ggplot2-tutorial/ioslide_modifications.html at master · tikiatua/ggplot2-tutorial · GitHub

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<!-- The code below will add some custom formatting and keyboard navigation
     to ioslides. Insert the code just before the closing body tag (</tbody>) -->

<style type="text/css">

	article {
		width: 100%;
		height: 100%;
		overflow-y: auto;
		margin-left: -60px;
		padding-left: 60px;
		padding-bottom: 160px;
		box-sizing: border-box;
	}

	article pre.prettyprint.lang-r:before{
		content: '';
		display: block;
		height: 100%;
		width: 60px;
		position: absolute;
		top: 0px;
		left: 0px;
		background-color: #e6e6e6;
	}

	 p + pre.prettyprint.lang-r, pre + pre.prettyprint.lang-r {
		margin-top: 80px;
	}

	@media print {
	    slides {
	      height: auto !important;
	    }

	    slide {
	      page-break-inside: avoid;
	    }

	    article p, article pre {
	      page-break-inside: avoid;
	    }
	  }
</style>

<script>
	function slideVertical(event){

		// handle only pressing of y (down) or a (up)
		if (event.keyCode == 89 || event.keyCode == 65) {

			var direction = null;
			var codeBlock = null;

			// set the direction of traversal
			if (event.keyCode == 89) {
				direction = "down";
			} else {
				direction = "up";
			}

			// get the current article
			var article = document.querySelector('slide.current article');

			// select all code blocks in the article
			var allBlocks = document.querySelectorAll('slide.current article pre.prettyprint');

			// jump slides if not code blocks are present
			if (allBlocks.length === 0) {
				if (direction === "down") {
					slidedeck.nextSlide();
				} else {
					slidedeck.prevSlide();
				}
				return;
			}

			// get the index of the currently active elements
			currentIndex = Array.prototype.reduce.call(allBlocks, function(previousValue, currentItem, index) {
				if (currentItem.className.includes('active-item')) {
					return index;
				}
				return previousValue;
			}, null);

			// remove the active-item class from all codeblocks
			Array.prototype.map.call(allBlocks, function(item){
				item.className = item.className.replace(/\bactive-item\b/, '').trim();
			});

			// set the current index to zero (first element) if no active element was found
			if (currentIndex === null) {
				currentIndex = 0;
			}

			// get the next/previous code block item
			if (direction === "down") {
				if (currentIndex < allBlocks.length - 1 ) {
					codeBlock = allBlocks[currentIndex + 1];
				} else {
					codeBlock = allBlocks[currentIndex];
					slidedeck.nextSlide();
				}

			} else {
				if (currentIndex >= 1) {
					codeBlock = allBlocks[currentIndex - 1];
				} else {
					codeBock = allBlocks[0];
					slidedeck.prevSlide();
				}

			}

			// if we are not at the last codeBlock
			if (codeBlock !== null) {
				// add the class active item to the code-block
				codeBlock.className = codeBlock.className + " active-item";

				// scroll/jump to the respective codeBlock
				article.scrollTop = codeBlock.offsetTop - article.offsetTop;
			}

		}

	}

	document.addEventListener('keydown', slideVertical, true);
</script>