make max pages per slide limit configurable

README.md

@@ -783,6 +783,8 @@ Reveal.initialize({
 Presentations can be exported to PDF via a special print stylesheet. This feature requires that you use [Google Chrome](http://google.com/chrome) or [Chromium](https://www.chromium.org/Home).
 Here's an example of an exported presentation that's been uploaded to SlideShare: http://www.slideshare.net/hakimel/revealjs-300.
 
+Export dimensions are inferred from the configured [presentation size](#presentation-size). Slides that are too tall to fit within a single page will expand onto multiple pages. You can limit how many pages a slide may expand onto using the `pdfMaxPagesPerSlide` config option, for example: `Reveal.configure({ pdfMaxPagesPerSlide: 1 })`.
+
 1. Open your presentation with `print-pdf` included anywhere in the query string. This triggers the default index HTML to load the PDF print stylesheet ([css/print/pdf.css](https://github.com/hakimel/reveal.js/blob/master/css/print/pdf.css)). You can test this with [lab.hakim.se/reveal-js?print-pdf](http://lab.hakim.se/reveal-js?print-pdf).
 2. Open the in-browser print dialog (CTRL/CMD+P).
 3. Change the **Destination** setting to **Save as PDF**.

js/reveal.js

@@ -153,6 +153,10 @@
 			parallaxBackgroundHorizontal: null,
 			parallaxBackgroundVertical: null,
 
+			// The maximum number of pages a single slide can expand onto when printing
+			// to PDF, unlimited by default
+			pdfMaxPagesPerSlide: Number.POSITIVE_INFINITY,
+
 			// Number of slides away from the current that are visible
 			viewDistance: 3,
 
@@ -592,6 +596,9 @@
 				var contentHeight = slide.scrollHeight;
 				var numberOfPages = Math.max( Math.ceil( contentHeight / pageHeight ), 1 );
 
+				// Adhere to configured pages per slide limit
+				numberOfPages = Math.min( numberOfPages, config.pdfMaxPagesPerSlide );
+
 				// Center slides vertically
 				if( numberOfPages === 1 && config.center || slide.classList.contains( 'center' ) ) {
 					top = Math.max( ( pageHeight - contentHeight ) / 2, 0 );