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(* -*- coding:utf-8 -*- *)
open Printf
open Cairo
let two_pi = 8. *. atan 1.
let () =
let cr = Cairo.create(Cairo.PDF.create "text_rotate.pdf" ~w:400. ~h:400.) in
(* Take the cont from the command line if given: *)
let font = try Sys.argv.(1) with _ -> "Georgia" in
select_font_face cr font;
set_font_size cr 50.0;
let x0 = 200. and y0 = 200. in
translate cr x0 y0;
save cr;
set_source_rgba cr 1. 0. 0. 0.5;
move_to cr (-150.) 0.; line_to cr 300. 0.; stroke cr;
move_to cr 0. (-150.); line_to cr 0. 300.; stroke cr;
restore cr;
let n = 4 in
let da = two_pi /. float n in
move_to cr 0. 0.;
for i = 0 to n - 1 do
save cr;
let angle = float i *. da in
set_source_rgba cr 0. 0. 0. (float(n - i) /. float n);
rotate cr angle;
show_text cr (sprintf "j φ=%g°" (360. *. float i /. float n));
set_source_rgba cr 0. 0. 1. 0.3;
arc cr 0. 0. ~r:2. ~a1:0. ~a2:two_pi;
fill cr;
restore cr;
done;
Surface.finish(get_target cr)
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