From e57ff233a4830de7729a7235b2ec120179feb581 Mon Sep 17 00:00:00 2001
From: Jeroen Hermans <jeroen@datacamp.com>
Date: Mon, 16 Nov 2020 09:47:58 +0100
Subject: [PATCH] Group background reads and writes

---
 js/controllers/backgrounds.js | 40 +++++++++++++++++------------------
 1 file changed, 20 insertions(+), 20 deletions(-)

diff --git a/js/controllers/backgrounds.js b/js/controllers/backgrounds.js
index e8cc996..1327b9f 100644
--- a/js/controllers/backgrounds.js
+++ b/js/controllers/backgrounds.js
@@ -27,8 +27,6 @@ export default class Backgrounds {
 	 */
 	create() {
 
-		let printMode = this.Reveal.isPrintingPDF();
-
 		// Clear prior backgrounds
 		this.element.innerHTML = '';
 		this.element.classList.add( 'no-transition' );
@@ -114,9 +112,24 @@ export default class Backgrounds {
 	 */
 	sync( slide ) {
 
-		let element = slide.slideBackgroundElement,
+		const element = slide.slideBackgroundElement,
 			contentElement = slide.slideBackgroundContentElement;
 
+		const data = {
+			background: slide.getAttribute( 'data-background' ),
+			backgroundSize: slide.getAttribute( 'data-background-size' ),
+			backgroundImage: slide.getAttribute( 'data-background-image' ),
+			backgroundVideo: slide.getAttribute( 'data-background-video' ),
+			backgroundIframe: slide.getAttribute( 'data-background-iframe' ),
+			backgroundColor: slide.getAttribute( 'data-background-color' ),
+			backgroundRepeat: slide.getAttribute( 'data-background-repeat' ),
+			backgroundPosition: slide.getAttribute( 'data-background-position' ),
+			backgroundTransition: slide.getAttribute( 'data-background-transition' ),
+			backgroundOpacity: slide.getAttribute( 'data-background-opacity' ),
+		};
+
+		const dataPreload = slide.hasAttribute( 'data-preload' );
+
 		// Reset the prior background state in case this is not the
 		// initial sync
 		slide.classList.remove( 'has-dark-background' );
@@ -135,19 +148,6 @@ export default class Backgrounds {
 		contentElement.style.opacity = '';
 		contentElement.innerHTML = '';
 
-		let data = {
-			background: slide.getAttribute( 'data-background' ),
-			backgroundSize: slide.getAttribute( 'data-background-size' ),
-			backgroundImage: slide.getAttribute( 'data-background-image' ),
-			backgroundVideo: slide.getAttribute( 'data-background-video' ),
-			backgroundIframe: slide.getAttribute( 'data-background-iframe' ),
-			backgroundColor: slide.getAttribute( 'data-background-color' ),
-			backgroundRepeat: slide.getAttribute( 'data-background-repeat' ),
-			backgroundPosition: slide.getAttribute( 'data-background-position' ),
-			backgroundTransition: slide.getAttribute( 'data-background-transition' ),
-			backgroundOpacity: slide.getAttribute( 'data-background-opacity' )
-		};
-
 		if( data.background ) {
 			// Auto-wrap image urls in url(...)
 			if( /^(http|file|\/\/)/gi.test( data.background ) || /\.(svg|png|jpg|jpeg|gif|bmp)([?#\s]|$)/gi.test( data.background ) ) {
@@ -179,7 +179,7 @@ export default class Backgrounds {
 		if( data.backgroundColor ) element.style.backgroundColor = data.backgroundColor;
 		if( data.backgroundTransition ) element.setAttribute( 'data-background-transition', data.backgroundTransition );
 
-		if( slide.hasAttribute( 'data-preload' ) ) element.setAttribute( 'data-preload', '' );
+		if( dataPreload ) element.setAttribute( 'data-preload', '' );
 
 		// Background image options are set on the content wrapper
 		if( data.backgroundSize ) contentElement.style.backgroundSize = data.backgroundSize;
@@ -194,14 +194,14 @@ export default class Backgrounds {
 
 		// If no bg color was found, check the computed background
 		if( !contrastColor ) {
-			let computedBackgroundStyle = window.getComputedStyle( element );
+			const computedBackgroundStyle = window.getComputedStyle( element );
 			if( computedBackgroundStyle && computedBackgroundStyle.backgroundColor ) {
 				contrastColor = computedBackgroundStyle.backgroundColor;
 			}
 		}
 
 		if( contrastColor ) {
-			let rgb = colorToRgb( contrastColor );
+			const rgb = colorToRgb( contrastColor );
 
 			// Ignore fully transparent backgrounds. Some browsers return
 			// rgba(0,0,0,0) when reading the computed background color of
@@ -394,4 +394,4 @@ export default class Backgrounds {
 
 	}
 
-}
\ No newline at end of file
+}