( function( window, document, settings ) {
var src, ready;
/**
* Detect if the browser supports rendering emoji or flag emoji. Flag emoji are a single glyph
* made of two characters, so some browsers (notably, Firefox OS X) don't support them.
*
* @since 4.2.0
*
* @param type {String} Whether to test for support of "simple" or "flag" emoji.
* @return {Boolean} True if the browser can render emoji, false if it cannot.
*/
function browserSupportsEmoji( type ) {
var canvas = document.createElement( 'canvas' ),
context = canvas.getContext && canvas.getContext( '2d' );
if ( ! context || ! context.fillText ) {
return false;
}
/*
* Chrome on OS X added native emoji rendering in M41. Unfortunately,
* it doesn't work when the font is bolder than 500 weight. So, we
* check for bold rendering support to avoid invisible emoji in Chrome.
*/
context.textBaseline = 'top';
context.font = '600 32px Arial';
if ( type === 'flag' ) {
/*
* This works because the image will be one of three things:
* - Two empty squares, if the browser doesn't render emoji
* - Two squares with 'G' and 'B' in them, if the browser doesn't render flag emoji
* - The British flag
*
* The first two will encode to small images (1-2KB data URLs), the third will encode
* to a larger image (4-5KB data URL).
*/
context.fillText( String.fromCharCode( 55356, 56812, 55356, 56807 ), 0, 0 );
return canvas.toDataURL().length > 3000;
} else {
/*
* This creates a smiling emoji, and checks to see if there is any image data in the
* center pixel. In browsers that don't support emoji, the character will be rendered
* as an empty square, so the center pixel will be blank.
*/
context.fillText( String.fromCharCode( 55357, 56835 ), 0, 0 );
return context.getImageData( 16, 16, 1, 1 ).data[0] !== 0;
}
}
function addScript( src ) {
var script = document.createElement( 'script' );
script.src = src;
script.type = 'text/javascript';
document.getElementsByTagName( 'head' )[0].appendChild( script );
}
settings.supports = {
simple: browserSupportsEmoji( 'simple' ),
flag: browserSupportsEmoji( 'flag' )
};
settings.DOMReady = false;
settings.readyCallback = function() {
settings.DOMReady = true;
};
if ( ! settings.supports.simple || ! settings.supports.flag ) {
ready = function() {
settings.readyCallback();
};
if ( document.addEventListener ) {
document.addEventListener( 'DOMContentLoaded', ready, false );
window.addEventListener( 'load', ready, false );
} else {
window.attachEvent( 'onload', ready );
document.attachEvent( 'onreadystatechange', function() {
if ( 'complete' === document.readyState ) {
settings.readyCallback();
}
} );
}
src = settings.source || {};
if ( src.concatemoji ) {
addScript( src.concatemoji );
} else if ( src.wpemoji && src.twemoji ) {
addScript( src.twemoji );
addScript( src.wpemoji );
}
}
} )( window, document, window._wpemojiSettings );