morphing-string

Morph one string into another, one edit at a time.

morphing-string computes a minimal sequence of single-character edits — insertions, deletions, and substitutions — that turns one string into another, then applies them one per call. Driving it from a render loop gives you a text-morphing effect:

Usage

use morphing_string::MorphingString;

let mut string = MorphingString::new("kitten");
string.set_target("mittens");

while !string.progress().is_complete() {
    println!("{}", string.value());
    string.advance();
}

assert_eq!(string.value(), "mittens");

Call advance() to apply one edit and get back a Progress telling you how far along the morph is. Each call does a constant amount of work, independent of how different the two strings are, so you can advance on whatever cadence suits your app — one edit per frame, or a burst per tick.

advance() is a no-op once the morph completes, so a loop of the form while !string.advance().is_complete() is safe to run to exhaustion.

Example

A terminal demo that morphs between lines of a poem, one edit per frame:

cargo run --example tui_poem

The same poem but in a GUI. Source of the demo gif in readme.

cargo run --example gui_poem

Notes

• Zero runtime dependencies.
• Operates on chars, so multi-byte UTF-8 is handled correctly.
• Where the shortest sequence of edits is ambiguous, substitutions are preferred over insertions, and insertions over deletions, which keeps unchanged characters in place for as long as possible.

License

Licensed under the fuck around and find out license v0.1.