https://www.pm.gc.ca/themes/pm_theme/js/textresizedetector.js?tm7t0n

1/**
2 * @fileoverview TextResizeDetector
3 *
4 * Detects changes to font sizes when user changes browser settings
5 * <br>Fires a custom event with the following data:<br><br>
6 *    iBase  : base font size
7 *    iDelta : difference in pixels from previous setting<br>
8 *    iSize  : size in pixel of text<br>
9 *
10 * @author Lawrence Carvalho [email protected]
11 * @version 1.0
12 */
13
14/**
15 * @constructor
16 */
17TextResizeDetector = function () {
18  var el = null;
19  var iIntervalDelay = 200;
20  var iInterval = null;
21  var iCurrSize = -1;
22  var iBase = -1;
23  var aListeners = [];
24  var createControlElement = function () {
25    el = document.createElement('span');
26    el.id = 'textResizeControl';
27    el.innerHTML = '&nbsp;';
28    el.style.position = "absolute";
29    el.style.left = "-9999px";
30    var elC = document.getElementById(TextResizeDetector.TARGET_ELEMENT_ID);
31    // insert before firstChild
32    if (elC) {
33      elC.insertBefore(el,elC.firstChild);
34    }
35    iBase = iCurrSize = TextResizeDetector.getSize();
36  };
37
38  function _stopDetector() {
39    window.clearInterval(iInterval);
40    iInterval = null;
41  };
42  function _startDetector() {
43    if (!iInterval) {
44      iInterval = window.setInterval('TextResizeDetector.detect()',iIntervalDelay);
45    }
46  };
47
48  function _detect() {
49    var iNewSize = TextResizeDetector.getSize();
50
51    if (iNewSize !== iCurrSize) {
52      for (var i = 0; i < aListeners.length; i++) {
53        aListnr = aListeners[i];
54        var oArgs = {  iBase: iBase,iDelta:((iCurrSize != -1) ? iNewSize - iCurrSize + 'px' : "0px"),iSize : iCurrSize = iNewSize};
55        if (!aListnr.obj) {
56          aListnr.fn('textSizeChanged',[oArgs]);
57        }
58        else  {
59          aListnr.fn.apply(aListnr.obj,['textSizeChanged',[oArgs]]);
60        }
61      }
62
63    }
64    return iCurrSize;
65  };
66  var onAvailable = function () {
67
68    if (!TextResizeDetector.onAvailableCount_i ) {
69      TextResizeDetector.onAvailableCount_i = 0;
70    }
71
72    if (document.getElementById(TextResizeDetector.TARGET_ELEMENT_ID)) {
73      TextResizeDetector.init();
74      if (TextResizeDetector.USER_INIT_FUNC){
75        TextResizeDetector.USER_INIT_FUNC();
76      }
77      TextResizeDetector.onAvailableCount_i = null;
78    }
79    else {
80      if (TextResizeDetector.onAvailableCount_i < 600) {
81        TextResizeDetector.onAvailableCount_i++;
82        setTimeout(onAvailable,200)
83      }
84    }
85  };
86  setTimeout(onAvailable,500);
87
88  return {
89    /*
90      * Initializes the detector
91      *
92      * @param {String} sId The id of the element in which to create the control element
93      */
94    init: function () {
95      createControlElement();
96      _startDetector();
97    },
98    /**
99     * Adds listeners to the ontextsizechange event.
100     * Returns the base font size
101     *
102     */
103    addEventListener:function (fn,obj,bScope) {
104      aListeners[aListeners.length] = {
105        fn: fn,
106        obj: obj
107      }
108      return iBase;
109    },
110    /**
111     * performs the detection and fires textSizeChanged event
112     * @return the current font size
113     * @type {integer}
114     */
115    detect:function () {
116      return _detect();
117    },
118    /**
119     * Returns the height of the control element
120     *
121     * @return the current height of control element
122     * @type {integer}
123     */
124    getSize:function () {
125        var iSize;
126        return el.offsetHeight;
127    },
128    /**
129     * Stops the detector
130     */
131    stopDetector:function () {
132      return _stopDetector();
133    },
134    /*
135      * Starts the detector
136      */
137    startDetector:function () {
138      return _startDetector();
139    }
140  }
141}();
142
143TextResizeDetector.TARGET_ELEMENT_ID = 'doc';
144TextResizeDetector.USER_INIT_FUNC = null;