Implementation of the selection of the photo area and commenting?

Question

JavaScript

Please tell me the implementation of highlighting the photo area and commenting on Rails and jquery.
There is a picture, you need to select a rectangular area (or several) and leave comments.

Answer 1

Here is a plugin for highlighting an area, but then I think everything is clear.

Answer 2

Option 1) Newfangled Canvas. You can do anything, any whistles and embellishments are limited only by a flight of wild imagination, you can at least stir up a mini-graphic editor. But a significant disadvantage: it will only work in very new browsers.
Option 2) Good old rectangular Div positioned above the image. The implementation is cheap and cheerful: mousedown over the picture - remember the mouse x1,y1, and when mouseup occurs - we take the mouse x2,y2 and stretch the div at position x1,y1 with a width of x2-x1 and a height of y2-y1. It will probably look condo, but after dancing for a few minutes with a tambourine, you can make it work even in prehistoric browsers.

Answer 3

I think it should happen on the client. Drip towards HTML.