Re-encode example

[hoijui]

Hey! :-)
I would like to just add an iTXt text junk to an image, but otherwise leave it as it is, as much as possible.

There is docu for how to add the text junk when writing,
and there is docu for decoding and encoding separately.
I tried to figure out how to decode and encode again, 1:1, but I could not figure it out.
I imagine it is possible, as it is mentioned in #253,
but it is not shown there.
Would it be possible to add an example source file that decodes and encodes and changes a little thing in-between?
I'd be happy to provide the example, if I get some hints for how to do this.

[hoijui]

I am a it puzzled by the whole interface.
there is an Info struct that seems to contain (all)? the settings. It is used by Decoder and Encoder, and it can be fetched from the Decoder, but not set on the Encoder, one has to manually transfer each setting ...
does this mimic some C interface, or why is it like that?

[fintelia]

The overall interface predates my time as a maintainer and much of it likely even predates Rust 1.0. I wouldn't read too much into how the API is currently designed. At some point it would be nice to clean things up, but it has never been a priority.

I think it would be good to have an example like you describe, though as you're discovering it probably wouldn't end up looking very elegant.