The code is there already. We call it viewport, like in
https://github.com/koreader/koreader...evice.lua#L147
It is a bit difficult to port it to android as is because, unlike in other platforms, all devices are defined as a single Device instance (we rely on
https://github.com/koreader/android-luajit-launcher to fill the holes for each specific device)
But we can get something usable without too much tinker. Just need to know the specific pixels covered by the bezel as changing one of its values requires rebuilding the app.