import hljs from './highlight-core.js' import './highlight-line-numbers.js' /*! * reveal.js plugin that adds syntax highlight support. */ let Plugin = { id: 'highlight', HIGHLIGHT_STEP_DELIMITER: '|', HIGHLIGHT_LINE_DELIMITER: ',', HIGHLIGHT_LINE_RANGE_DELIMITER: '-', /** * Highlights code blocks withing the given deck. * * Note that this can be called multiple times if * there are multiple presentations on one page. * * @param {Reveal} reveal the reveal.js instance */ init: function( reveal ) { // Read the plugin config options and provide fallbacks var config = reveal.getConfig().highlight || {}; config.highlightOnLoad = typeof config.highlightOnLoad === 'boolean' ? config.highlightOnLoad : true; config.escapeHTML = typeof config.escapeHTML === 'boolean' ? config.escapeHTML : true; [].slice.call( reveal.getRevealElement().querySelectorAll( 'pre code' ) ).forEach( function( block ) { // Trim whitespace if the "data-trim" attribute is present if( block.hasAttribute( 'data-trim' ) && typeof block.innerHTML.trim === 'function' ) { block.innerHTML = betterTrim( block ); } // Escape HTML tags unless the "data-noescape" attrbute is present if( config.escapeHTML && !block.hasAttribute( 'data-noescape' )) { block.innerHTML = block.innerHTML.replace( //g, '>' ); } // Re-highlight when focus is lost (for contenteditable code) block.addEventListener( 'focusout', function( event ) { hljs.highlightBlock( event.currentTarget ); }, false ); if( config.highlightOnLoad ) { Plugin.highlightBlock( block ); } } ); // If we're printing to PDF, scroll the code highlights of // all blocks in the deck into view at once reveal.on( 'pdf-ready', function() { [].slice.call( reveal.getRevealElement().querySelectorAll( 'pre code[data-line-numbers].current-fragment' ) ).forEach( function( block ) { Plugin.scrollHighlightedLineIntoView( block, {}, true ); } ); } ); }, /** * Highlights a code block. If the node has the * 'data-line-numbers' attribute we also generate slide * numbers. * * If the block contains multiple line highlight steps, * we clone the block and create a fragment for each step. */ highlightBlock: function( block ) { hljs.highlightBlock( block ); // Don't generate line numbers for empty code blocks if( block.innerHTML.trim().length === 0 ) return; if( block.hasAttribute( 'data-line-numbers' ) ) { hljs.lineNumbersBlock( block, { singleLine: true } ); var scrollState = { currentBlock: block }; // If there is at least one highlight step, generate // fragments var highlightSteps = Plugin.deserializeHighlightSteps( block.getAttribute( 'data-line-numbers' ) ); if( highlightSteps.length > 1 ) { // If the original code block has a fragment-index, // each clone should follow in an incremental sequence var fragmentIndex = parseInt( block.getAttribute( 'data-fragment-index' ), 10 ); if( typeof fragmentIndex !== 'number' || isNaN( fragmentIndex ) ) { fragmentIndex = null; } // Generate fragments for all steps except the original block highlightSteps.slice(1).forEach( function( highlight ) { var fragmentBlock = block.cloneNode( true ); fragmentBlock.setAttribute( 'data-line-numbers', Plugin.serializeHighlightSteps( [ highlight ] ) ); fragmentBlock.classList.add( 'fragment' ); block.parentNode.appendChild( fragmentBlock ); Plugin.highlightLines( fragmentBlock ); if( typeof fragmentIndex === 'number' ) { fragmentBlock.setAttribute( 'data-fragment-index', fragmentIndex ); fragmentIndex += 1; } else { fragmentBlock.removeAttribute( 'data-fragment-index' ); } // Scroll highlights into view as we step through them fragmentBlock.addEventListener( 'visible', Plugin.scrollHighlightedLineIntoView.bind( Plugin, fragmentBlock, scrollState ) ); fragmentBlock.addEventListener( 'hidden', Plugin.scrollHighlightedLineIntoView.bind( Plugin, fragmentBlock.previousSibling, scrollState ) ); } ); block.removeAttribute( 'data-fragment-index' ) block.setAttribute( 'data-line-numbers', Plugin.serializeHighlightSteps( [ highlightSteps[0] ] ) ); } // Scroll the first highlight into view when the slide // becomes visible. Note supported in IE11 since it lacks // support for Element.closest. var slide = typeof block.closest === 'function' ? block.closest( 'section:not(.stack)' ) : null; if( slide ) { var scrollFirstHighlightIntoView = function() { Plugin.scrollHighlightedLineIntoView( block, scrollState, true ); slide.removeEventListener( 'visible', scrollFirstHighlightIntoView ); } slide.addEventListener( 'visible', scrollFirstHighlightIntoView ); } Plugin.highlightLines( block ); } }, /** * Animates scrolling to the first highlighted line * in the given code block. */ scrollHighlightedLineIntoView: function( block, scrollState, skipAnimation ) { cancelAnimationFrame( scrollState.animationFrameID ); // Match the scroll position of the currently visible // code block if( scrollState.currentBlock ) { block.scrollTop = scrollState.currentBlock.scrollTop; } // Remember the current code block so that we can match // its scroll position when showing/hiding fragments scrollState.currentBlock = block; var highlightBounds = this.getHighlightedLineBounds( block ) var viewportHeight = block.offsetHeight; // Subtract padding from the viewport height var blockStyles = getComputedStyle( block ); viewportHeight -= parseInt( blockStyles.paddingTop ) + parseInt( blockStyles.paddingBottom ); // Scroll position which centers all highlights var startTop = block.scrollTop; var targetTop = highlightBounds.top + ( Math.min( highlightBounds.bottom - highlightBounds.top, viewportHeight ) - viewportHeight ) / 2; // Account for offsets in position applied to the // that holds our lines of code var lineTable = block.querySelector( '.hljs-ln' ); if( lineTable ) targetTop += lineTable.offsetTop - parseInt( blockStyles.paddingTop ); // Make sure the scroll target is within bounds targetTop = Math.max( Math.min( targetTop, block.scrollHeight - viewportHeight ), 0 ); if( skipAnimation === true || startTop === targetTop ) { block.scrollTop = targetTop; } else { // Don't attempt to scroll if there is no overflow if( block.scrollHeight <= viewportHeight ) return; var time = 0; var animate = function() { time = Math.min( time + 0.02, 1 ); // Update our eased scroll position block.scrollTop = startTop + ( targetTop - startTop ) * Plugin.easeInOutQuart( time ); // Keep animating unless we've reached the end if( time < 1 ) { scrollState.animationFrameID = requestAnimationFrame( animate ); } }; animate(); } }, /** * The easing function used when scrolling. */ easeInOutQuart: function( t ) { // easeInOutQuart return t<.5 ? 8*t*t*t*t : 1-8*(--t)*t*t*t; }, getHighlightedLineBounds: function( block ) { var highlightedLines = block.querySelectorAll( '.highlight-line' ); if( highlightedLines.length === 0 ) { return { top: 0, bottom: 0 }; } else { var firstHighlight = highlightedLines[0]; var lastHighlight = highlightedLines[ highlightedLines.length -1 ]; return { top: firstHighlight.offsetTop, bottom: lastHighlight.offsetTop + lastHighlight.offsetHeight } } }, /** * Visually emphasize specific lines within a code block. * This only works on blocks with line numbering turned on. * * @param {HTMLElement} block a block * @param {String} [linesToHighlight] The lines that should be * highlighted in this format: * "1" = highlights line 1 * "2,5" = highlights lines 2 & 5 * "2,5-7" = highlights lines 2, 5, 6 & 7 */ highlightLines: function( block, linesToHighlight ) { var highlightSteps = Plugin.deserializeHighlightSteps( linesToHighlight || block.getAttribute( 