/* Image loading / handling */

type t;

exception ImageLoadException(string);

type successCallback = t => unit;
type failureCallback = string => unit;

external raw_load: (string, successCallback, failureCallback) => unit =
  "caml_stb_image_load";
external debug_print: t => unit = "caml_stb_image_debug_print";

external fromColor: (int, int, int, int) => t = "caml_stb_image_from_color";

type dimensions = {
  width: int,
  height: int,
};

external getDimensions: t => dimensions = "caml_stb_image_dimensions";

let load = imgName => {
  let (promise, resolver) = Lwt.task();

  let success = img => Lwt.wakeup_later(resolver, img);
  let failure = message =>
    Lwt.wakeup_later_exn(resolver, ImageLoadException(message));

  raw_load(imgName, success, failure);
  promise;
};

external create:
  Bigarray.Array2.t(int, Bigarray.int8_unsigned_elt, Bigarray.c_layout) => t =
  "caml_createImage";
external destroy: t => unit = "caml_destroyImage";
external getPixels:
  t => Bigarray.Array2.t(int, Bigarray.int8_unsigned_elt, Bigarray.c_layout) =
  "caml_getImagePixels";
external setPixels:
  (
    t,
    Bigarray.Array2.t(int, Bigarray.int8_unsigned_elt, Bigarray.c_layout)
  ) =>
  unit =
  "caml_setImagePixels";
external save: (t, string) => unit = "caml_saveImage";