Crate jiwa 

Terminal text reveal animations.

Two small primitives, both deliberately renderer-agnostic:

• RevealHandle — typewriter that appears one grapheme at a time, each grapheme fading from one Rgb to another over a configurable window.
• PulseHandle — a single symbol that “breathes” between two colors on a sinusoidal cycle.

Both handles are pure: no I/O, no thread, no global clock. Every time-bearing entry point takes an explicit std::time::Instant so tests can step time deterministically and so the caller controls when frames are emitted. You snapshot each animation once per redraw at whatever cadence your renderer already runs (a TUI event loop, a crossterm poll, etc.) and map the returned Rgb values to your renderer’s color type.

Example

use std::time::{Duration, Instant};
use jiwa::{RevealHandle, RevealOpts};

let start = Instant::now();
let reveal = RevealHandle::start_at("Hello, 世界", RevealOpts::default(), start);

// Render at any later instant — the caller chooses the cadence.
let frame = reveal.snapshot(start + Duration::from_millis(100));
for g in &frame {
    // `g.text` is the grapheme cluster to draw, `g.color` is the
    // RGB to draw it in, `g.progress` is the 0..=1 fade progress.
    print!("{}", g.text);
}

Why “jiwa”

Japanese onomatopoeia for something appearing slowly, “じわじわ” — the visual feel the typewriter+fade combination is going for.

Renderer mapping

Rgb is intentionally not a wrapper around crossterm::style::Color or ratatui::style::Color — pulling either in would force every downstream caller to agree on the same renderer. Map at the call site instead:

use ratatui::style::Color;
let g = reveal.snapshot(now);
let color = Color::Rgb(g[0].color.0, g[0].color.1, g[0].color.2);

Re-exports

pub use color::lerp_rgb;

pub use color::Rgb;

pub use pulse::PulseFrame;

pub use pulse::PulseHandle;

pub use pulse::PulseOpts;

pub use reveal::RevealHandle;

pub use reveal::RevealOpts;

pub use reveal::RevealedGrapheme;

Modules

color

24-bit color primitives shared by reveal and pulse.

pulse

Single-symbol “breathing” animation.

reveal

Typewriter + per-grapheme fade-in.