include references to previous/current sldie DOM elements in slidechange event

4 files changed, 32 insertions, 14 deletions

diff --git a/README.md b/README.md
index b72e69f..8b7cab5 100644
--- a/README.md
+++ b/README.md
@@ -81,11 +81,11 @@ Reveal.addEventListener( 'somestate', function() {
 
 ### Slide change event
 
-An 'slidechanged' event is fired each time the slide is changed (regardless of state). The event object holds the index of the current slide.
+An 'slidechanged' event is fired each time the slide is changed (regardless of state). The event object holds the index values of the current slide as well as a reference to the previous and current slide HTML nodes.
 
 ```
 Reveal.addEventListener( 'slidechanged', function( event ) {
-	// event.indexh & event.indexv
+	// event.previousSlide, event.currentSlide, event.indexh, event.indexv
 } );
 ```
 
diff --git a/index.html b/index.html
index 691ff4b..a68dd6a 100644
--- a/index.html
+++ b/index.html
@@ -279,7 +279,7 @@ linkify( 'a' );
 
 			// Fires each time a new slide is activated
 			Reveal.addEventListener( 'slidechanged', function( event ) {
-				// event.indexh & event.indexv
+				// event.previousSlide, event.currentSlide, event.indexh, event.indexv
 			} );
 
 			Reveal.initialize({
diff --git a/js/reveal.js b/js/reveal.js
index dbe11f5..8ff8e0b 100644
--- a/js/reveal.js
+++ b/js/reveal.js
@@ -661,11 +661,29 @@ var Reveal = (function(){
 		clearTimeout( writeURLTimeout );
 		writeURLTimeout = setTimeout( writeURL, 1500 );
 
