Extract a separate unfiltered_rows_buffer module.

[anforowicz]

Just a minor refactoring to simplify mod.rs and push some of the complexity into a separate, new unfiltered_rows_buffer module.

[fintelia]

The code itself looks good to me, but I'm not thrilled with the naming. The buffer generally holds both filtered and unfiltered data at the same time and while it is true that the current and previous rows are present, there also might be tens/hundreds of kilobytes of data beyond that which doesn't correspond to a specific number of rows. I'm not quite sure what a better name might be

[anforowicz]

The code itself looks good to me, but I'm not thrilled with the naming. The buffer generally holds both filtered and unfiltered data at the same time and while it is true that the current and previous rows are present, there also might be tens/hundreds of kilobytes of data beyond that which doesn't correspond to a specific number of rows. I'm not quite sure what a better name might be

Fair feedback :-). RawImageData? RawScanlines? UnfilteringBuffer?

[HeroicKatora]

I like UnfilteringBuffer, it clearly points to the responsibilities and its use.

[HeroicKatora]

Thank you, both code and naming fit well in the existing code flow 👍