wp-includes/js/wp-emoji-loader.js

   1 ( function( window, document, settings ) {
   2         var src, ready;
   3
   4         /**
   5          * Detect if the browser supports rendering emoji or flag emoji. Flag emoji are a single glyph
   6          * made of two characters, so some browsers (notably, Firefox OS X) don't support them.
   7          *
   8          * @since 4.2.0
   9          *
  10          * @param type {String} Whether to test for support of "simple" or "flag" emoji.
  11          * @return {Boolean} True if the browser can render emoji, false if it cannot.
  12          */
  13         function browserSupportsEmoji( type ) {
  14                 var canvas = document.createElement( 'canvas' ),
  15                         context = canvas.getContext && canvas.getContext( '2d' ),
  16                         stringFromCharCode = String.fromCharCode,
  17                         tone;
  18
  19                 if ( ! context || ! context.fillText ) {
  20                         return false;
  21                 }
  22
  23                 /*
  24                  * Chrome on OS X added native emoji rendering in M41. Unfortunately,
  25                  * it doesn't work when the font is bolder than 500 weight. So, we
  26                  * check for bold rendering support to avoid invisible emoji in Chrome.
  27                  */
  28                 context.textBaseline = 'top';
  29                 context.font = '600 32px Arial';
  30
  31                 if ( 'flag' === type ) {
  32                         /*
  33                          * This works because the image will be one of three things:
  34                          * - Two empty squares, if the browser doesn't render emoji
  35                          * - Two squares with 'A' and 'U' in them, if the browser doesn't render flag emoji
  36                          * - The Australian flag
  37                          *
  38                          * The first two will encode to small images (1-2KB data URLs), the third will encode
  39                          * to a larger image (4-5KB data URL).
  40                          */
  41                         context.fillText( stringFromCharCode( 55356, 56806, 55356, 56826 ), 0, 0 );
  42                         return canvas.toDataURL().length > 3000;
  43                 } else if ( 'diversity' === type ) {
  44                         /*
  45                          * This tests if the browser supports the Emoji Diversity specification, by rendering an
  46                          * emoji with no skin tone specified (in this case, Santa). It then adds a skin tone, and
  47                          * compares if the emoji rendering has changed.
  48                          */
  49                         context.fillText( stringFromCharCode( 55356, 57221 ), 0, 0 );
  50                         tone = context.getImageData( 16, 16, 1, 1 ).data.toString();
  51                         context.fillText( stringFromCharCode( 55356, 57221, 55356, 57343 ), 0, 0 );
  52                         // Chrome has issues comparing arrays, so we compare it as a  string, instead.
  53                         return tone !== context.getImageData( 16, 16, 1, 1 ).data.toString();
  54                 } else {
  55                         if ( 'simple' === type ) {
  56                                 /*
  57                                  * This creates a smiling emoji, and checks to see if there is any image data in the
  58                                  * center pixel. In browsers that don't support emoji, the character will be rendered
  59                                  * as an empty square, so the center pixel will be blank.
  60                                  */
  61                                 context.fillText( stringFromCharCode( 55357, 56835 ), 0, 0 );
  62                         } else {
  63                                 /*
  64                                  * To check for Unicode 8 support, let's try rendering the most important advancement
  65                                  * that the Unicode Consortium have made in years: the burrito.
  66                                  */
  67                                 context.fillText( stringFromCharCode( 55356, 57135 ), 0, 0 );
  68                         }
  69                         return context.getImageData( 16, 16, 1, 1 ).data[0] !== 0;
  70                 }
  71         }
  72
  73         function addScript( src ) {
  74                 var script = document.createElement( 'script' );
  75
  76                 script.src = src;
  77                 script.type = 'text/javascript';
  78                 document.getElementsByTagName( 'head' )[0].appendChild( script );
  79         }
  80
  81         settings.supports = {
  82                 simple:    browserSupportsEmoji( 'simple' ),
  83                 flag:      browserSupportsEmoji( 'flag' ),
  84                 unicode8:  browserSupportsEmoji( 'unicode8' ),
  85                 diversity: browserSupportsEmoji( 'diversity' )
  86         };
  87
  88         settings.DOMReady = false;
  89         settings.readyCallback = function() {
  90                 settings.DOMReady = true;
  91         };
  92
  93         if ( ! settings.supports.simple || ! settings.supports.flag || ! settings.supports.unicode8 || ! settings.supports.diversity ) {
  94                 ready = function() {
  95                         settings.readyCallback();
  96                 };
  97
  98                 if ( document.addEventListener ) {
  99                         document.addEventListener( 'DOMContentLoaded', ready, false );
 100                         window.addEventListener( 'load', ready, false );
 101                 } else {
 102                         window.attachEvent( 'onload', ready );
 103                         document.attachEvent( 'onreadystatechange', function() {
 104                                 if ( 'complete' === document.readyState ) {
 105                                         settings.readyCallback();
 106                                 }
 107                         } );
 108                 }
 109
 110                 src = settings.source || {};
 111
 112                 if ( src.concatemoji ) {
 113                         addScript( src.concatemoji );
 114                 } else if ( src.wpemoji && src.twemoji ) {
 115                         addScript( src.twemoji );
 116                         addScript( src.wpemoji );
 117                 }
 118         }
 119
 120 } )( window, document, window._wpemojiSettings );