grapher.ml

open Graphics

let string_of_float f =
  let st = string_of_float f in
  if st.[(String.length st) - 1] = '.'
  then st ^ "0"
  else st

let set_up title minx maxx miny maxy assoc_lst =

  Graphics.open_graph "";
  resize_window 800 800;
  set_window_title ("OCalc - graphing " ^ title);
  set_color black;
  set_line_width 1;
  moveto 80 720;
  set_text_size 1000;
  draw_string title;
  (*plot axes*)
  let xoffsets = (maxx -. minx) /. 10. in
  let yoffsets = (maxy -. miny) /. 10. in
  moveto 400 0;
  lineto 400 800;
  moveto 0 400;
  lineto 800 400;

  (*set markers*)
  let x = ref 0 in
  let xm = ref 0. in
  while !x < 800 do
    moveto !x 385;
    lineto !x 415;
    moveto !x 360;
    draw_string ((minx +. !xm) |> string_of_float);
    xm := (!xm +. xoffsets);
    x := (!x + 80);
  done;

  let y = ref 0 in
  let ym = ref 0. in
  while !y < 800 do
    moveto 385 !y;
    lineto 415 !y;
    moveto 415 !y;
    draw_string ((miny +. !ym) |> string_of_float);
    ym := (!ym +. yoffsets);
    y := (!y + 80);
  done;

  let transformx x = ((x -. minx) /. (maxx -. minx)) *. 800. in
  let transformy y = ((y -. miny) /. (maxy -. miny)) *. 800. in
  let finallst = List.map (fun (x, y) -> (transformx x),(transformy y)) assoc_lst in
  let filterlst = List.filter (fun (x, y) -> y >0. && y < 800.) finallst in

  let firstx = List.hd filterlst |> fst |> int_of_float in
  let firsty = List.hd filterlst |> snd |> int_of_float in
  moveto firstx firsty;
  set_color magenta;
  set_line_width 3;
  for i=0 to (List.length filterlst)-1 do
    let y = (i |> List.nth filterlst |> snd |> int_of_float) in
    if y > 0 && y < 800 then
    lineto (i |> List.nth filterlst |> fst |> int_of_float) y
    else ()
  done;

  ()