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 ( type === 'flag' ) {

    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 'G' and 'B' in them, if the browser doesn't render flag emoji

    34 			 * - The British 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, 56812, 55356, 56807 ), 0, 0 );

    40 			return canvas.toDataURL().length > 3000;

    41 		} else {

    42 			/*

    43 			 * This creates a smiling emoji, and checks to see if there is any image data in the

    44 			 * center pixel. In browsers that don't support emoji, the character will be rendered

    45 			 * as an empty square, so the center pixel will be blank.

    46 			 */

    47 			context.fillText( String.fromCharCode( 55357, 56835 ), 0, 0 );

    48 			return context.getImageData( 16, 16, 1, 1 ).data[0] !== 0;

    49 		}

    50 	}

    51 

    52 	function addScript( src ) {

    53 		var script = document.createElement( 'script' );

    54 

    55 		script.src = src;

    56 		script.type = 'text/javascript';

    57 		document.getElementsByTagName( 'head' )[0].appendChild( script );

    58 	}

    59 

    60 	settings.supports = {

    61 		simple: browserSupportsEmoji( 'simple' ),

    62 		flag:   browserSupportsEmoji( 'flag' )

    63 	};

    64 

    65 	settings.DOMReady = false;

    66 	settings.readyCallback = function() {

    67 		settings.DOMReady = true;

    68 	};

    69 

    70 	if ( ! settings.supports.simple || ! settings.supports.flag ) {

    71 		ready = function() {

    72 			settings.readyCallback();

    73 		};

    74 

    75 		if ( document.addEventListener ) {

    76 			document.addEventListener( 'DOMContentLoaded', ready, false );

    77 			window.addEventListener( 'load', ready, false );

    78 		} else {

    79 			window.attachEvent( 'onload', ready );

    80 			document.attachEvent( 'onreadystatechange', function() {

    81 				if ( 'complete' === document.readyState ) {

    82 					settings.readyCallback();

    83 				}

    84 			} );

    85 		}

    86 

    87 		src = settings.source || {};

    88 

    89 		if ( src.concatemoji ) {

    90 			addScript( src.concatemoji );

    91 		} else if ( src.wpemoji && src.twemoji ) {

    92 			addScript( src.twemoji );

    93 			addScript( src.wpemoji );

    94 		}

    95 	}

    96 

    97 } )( window, document, window._wpemojiSettings );