Using the Carousel Control to Spotlight the Selected Item

Here we will use the YUI Carousel Control's itemSelected event to display the selected image.

This example has the following dependencies:

<link type="text/css" rel="stylesheet" href="http://yui.yahooapis.com/2.6.0/build/carousel/assets/skins/sam/carousel.css"> <script src="http://yui.yahooapis.com/2.6.0/build/yahoo/yahoo-dom-event.js"></script> <script src="http://yui.yahooapis.com/2.6.0/build/element/element-beta-min.js"></script> <script src="http://yui.yahooapis.com/2.6.0/build/carousel/carousel-beta-min.js"></script>

This example uses progressive enhancement; the Carousel is created from an ordered list.

<div id="container"> <ol> <li> <img src="http://farm1.static.flickr.com/135/342099636_7b05b7cde5_s.jpg"> </li> <li> <img src="http://farm1.static.flickr.com/136/342099938_fdef3ca3b5_s.jpg"> </li> <li> <img src="http://farm1.static.flickr.com/147/342099522_3827eaa929_s.jpg"> </li> <li> <img src="http://farm1.static.flickr.com/143/342100011_ec4d338c71_s.jpg"> </li> <li> <img src="http://farm1.static.flickr.com/161/342100080_0fe4f9ccb0_s.jpg"> </li> <li> <img src="http://farm1.static.flickr.com/153/342100324_82589c0ebe_s.jpg"> </li> <li> <img src="http://farm1.static.flickr.com/147/342100376_d0336252a7_s.jpg"> </li> <li> <img src="http://farm1.static.flickr.com/156/342100472_b9bc985fa4_s.jpg"> </li> <li> <img src="http://farm1.static.flickr.com/133/342100566_39dae4698f_s.jpg"> </li> </ol> </div>

We will add a container element where we can display the spotlight image.

<div id="spotlight"></div>

We'll have only one CSS rule to set the height for the Carousel items.

.yui-carousel-element li { height: 75px; width: 75px; }

Since we have the elements in place, we can invoke the Carousel's constructor to create the widget. The Carousel's selectedItem property returns the index of the currently selected item. So, using that property and the getElementForItem() API, we can display the image of the selected item when the Carousel is rendered.

YAHOO.util.Event.onDOMReady(function (ev) { var carousel = new YAHOO.widget.Carousel("container"); carousel.render(); // get ready for rendering the widget carousel.show(); // display the widget // display the first selected item in the spotlight spotlight.innerHTML = "<img src=\"" + getImage(carousel.getElementForItem(carousel.get("selectedItem"))) + "\">"; }

Now, we can subscribe to the selectedItem event that the Carousel exposes. This event is triggered whenever an item is selected and it returns the index of the selected item. With the index of the item, we can use the Carousel's getElementForItem() API to get the reference to the Carousel's item (an li element in our case).

carousel.on("itemSelected", function (index) { // item has the reference to the Carousel's item var item = carousel.getElementForItem(index); });

Once the reference to the Carousel's item is obtained, it is straightforward to implement a function that extracts the image within it.

// Get the image link from within its (parent) container. function getImage(parent) { var el = parent.firstChild; while (el) { // walk through till as long as there's an element if (el.nodeName.toUpperCase() == "IMG") { // found an image // flickr uses "_s" suffix for small, and "_m" for big images respectively return el.src.replace(/_s\.jpg$/, "_m.jpg"); } el = el.nextSibling; } return "";