git.iko.soy/elk
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elk/libraries/Native/Signal/Time.js
63 lines 1.8 kB history raw
2Elm.Native.Time = function(elm) {
3 'use strict';
5 var Signal = Elm.Signal(elm);
6 var Maybe = Elm.Maybe(elm);
7 var Utils = Elm.Native.Utils(elm);
9 function fpsWhen(desiredFPS, isOn) {
10 var msPerFrame = 1000 / desiredFPS;
11 var prev = Date.now(), curr = prev, diff = 0, wasOn = true;
12 var ticker = Signal.constant(diff);
13 function tick(zero) { return function() {
14 curr = Date.now();
15 diff = zero ? 0 : curr - prev;
16 prev = curr;
17 elm.notify(ticker.id, diff);
18 };
19 }
20 var timeoutID = 0;
21 function f(isOn, t) {
22 if (isOn) {
23 timeoutID = setTimeout(tick(!wasOn && isOn), msPerFrame);
24 } else if (wasOn) {
25 clearTimeout(timeoutID);
26 }
27 wasOn = isOn;
28 return t;
29 }
30 return A3( Signal.lift2, F2(f), isOn, ticker );
31 }
33 function everyWhen(t, isOn) {
34 var clock = Signal.constant(Date.now());
35 var id = setInterval(function tellTime() {
36 if (!elm.notify(clock.id, Date.now())) {
37 clearInterval(id);
38 }
39 }, t);
40 return clock;
41 }
43 function since(t, s) {
44 function cmp(a,b) { return !Utils.eq(a,b); }
45 var dcount = Signal.count(A2(Signal.delay, t, s));
46 return A3( Signal.lift2, F2(cmp), Signal.count(s), dcount );
47 }
48 function read(s) {
49 var t = Date.parse(s);
50 return isNaN(t) ? Maybe.Nothing : Maybe.Just(t);
51 }
52 return elm.Native.Time = {
53 fpsWhen : F2(fpsWhen),
54 fps : function(t) { return fpsWhen(t, Signal.constant(true)); },
55 every : function(t) { return everyWhen(t, Signal.constant(true)) },
56 delay : Signal.delay,
57 timestamp : Signal.timestamp,
58 since : F2(since),
59 toDate : function(t) { return new window.Date(t); },
60 read : read
61 };
63};