Fixing hard-coded fieldname

To make it easier to figure out what has changed, here is the interdiff between the patch in the original post and the patch in #2488292: Dependency injection ... we should have some of that

I started looking at this ... first step was to confirm premise of the issue:

Currently the latest d8 release simply does not work (it cannot save the focal points).

This is not the case as far as I can tell. I have a vanilla D8 install (fairly up-to-date) and everything works fine with the latest dev release of focal_point. Were you only seeing this issue of fields not saving correctly after you applied the patch in #2488292: Dependency injection ... we should have some of that? If so, can you continue this discussion there.

If not, I have a thought about something I just noticed ... Is your field named something other than "image"? If so, this might be the issue:

/**
 * Implements hook_entity_presave().
 *
 * Saves the focal point value for the image file entity about to be saved.
 */
function focal_point_entity_presave(EntityInterface $entity) {
  if (isset($entity->field_image)) {
    foreach($entity->field_image as $item) {
      $focal_point = new FocalPoint($item->target_id);
      $focal_point->saveFocalPoint($item->focal_point);
    }
  }
}

The presave function has "field_image" hard-coded. YIKES!

I made some small tweaks, but ultimately this is great. Thanks!!

... If you have a few mins to take a look at #2488292: Dependency injection ... we should have some of that that would be awesome.