Drupal 7 Module Development

Chapter 11
For full details of these and other functions available in the Image API
refer to http://api.drupal.org/api/group/image/7
Let's take a look at how to we might integrate some of these functions with our
Twitpic module. First, let's make create a hook_menu() implementation that we
can use to trigger our code.
/**
* Implement hook_menu().
*/
function twitpic_menu() {
$items = array();
$items['twitpic/munge/%'] = array(
'title' => 'Munge a Twitpic image',
'description' => 'Displays a Twitpic image, munged in various ways
(cropped, rotated, etc).',
'page callback' => 'twitpic_image_munge',
'access arguments' => array('access_content'),
'type' => MENU_CALLBACK,
);
}
return $items;
When the URL twitpic/munge is requested, this hook will call the function
twitpic_image_munge(), which takes two arguments. The first is the ID of
the Twitpic image we want to manipulate, and the second is an operation to be
performed. The allowed operations are rotate, scale, and desaturate. These
arguments will be automatically passed to twitpic_image_munge() when
appended to the URL, as discussed in Chapter 5, Building an Admin Interface.
Let's look at the callback function now:
/**
* Munge an image from Twitpic by applying a resize, crop or
* rotate to it.
*
* @param $id
* The image's ID, as extracted from its original URL.
* @param $operation
* An operation to perform on the image. Can be 'rotate',
* 'scale', or 'desaturate'.
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