Initial commit. State 04.2021.

wp-includes/js/wp-emoji-loader.js

@@ -0,0 +1,97 @@
+( 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 );