Allow rendering to stderr or custom writers

[sandydoo]

We have a use-case where we'd like to show an interface on stderr, but also pipe/capture some result to stdout.

Something along the lines of:

use std::io::{stderr, BufWriter};
element.render_loop().output(BufWriter::new(stderr())).await

[sandydoo]

The one complication I foresee is getting the stdout/stderr hooks to work correctly. There's some cursor manipulation to support hook print!s without adding new lines.

[ccbrown]

Ink has options for overriding stdout, stderr, and stdin: https://github.com/vadimdemedes/ink?tab=readme-ov-file#stdout-1

Adding the same options to iocraft seems reasonable. They would still need to be attached to a TTY to function correctly though.

Would that meet your needs?

Alternatively, it might be a little messy, but you might be able to accomplish what you need to with mock_terminal_render_loop, which allows you to capture the output of each render in-memory. You could then write those outputs to whatever you'd like.

[sandydoo]

Ink has options for overriding stdout, stderr, and stdin
Adding the same options to iocraft seems reasonable. They would still need to be attached to a TTY to function correctly though.

Yes, this is the approach I ended up going for. I'll open a PR in a bit.