+		// Only fire if the slide index is different from before
 		if( indexh !== indexhBefore || indexv !== indexvBefore ) {
+			// Query all horizontal slides in the deck
+			var horizontalSlides = document.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR );
+
+			// Find the previous and current horizontal slides
+			var previousHorizontalSlide = horizontalSlides[ indexhBefore ],
+				currentHorizontalSlide = horizontalSlides[ indexh ];
+
+			// Query all vertical slides inside of the previous and current horizontal slides
+			var previousVerticalSlides = previousHorizontalSlide.querySelectorAll( 'section' );
+				currentVerticalSlides = currentHorizontalSlide.querySelectorAll( 'section' );
+
 			// Dispatch an event notifying observers of the change in slide
 			dispatchEvent( 'slidechanged', {
+				// Include the current indices in the event
 				'indexh': indexh, 
-				'indexv': indexv
+				'indexv': indexv,
+
+				// Passes direct references to the slide HTML elements, attempts to find
+				// a vertical slide and falls back on the horizontal parent
+				'previousSlide': previousVerticalSlides[ indexvBefore ] || previousHorizontalSlide,
+				'currentSlide': currentVerticalSlides[ indexv ] || currentHorizontalSlide
 			} );
 		}
 	}
diff --git a/js/reveal.min.js b/js/reveal.min.js
index 065cd2f..095f6c2 100644
--- a/js/reveal.min.js
+++ b/js/reveal.min.js
@@ -42,17 +42,17 @@ c=this.getAttribute("data-index-v");b();}}function U(W,Y){var aa=Array.prototype
 if(Y<0){Y=ab+Y;}}Y=Math.max(Math.min(Y,ab-1),0);for(var Z=0;Z<ab;Z++){var V=aa[Z];if(O()===false){var ac=Math.abs((Y-Z)%(ab-3))||0;V.style.display=ac>3?"none":"block";
 }aa[Z].classList.remove("past");aa[Z].classList.remove("present");aa[Z].classList.remove("future");if(Z<Y){aa[Z].classList.add("past");}else{if(Z>Y){aa[Z].classList.add("future");
 }}if(V.querySelector("section")){aa[Z].classList.add("stack");}}aa[Y].classList.add("present");var X=aa[Y].getAttribute("data-state");if(X){T=T.concat(X.split(" "));
-}}else{Y=0;}return Y;}function b(aa,W){var ac=T.concat();T.length=0;var ab=k,Z=c;k=U(j,aa===undefined?k:aa);c=U(a,W===undefined?c:W);stateLoop:for(var Y=0,V=T.length;
-Y<V;Y++){for(var X=0;X<ac.length;X++){if(ac[X]===T[Y]){ac.splice(X,1);continue stateLoop;}}document.documentElement.classList.add(T[Y]);o(T[Y]);}while(ac.length){document.documentElement.classList.remove(ac.pop());
+}}else{Y=0;}return Y;}function b(Z,ad){var X=T.concat();T.length=0;var ab=k,V=c;k=U(j,Z===undefined?k:Z);c=U(a,ad===undefined?c:ad);stateLoop:for(var Y=0,aa=T.length;
+Y<aa;Y++){for(var W=0;W<X.length;W++){if(X[W]===T[Y]){X.splice(W,1);continue stateLoop;}}document.documentElement.classList.add(T[Y]);o(T[Y]);}while(X.length){document.documentElement.classList.remove(X.pop());
 }if(H.progress){d.progressbar.style.width=(k/(document.querySelectorAll(j).length-1))*window.innerWidth+"px";}if(O()){B();}p();clearTimeout(writeURLTimeout);
-writeURLTimeout=setTimeout(g,1500);if(k!==ab||c!==Z){o("slidechanged",{indexh:k,indexv:c});}}function p(){var V=f();[d.controlsLeft,d.controlsRight,d.controlsUp,d.controlsDown].forEach(function(W){W.classList.remove("enabled");
-});if(V.left){d.controlsLeft.classList.add("enabled");}if(V.right){d.controlsRight.classList.add("enabled");}if(V.up){d.controlsUp.classList.add("enabled");
-}if(V.down){d.controlsDown.classList.add("enabled");}}function f(){var V=document.querySelectorAll(j);var W=document.querySelectorAll(a);return{left:k>0,right:k<V.length-1,up:c>0,down:c<W.length-1};
-}function D(){var V=window.location.hash.slice(2).split("/");k=parseInt(V[0])||0;c=parseInt(V[1])||0;F(k,c);}function g(){if(H.history){var V="/";if(k>0||c>0){V+=k;
-}if(c>0){V+="/"+c;}window.location.hash=V;}}function o(W,V){var X=document.createEvent("HTMLEvents",1,2);X.initEvent(W,true,true);q(X,V);d.wrapper.dispatchEvent(X);
-}function s(){if(document.querySelector(a+".present")){var W=document.querySelectorAll(a+".present .fragment:not(.visible)");if(W.length){W[0].classList.add("visible");
-o("fragmentshown",{fragment:W[0]});return true;}}else{var V=document.querySelectorAll(j+".present .fragment:not(.visible)");if(V.length){V[0].classList.add("visible");
-o("fragmentshown",{fragment:V[0]});return true;}}return false;}function G(){if(document.querySelector(a+".present")){var W=document.querySelectorAll(a+".present .fragment.visible");
+writeURLTimeout=setTimeout(g,1500);if(k!==ab||c!==V){var ac=document.querySelectorAll(j);slidesv=document.querySelectorAll(a);o("slidechanged",{indexh:k,indexv:c,slide:slidesv.length?slidesv[c]:ac[k]});
+}}function p(){var V=f();[d.controlsLeft,d.controlsRight,d.controlsUp,d.controlsDown].forEach(function(W){W.classList.remove("enabled");});if(V.left){d.controlsLeft.classList.add("enabled");
+}if(V.right){d.controlsRight.classList.add("enabled");}if(V.up){d.controlsUp.classList.add("enabled");}if(V.down){d.controlsDown.classList.add("enabled");
+}}function f(){var V=document.querySelectorAll(j);var W=document.querySelectorAll(a);return{left:k>0,right:k<V.length-1,up:c>0,down:c<W.length-1};}function D(){var V=window.location.hash.slice(2).split("/");
+k=parseInt(V[0])||0;c=parseInt(V[1])||0;F(k,c);}function g(){if(H.history){var V="/";if(k>0||c>0){V+=k;}if(c>0){V+="/"+c;}window.location.hash=V;}}function o(W,V){var X=document.createEvent("HTMLEvents",1,2);
+X.initEvent(W,true,true);q(X,V);d.wrapper.dispatchEvent(X);}function s(){if(document.querySelector(a+".present")){var W=document.querySelectorAll(a+".present .fragment:not(.visible)");
+if(W.length){W[0].classList.add("visible");o("fragmentshown",{fragment:W[0]});return true;}}else{var V=document.querySelectorAll(j+".present .fragment:not(.visible)");
+if(V.length){V[0].classList.add("visible");o("fragmentshown",{fragment:V[0]});return true;}}return false;}function G(){if(document.querySelector(a+".present")){var W=document.querySelectorAll(a+".present .fragment.visible");
 if(W.length){W[W.length-1].classList.remove("visible");o("fragmenthidden",{fragment:W[0]});return true;}}else{var V=document.querySelectorAll(j+".present .fragment.visible");
 if(V.length){V[V.length-1].classList.remove("visible");o("fragmenthidden",{fragment:V[0]});return true;}}return false;}function F(W,V){b(W,V);}function w(){if(O()||G()===false){b(k-1,0);
 }}function i(){if(O()||s()===false){b(k+1,0);}}function r(){if(O()||G()===false){b(k,c-1);}}function A(){if(O()||s()===false){b(k,c+1);}}function N(){if(G()===false){if(f().up){r();