Panic in insert_before if viewport fills entire screen

[chris-olszewski]

Description

It's possible to cause a panic with an Inline viewport if it is the size of the screen. If this happens, then max_chunk_size will end up being 0 causing chunks to panic.

To Reproduce

use ratatui::{
    backend::{Backend, CrosstermBackend},
    text::Text,
    widgets::Widget,
    Terminal, TerminalOptions,
};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    crossterm::terminal::enable_raw_mode()?;

    let backend = CrosstermBackend::new(std::io::stdout());
    let size = backend.size()?;
    let mut terminal = Terminal::with_options(
        backend,
        TerminalOptions {
            viewport: ratatui::Viewport::Inline(size.height),
        },
    )?;
    terminal.insert_before(1, |buf| Text::raw("Hello World!").render(buf.area, buf))?;

    crossterm::terminal::disable_raw_mode()?;
    Ok(())
}

Expected behavior

Either:

• Write to a line in the scrollback
• Error instead of panic

Environment

• OS: macOS
• Terminal Emulator: iTerm2
• Font: N/A
• Crate version: 0.26.1
• Backend: Crossterm

[joshka]

Unfortunately we cant' change things easily to return errors as there are lots of apps that this would break, but we can add new methods that do this (and it's one of those things we've spoken about a few times), so the first option is really orthogonal to this problem. Ideally we should never panic for things that are expected (and sometimes even for things which can be handled by ignoring the problem).

Here, I think this probably should succeed and write the line above the viewport.

Would you consider submitting a PR to fix this?

I'd suggest adding a unit / integration test if possible that shows this panicking and then make that unit test succeed.

[chris-olszewski]

Would you consider submitting a PR to fix this?

Yes! Thanks for the guidance.