XF 2.0 Crop image attachments

[XenConcept]

I am trying to resize the image of attachments. When I upload an image I would like to resize it to a specific size is it possible?

So far I'm getting the following error :

$image = $this->app->imageManager()->imageFromFile($attachment->getThumbnailUrl());

I tried various methods without success.

Regards

 

[PrettyPixels]

I'd like to know this as well. Anyone?