git.iko.soy/elk
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elk/core/Native/Time.js
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1/*
2import Signal
3import Maybe
4*/
6(function() {
7 'use strict';
9 function timeNow() { return (new window.Date).getTime(); }
11 function fpsWhen(desiredFPS, isOn) {
12 var msPerFrame = 1000 / desiredFPS;
13 var prev = timeNow(), curr = prev, diff = 0, wasOn = true;
14 var ticker = Elm.Signal.constant(diff);
15 function tick(zero) { return function() {
16 curr = timeNow();
17 diff = zero ? 0 : curr - prev;
18 prev = curr;
19 Dispatcher.notify(ticker.id, diff);
20 };
21 }
22 var timeoutID = 0;
23 function f(isOn, t) {
24 if (isOn) {
25 timeoutID = setTimeout(tick(!wasOn && isOn), msPerFrame);
26 } else if (wasOn) {
27 clearTimeout(timeoutID);
28 }
29 wasOn = isOn;
30 return t;
31 }
32 return Elm.Signal.lift2(F2(f))(isOn)(ticker);
33 }
35 function everyWhen(t, isOn) {
36 var clock = Elm.Signal.constant(timeNow());
37 function tellTime() { Dispatcher.notify(clock.id, timeNow()); }
38 setInterval(tellTime, t);
39 return clock;
40 }
42 function since(t, s) {
43 function cmp(a,b) { return !Value.eq(a,b) }
44 var dcount = Elm.Signal.count(Elm.Signal.delay(t)(s));
45 return Elm.Signal.lift2(F2(cmp))(Elm.Signal.count(s))(dcount);
46 }
47 function after(t) {
48 t *= 1000;
49 var thread = Elm.Signal.constant(false);
50 setTimeout(function() { Dispatcher.notify(thread.id, true); }, t);
51 return thread;
52 }
53 function before(t) {
54 t *= 1000;
55 var thread = Elm.Signal.constant(true);
56 setTimeout(function() { Dispatcher.notify(thread.id, false); }, t);
57 return thread;
58 }
59 function read(s) {
60 var t = window.Date.parse(s);
61 return isNaN(t) ? Elm.Maybe.Nothing : Elm.Maybe.Just(t);
62 }
63 Elm.Native.Time = {
64 fpsWhen : F2(fpsWhen),
65 fps : function(t) { return fpsWhen(t, Elm.Signal.constant(true)); },
66 every : function(t) { return everyWhen(t, Elm.Signal.constant(true)) },
67 delay : Elm.Signal.delay,
68 since : F2(since),
69 after : after,
70 before : before,
71 toDate : function(t) { return new window.Date(t); },
72 read : read
73 };
75}());