fa23-si/plugin/highlight/highlight.js
2020-04-29 11:56:43 +02:00

415 lines
12 KiB
JavaScript

import hljs from './highlight-core.js'
import './highlight-line-numbers.js'
/*!
* reveal.js plugin that adds syntax highlight support.
*/
const 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,"&lt;").replace(/>/g, '&gt;' );
}
// 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 <code> 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
// <table> 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 <code> 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;