function layout()

in js/reveal.js [862:963]
77 lines of code
15 McCabe index (conditional complexity)

	function layout() {

		if( dom.wrapper && !print.isPrintingPDF() ) {

			if( !config.disableLayout ) {

				// On some mobile devices '100vh' is taller than the visible
				// viewport which leads to part of the presentation being
				// cut off. To work around this we define our own '--vh' custom
				// property where 100x adds up to the correct height.
				//
				// https://css-tricks.com/the-trick-to-viewport-units-on-mobile/
				if( Device.isMobile && !config.embedded ) {
					document.documentElement.style.setProperty( '--vh', ( window.innerHeight * 0.01 ) + 'px' );
				}

				const size = getComputedSlideSize();

				const oldScale = scale;

				// Layout the contents of the slides
				layoutSlideContents( config.width, config.height );

				dom.slides.style.width = size.width + 'px';
				dom.slides.style.height = size.height + 'px';

				// Determine scale of content to fit within available space
				scale = Math.min( size.presentationWidth / size.width, size.presentationHeight / size.height );

				// Respect max/min scale settings
				scale = Math.max( scale, config.minScale );
				scale = Math.min( scale, config.maxScale );

				// Don't apply any scaling styles if scale is 1
				if( scale === 1 ) {
					dom.slides.style.zoom = '';
					dom.slides.style.left = '';
					dom.slides.style.top = '';
					dom.slides.style.bottom = '';
					dom.slides.style.right = '';
					transformSlides( { layout: '' } );
				}
				else {
					dom.slides.style.zoom = '';
					dom.slides.style.left = '50%';
					dom.slides.style.top = '50%';
					dom.slides.style.bottom = 'auto';
					dom.slides.style.right = 'auto';
					transformSlides( { layout: 'translate(-50%, -50%) scale('+ scale +')' } );
				}

				// Select all slides, vertical and horizontal
				const slides = Array.from( dom.wrapper.querySelectorAll( SLIDES_SELECTOR ) );

				for( let i = 0, len = slides.length; i < len; i++ ) {
					const slide = slides[ i ];

					// Don't bother updating invisible slides
					if( slide.style.display === 'none' ) {
						continue;
					}

					if( config.center || slide.classList.contains( 'center' ) ) {
						// Vertical stacks are not centred since their section
						// children will be
						if( slide.classList.contains( 'stack' ) ) {
							slide.style.top = 0;
						}
						else {
							slide.style.top = Math.max( ( size.height - slide.scrollHeight ) / 2, 0 ) + 'px';
						}
					}
					else {
						slide.style.top = '';
					}

				}

				if( oldScale !== scale ) {
					dispatchEvent({
						type: 'resize',
						data: {
							oldScale,
							scale,
							size
						}
					});
				}
			}

			dom.viewport.style.setProperty( '--slide-scale', scale );

			progress.update();
			backgrounds.updateParallax();

			if( overview.isActive() ) {
				overview.update();
			}

		}

	}