feat: add repeat-from animation mode

[cristicbz]

Adds AnimationMode::RepeatFrom(index) which repeats from a given index rather than going all the way back to zero. This super handy for simple animations like e.g. a torch being lit then staying lit, or a missile lighting up its motor and then looping.

Because AnimationMode is non_exhaustive I believe this is not a breaking change.

I considered getting rid of AnimiationMode::Repeat and using Animation::RepeatFrom(0) in fn repeat(self), but we can't do this without a breaking change.

I was wondering, why even expose the AnimationMode enum? It looks to me like it's not actually returned or taken as argument by any APIs. Could it be private to the crate? It would make it easier to make changes like this, which generalise an existing animation mode without it being a breaking change.

[jcornaz]

Adds AnimationMode::RepeatFrom(index) which repeats from a given index rather than going all the way back to zero. This super handy for simple animations like e.g. a torch being lit then staying lit, or a missile lighting up its motor and then looping.

sounds good to me, thanks for the contribution 👍

Because AnimationMode is non_exhaustive I believe this is not a breaking change.

indeed, it is not a breaking change.

I considered getting rid of AnimiationMode::Repeat and using Animation::RepeatFrom(0) in fn repeat(self), but we can't do this without a breaking change.

I was wondering, why even expose the AnimationMode enum? It looks to me like it's not actually returned or taken as argument by any APIs. Could it be private to the crate? It would make it easier to make changes like this, which generalise an existing animation mode without it being a breaking change.

Yeah, I made the mistake of making it public even though that wasn't needed. But we can go for the solution you suggest without making a breaking change. here is how:

1. Create a new enum which is pub(crate). You may simply name it Mode. (no need to use non_exhaustive if it is private)
2. Change internal implementation to use the new enum.
3. Deprecate the now unused old public enum AnimationMode.

You may do that in a different PR if you wish. Or you may do it here, as you prefer.

Let me know if you don't have time or don't want to do that refactoring, in that case, I'll merge as-is and refactor myself later.

[cristicbz]

@jcornaz Ok, great, didn't want to go hacking on your codebase before checking with you on the design! Just push-forced a commit that does the refactor you described---the old changes didn't really make sense as the first commit so I replaced the commit instead.

I can have a go at splitting up into two commits instead: refactor first, add RepeatFrom second, but it's a bit of a faff and weren't sure if you cared enough.

[jcornaz]

looks good to me thanks!