I've almost finished to write a graphic driver for NavIt and I would be glad to share it. There's some bugs to tracks yet, and overlay rendering is WIP.
I use SDL2, for events handling and EGL context creation and SDL2-image.
: I created a Git repository here : https://github.com/cedricp/navit_rpi
that contains changes
* Added multisampling rendring (OK)
* Overlays are now working (all is rendered in an offscreen framebuffer)
* Good reactivity
Still having issues with SDL2 mouse drawing (sometimes freezes the Pi, Ok if I disable cursor) and a crash at startup if I enable compass OSD, but zoom buttons OSD are OK :/
Hope you'll like it.