Implement video::get_video_info

[robn]

Also with needed conversion for SDL_PixelFormat and SDL_Palette to their Rust counterparts.

This is the first Rust code I've written, so please point out anywhere that would be better served by some core function or idiom I haven't seen yet. In particular I think the palette member of PixelFormat should perhaps be an Option. You let me know and I'll update things :)

[AngryLawyer]

Nice.

Definitely agree that pallette should be an Option if it's ever going to possibly have some sort of Null. Makes it much easier to keep track of it.

[robn]

Ok, redone with an Option. Nicer.

As you see, I've implemented it like this:

palette: match fmt.palette {
    None => ptr::null(),
    Some(_) => ptr::addr_of(&unwrap_palette(fmt.palette.get_ref()))
},

I wanted to do:

    Some(p) => ptr::addr_of(&unwrap_palette(&p))

But that errors for reasons that I don't fully understand and can't find answers to:

src/video.rs:227:22: 227:25 error: use of partially moved value: `fmt`
src/video.rs:227         BitsPerPixel: fmt.bpp,
                                       ^~~
src/video.rs:223:23: 223:34 note: field of `fmt` moved here because the field has type core::option::Option<video::Palette>, which is moved by default (use `copy` to override)
src/video.rs:223         palette: match fmt.palette {
                                        ^~~~~~~~~~~

So this will have to do.

[pcwalton]

You need to use ref p in the pattern instead of using p. The error message should be clearer here.