I'd like to quickly prototype an app. It would be a single web page that gets an image and some (x,y) coordinates via http. It renders the image, and then draws red dots on the image at certain (x, y) coordinates on the image. I would will also be drawing line segments between some of the dots.
What I'm looking to do is to have a user be able to grab a dot, and move it to another (x, y) position on the image. And then i'd be able to send the udpated x,y coordinates to a backend service. The images are pngs.
I'm comfortable with the http calls, more interested in an easy frontend technology that allow you to drag and drop points and access the x,y coordinates of those points on an image.