<link href="//netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//netdna.bootstrapcdn.com/bootstrap/3.0.0/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<!------ Include the above in your HEAD tag ---------->
<div class="magnify">
<!-- This is the large magnifying class which holds the large version of the image-->
<div class="large"></div>
<!-- This is the small image -->
<img src="http://placepu.gs/300/300" width="200" class="original"/>
</div>
<script>
$(document).ready(function(){
var native_width = 0;
var native_height = 0;
//Now the mousemove function
$(".magnify").mousemove(function(e){
//When the user hovers on the image, the script will first calculate
//the native dimensions if they don't exist. Only after the native dimensions
//are available, the script will show the zoomed version.
if(!native_width && !native_height)
{
//This will create a new image object with the same image as that in .small
//We cannot directly get the dimensions from .small because of the
//width specified to 200px in the html. To get the actual dimensions we have
//created this image object.
var image_object = new Image();
image_object.src = $(".original").attr("src");
//This code is wrapped in the .load function which is important.
//width and height of the object would return 0 if accessed before
//the image gets loaded.
native_width = image_object.width;
native_height = image_object.height;
}
else
{
//x/y coordinates of the mouse
//This is the position of .magnify with respect to the document.
var magnify_offset = $(this).offset();
//We will deduct the positions of .magnify from the mouse positions with
//respect to the document to get the mouse positions with respect to the
//container(.magnify)
var mx = e.pageX - magnify_offset.left;
var my = e.pageY - magnify_offset.top;
//Finally the code to fade out the glass if the mouse is outside the container
if(mx < $(this).width() && my < $(this).height() && mx > 0 && my > 0)
{
$(".large").fadeIn(100);
}
else
{
$(".large").fadeOut(100);
}
if($(".large").is(":visible"))
{
//The background position of .large will be changed according to the position
//of the mouse over the .small image. So we will get the ratio of the pixel
//under the mouse pointer with respect to the image and use that to position the
//large image inside the magnifying glass
var rx = Math.round(mx/$(".original").width()*native_width - $(".large").width()/2)*-1;
var ry = Math.round(my/$(".original").height()*native_height - $(".large").height()/2)*-1;
var bgp = rx + "px " + ry + "px";
//Time to move the magnifying glass with the mouse
var px = mx - $(".large").width()/2;
var py = my - $(".large").height()/2;
//Now the glass moves with the mouse
//The logic is to deduct half of the glass's width and height from the
//mouse coordinates to place it with its center at the mouse coordinates
//If you hover on the image now, you should see the magnifying glass in action
$(".large").css({left: px, top: py, backgroundPosition: bgp});
}
}
});
});
</script>
