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