Possible to select and area of an uploaded image?

What I’d like to be able to do would be to upload an image (like a floorplan) and save that image. When the user returns to that page, they see the image and they are able to then select sections of the image, like a room. It could be as simple as just click and drag an area, or click and drag lines that connect to make an area. I would then need to save this highlighted area so that they could come back later and see that area.

Then they could drag and drop components (like a light buib) onto that select area to associate the bulb to that room.

Is any of this possible in vaadin, or do I have to do it in javascript etc outside of vaadin?

There are no Vaadin components that do image handling in the way you describe. There are a number of add-ons in the add-ons directory https://vaadin.com/directory that provide various image management features. However, I don’t think that any one of them do exactly what you describe. You probably need to develop some client-side widget for this (see the Vaadin book chapters 13-15)

I wonder if it would be possible to use the html5 canvas addon with polyclip.js or something similar to that…

That could be an option. It is possible to have Javascript extensions of components, see
https://vaadin.com/book/-/page/gwt.javascript.html for Javascript components and
https://vaadin.com/wiki/-/wiki/Main/Integrating%20a%20JavaScript%20library%20as%20an%20 for extensions.

Combined with JSNI in GWT, see http://www.gwtproject.org/doc/latest/DevGuideCodingBasicsJSNI.html, it would be possible to extend the canvas add-on to use the polyclip.js library to manipulate images.