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/2.9.0/build/carousel/assets/skins/sam/carousel.css"> <script src="http://yui.yahooapis.com/2.9.0/build/yahoo/yahoo-dom-event.js"></script> <script src="http://yui.yahooapis.com/2.9.0/build/element/element-min.js"></script> <script src="http://yui.yahooapis.com/2.9.0/build/carousel/carousel-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 (but necessary) CSS rule to set the height for the Carousel items.

/* Always be sure to give your carousel items a width and a height */ .yui-carousel-element li { height: 75px; width: 75px; opacity: 0.6; }

Since we have the elements in place, we can invoke the Carousel's constructor to create the widget. After having the Carousel object, we can subscribe to the itemSelected event that it 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).

YAHOO.util.Event.onDOMReady(function (ev) { var carousel = new YAHOO.widget.Carousel("container"); carousel.on("itemSelected", function (index) { var item = carousel.getElementForItem(index); if (item) { spotlight.innerHTML = "<img src=http://developer.yahoo.com/ + getImage(item) + "\">"; } }); carousel.render(); // get ready for rendering the widget carousel.show(); // display the widget });

The getImage() function is quite easy to implement. Since we have the reference to the Carousel's item, 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 ""; }