zoom viewport is centered on target element #900

1 files changed, 64 insertions, 56 deletions

diff --git a/plugin/zoom-js/zoom.js b/plugin/zoom-js/zoom.js
index cd5b06f..a672af4 100644
--- a/plugin/zoom-js/zoom.js
+++ b/plugin/zoom-js/zoom.js
@@ -16,11 +16,11 @@
 })();
 
 /*!
- * zoom.js 0.2 (modified version for use with reveal.js)
+ * zoom.js 0.3 (modified for use with reveal.js)
  * http://lab.hakim.se/zoom-js
  * MIT licensed
  *
- * Copyright (C) 2011-2012 Hakim El Hattab, http://hakim.se
+ * Copyright (C) 2011-2014 Hakim El Hattab, http://hakim.se
  */
 var zoom = (function(){
 
@@ -35,8 +35,6 @@ var zoom = (function(){
 	var panEngageTimeout = -1,
 		panUpdateInterval = -1;
 
-	var currentOptions = null;
-
 	// Check for transform support so that we can fallback otherwise
 	var supportsTransforms = 	'WebkitTransform' in document.body.style ||
 								'MozTransform' in document.body.style ||
@@ -58,7 +56,7 @@ var zoom = (function(){
 		if( level !== 1 && event.keyCode === 27 ) {
 			zoom.out();
 		}
-	}, false );
+	} );
 
 	// Monitor mouse movement for panning
 	document.addEventListener( 'mousemove', function( event ) {
@@ -66,38 +64,56 @@ var zoom = (function(){
 			mouseX = event.clientX;
 			mouseY = event.clientY;
 		}
-	}, false );
+	} );
 
 	/**
-	 * Applies the CSS required to zoom in, prioritizes use of CSS3
+	 * Applies the CSS required to zoom in, prefers the use of CSS3
 	 * transforms but falls back on zoom for IE.
 	 *
-	 * @param {Number} pageOffsetX
-	 * @param {Number} pageOffsetY
-	 * @param {Number} elementOffsetX
-	 * @param {Number} elementOffsetY
+	 * @param {Object} rect
 	 * @param {Number} scale
 	 */
-	function magnify( pageOffsetX, pageOffsetY, elementOffsetX, elementOffsetY, scale ) {
+	function magnify( rect, scale ) {
+
+		var scrollOffset = getScrollOffset();
+
+		// Ensure a width/height is set
+		rect.width = rect.width || 1;
+		rect.height = rect.height || 1;
+
+		// Center the rect within the zoomed viewport
+		rect.x -= ( window.innerWidth - ( rect.width * scale ) ) / 2;
+		rect.y -= ( window.innerHeight - ( rect.height * scale ) ) / 2;
 
 		if( supportsTransforms ) {
-			var origin = pageOffsetX +'px '+ pageOffsetY +'px',
-				transform = 'translate('+ -elementOffsetX +'px,'+ -elementOffsetY +'px) scale('+ scale +')';
-
-			document.body.style.transformOrigin = origin;
-			document.body.style.OTransformOrigin = origin;
-			document.body.style.msTransformOrigin = origin;
-			document.body.style.MozTransformOrigin = origin;
-			document.body.style.WebkitTransformOrigin = origin;
-
-			document.body.style.transform = transform;
-			document.body.style.OTransform = transform;
-			document.body.style.msTransform = transform;
-			document.body.style.MozTransform = transform;
-			document.body.style.WebkitTransform = transform;
+			// Reset
+			if( scale === 1 ) {
+				document.body.style.transform = '';
+				document.body.style.OTransform = '';
+				document.body.style.msTransform = '';
+				document.body.style.MozTransform = '';
+				document.body.style.WebkitTransform = '';
+			}
+			// Scale
+			else {
+				var origin = scrollOffset.x +'px '+ scrollOffset.y +'px',
+					transform = 'translate('+ -rect.x +'px,'+ -rect.y +'px) scale('+ scale +')';
+
+				document.body.style.transformOrigin = origin;
+				document.body.style.OTransformOrigin = origin;
+				document.body.style.msTransformOrigin = origin;
+				document.body.style.MozTransformOrigin = origin;
+				document.body.style.WebkitTransformOrigin = origin;
+
+				document.body.style.transform = transform;
+				document.body.style.OTransform = transform;
+				document.body.style.msTransform = transform;
+				document.body.style.MozTransform = transform;
+				document.body.style.WebkitTransform = transform;
+			}
 		}
 		else {
-			// Reset all values
+			// Reset
 			if( scale === 1 ) {
 				document.body.style.position = '';
 				document.body.style.left = '';
@@ -106,11 +122,11 @@ var zoom = (function(){
 				document.body.style.height = '';
 				document.body.style.zoom = '';
 			}
-			// Apply scale
+			// Scale
 			else {
 				document.body.style.position = 'relative';
-				document.body.style.left = ( - ( pageOffsetX + elementOffsetX ) / scale ) + 'px';
-				document.body.style.top = ( - ( pageOffsetY + elementOffsetY ) / scale ) + 'px';
+				document.body.style.left = ( - ( scrollOffset.x + rect.x ) / scale ) + 'px';
+				document.body.style.top = ( - ( scrollOffset.y + rect.y ) / scale ) + 'px';
 				document.body.style.width = ( scale * 100 ) + '%';
 				document.body.style.height = ( scale * 100 ) + '%';
 				document.body.style.zoom = scale;
@@ -119,11 +135,13 @@ var zoom = (function(){
 
