git.iko.soy/elk
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elk/libraries/Native/Signal/Keyboard.js
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1Elm.Native.Keyboard = {};
2Elm.Native.Keyboard.make = function(elm) {
4 elm.Native = elm.Native || {};
5 elm.Native.Keyboard = elm.Native.Keyboard || {};
6 if (elm.Native.Keyboard.values) return elm.Native.Keyboard.values;
8 // Duplicated from Native.Signal
9 function send(node, timestep, changed) {
10 var kids = node.kids;
11 for (var i = kids.length; i--; ) {
12 kids[i].recv(timestep, changed, node.id);
13 }
14 }
16 var Signal = Elm.Signal.make(elm);
17 var NList = Elm.Native.List.make(elm);
18 var Utils = Elm.Native.Utils.make(elm);
20 var downEvents = Signal.constant(0);
21 var upEvents = Signal.constant(0);
22 var blurEvents = Signal.constant(0);
24 elm.addListener([downEvents.id], document, 'keydown', function down(e) {
25 elm.notify(downEvents.id, e.keyCode);
26 });
28 elm.addListener([upEvents.id], document, 'keyup', function up(e) {
29 elm.notify(upEvents.id, e.keyCode);
30 });
32 elm.addListener([blurEvents.id], document, 'blur', function blur(e) {
33 elm.notify(blurEvents.id, NList.Nil);
34 });
36 function KeyMerge(down, up, blur) {
37 var args = [down,up,blur];
38 this.id = Utils.guid();
39 // Ignore starting values here
40 this.value = NList.Nil
41 this.kids = [];
43 var n = args.length;
44 var count = 0;
45 var isChanged = false;
47 this.recv = function(timestep, changed, parentID) {
48 ++count;
49 if (changed) {
50 // We know this a change must only be one of the following cases
51 if (parentID === down.id && !(NList.member(down.value)(this.value))) {
52 isChanged = true;
53 this.value = NList.Cons(down.value, this.value);
54 }
55 if (parentID === up.id) {
56 isChanged = true;
57 var notEq = function(kc) { return kc !== up.value };
58 this.value = NList.filter(notEq)(this.value);
59 }
60 if (parentID === blur.id) {
61 isChanged = true;
62 this.value = NList.Nil;
63 }
64 }
65 if (count == n) {
66 send(this, timestep, isChanged);
67 isChanged = false;
68 count = 0;
69 }
70 };
72 for (var i = n; i--; ) { args[i].kids.push(this); }
74 }
76 var keysDown = Signal.dropRepeats(new KeyMerge(downEvents,upEvents,blurEvents));
78 function keySignal(f) {
79 var signal = A2(Signal.lift, f, keysDown);
80 // must set the default number of kids to make it possible to filter
81 // these signals if they are not actually used.
82 keysDown.defaultNumberOfKids += 1;
83 signal.defaultNumberOfKids = 1;
84 var filtered = Signal.dropRepeats(signal)
85 filtered.defaultNumberOfKids = 0;
86 return filtered;
87 }
89 function dir(up, down, left, right) {
90 function f(ks) {
91 var x = 0, y = 0;
92 while (ks.ctor === "::") {
93 switch (ks._0) {
94 case left : --x; break;
95 case right: ++x; break;
96 case up : ++y; break;
97 case down : --y; break;
98 }
99 ks = ks._1;
100 }
101 return { _:{}, x:x, y:y };
102 }
103 return keySignal(f);
104 }
106 function is(key) { return keySignal(NList.member(key)); }
108 var lastPressed = downEvents;
110 return elm.Native.Keyboard.values = {
111 isDown:is,
112 directions:F4(dir),
113 keysDown:keysDown,
114 lastPressed:lastPressed
115 };
117};