Support for saving to memory needs better documention or consistent api

[Timmmm]

Currently the only way to write a PNG image is to save it to a file. It would be nice if there was an API that took a std::io::Write (or std::io::Write + std::io::Seek) for cases when you want an in-memory image.

My use case is writing an SVG with an embedded image. I need to encode to PNG, then base64-encode the result and then write to disk.

[HeroicKatora]

This is possible with a DynamicImage or by using the png encoder interface directly. DynamicImage is a public enum of different ImageBuffer variants. But the api could be more consistent. Does this fit your usecase?

[Timmmm]

Ah yeah that works - probably sufficient to mention those in the ImageBuffer::save() API docs for now.

[saiintbrisson]

@HeroicKatora I think you may close this issue now as #1449 solved it.