CODEWITHSUNDEEP
ocaml
Thomas Vanhelden
Thomas Vanhelden

Reputation: 897

OCaml - Keeping a visual timer

I'm making a sudoku game with in OCaml with the Graphics library.

I'm trying to add a timer at the top so that the player can see how long he's taking to solve the sudoku. I've looked around and the Lwt library seems to be what I'm looking for.

To draw the timer I wrote a function draw_time, the content of the function is too long and not important, but it has this kind of structure:

let rec hello () = 
    Lwt.bind (Lwt_unix.sleep 14400.) 
       (fun () -> print_endline "Hello, world !"; hello ())
Lwt.async (hello)

I've tested it and the function does work as it's supposed to.

The main loop of my game looks like this:

let main_loop gs f_init f_end f_key f_mouse = 

    f_init;
        let timer = draw_time () in
        try 
            while true do
                try 
                    if gs.completed <> true then
                        let event = Graphics.wait_next_event event_types in
                            if event.Graphics.keypressed then 
                                f_key event.Graphics.key
                            else if event.Graphics.button then 
                                f_mouse event.Graphics.mouse_x event.Graphics.mouse_y               
                with 
                | _ -> raise End
            done
        with 
        | End  -> f_end () 
    ;;

This doesn't seem to work. The program only executes draw_time when I close the window (and the program) and not when the window is open and the timer is supposed to be drawn.

What am I doing wrong exactly?

Upvotes: 0

Views: 340

Answers (1)

ivg
ivg

Reputation: 35270

In order to run Lwt program, you need to start the main loop, that will process your threads, 

let () = Lwt_main.run (Lwt_io.printl "Hello, world!")

Lwt has code that will integrate Lwt main loop into the Glib. But, as far as I know, there is no such integration for Graphics module.

You may find async_graphics interesting, it is an integration of the Async library, that is quite near to Lwt with Graphics module. It was even mentioned in Real World OCaml

Upvotes: 2

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