Use FFI types to enforce sane resolution values.

[seanhandley]

Also includes some changes to make the attach_function more readable i.e. alias int and pointer to more descriptive values.

[fxn]

Good refactor, the declarations read better.

Also, super clean way to validate resolutions and have parameter types documented in one shot!

Only feedback would be that the natural type to represent a range in Ruby is Range. While the current array-based code works, I believe it would be even more concise to do this:

RES_RANGE = 0..15

There is no need to freeze because ranges are inmutable.

Then, efficient testing is

RES_RANGE.cover?(value)

and there is also API to get both ends of the range for the error message.

[seanhandley]

Ooh nice - I didn't realise this method existed 😁

Thanks!

[fxn]

🎄