Show a 20,000-line log

Log is a pane a screen embeds. It holds the lines once (Arc), builds only the rows on screen, clips rather than wraps, and scrolls, pages and jumps to either end. Drawing the demo’s Log screen at 200x60 took 0.314 ms on average.

struct Journal {
    log: Log,
}

impl Journal {
    fn new(lines: Vec<Line<'static>>) -> Self {
        let mut log = Log::new("Find")
            .placeholder("type to find in the log")
            .hint("enter keeps it · esc clears it · n and N step through");
        log.set_lines(Arc::new(lines));
        Journal { log }
    }
}

impl Screen<Msg> for Journal {
    fn draw(&mut self, frame: &mut Frame, area: Rect, palette: &Palette) {
        self.log.draw(frame, area, palette);
    }

    fn key(&mut self, key: KeyEvent, cx: &mut Cx<'_, Msg>) {
        if let log::Turn::Copy(text) = self.log.key(key) {
            if cx.copy(text) {
                cx.say("Copied.", footer::Tone::Good);
            } else {
                cx.say("Too long to copy; y copies the page.", footer::Tone::Alert);
            }
        }
    }

    fn paste(&mut self, text: &str, _cx: &mut Cx<'_, Msg>) {
        self.log.paste(text);
    }

    fn typing(&self) -> bool {
        self.log.typing()
    }

    fn input(&self) -> Option<InputBar<'_>> {
        self.log.bar()
    }
}

The keys, each the app’s to change (keys, search_keys, hit_keys, copy_keys):

Key	Does
arrows or j, k	scroll a line
pgup, pgdn or ctrl+u, ctrl+d	scroll a page
g, G or home, end	jump to the first or last line
/	find every line holding each word of the query
n, N	step to the next or previous hit
y, Y	copy the page, or every line (OSC 52, up to 48 KiB)

At the bottom it follows new lines as set_lines replaces them, unless follow(false) keeps its place. top(), len(), hits() and hit() feed the screen’s facts. The scrollbar and the range count come from the palette’s bar and count (Colours and words).

$ demo --dump 90x14 --keys "3 / 1999 enter n"
 ───────────────────────────────────────── demo ───────────────────────── workspace one ─
                             1 Home  2 What to do next  3 Log
                           line 11998 of 20000 · 2 of 12 found
 ─ Log ──────────────────────────────────────────────────────────────────────────────────
  11998  test      tested part 11998 of 20000                                          │
  11999  package   packed part 11999 of 20000                                          │
  12000  fetch     fetched part 12000 of 20000                                         ╽
  12001  compile   compiled part 12001 of 20000                                        ╿
  12002  link      linked part 12002 of 20000                                          │
                                                                 11,998–12,002 of 20,000

 ────────────────────────────────────────────────────────────────────────────────────────
 ↑↓ scroll · g/G ends · / find · n/N next · o jobs · ctrl+k go to · ctrl+c twice quit

A list that big, rather than a log, wants pito-list’s Shared, which builds only the rows on screen from the app’s own items. The activity screen’s detail is a Log too.

Next: Dumps, benches and frame captures.