make it possible to load/unload slides via the api

js/reveal.js

@@ -2748,10 +2748,10 @@
 
 				// Show the horizontal slide if it's within the view distance
 				if( distanceX < viewDistance ) {
-					showSlide( horizontalSlide );
+					loadSlide( horizontalSlide );
 				}
 				else {
-					hideSlide( horizontalSlide );
+					unloadSlide( horizontalSlide );
 				}
 
 				if( verticalSlidesLength ) {
@@ -2764,10 +2764,10 @@
 						distanceY = x === ( indexh || 0 ) ? Math.abs( ( indexv || 0 ) - y ) : Math.abs( y - oy );
 
 						if( distanceX + distanceY < viewDistance ) {
-							showSlide( verticalSlide );
+							loadSlide( verticalSlide );
 						}
 						else {
-							hideSlide( verticalSlide );
+							unloadSlide( verticalSlide );
 						}
 					}
 
@@ -3166,14 +3166,9 @@
 	 *
 	 * @param {HTMLElement} slide Slide to show
 	 */
-	/**
-	 * Called when the given slide is within the configured view
-	 * distance. Shows the slide element and loads any content
-	 * that is set to load lazily (data-src).
-	 *
-	 * @param {HTMLElement} slide Slide to show
-	 */
-	function showSlide( slide ) {
+	function loadSlide( slide, options ) {
+
+		options = options || {};
 
 		// Show the slide element
 		slide.style.display = config.display;
@@ -3253,7 +3248,7 @@
 					background.appendChild( video );
 				}
 				// Iframes
-				else if( backgroundIframe ) {
+				else if( backgroundIframe && options.excludeIframes !== true ) {
 					var iframe = document.createElement( 'iframe' );
 					iframe.setAttribute( 'allowfullscreen', '' );
 					iframe.setAttribute( 'mozallowfullscreen', '' );
@@ -3282,12 +3277,12 @@
 	}
 
 	/**
-	 * Called when the given slide is moved outside of the
-	 * configured view distance.
+	 * Unloads and hides the given slide. This is called when the
+	 * slide is moved outside of the configured view distance.
 	 *
 	 * @param {HTMLElement} slide
 	 */
-	function hideSlide( slide ) {
+	function unloadSlide( slide ) {
 
 		// Hide the slide element
 		slide.style.display = 'none';
@@ -5117,6 +5112,10 @@
 		isAutoSliding: isAutoSliding,
 		isSpeakerNotes: isSpeakerNotes,
 
+		// Slide preloading
+		loadSlide: loadSlide,
+		unloadSlide: unloadSlide,
+
 		// Adds or removes all internal event listeners (such as keyboard)
 		addEventListeners: addEventListeners,
 		removeEventListeners: removeEventListeners,