Blogger Trick

Do you have jQuery in your blog and space to insert 10 lines of code? If the answer is yes and you also want to have an automatic slideshow, this is the simplest code I've seen so far.

That code having a succession of simple images placed inside a box with a common general container would give this result:


1. Adding the JavaScript

If you do not have jQuery, then you should add this line just after ]]></b:skin> to load this popular slideshow:

<script src='http://ajax.googleapis.com/ajax/libs/jquery/1.8/jquery.min.js' type='text/javascript'/>

Once confident that we have the library in our template, we need to add the same line to make the series of images function as a slider:

<script type="text/javascript">//<![CDATA[
$(function(){
    $('#slider div:gt(0)').hide();
    setInterval(function(){
      $('#slider div:first-child').fadeOut(0)
         .next('div').fadeIn(1000)
         .end().appendTo('#slider');}, 4000);
});
//]]></script>

We can save changes to the template because that is all. It is simple but you will see that it works and does what it has to do. Now we just have to put the images where we want to display, in the manner discussed below.

2. Create the slider

After adding the codes above in our template (although you could add it directly into a gadget, on a page or even in an entry as you see here) we can create a viewer as you saw above. We just have to use this HTML structure below to add the images:

<div id="slider">
    <div><img src="IMAGE_URL"/></div>
    <div><img src="IMAGE_URL"/></div>
    <div><img src="IMAGE_URL"/></div>
</div>

I do not know how you see it but it is all you need.

For me this is quite lightweight and efficient, much more than most libraries that are used perhaps too often.

Settings

The last three numbers of the plugin allow us to adjust some things. All are expressed in milliseconds (4000 = 4 seconds)

fadeOut(0): Time for the outgoing image
fadeIn(1000): Time for the next image
('#slider');},4000): Time spent in each image

How it Works

And for the curious who want to learn things...

$('#slider div:gt(0)').hide();
With gt(x) we select all the divs from number x. In this case 0 is the first, so what we do with this line is to hide (hide) all the boxes except the first, which will be the image visible initially.

setInterval(function(){ [what we will do] }, 4000);
We need to reiterate a few things from time to time and we do with setInterval, indicating the delay time between each set.

$('#slider div:first-child').fadeOut(0)
Within each of these intervals we remove (fadeOut) the first box (div:first-child) that is in the relationship of images...

.next('div').fadeIn(1000)
...and we make the following box (next) appearing gradually (fadeIn).

.end().appendTo('#slider');
Finally we have the first image and place it at the end (appendTo) of the "list".

end() resets the count of elements that we move forward with next(). Thus, the first child made earlier to disappear is the one we sent down the stack and not the image that is now visible.

Variants and customization

As you have seen CSS is not necessary for the slider to work, but using it we can change its look, allow the use of images of different sizes, include labels and even improve the transition. Here are some ideas.



We can limit the overall container size and prevent overflow for larger images. And then we will put rounded corners, border and then center them.

#slider {
overflow: hidden;
width: 500px;
height: 300px;
border:3px solid #b8b8b8;
border-radius: 40px;
margin: 0 auto;
padding: 0;
position: relative;
}

If we place the parent boxes of the images absolutely with respect to the general container (for that we put before the relative), these will overlap each other. In this way the fadeOut may give them some time to be "visible" (we changed 0 to 1000) and a smoother transition between images. The mixture of images is produced in the second demo.

In the images, the max-width serves us to always take up the entire width and min-height so that even if they are distorted, there will remain no space below when they are less than 300px.

#slider > div {
position:absolute;
top:0;
left:0;
}
#slider img {
width:100%;
min-height:300px;
margin:0;
padding:0;
border:0;
}

And if we add other elements on the images (in this example a text), we'll just label them with a span or paragraph (p) and position them in the CSS in an absolute manner, placing them in the exact place where we want with top/bottom - left/right.

#slider p {
position: absolute;
bottom: 30px;
left: 0;
display: block;
width: 400px;
height: 24px;
margin:0;
padding: 5px 0;
color: #eee;
background: #990000;
font-size: 22px;
line-height:22px;
text-align:center;
}

The markup in the HTML for this last, includes also a link to the image, so it would be like this:

<div id="slider">
<div><a href="Link_URL1"><img src="Image_URL1" /></a><p>TEXT1</p></div>
<div><a href="Link_URL2"><img src="Image_URL2" /></a><p>TEXT2</p></div>
<div><a href="Link_URL3"><img src="Image_URL3" /></a><p>TEXT3</p></div>
</div>