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(* Demo to show how one could achieve cairo drawing on a Graphics
window. Note that using XLib or GTK would be *much* faster. *)
open Printf
open Bigarray
open Cairo
let pi2 = 8. *. atan 1.
let lastfps = ref (Unix.gettimeofday ())
let frames = ref 0
let fps = ref 0.
let update_fps () =
let t = Unix.gettimeofday () in
let dt = t -. !lastfps in
if dt > 0.5 then (
fps := float !frames /. dt;
frames := 0;
lastfps := t
);
incr frames
let draw cr width height x y =
let x = x -. width *. 0.5 and y = y -. height *. 0.5 in
let r = 0.5 *. sqrt (x *. x +. y *. y) in
set_source_rgba cr 0. 1. 0. 0.5;
arc cr (0.5 *. width) (0.35 *. height) r 0. pi2;
fill cr;
set_source_rgba cr 1. 0. 0. 0.5;
arc cr (0.35 *. width) (0.65 *. height) r 0. pi2;
fill cr;
set_source_rgba cr 0. 0. 1. 0.5;
arc cr (0.65 *. width) (0.65 *. height) r 0. pi2;
fill cr;
set_source_rgba cr 1. 1. 0. 1.;
move_to cr (0.05 *. width) (0.95 *. height);
show_text cr (sprintf "%gx%g -- %.0f fps" width height !fps)
let expose () =
let sx = Graphics.size_x ()
and sy = Graphics.size_y ()
and mx, my = Graphics.mouse_pos () in
(* Create a cairo context from a cairo surface and do our drawings
on it. Note: we may cache it between expose events for
incremental drawings but its creation and initialization is not
the time bottleneck here. *)
let cr_img = Image.create Image.RGB24 sx sy in
let cr = create cr_img in
draw cr (float sx) (float sy) (float mx) (float my);
(* Don't forget to flush the surface before using its content. *)
Surface.flush cr_img;
(* Now, access the surface data and convert it to a Graphics.image
that can be drawn on the Graphics window. *)
let data32 = Image.get_data32 cr_img in
let data_img =
Array.init sy
(fun y -> Array.init sx (fun x -> Int32.to_int (data32.{y, x})))
in
Graphics.draw_image (Graphics.make_image data_img) 0 0;
Graphics.synchronize ();
(* Update our fps counter. *)
update_fps ()
let () =
Graphics.open_graph "";
Graphics.auto_synchronize false;
while true do
expose ()
done
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