Process image thumbnails "on upload". ImageAPI or your own API compatible with it?

I was going to base things on ImageCache, but there are some issues, namely the limitation of where you can write/save files to. Because of this, I am considering using the ImageApi directly, not only for the image thumbnails but also any post upload modifications. Hopefully I'll get some free time soon to look into this some more.

My current thoughts are to:

• Make ImageApi a strongly recommended dependency, but not to enforce this.
• Field thumbs:
  • If ImageApi is present, use it to stream the image thumbs
  • Otherwise no resizing, constrain the preview thumb with width/height attributes.

I thought that this was going to a nice small afternoon project too, but ended up being considerably longer... I still haven't actually used it for the project that I was designing it for at the time.

I have just got some time to rework this module, and I'm refactoring significantly.

I am considering to use the the imageapi directly.

Each element will be able to specify 1 or more imageapi actions.

Each action is a simple, non-keyed array. The first element must be a valid function after 'imageapi_image_' is prefixed to it, with any additional values passed to the function as additional parameters after the image object.

<?php

$element['image-actions'] = array(
  array('scale_and_crop', 80, 90),
  array('rotate', 90, 0xffffff)
);

# resulting in the following internal calls

imageapi_image_scale_and_crop ($image, 80, 90); 
imageapi_image_rotate ($image, 90, 0xffffff); 

# untested implementation

function ue_apply_imageapi_actions($src, $actions) {
  if (image_get_info($src)) {
    if ($image = imageapi_image_open ($src)) {
      foreach ($actions as $params) {
        $function = 'imageapi_image_'. array_shift($params);
        if (function_exists($function)) {
          array_unshift($params, $image);
          call_user_func_array($function, $params);
        }
      }
      imageapi_image_close($image);
    }
  }
}

?>

I'm not releasing any new features any more with the end of the road in sight with the release of Drupal 7.