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(* Examples by Øyvind Kolås taken from http://cairographics.org/samples/ *)
let pi = 4. *. atan 1.
let draw_arc cr arc =
let xc = 128.
and yc = 128. in
let radius = 100. in
let angle1 = 45. *. pi /. 180.0 in
let angle2 = 180. *. pi /. 180.0 in
Cairo.set_line_width cr 10.;
arc cr xc yc ~r:radius ~a1:angle1 ~a2:angle2;
Cairo.stroke cr;
(* draw helping lines *)
Cairo.set_source_rgba cr 1. 0.2 0.2 0.6;
Cairo.set_line_width cr 6.;
Cairo.arc cr xc yc ~r:10. ~a1:0. ~a2:(2. *. pi);
Cairo.fill cr;
Cairo.arc cr xc yc ~r:radius ~a1:angle1 ~a2:angle1;
Cairo.line_to cr xc yc;
Cairo.arc cr xc yc ~r:radius ~a1:angle2 ~a2:angle2;
Cairo.line_to cr xc yc;
Cairo.stroke cr
let () =
let surface = Cairo.SVG.create "arcs.svg" ~w:500. ~h:300. in
let cr = Cairo.create surface in
(* Arc *)
draw_arc cr Cairo.arc;
Cairo.translate cr 200. 0.;
(* Arc negative *)
Cairo.set_source_rgb cr 0. 0.8 0.;
draw_arc cr Cairo.arc_negative;
Cairo.PNG.write surface "arcs.png";
Cairo.Surface.finish surface
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