Correct way to get the screen's refresh rate?

[crsaracco]

I'm attempting to get the refresh rate of the screen, similar to the info that xrandr gives you.

Here's what I have so far (not final API for what I'm doing, but good enough to post here):

fn refresh_rate(&self) {
    let conn = Application::get_connection();

    let cookie = xcb::randr::get_screen_info(&conn, self.window_id);
    let reply = cookie.get_reply().unwrap();

    let rates = reply.rates();
    for (i, rate) in rates.enumerate() {
        println!("{:?}", rate.rates());
    }
}

That println gives me [50], but xrandr is giving me 60.00.

Questions:

• Obviously, first, why is it different? What's the correct way to do it?
• What units is the result in? I'm surprised it's in u16s, instead of something like a float (that xrandr is giving me)
• I saw somewhere else that I might have to call xcb_randr_query_version on my connection (major.minor >= 1.1) to get this to work right -- is this the case? I'm doing it as of right now, but I'm not sure if I'm doing it correctly. Also, what's a good major/minor to set here? Any good safe defaults for portability?
• Is it worth updating randr_screen_info.rs to show how to get this information?

Thanks!

[rtbo]

Hi, What I get with get_screen_info.rates seems completely erratic (thousands of fields, most of them are zero ?? could be a bug here...). This is not the right way to do.

Looking at the source of xrandr, the refresh rate is obtained from randr::get_screen_resources, then modes. The actual rate is calculated by mode_refresh