'data-line-numbers' ) ); if( highlightSteps.length ) { highlightSteps[0].forEach( function( highlight ) { var elementsToHighlight = []; // Highlight a range if( typeof highlight.end === 'number' ) { elementsToHighlight = [].slice.call( block.querySelectorAll( 'table tr:nth-child(n+'+highlight.start+'):nth-child(-n+'+highlight.end+')' ) ); } // Highlight a single line else if( typeof highlight.start === 'number' ) { elementsToHighlight = [].slice.call( block.querySelectorAll( 'table tr:nth-child('+highlight.start+')' ) ); } if( elementsToHighlight.length ) { elementsToHighlight.forEach( function( lineElement ) { lineElement.classList.add( 'highlight-line' ); } ); block.classList.add( 'has-highlights' ); } } ); } }, /** * Parses and formats a user-defined string of line * numbers to highlight. * * @example * Plugin.deserializeHighlightSteps( '1,2|3,5-10' ) * // [ * // [ { start: 1 }, { start: 2 } ], * // [ { start: 3 }, { start: 5, end: 10 } ] * // ] */ deserializeHighlightSteps: function( highlightSteps ) { // Remove whitespace highlightSteps = highlightSteps.replace( /\s/g, '' ); // Divide up our line number groups highlightSteps = highlightSteps.split( Plugin.HIGHLIGHT_STEP_DELIMITER ); return highlightSteps.map( function( highlights ) { return highlights.split( Plugin.HIGHLIGHT_LINE_DELIMITER ).map( function( highlight ) { // Parse valid line numbers if( /^[\d-]+$/.test( highlight ) ) { highlight = highlight.split( Plugin.HIGHLIGHT_LINE_RANGE_DELIMITER ); var lineStart = parseInt( highlight[0], 10 ), lineEnd = parseInt( highlight[1], 10 ); if( isNaN( lineEnd ) ) { return { start: lineStart }; } else { return { start: lineStart, end: lineEnd }; } } // If no line numbers are provided, no code will be highlighted else { return {}; } } ); } ); }, /** * Serializes parsed line number data into a string so * that we can store it in the DOM. */ serializeHighlightSteps: function( highlightSteps ) { return highlightSteps.map( function( highlights ) { return highlights.map( function( highlight ) { // Line range if( typeof highlight.end === 'number' ) { return highlight.start + Plugin.HIGHLIGHT_LINE_RANGE_DELIMITER + highlight.end; } // Single line else if( typeof highlight.start === 'number' ) { return highlight.start; } // All lines else { return ''; } } ).join( Plugin.HIGHLIGHT_LINE_DELIMITER ); } ).join( Plugin.HIGHLIGHT_STEP_DELIMITER ); } } // Function to perform a better "data-trim" on code snippets // Will slice an indentation amount on each line of the snippet (amount based on the line having the lowest indentation length) function betterTrim(snippetEl) { // Helper functions function trimLeft(val) { // Adapted from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim#Polyfill return val.replace(/^[\s\uFEFF\xA0]+/g, ''); } function trimLineBreaks(input) { var lines = input.split('\n'); // Trim line-breaks from the beginning for (var i = 0; i < lines.length; i++) { if (lines[i].trim() === '') { lines.splice(i--, 1); } else break; } // Trim line-breaks from the end for (var i = lines.length-1; i >= 0; i--) { if (lines[i].trim() === '') { lines.splice(i, 1); } else break; } return lines.join('\n'); } // Main function for betterTrim() return (function(snippetEl) { var content = trimLineBreaks(snippetEl.innerHTML); var lines = content.split('\n'); // Calculate the minimum amount to remove on each line start of the snippet (can be 0) var pad = lines.reduce(function(acc, line) { if (line.length > 0 && trimLeft(line).length > 0 && acc > line.length - trimLeft(line).length) { return line.length - trimLeft(line).length; } return acc; }, Number.POSITIVE_INFINITY); // Slice each line with this amount return lines.map(function(line, index) { return line.slice(pad); }) .join('\n'); })(snippetEl); } export default () => Plugin;