[xwiki-devs] [Proposal] Add cropping API to image plugin

Hi devs, I've already proposed a thumbnail module in the past (http://markmail.org/thread/3le7qxziog2p7bsd) but it felt short in terms of design. I reckon it's more of a URL cache module for images/thumbnails and probably doesn't make much sense in the platform. I would like still to propose one change separately, that was going together with this module : adding a cropping API to the current image plugin. This would allow to not only pass dimensions information when downloading an image, but also to pass coordinates to crop a subimage out of the original image. Practically, it's adding a "boundaries" URL parameter (in addition to the existing width, height, quality and keepAspectRatio existing parameters), that is a comma separated list of x, y, width and height used to construct the subimage. Right now the code is in https://github.com/jvelo/xwiki-platform-thumbnails/tree/master/src/main/jav…, I will make a proper pull request to discuss the patch if their is interest. Note I also have a generic UI component to perform resizing and store image boundaries for an attachment in an XObject that I can share (and even plug into the user profile for example). On the longer term, their is a discussion to have around how to wire attachment transformation from URLs. Maybe a "transformations" URL parameter that takes a list of hints of transformation components ? Then the resizing/cropping could be implemented as transformations in a new image module ? WDYT ? Finally, finishing note, I've also written a new image processor for the current image plugin API, based on https://code.google.com/p/java-image-scaling/ that yields images of much better quality compared to the current implementation based on awt/graphics2d. See for example the before/after : http://imgur.com/oU9v5 (for the before, those had a quality param of "1", i.e. maxed out). Code is there : https://github.com/jvelo/xwiki-platform-thumbnails/blob/master/src/main/jav…. One thing I didn't do yet is to extract a superclass from it and the base impl. If there is interest, we could provide this processor as an alternative. Maybe with a parameter config to pass the hint of the processor to use. WDYT ? Thanks, Jerome