[Scummvm-devel] Moving platform specific (down)scalers into the core of ScummVM

[Max Horn]

Hi again,

first off: Yeah, maybe "small devices backend" should become "small  
screen backend"... or not... The name is not so important in my eyes.  
In fact, to me the SDB always was more of a meta-level thing, a  
concept, not necessarily something that has to be implemented  
explicitly as one single backend. The idea always was to provide as  
many useful generic components as possible to backend authors -- as  
long as it makes sense, at least.

[Side remark:
One part of that meta level goal always was to make the SDL backend  
easier to subclass. For example, it would be a nice thing to split the  
single monolithic event handler function in the SDL backend, by adding  
several handleMouseDown, handleKeyDown etc. callbacks (similar to our  
GUI code), which do the actual work. That way, new ports can easily  
insert say an alternate hotkey -- they only have to overload a single  
method (and can still invoke the original implementation of it, too),  
and don't have to copy all the other identical code in the event  
handler. It also would allow getting rid of the alternate strategy  
porters employed to customize the hotkeys: Nameley, scattering tons of  
#ifdef's through OSystem_SDL::pollEvent ;)
]


You ask whether it makes sense to subclass the SDL backend for  
downscaler support, citing systems that just use the plain vanilla SDL  
backend which still want to use downscaling...
Well, those systems could be switched use the plain vanilla SDL_small  
backend, too, so this seems like a minor point to me.

Of course you could now argue that users might want to use downscaling  
even on a desktop machine. While I consider that absurd, it might  
indeed be helpful for testing purposes to be able *as a developer* to  
use a downscaler.

So, I am not opposed to add downscaling to the SDL backend itself.  
*If* this doesn't complicate the backend too much. That's a big "if"  
in my eyes. But if that can be achieved, why not.



Cheers,
Max