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      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 })();
    136