Feature addition: Include an element's size in the draggable interface

Hi all,

First-time contributor so please forgive any errors or faux pas!

I have been working on a project these last few weeks that required a div that is draggable and resizable, and after trying to build it from scratch by myself for wayyyy longer than I should have done, it was still a mess. I decided at that point, more in hope than expectation, to see if jQuery had a way to make it easier and, well, here we are!

What I have been building is an image uploader that then crops the image to the user's wishes, which has meant having a canvas drawing the part of the picture that is covered by the overlaying <div> whenever it is moved or resized. One thing I noticed however is that whilst resizable's ui object returns the position and size, draggable's only returns the position, so the addition of the element's size is what I am looking to add in here. I have the code ready to go (at least according to my local testing) but thought better than just submitting a PR out of the blue. The branch is at https://github.com/gavinsykes/jquery-ui/tree/add-size-data-to-draggable-ui

Any questions, please ask! 😄

Review the existing draggable and resizable interfaces, then inspect the contributor's branch at gavinsykes/jquery-ui/tree/add-size-data-to-draggable-ui. Compare the proposed draggable UI data with the resizable UI object and verify that the element's size is included without breaking existing behavior.