I have a closed-source data entry app which I need to add a few features to. Since the app itself should not be modified, I need somebody to write a small overlay application which displays icons for the additional data I need to enter.
That app should contact my server, via Websocket or similar. The server will send messages containing the names of some icons (PNG). The app shall download and display these icons (one single row across the screen, image scaling is not necessary). The icons can be retrieved via an HTTP URL and need to be cached on the client (caching in memory is fine). Each request supersedes the previous request; the list may be empty in which case nothing shall be overlaid onto the screen.
The icons' position shall be changeable by dragging the row of icons across the screen; if the user taps on one of the icons, a notification about which icon has been tapped shall be sent to the server (also via that websocket). The rest of the screen and the underlying app shall not be affected.
I need a setup dialog with username+password; the URL of the server should be hardcoded.
Deliverables: source code for Android Lollipop or earlier, build instructions for Linux, working binary (test server to be supplied by me).
Please answer with specific details about my proposal. Boilerplate replies will be rejected.
The overlay application you'd contract to write does not need to interact with the underlying app in any way, it only talks to the server.
The websocket server is written by me, you get a login for it and the server then sends some test data to you.