Computer graphics like it's MS-DOS

minimal_cairo_xcb.rs

// Small example of drawing on a Linux graphics screen, with relatively sane graphics
// primitives and a minimal amount of wacko libraries.
// See: The Unix-Haters Handbook, chapter 7 "The X-Windows Disaster"


extern crate xcb;
extern crate cairo;
extern crate cairo_sys;

use std::mem::transmute;


fn find_visual(conn: &xcb::Connection, visual: xcb::ffi::xcb_visualid_t) -> Option<xcb::Visualtype> {
    let setup: xcb::Setup = conn.get_setup();
    for screen in setup.roots() {
        let d_iter: xcb::DepthIterator = screen.allowed_depths();
        for depth in d_iter {
            for vis in depth.visuals() {
                if visual == vis.visual_id() {
                    return Some(vis)
                }
            }
        }
    }
    None
}

fn main() {
    let (conn, screen_num) = xcb::Connection::connect(None).unwrap();
    let setup = conn.get_setup();
    let screen = setup.roots().nth(screen_num as usize).unwrap();

    let win = conn.generate_id();
    xcb::create_window(&conn,
        xcb::COPY_FROM_PARENT as u8,
        win,
        screen.root(),
        0, 0,
        1024, 768,
        10,
        xcb::WINDOW_CLASS_INPUT_OUTPUT as u16,
        screen.root_visual(), &[
            (xcb::CW_BACK_PIXEL, screen.white_pixel()),
            (xcb::CW_EVENT_MASK,
             xcb::EVENT_MASK_EXPOSURE | xcb::EVENT_MASK_KEY_PRESS),
        ]
    );
    xcb::map_window(&conn, win);
    conn.flush();

    let cairo_conn = cairo::XCBConnection(unsafe { transmute(conn.get_raw_conn()) });
    let cairo_win = cairo::XCBDrawable(win);
    let visual = find_visual(&conn, screen.root_visual());
    let cairo_visual = cairo::XCBVisualType(unsafe { transmute(&mut visual.unwrap().base) });
    let surface = cairo::XCBSurface::create(
        &cairo_conn,
        &cairo_win,
        &cairo_visual,
        1024,
        768).unwrap();

    loop {
        let event = conn.wait_for_event();
        match event {
            None => { break; }
            Some(event) => {
                let r = event.response_type() & !0x80;
                match r {
                    xcb::EXPOSE => {
                        let cr = cairo::Context::new(&surface);
                        cr.scale(120.0, 120.0);
                        cr.set_line_width(0.1);
                        cr.set_source_rgb(0.0, 0.0, 0.0);
                        cr.rectangle(0.25, 0.25, 0.5, 0.5);
                        cr.stroke();
                        conn.flush();
                    },
                    xcb::KEY_PRESS => {
                        let key_press: &xcb::KeyPressEvent = unsafe {
                            xcb::cast_event(&event)
                        };
                        let key_code = key_press.detail();
                        // q to exit
                        if key_code == 24 {
                            break;
                        }
                    },
                    _ => {}
                }
            }
        }
    }
}