tweaks for #3568

js/controllers/scrollview.js

@@ -1,4 +1,4 @@
-import { HORIZONTAL_SLIDES_SELECTOR, SLIDES_BACKGROUNDS_SELECTOR } from '../utils/constants.js'
+import { HORIZONTAL_SLIDES_SELECTOR, HORIZONTAL_BACKGROUNDS_SELECTOR } from '../utils/constants.js'
 import { queryAll } from '../utils/util.js'
 
 const HIDE_SCROLLBAR_TIMEOUT = 500;
@@ -40,7 +40,7 @@ export default class ScrollView {
 		this.slideHTMLBeforeActivation = this.Reveal.getSlidesElement().innerHTML;
 
 		const horizontalSlides = queryAll( this.Reveal.getRevealElement(), HORIZONTAL_SLIDES_SELECTOR );
-		const slideBackgrounds = queryAll( this.Reveal.getRevealElement(), SLIDES_BACKGROUNDS_SELECTOR );
+		const horizontalBackgrounds = queryAll( this.Reveal.getRevealElement(), HORIZONTAL_BACKGROUNDS_SELECTOR );
 
 		this.viewportElement.classList.add( 'loading-scroll-mode', 'reveal-scroll' );
 
@@ -58,7 +58,7 @@ export default class ScrollView {
 
 		// Creates a new page element and appends the given slide/bg
 		// to it.
-		const createPageElement = ( slide, h, v ) => {
+		const createPageElement = ( slide, h, v, isVertical ) => {
 
 			let contentContainer;
 
@@ -78,15 +78,16 @@ export default class ScrollView {
 				pageElements.push( page );
 
 				// This transfers over the background of the vertical stack containing
-				//  the slide if it exists. Otherwise, it uses the presentation-wide
-				//  background.
-				if( slideBackgrounds && slideBackgrounds.length > h ) {
-					const slideBackground = slideBackgrounds[h];
+				// the slide if it exists. Otherwise, it uses the presentation-wide
+				// background.
+				if( isVertical && horizontalBackgrounds.length > h ) {
+					const slideBackground = horizontalBackgrounds[h];
 					const pageBackground = window.getComputedStyle( slideBackground );
-					
+
 					if( pageBackground && pageBackground.background ) {
 						page.style.background = pageBackground.background;
-					} else if( presentationBackground ) {
+					}
+					else if( presentationBackground ) {
 						page.style.background = presentationBackground;
 					}
 				} else if( presentationBackground ) {
@@ -122,7 +123,7 @@ export default class ScrollView {
 
 			if( this.Reveal.isVerticalStack( horizontalSlide ) ) {
 				horizontalSlide.querySelectorAll( 'section' ).forEach( ( verticalSlide, v ) => {
-					createPageElement( verticalSlide, h, v );
+					createPageElement( verticalSlide, h, v, true );
 				});
 			}
 			else {

js/utils/constants.js

@@ -2,7 +2,7 @@
 export const SLIDES_SELECTOR = '.slides section';
 export const HORIZONTAL_SLIDES_SELECTOR = '.slides>section';
 export const VERTICAL_SLIDES_SELECTOR = '.slides>section.present>section';
-export const SLIDES_BACKGROUNDS_SELECTOR = '.backgrounds>.slide-background';
+export const HORIZONTAL_BACKGROUNDS_SELECTOR = '.backgrounds>.slide-background';
 
 // Methods that may not be invoked via the postMessage API
 export const POST_MESSAGE_METHOD_BLACKLIST = /registerPlugin|registerKeyboardShortcut|addKeyBinding|addEventListener|showPreview/;