Make Rav1dPicAllocator fully safe

[kkysen]

This should be possible, leaving the only unsafe in the Dav1dPicAllocator conversions, but it's fairly tricky, so we can save it for later.

[rinon]

Is this done now?

[kkysen]

Is this done now?

No. I wasn't planning on doing this unless someone wanted it. The current API is unsafe, while what this issue suggested was a rewrite to make the API fully safe from Rust.

[rinon]

Ah I see, I think that could go along with a safe Rust API, if you're only using the C API then would it even make sense to try to make this fully safe?

[kkysen]

Ah I see, I think that could go along with a safe Rust API, if you're only using the C API then would it even make sense to try to make this fully safe?

Yeah that would make sense to go together. You're right, the C API wouldn't get safer from this (though internally we'd use the Rust API for the default, and that's what usually used).