How to overlay images

I want to overlay one image with another using CSS. An example of this is the first image (the background if you like) will be a thumbnail link of a product, with the link opening a lightbox / popup showing a larger version of the image.

On top of this linked image I would like an image of a magnifying glass, to show people that the image can be clicked to enlarge it (apparently this isn't obvious without the magnifying glass).

I just got done doing this exact thing in a project. The HTML side looked a bit like this:

<a href="[fullsize]" class="gallerypic" title="">
  <img src="[thumbnail pic]" height="90" width="140" alt="[Gallery Photo]" class="pic" />
  <span class="zoom-icon">
      <img src="/images/misc/zoom.gif" width="32" height="32" alt="Zoom">
  </span>
</a>

Then using CSS:

a.gallerypic{
  width:140px;
  text-decoration:none;
  position:relative;
  display:block;
  border:1px solid #666;
  padding:3px;
  margin-right:5px;
  float:left;
}

a.gallerypic span.zoom-icon{
  visibility:hidden;
  position:absolute;
  left:40%;
  top:35%;
  filter:alpha(opacity=50);
  -moz-opacity:0.5;
  -khtml-opacity: 0.5;
  opacity: 0.5;
}

a.gallerypic:hover span.zoom-icon{
  visibility:visible;
}

I left a lot of the sample in there on the CSS so you can see how I decided to do the style. Note I lowered the opacity so you could see through the magnifying glass.

Hope this helps.

EDIT: To clarify for your example - you could ignore the visibility:hidden; and kill the :hover execution if you wanted, this was just the way I did it.

One technique, suggested by http://www.tjkdesign.com/articles/png_overlay_with_no_extra_markup.asp">this article, would be to do this:

<img style="background:url(thumbnail1.jpg)" src="magnifying_glass.png" />

> A simple way of doing that with CSS > only without modifying the content > with additional tags is shown here > (with code and example): > http://soukie.net/2009/08/20/typography-and-css/#example

This works, as long as the parent element is not using static positioning. Simply setting it to relative positioning does the trick. Also, IE <8 don't support the :before selector or content.

Edit: Link above no longer works but is visible on the WayBack Machine: https://web.archive.org/web/20120213121217/https://soukie.net/2009/08/20/typography-and-css/

Here is how I did it recently. Not perfect semantically, but gets the job done.

<div class="container" style="position: relative">
<img style="z-index: 32; left: 8px; position: relative;" alt="bottom image" src="images/bottom-image.jpg">
<div style="z-index: 100; left: 72px; position: absolute; top: 39px">
<img alt="top image" src="images/top-image.jpg"></div></div>

You might want to check out this tutorial: http://www.webdesignerwall.com/tutorials/css-decorative-gallery/

In it the writer uses an empty span element to add an overlaying image. You can use jQuery to inject said span elements, if you'd like to keep your code as clean as possible. An example is also given in the aforementioned article.

Hope this helps!

-Dave

If you're only wanting the magnifing glass on hover then you can use

a:hover img { cursor: url(glass.cur); }

http://www.javascriptkit.com/dhtmltutors/csscursors.shtml

If you want it there permanently you should probably either have it included in the original thumnail, or add it using JavaScript rather than adding it to the HTML (this is purely style and shouldn't be in the content).

Let me know if you want help on the JavaScript side.

In CSS3, you can do the following:

.double-image {
    background-image: url(images/img1.png), url(images/img2.png);
}

Took from https://stackoverflow.com/questions/423172/can-i-have-multiple-background-images-using-css

All we want is parent above child. This is how you do it.

You put img into span, set z-index & position for both elements, and extra display for span. Add hover to span so you can test it and you got it!

HTML:

<span><img src="/images/"></span>

CSS

span img {
    position:relative;
    z-index:-1;
}
span {
    position:relative;
    z-index:initial;
    display:inline-block;
}
span:hover {
    background-color:#000;
}

Unless you use the <img> tag, which displays an image by itself, you will not be able to achieve this with pure CSS alone. You will also need TWO HTML elements as well - one for each picture. This is because the only way you can make an element display a picture via CSS is with the background-image property, and every element can have only one background image. Which two elements you choose and how you position them is up to you. There are many ways how you can position one HTML element above another.

