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