 		level = scale;
 
-		if( level !== 1 && document.documentElement.classList ) {
-			document.documentElement.classList.add( 'zoomed' );
-		}
-		else {
-			document.documentElement.classList.remove( 'zoomed' );
+		if( document.documentElement.classList ) {
+			if( level !== 1 ) {
+				document.documentElement.classList.add( 'zoomed' );
+			}
+			else {
+				document.documentElement.classList.remove( 'zoomed' );
+			}
 		}
 	}
 
@@ -159,7 +177,7 @@ var zoom = (function(){
 	function getScrollOffset() {
 		return {
 			x: window.scrollX !== undefined ? window.scrollX : window.pageXOffset,
-			y: window.scrollY !== undefined ? window.scrollY : window.pageXYffset
+			y: window.scrollY !== undefined ? window.scrollY : window.pageYOffset
 		}
 	}
 
@@ -175,6 +193,7 @@ var zoom = (function(){
 		 *   - scale: can be used instead of width/height to explicitly set scale
 		 */
 		to: function( options ) {
+
 			// Due to an implementation limitation we can't zoom in
 			// to another element without zooming out first
 			if( level !== 1 ) {
@@ -188,11 +207,12 @@ var zoom = (function(){
 				if( !!options.element ) {
 					// Space around the zoomed in element to leave on screen
 					var padding = 20;
+					var bounds = options.element.getBoundingClientRect();
 
-					options.width = options.element.getBoundingClientRect().width + ( padding * 2 );
-					options.height = options.element.getBoundingClientRect().height + ( padding * 2 );
-					options.x = options.element.getBoundingClientRect().left - padding;
-					options.y = options.element.getBoundingClientRect().top - padding;
+					options.x = bounds.left - padding;
+					options.y = bounds.top - padding;
+					options.width = bounds.width + ( padding * 2 );
+					options.height = bounds.height + ( padding * 2 );
 				}
 
 				// If width/height values are set, calculate scale from those values
@@ -204,13 +224,7 @@ var zoom = (function(){
 					options.x *= options.scale;
 					options.y *= options.scale;
 
-					var scrollOffset = getScrollOffset();
-
-					if( options.element ) {
-						scrollOffset.x -= ( window.innerWidth - ( options.width * options.scale ) ) / 2;
-					}
-
-					magnify( scrollOffset.x, scrollOffset.y, options.x, options.y, options.scale );
+					magnify( options, options.scale );
 
 					if( options.pan !== false ) {
 
@@ -222,8 +236,6 @@ var zoom = (function(){
 
 					}
 				}
-
-				currentOptions = options;
 			}
 		},
 
@@ -234,13 +246,7 @@ var zoom = (function(){
 			clearTimeout( panEngageTimeout );
 			clearInterval( panUpdateInterval );
 
-			var scrollOffset = getScrollOffset();
-
-			if( currentOptions && currentOptions.element ) {
-				scrollOffset.x -= ( window.innerWidth - ( currentOptions.width * currentOptions.scale ) ) / 2;
-			}
-
-			magnify( scrollOffset.x, scrollOffset.y, 0, 0, 1 );
+			magnify( { x: 0, y: 0 }, 1 );
 
 			level = 1;
 		},
@@ -256,3 +262,5 @@ var zoom = (function(){
 
 })();
 
+
+