Here's a good technique to display an overlay image that is centered with a semi-transparent background over an image link:

HTML

<div class="image-container">
	<a class="link" href="#" >	
		<img class="image" src="/img/thumbnail.png"/>
		<span class="overlay-image"><img src="/img/overlay.png"></span>
	</a>	
</div>

CSS

div.image-container{
	position: relative;
}
a.link{
	text-decoration: none;	
	position: relative;
	display: block;
}

a.link span.overlay-image{
	visibility: hidden;
	position: absolute;
	left: 0px;
	top: 0px;
	bottom: 0px;
	right: 0px;
	background-color: rgba(0,0,0,0.2); /* black background with 20% alpha */
}

a.link span.overlay-image:before {    /* create a full-height inline block pseudo=element */
    content: ' ';
    display: inline-block;
    vertical-align: middle;  /* vertical alignment of the inline element */
    height: 100%;	
}

a.link:hover span.overlay-image img{
	display: inline-block;	
	vertical-align: middle;		
}

a.link:hover span.overlay-image{
	visibility: visible;
}

Here's a JQuery Technique with semi-transparent background.

HTML

<html>
<head>
	<link rel="stylesheet" href="css/style.css" type="text/css" media="screen" title="no title" charset="utf-8">
	<title>Image Gallery</title>
</head>
<body>
	<h1>Image Gallery</h1>
	
	<ul id="imageGallery">
		<li><a href="images/refferal_machine.png"><img src="images/refferal_machine.png" width="100" alt="Refferal Machine By Matthew Spiel"></a></li>
		<li><a href="images/space-juice.png"><img src="images/space-juice.png" width="100" alt="Space Juice by Mat Helme"></a></li>
		<li><a href="images/education.png"><img src="images/education.png" width="100" alt="Education by Chris Michel"></a></li>
		<li><a href="images/copy_mcrepeatsalot.png"><img src="images/copy_mcrepeatsalot.png" width="100" alt="Wanted: Copy McRepeatsalot by Chris Michel"></a></li>
		<li><a href="images/sebastian.png"><img src="images/sebastian.png" width="100" alt="Sebastian by Mat Helme"></a></li>
		<li><a href="images/skill-polish.png"><img src="images/skill-polish.png" width="100" alt="Skill Polish by Chris Michel"></a></li>
		<li><a href="images/chuck.png"><img src="images/chuck.png" width="100" alt="Chuck by Mat Helme"></a></li>
		<li><a href="images/library.png"><img src="images/library.png" width="100" alt="Library by Tyson Rosage"></a></li>
		<li><a href="images/boat.png"><img src="images/boat.png" width="100" alt="Boat by Griffin Moore"></a></li>
		<li><a href="images/illustrator_foundations.png"><img src="images/illustrator_foundations.png" width="100" alt="Illustrator Foundations by Matthew Spiel"></a></li>
		<li><a href="images/treehouse_shop.jpg"><img src="images/treehouse_shop.jpg" width="100" alt="Treehouse Shop by Eric Smith"></a></li>
	</ul>
	
	<script src="http://code.jquery.com/jquery-1.11.0.min.js" type="text/javascript" charset="utf-8"></script>
	<script src="js/app.js" type="text/javascript" charset="utf-8"></script>
</body>
</html>

CSS

/** Start Coding Here **/
#overlay {
  background:rgba(0,0,0,0.7);
  width:100%;
  height:100%;
  position:absolute;
  top:0;
  left:0;
  display:none;
  text-align:center;
}

#overlay img {
 margin-top: 10%; 
}

#overlay p {
 color:white; 
}

app.js

var $overlay = $('<div id="overlay"></div>');
var $image = $("<img>");
var $caption = $("<p></p>");

// 1. Capture the click event on a link to an image
$("#imageGallery a").click(function(event){
  event.preventDefault();
  
  var imageLocation = $(this).attr("href");
  
  // 1.1 Show the overlay.
  $overlay.show();
  
  // 1.2 Update overlay with the image linked in the link
  $image.attr("src", imageLocation);
    
  // 1.3 Get child's alt attribute and set caption
  var captionText = $(this).children("img").attr("alt");
  $caption.text(captionText);
  
  
 // 2. Add overlay
 $("body").append($overlay);

	// 2.1 An image to overlay
	$overlay.append($image);

	// 2.2 A caption to overlay
	$overlay.append($caption);

});

//When overlay is clicked
$overlay.click(function(){
  //Hide the overlay
  $overlay.hide();
});