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open Cairo
let pi2 = 8. *. atan 1.
let draw cr width height =
let r = 0.25 *. width in
set_source_rgba cr 0. 1. 0. 0.5;
arc cr (0.5 *. width) (0.35 *. height) ~r ~a1:0. ~a2:pi2;
fill cr;
set_source_rgba cr 1. 0. 0. 0.5;
arc cr (0.35 *. width) (0.65 *. height) ~r ~a1:0. ~a2:pi2;
fill cr;
set_source_rgba cr 0. 0. 1. 0.5;
arc cr (0.65 *. width) (0.65 *. height) ~r ~a1:0. ~a2:pi2;
fill cr;
;;
let expose drawing_area _ev =
let cr = Cairo_gtk.create drawing_area#misc#window in
let allocation = drawing_area#misc#allocation in
draw cr (float allocation.Gtk.width) (float allocation.Gtk.height);
true
let () =
ignore(GMain.init());
let w = GWindow.window ~title:"Gtk demo" ~width:500 ~height:400 () in
ignore(w#connect#destroy ~callback:GMain.quit);
let d = GMisc.drawing_area ~packing:w#add () in
ignore(d#event#connect#expose ~callback:(expose d));
w#show();
GMain.main()
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