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Ingy döt Net 2023-07-01 11:58:00 -04:00
parent 7387c8f97b
commit cb5bb5e222
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Task/Call-a-function-in-a-shared-library/OCaml/call-a-function-in-a-shared-library.ocaml Normal file
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open Dlffi
let get_int = function Int v -> v | _ -> failwith "get_int"
let get_ptr = function Ptr v -> v | _ -> failwith "get_ptr"
let get_float = function Float v -> v | _ -> failwith "get_float"
let get_double = function Double v -> v | _ -> failwith "get_double"
let get_string = function String v -> v | _ -> failwith "get_string"
let () =
(* load the library *)
let xlib = dlopen "/usr/lib/libX11.so" [RTLD_LAZY] in
(* load the functions *)
let _open_display = dlsym xlib "XOpenDisplay"
and _default_screen = dlsym xlib "XDefaultScreen"
and _display_width = dlsym xlib "XDisplayWidth"
and _display_height = dlsym xlib "XDisplayHeight"
in
(* wrap functions to provide a higher level interface *)
let open_display ~name = get_ptr(fficall _open_display [| String name |] Return_ptr)
and default_screen ~dpy = get_int(fficall _default_screen [| (Ptr dpy) |] Return_int)
and display_width ~dpy ~scr = get_int(fficall _display_width [| (Ptr dpy); (Int scr) |] Return_int)
and display_height ~dpy ~scr = get_int(fficall _display_height [| (Ptr dpy); (Int scr) |] Return_int)
in
(* use our functions *)
let dpy = open_display ~name:":0" in
let screen_number = default_screen ~dpy in
let width = display_width ~dpy ~scr:screen_number
and height = display_height ~dpy ~scr:screen_number in
Printf.printf "# Screen dimensions are: %d x %d pixels\n" width height;
dlclose xlib;
;;