2D graphics animation tool using cairo rust binding and ffmpeg

00_rust_cairo

2D graphics animation tool using cairo rust binding and ffmpeg

main.rs

extern crate cairo;

use std::io::Write;
use std::process::{Command, Stdio};
use std::f64::consts::PI;
use cairo::{ImageSurface, Format, Context};

fn draw(surface: &ImageSurface, f: i32) {
    let cr = Context::new(surface);
    let width = surface.get_width() as f64;
    let height = surface.get_height() as f64;
    let dx = f as f64 * 1.0;

    cr.set_source_rgb(1.0, 1.0, 1.0);
    cr.paint();

    let cx = width / 2.0;
    let cy = height / 2.0;
    let r = cy;
    let cstart = -0.5 * PI;
    let cend = cstart + 2.0 * PI * ((f + 1) as f64) / 300.0;
    cr.move_to(cx, cy);
    cr.line_to(cx, 0.0);
    cr.arc(cx, cy, r, cstart, cend);
    cr.line_to(cx, cy);
    cr.set_source_rgba(0.0, 0.5, 0.0, 0.2);
    cr.fill();

    cr.select_font_face(
        "sans-serif",
        cairo::FontSlant::Normal,
        cairo::FontWeight::Normal,
    );
    cr.set_font_size(70.0);
    cr.move_to(600.0 - dx, 100.0);
    cr.set_source_rgb(0.0, 0.0, 1.0);
    cr.show_text("Hello, world! 1234567890");
    cr.fill();
}

fn make_cmdline(width: i32, height: i32, framerate: i32) -> String {
    format!(
        "ffmpeg -f rawvideo -pix_fmt bgra -s {width}x{height} -i - -pix_fmt yuv420p -r {framerate} -y out.mp4",
        width = width,
        height = height,
        framerate = framerate
    )
}

fn make_movie(width: i32, height: i32, framerate: i32, frames: i32) {
    let mut surface =
        ImageSurface::create(Format::ARgb32, width, height).expect("Couldn't create surface");
    let mut child = Command::new("/bin/sh")
        .args(&["-c", &make_cmdline(width, height, framerate)])
        .stdin(Stdio::piped())
        .spawn()
        .expect("failed to execute child");
    {
        // limited borrow of stdin
        let child_stdin = child.stdin.as_mut().expect("failed to get stdin");

        (0..frames).for_each(|f| {
            draw(&surface, f);
            let d = surface.get_data().expect("Failed to get_data");
            child_stdin.write_all(&d).expect("Failed to write to file");
        });
    }
    child.wait().expect("child process wasn't running");
}

fn main() {
    make_movie(1280, 720, 30, 300);
}