[hatari-devel] SDL2 support

[Thomas Huth <th.huth@xxxxxx>]

 Hi all,

I've now committed all my patches for compiling with SDL2. You can now
build Hatari with SDL2 support by using the "--enable-sdl2" option of
the configure script or by setting the ENABLE_SDL2 option when running
cmake.

Please note that this is currently the bare minimum to get Hatari
working with SDL2. Some things are still limited or disabled:

- Keyboard handling has changed quite a bit in SDL2. The code in
  keymap.c is currently rather a quick than a real solution, e.g.
  loading a keyboard mapping file currently does not work anymore.

- The desktop resolution code in resolution.c is mostly disabled.
  Should not be a big issue though since SDL2 features a nice zoom
  to desktop size in the library itself.

- SDL_UpdateRects was gone in SDL2. I've added a simple wrapper in
  screen.c which now always refreshes the whole screen instead.
  I.e. partial screen updates are now gone (and we should continue
  to make sure that SDL_UpdateRects is only called once per frame)

- Support of 8 bits per pixel surfaces is also somewhat hacky now...
  But I wonder whether we still should support these today, or whether
  we could start to get rid of this color depths nowadays (but we need
  to rewrite the VDI resolution convert functions for this)

.... and there are likely a bunch of more shortcomings, I haven't tested
everything yet, so if you're interested, please have a try and write
your bug reports to the list!

 Thomas