Simple JQuery Image Slide Show with Semi-Transparent Caption

Introduction

Update 17 Dec 2009: I have created a new version of this image slide show. It's more efficient, clean and simple. Please visit: jQuery Photo Slide Show with Slick Caption Tutorial Revisited

I will no longer provide support for this old tutorial

Image Slide Show is one of the famous components in web design and development. A lot of the websites display news headlines in an image slide show to attract viewers attention, of course, with caption/excerpt. No doubt about it, this is a clever method not only to gain attentions, but it also makes the website more alive (not too static, dull).

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So, here we go again, I separated my codes into 3 sections: html, css and javascript and I will explain how it works in each section.

1. HTML

My ultimate objective is - to keep the html as simple as possible. So, the final product is as following. The first image has a class called "show". Class show has higher z-index, so image with this class will display on top, thus image with this class will always display on top of the rest. The second thing you need to know is the DIV with "caption" class. It has the highest z-index. That DIV will be used to display the caption. The caption is retrieve from the REL attribute in the img element. You can put html element in the REL attribute. Be aware of extra padding and margin of the html elements you used. (eg h1, p).

Have a look at the html code:

<div id="gallery">

	<a href="#" class="show">
	<img data-src="images/flowing-rock.jpg" alt="Flowing Rock" alt="" title="" width="580" height="360" rel="<h3>Flowing Rock</h3>You can put html element 
	inside the REL attribute."/></a>
	</a>
	
	<a href="#">
		<img data-src="images/grass-blades.jpg" alt="Grass Blades" alt="" title="" width="580" height="360" rel="<h3>Grass Blades</h3>description"/>
	</a>
	
	......
	......
	......

	<div class="caption"><div class="content"></div></div>
</div>
<div class="clear"></div>

2. CSS

In this section, I declared a container #gallery for this image slide show. The CSS for this tutorial is pretty straight foward, the most importance thing is the z-index. You have to make sure the "show" class z-index is lower than the "caption" z-index.

body{
	font-family:arial
}

.clear {
	clear:both
}

#gallery {
	position:relative;
	height:360px
}
	#gallery a {
		float:left;
		position:absolute;
	}
	
	#gallery a img {
		border:none;
	}
	
	#gallery a.show {
		z-index:500
	}

	#gallery .caption {
		z-index:600; 
		background-color:#000; 
		color:#ffffff; 
		height:100px; 
		width:100%; 
		position:absolute;
		bottom:0;
	}

	#gallery .caption .content {
		margin:5px
	}
	
	#gallery .caption .content h3 {
		margin:0;
		padding:0;
		color:#1DCCEF;
	}

3. Javascript

Finally, the Javascript code. I have added comments in each line to explain what it does. My concept for this image slide show:

Hide all the images
Display the first image and caption
Find the image with "show" class, and grab the next image using next() method
Add "show" class to next image
Animate the image (fadeout the current image, fadein next image)
And, it repeats above steps over and over again

$(document).ready(function() {		
	
	//Execute the slideShow
	slideShow();

});

function slideShow() {

	//Set the opacity of all images to 0
	$('#gallery a').css({opacity: 0.0});
	
	//Get the first image and display it (set it to full opacity)
	$('#gallery a:first').css({opacity: 1.0});
	
	//Set the caption background to semi-transparent
	$('#gallery .caption').css({opacity: 0.7});

	//Resize the width of the caption according to the image width
	$('#gallery .caption').css({width: $('#gallery a').find('img').css('width')});
	
	//Get the caption of the first image from REL attribute and display it
	$('#gallery .content').html($('#gallery a:first').find('img').attr('rel'))
	.animate({opacity: 0.7}, 400);
	
	//Call the gallery function to run the slideshow, 6000 = change to next image after 6 seconds
	setInterval('gallery()',6000);
	
}

function gallery() {
	
	//if no IMGs have the show class, grab the first image
	var current = ($('#gallery a.show')?  $('#gallery a.show') : $('#gallery a:first'));

	//Get next image, if it reached the end of the slideshow, rotate it back to the first image
	var next = ((current.next().length) ? ((current.next().hasClass('caption'))? $('#gallery a:first') :current.next()) : $('#gallery a:first'));	
	
	//Get next image caption
	var caption = next.find('img').attr('rel');	
	
	//Set the fade in effect for the next image, show class has higher z-index
	next.css({opacity: 0.0})
	.addClass('show')
	.animate({opacity: 1.0}, 1000);

	//Hide the current image
	current.animate({opacity: 0.0}, 1000)
	.removeClass('show');
	
	//Set the opacity to 0 and height to 1px
	$('#gallery .caption').animate({opacity: 0.0}, { queue:false, duration:0 }).animate({height: '1px'}, { queue:true, duration:300 });	
	
	//Animate the caption, opacity to 0.7 and heigth to 100px, a slide up effect
	$('#gallery .caption').animate({opacity: 0.7},100 ).animate({height: '100px'},500 );
	
	//Display the content
	$('#gallery .content').html(caption);
		
}

Conclusion

Finally, you will have a nice and simple jQuery image slide show with a semi-transparent caption. Make sure you check out the demo and download the source code to play with it. Last but not least, I need your support :) If you like this article, please help me to promote it by adding this post into your bookmark. Or you can subscribe to my RSS for more posts. Thanks!

Update

14-4-2009: Fixed caption problem. Thanks to one of the readers kpastore.