don't lose the reading position after applying

enhancements.

lib/ComicBook.js

@@ -8,7 +8,6 @@
 		- trigger preload if requesting valid but not loaded images (can happen if network was interupted)
 		- loading and generally hackiness of pointer is buggy, fix.
 		- check for html5 feature support where used: diveintohtml5.org/everything.html or www.modernizr.com
-		- when applying enhancements reading position gets lost
 		- full browser test - IE9 / FF3.6+ / Chrome / Safari / Opera
 		- don't inlcude the closure compiler, expect it (or similar) to be installed instead
 
@@ -542,7 +541,10 @@ function ComicBook(id, srcs, opts) {
 	/**
 	 * Draw the current page in the canvas
 	 */
-	ComicBook.prototype.drawPage = function(page_no) {
+	ComicBook.prototype.drawPage = function(page_no, reset_scroll) {
+
+		var reset_scroll = (typeof reset_scroll !== "undefined") ? reset_scroll : true;
+		var scrollY = reset_scroll ? 0 : window.scrollY;
 
 		// if a specific page is given try to render it, if not bail and wait for preload() to render it
 		if (typeof page_no === "number" && page_no < srcs.length && page_no > 0) {
@@ -690,7 +692,7 @@ function ComicBook(id, srcs, opts) {
 		}
 
 		// make sure the top of the page is in view
-		window.scroll(0, 0);
+		window.scroll(0, scrollY);
 	};
 
 	/**
@@ -762,7 +764,7 @@ function ComicBook(id, srcs, opts) {
 			} else {
 				delete options.enhance[method];
 			}
-			ComicBook.prototype.drawPage();
+			ComicBook.prototype.drawPage(null, false);
 		},
 
 		/**
@@ -812,7 +814,7 @@ function ComicBook(id, srcs, opts) {
 		 */
 		resaturate: function() {
 			delete options.enhance.desaturate;
-			ComicBook.prototype.drawPage();
+			ComicBook.prototype.drawPage(null, false);
 		},
 
 		/**
@@ -840,7 +842,7 @@ function ComicBook(id, srcs, opts) {
 
 		desharpen: function() {
 			delete options.enhance.sharpen;
-			ComicBook.prototype.drawPage();
+			ComicBook.prototype.drawPage(null, false);
 		}
 	};