Home | History | Annotate | Download | only in elements 
      1 <!--
      2   -- Copyright 2013 The Chromium Authors. All rights reserved.
      3   -- Use of this source code is governed by a BSD-style license that can be
      4   -- found in the LICENSE file.
      5   -->
      6 
      7 <polymer-element name="kb-altkey-data" attributes="char list">
      8 <script>
      9   (function() {
     10     var altKeys = {};
     11     var idMap = {};
     12 
     13     /**
     14      * Creates a unique identifier based on the key provided.
     15      * This identifier is of the form 'idHASH' where HASH is
     16      * the concatenation of the keycodes of every character in the string.
     17      * @param {string} key Key for which we want an identifier.
     18      * @return {string} The unique id for key.
     19      */
     20     function createId(key) {
     21       var hash = key.split('').map(
     22         // Returns the key code for the character.
     23         function(character) {
     24           return character.charCodeAt(0);
     25         }
     26       ).join('');
     27       return 'id' + hash;
     28     }
     29 
     30     Polymer('kb-altkey-data', {
     31 
     32       /**
     33        * Retrieves a list of alternative keys to display on a long-press.
     34        * @param {string} char The base character.
     35        * @param {boolean=} opt_force If true, force the creation of a list
     36        *    even if empty. Used when constructing a set of alternates for keys
     37        *    with hintTexts.
     38        * @return {?Object.{id: string, list: string}}
     39        */
     40       getAltkeys: function(char, opt_force) {
     41         var id = idMap[char];
     42         if (id) {
     43           return {
     44             'id': id,
     45             'keys': altKeys[id]
     46           };
     47         }
     48         if (opt_force) {
     49           return {
     50             'id': createId(char),
     51             'keys': []
     52           };
     53         }
     54       },
     55 
     56       /**
     57        * Registers lists of alternative keys displayed on a long-press.
     58        * @param {Object.<string, Array.<string>>} data Mapping of characters to
     59        *     lists of alternatives.
     60        */
     61       registerAltkeys: function(data) {
     62         for (var key in data) {
     63           var id = idMap[key];
     64           if (!id)
     65             idMap[key] = id = createId(key);
     66           altKeys[id] = data[key];
     67         }
     68       },
     69 
     70       /**
     71        * Creates a list of alternate candidates to display in a popup on a
     72        * long-press.
     73        * @param {string} char The base character.
     74        * @param {number} maxLeftOffset Limits the number of candidates
     75        *      displayed to the left of the base character to prevent running
     76        *      past the left edge of the keyboard.
     77        * @param {number} maxRightOffset Limits the number of candidates
     78        *     displayed to the right of the base character to prvent running
     79        *     past the right edge of the keyboard.
     80        * @param {string=} opt_additionalKeys Optional list of additional keys
     81        *     to include in the candidates list.
     82        */
     83       createAltkeySet: function(char,
     84                                 maxLeftOffset,
     85                                 maxRightOffset,
     86                                 opt_additionalKeys) {
     87         var altKeys = this.getAltkeys(char, true /* forced */);
     88         if (altKeys) {
     89           var list = altKeys.keys;
     90           if (opt_additionalKeys)
     91             list = opt_additionalKeys.split('').concat(list);
     92           list = [char].concat(list);
     93 
     94           var set = document.createElement('kb-altkey-set');
     95           // Candiates are approximately in decreasing order of usage, and are
     96           // arranged in a single row in the popup display.  To reduce the
     97           // expected length of the drag gesture for selecting a candidate,
     98           // more likely candidates are placed in the center of the popup,
     99           // which is achieved by alternately appending and prepending
    100           // candiates in the alternatives popup.
    101           var prepend = false;
    102           var leftOffset = 0;
    103           var rightOffset = 0;
    104           for (var i = 0; i < list.length; i++) {
    105             var key = document.createElement('kb-altkey');
    106             key.textContent = list[i];
    107             if (prepend) {
    108               set.insertBefore(key, set.firstChild);
    109               leftOffset++;
    110             } else {
    111               set.appendChild(key);
    112               rightOffset++;
    113             }
    114             prepend = !prepend;
    115             // Verify that there is room remaining for an additional character.
    116             if (leftOffset == maxLeftOffset && rightOffset == maxRightOffset)
    117               break;
    118             if (leftOffset == maxLeftOffset)
    119               prepend = false;
    120             else if (rightOffset == maxRightOffset)
    121               prepend = true;
    122           }
    123           set.id = altKeys.id;
    124           set.offset = leftOffset;
    125           return set;
    126         }
    127       },
    128 
    129     });
    130   })();
    131 </script>
    132 </polymer-element>
    133