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
  17                 if ( ! context || ! context.fillText ) {
  18                         return false;
  19                 }
  20
  21                 /*
  22                  * Chrome on OS X added native emoji rendering in M41. Unfortunately,
  23                  * it doesn't work when the font is bolder than 500 weight. So, we
  24                  * check for bold rendering support to avoid invisible emoji in Chrome.
  25                  */
  26                 context.textBaseline = 'top';
  27                 context.font = '600 32px Arial';
  28
  29                 if ( 'flag' === type ) {
  30                         /*
  31                          * This works because the image will be one of three things:
  32                          * - Two empty squares, if the browser doesn't render emoji
  33                          * - Two squares with 'A' and 'U' in them, if the browser doesn't render flag emoji
  34                          * - The Australian flag
  35                          *
  36                          * The first two will encode to small images (1-2KB data URLs), the third will encode
  37                          * to a larger image (4-5KB data URL).
  38                          */
  39                         context.fillText( String.fromCharCode( 55356, 56806, 55356, 56826 ), 0, 0 );
  40                         return canvas.toDataURL().length > 3000;
  41                 } else {
  42                         if ( 'simple' === type ) {
  43                                 /*
  44                                  * This creates a smiling emoji, and checks to see if there is any image data in the
  45                                  * center pixel. In browsers that don't support emoji, the character will be rendered
  46                                  * as an empty square, so the center pixel will be blank.
  47                                  */
  48                                 context.fillText( String.fromCharCode( 55357, 56835 ), 0, 0 );
  49                         } else {
  50                                 /*
  51                                  * To check for Unicode 8 support, let's try rendering the most important advancement
  52                                  * that the Unicode Consortium have made in years: the burrito.
  53                                  */
  54                                 context.fillText( String.fromCharCode( 55356, 57135 ), 0, 0 );
  55                         }
  56                         return context.getImageData( 16, 16, 1, 1 ).data[0] !== 0;
  57                 }
  58         }
  59
  60         function addScript( src ) {
  61                 var script = document.createElement( 'script' );
  62
  63                 script.src = src;
  64                 script.type = 'text/javascript';
  65                 document.getElementsByTagName( 'head' )[0].appendChild( script );
  66         }
  67
  68         settings.supports = {
  69                 simple:   browserSupportsEmoji( 'simple' ),
  70                 flag:     browserSupportsEmoji( 'flag' ),
  71                 unicode8: browserSupportsEmoji( 'unicode8' )
  72         };
  73
  74         settings.DOMReady = false;
  75         settings.readyCallback = function() {
  76                 settings.DOMReady = true;
  77         };
  78
  79         if ( ! settings.supports.simple || ! settings.supports.flag || ! settings.supports.unicode8 ) {
  80                 ready = function() {
  81                         settings.readyCallback();
  82                 };
  83
  84                 if ( document.addEventListener ) {
  85                         document.addEventListener( 'DOMContentLoaded', ready, false );
  86                         window.addEventListener( 'load', ready, false );
  87                 } else {
  88                         window.attachEvent( 'onload', ready );
  89                         document.attachEvent( 'onreadystatechange', function() {
  90                                 if ( 'complete' === document.readyState ) {
  91                                         settings.readyCallback();
  92                                 }
  93                         } );
  94                 }
  95
  96                 src = settings.source || {};
  97
  98                 if ( src.concatemoji ) {
  99                         addScript( src.concatemoji );
 100                 } else if ( src.wpemoji && src.twemoji ) {
 101                         addScript( src.twemoji );
 102                         addScript( src.wpemoji );
 103                 }
 104         }
 105
 106 } )( window, document, window._wpemojiSettings );