it’s definitely
the wrong thing to do; in my case, I’m processing large image files (~4M or
so) and keeping my memory limit down. The easiest way to do this is to offload
the processing to another process. Something like ImageMagick perhaps? With a
custom action from ImageCache Actions, this is simple!
A quick Google led me to an article called Create PDF thumbnails with imagecache and ImageMagick while GD is still the default toolkit which supplies the following code (simplified a little by removing the PDF-y bits):
<?php
$w = 246; // change to your preferred thumbnail width
if (!_imageapi_imagemagick_convert($image->source.'[0]', $image->source.'.png', array(0 => '-thumbnail '.$w))) return FALSE;
$img = imagecreatefrompng($image->source.'.png');
file_delete($image->source.'.png');
$image->resource = $img;
$image->toolkit = 'imageapi_gd';
$image->info = array('extension' => 'jpeg');
return TRUE;
?>Alas, this code it pretty useless: because it stomps on $image->info any
further actions on this $image will probably break.
Thankfully, there’s an easy fix: when you update $image, make sure you
update everything that needs fixing. Here’s the amended code:
<?php
// "Thumbnail" the image
$width = 600;
if (!_imageapi_imagemagick_convert($image->source, $image->source.'.png', array(0 => '-thumbnail '.$width))) return FALSE;
// Load it back in as a GD resource
$img = imagecreatefrompng($image->source.'.png');
// Get the "deets" on the new image
$info = getimagesize($image->source.'.png');
$image->resource = $img;
$image->toolkit = 'imageapi_gd';
$image->info = array(
'width' => $info[0],
'height' => $info[1],
'extension' => 'png',
'file_size' => filesize($image->source.'.png'),
'mime_type' => $info['mime'],
);
// Clean up
file_delete($image->source.'.png');
return $image;
?>Make sure that you’ve enabled the ImageMagick toolkit, drop this code in a custom action and you’ll be on externally processing images in no time!