ui/keyboard/resources/elements/kb-modifier-key.js

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 (function () {
   6
   7   /**
   8    * The possible states of the key.
   9    * @const
  10    * @type {Enum}
  11    */
  12   var KEY_STATES = {
  13     PRESSED: "pressed", // Key-down.
  14     UNLOCKED: "unlocked", // Default state.
  15     TAPPED: "tapped", // Key-down followed by key-up.
  16     CHORDING: "chording", // Chording mode.
  17   };
  18
  19   /**
  20    * A map of the state of all modifier keys.
  21    * @type {Object}
  22    */
  23   var states = {};
  24
  25   Polymer('kb-modifier-key', {
  26     up: function(event) {
  27       if (this.state == KEY_STATES.PRESSED)
  28         this.state = KEY_STATES.TAPPED;
  29       else
  30         this.state = KEY_STATES.UNLOCKED;
  31       this.super([event]);
  32     },
  33
  34     down: function(event) {
  35       // First transition state so that populateDetails generates
  36       // correct data.
  37       switch (this.state) {
  38         case KEY_STATES.UNLOCKED:
  39           this.state = KEY_STATES.PRESSED;
  40           break;
  41         case KEY_STATES.TAPPED:
  42           this.state = KEY_STATES.UNLOCKED;
  43           break;
  44         case KEY_STATES.PRESSED:
  45         case KEY_STATES.CHORDING:
  46           // We pressed another key at the same time,
  47           // so ignore second press.
  48           return;
  49         default:
  50           console.error("Undefined key state: " + state);
  51           break;
  52       }
  53       this.super([event]);
  54     },
  55
  56     /**
  57      * Returns whether the modifier for this key is active.
  58      * @return {boolean}
  59      */
  60     isActive: function() {
  61       return this.state != KEY_STATES.UNLOCKED;
  62     },
  63
  64     /**
  65      * Notifies key that a non-control keyed down.
  66      * A control key is defined as one of shift, control or alt.
  67      */
  68     onNonControlKeyDown: function() {
  69       switch(this.state) {
  70         case (KEY_STATES.PRESSED):
  71           this.state = KEY_STATES.CHORDING;
  72           break;
  73       }
  74     },
  75
  76     /**
  77      * Notifies key that a non-control keyed was typed.
  78      * A control key is defined as one of shift, control or alt.
  79      */
  80     onNonControlKeyTyped: function() {
  81        switch(this.state) {
  82          case (KEY_STATES.TAPPED):
  83            this.state = KEY_STATES.UNLOCKED;
  84            break;
  85        }
  86     },
  87
  88     /**
  89      * Called on a pointer-out event. Ends chording.
  90      * @param {event} event The pointer-out event.
  91      */
  92     out: function(event) {
  93       // TODO(rsadam): Add chording event so that we don't reset
  94       // when shift-chording.
  95       if (this.state == KEY_STATES.CHORDING) {
  96         this.state = KEY_STATES.UNLOCKED;
  97       }
  98     },
  99
 100     /*
 101      * Overrides the autoRelease function to enable chording.
 102      */
 103     autoRelease: function() {
 104     },
 105
 106     populateDetails: function(caller) {
 107       var detail = this.super([caller]);
 108       if (this.state != KEY_STATES.UNLOCKED)
 109         detail.activeModifier = this.charValue;
 110       return detail;
 111     },
 112
 113     /**
 114      *  Resets the modifier key state.
 115      */
 116     reset: function() {
 117       this.state = KEY_STATES.UNLOCKED;
 118     },
 119
 120     get state() {
 121       var key = this.charValue;
 122       if (!key)
 123         console.error("missing key for kb-modifier-key state: " + this);
 124       // All keys default to the unlock state.
 125       if (!(key in states))
 126         states[key] = KEY_STATES.UNLOCKED;
 127       return states[key];
 128     },
 129
 130     set state(value) {
 131       var key = this.charValue;
 132       states[key] = value;
 133     }
 134   });
 135 })();