Expandable button animation using fltk-rs

expand_button.rs

use fltk::{prelude::*, *};

fn main() {
    let app = app::App::default();
    app::set_visible_focus(false);
    let mut win = window::Window::default().with_size(400, 300);
    win.set_color(enums::Color::White);
    let mut but = button::Button::default()
        .with_size(80, 40)
        .with_label("Expand!")
        .center_of_parent();
    but.set_color(enums::Color::Cyan);
    but.set_frame(enums::FrameType::RFlatBox);
    win.end();
    win.show();
    but.set_callback(|b| {
        if b.y() == 0 {
            return;
        }
        let mut b = b.clone();
        std::thread::spawn(move || loop {
            if b.y() == 0 {
                break;
            }
            b.resize(b.x() - 1, b.y() - 1, b.w() + 2, b.h());
            app::sleep(0.005);
            b.parent().unwrap().redraw();
        });
    });
    app.run().unwrap();
}