Make columns fit any width

The demo list at 96 columns: Job, Version, Owner, Size and Message all shown

The same list at 46 and 38 columns: first Size drops, then Version, while Job and Owner stay and the message clips with “…”.

The same list at 46 columns: the Size column dropped, the messages clipped with an ellipsis The same list at 38 columns: Size and Version dropped, Job and Owner kept

Minimum, preferred and priority

Column::new(title, min, preferred) makes a column. Every column pads its cells to its width so the rows line up, and a cell wider than it is clipped with “…”. The widths are worked out at each draw:

When the minimums don’t all fit, the column with the highest priority(n) drops first (the later one on a tie). A pinned() column never drops.
A column that is kept never shrinks below its minimum.
Spare width goes to the columns up to their preferred widths, left to right.
The flexible column takes what’s left and is never dropped. It is the last column unless another is marked flex(), so number columns can follow a wide name.

use pito_list::{Column, List, ListView, Row};
use ratatui::{buffer::Buffer, layout::Rect, widgets::Widget};

let columns = [
    Column::new("Job", 10, 12).pinned(),
    Column::new("Version", 7, 9).priority(2),
    Column::new("Owner", 5, 6).priority(1),
    Column::new("Size", 6, 0).priority(3).right(),
    Column::new("Message", 8, 0),
];
let mut list = List::new().with_rows([
    Row::new(["deploy api", "v1.4", "web", "12 MB", "uploading the bundle"]),
    Row::new(["build docs", "v0.9", "docs", "640 kB", "waiting for a runner"]),
]);
for width in [64, 44, 36] {
    let area = Rect::new(0, 0, width, 3);
    let mut buffer = Buffer::empty(area);
    ListView::new(&mut list, &columns).header(true).render(area, &mut buffer);
}

At 64, 44 and 36 cells, Size drops first (priority 3), then Version (priority 2), while Owner (priority 1) stays:

  Job           Version    Owner     Size  Message
▌ deploy api    v1.4       web      12 MB  uploading the bundle
  build docs    v0.9       docs    640 kB  waiting for a runner

  Job           Version    Owner   Message
▌ deploy api    v1.4       web     uploadin…
  build docs    v0.9       docs    waiting …

  Job           Owner   Message
▌ deploy api    web     uploading t…
  build docs    docs    waiting for…

right() aligns a column’s cells and title to its right edge, for numbers. gap(n) on the ListView sets the space between columns (2 by default), and cursor(text) the marker in front of the selected row (“▌ “ by default).

Columns as wide as their cells

fit(max) makes a column as wide as its widest cell among the rows on screen, and its title when the header is drawn, up to max. That width stands in for the preferred one, so the column still keeps its minimum and drops by its priority. Only the rows on screen are measured, so the width follows the view as the list scrolls.

A cell across the columns after it

Cell::new(text).rest() draws a cell from its column to the end of the row as one clipped cell, over the columns after it, for a note on a row that has no values for them. It takes its column’s alignment and drops with its column (pin the column to keep it).

Where the columns were drawn

After a draw, List::columns() lists each column drawn as (column index, x, width) in terminal cells, left to right; a dropped column is absent. With List::top() it places a widget over one cell: row index is on line area.y + header + index - top().

Widths are counted in terminal cells with Unicode widths, so diacritics, wide glyphs and “…” measure, pad and clip cleanly, and a wide glyph is never cut in half. A list draws inside its area only: beside a detail pane, it never writes over the pane.