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

   1 ( function( window, document, settings ) {
   2         var src, ready, ii, tests;
   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", "flag", "diversity" or "unicode8" 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                         tonedata, tone, tone2;
  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                 switch ( type ) {
  32                         case 'flag':
  33                                 /*
  34                                  * This works because the image will be one of three things:
  35                                  * - Two empty squares, if the browser doesn't render emoji
  36                                  * - Two squares with 'A' and 'U' in them, if the browser doesn't render flag emoji
  37                                  * - The Australian flag
  38                                  *
  39                                  * The first two will encode to small images (1-2KB data URLs), the third will encode
  40                                  * to a larger image (4-5KB data URL).
  41                                  */
  42                                 context.fillText( stringFromCharCode( 55356, 56806, 55356, 56826 ), 0, 0 );
  43                                 return canvas.toDataURL().length > 3000;
  44                         case 'diversity':
  45                                 /*
  46                                  * This tests if the browser supports the Emoji Diversity specification, by rendering an
  47                                  * emoji with no skin tone specified (in this case, Santa). It then adds a skin tone, and
  48                                  * compares if the emoji rendering has changed.
  49                                  */
  50                                 context.fillText( stringFromCharCode( 55356, 57221 ), 0, 0 );
  51                                 tonedata = context.getImageData( 16, 16, 1, 1 ).data;
  52
  53                                 context.fillText( stringFromCharCode( 55356, 57221, 55356, 57343 ), 0, 0 );
  54                                 // Chrome has issues comparing arrays, and Safari has issues converting arrays to strings.
  55                                 // So, we create our own string and compare that, instead.
  56                                 tonedata = context.getImageData( 16, 16, 1, 1 ).data;
  57                                 tone2 = tonedata[0] + ',' + tonedata[1] + ',' + tonedata[2] + ',' + tonedata[3];
  58
  59                                 return tone !== tone2;
  60                         case 'simple':
  61                                 /*
  62                                  * This creates a smiling emoji, and checks to see if there is any image data in the
  63                                  * center pixel. In browsers that don't support emoji, the character will be rendered
  64                                  * as an empty square, so the center pixel will be blank.
  65                                  */
  66                                 context.fillText( stringFromCharCode( 55357, 56835 ), 0, 0 );
  67                                 return context.getImageData( 16, 16, 1, 1 ).data[0] !== 0;
  68                         case 'unicode8':
  69                                 /*
  70                                  * To check for Unicode 8 support, let's try rendering the most important advancement
  71                                  * that the Unicode Consortium have made in years: the burrito.
  72                                  */
  73                                 context.fillText( stringFromCharCode( 55356, 57135 ), 0, 0 );
  74                                 return context.getImageData( 16, 16, 1, 1 ).data[0] !== 0;
  75                 }
  76
  77                 return false;
  78         }
  79
  80         function addScript( src ) {
  81                 var script = document.createElement( 'script' );
  82
  83                 script.src = src;
  84                 script.type = 'text/javascript';
  85                 document.getElementsByTagName( 'head' )[0].appendChild( script );
  86         }
  87
  88         tests = Array( 'simple', 'flag', 'unicode8', 'diversity' );
  89
  90         settings.supports = {
  91                 everything: true,
  92                 everythingExceptFlag: true
  93         };
  94
  95         for( ii = 0; ii < tests.length; ii++ ) {
  96                 settings.supports[ tests[ ii ] ] = browserSupportsEmoji( tests[ ii ] );
  97
  98                 settings.supports.everything = settings.supports.everything && settings.supports[ tests[ ii ] ];
  99
 100                 if ( 'flag' !== tests[ ii ] ) {
 101                         settings.supports.everythingExceptFlag = settings.supports.everythingExceptFlag && settings.supports[ tests[ ii ] ];
 102                 }
 103         }
 104
 105         settings.supports.everythingExceptFlag = settings.supports.everythingExceptFlag && ! settings.supports.flag;
 106
 107         settings.DOMReady = false;
 108         settings.readyCallback = function() {
 109                 settings.DOMReady = true;
 110         };
 111
 112         if ( ! settings.supports.everything ) {
 113                 ready = function() {
 114                         settings.readyCallback();
 115                 };
 116
 117                 if ( document.addEventListener ) {
 118                         document.addEventListener( 'DOMContentLoaded', ready, false );
 119                         window.addEventListener( 'load', ready, false );
 120                 } else {
 121                         window.attachEvent( 'onload', ready );
 122                         document.attachEvent( 'onreadystatechange', function() {
 123                                 if ( 'complete' === document.readyState ) {
 124                                         settings.readyCallback();
 125                                 }
 126                         } );
 127                 }
 128
 129                 src = settings.source || {};
 130
 131                 if ( src.concatemoji ) {
 132                         addScript( src.concatemoji );
 133                 } else if ( src.wpemoji && src.twemoji ) {
 134                         addScript( src.twemoji );
 135                         addScript( src.wpemoji );
 136                 }
 137         }
 138
 139 } )( window, document, window._wpemojiSettings );