jQuery plugin to calculate the offset <area>'s in an image <map>. It can count the top left offset of the shape whether it be a rectangle a circle or a polygon, as well as the center of it.
<!DOCTYPE HTML>
<html lang="en-US">
<head>
<meta charset="UTF-8">
<style type="text/css">
img {
border-style: none;
}
dl.menu {
display: none;
border: 1px solid black;
position: absolute;
margin: 0;
padding: 10px;
background: gold;
}
dl.menu-show {
display: block;
}
nav {
display: block;
position: relative;
}
</style>
<title>ImageMap</title>
</head>
<body>
<nav>
<p>The plantes of the solar system serving as a navigation:</p>
<map name="planetmap" id="planetmap">
<area shape="circle" coords="84,214,14" href="#mercury" alt="Mercury" id="map-mercury" />
<area shape="circle" coords="125,190,26" href="#venus" alt="Venus" id="map-venus" />
<area shape="circle" coords="175,161,26" href="#earth" alt="Earth" id="map-earth" />
<area shape="circle" coords="223,135,22" href="#mars" alt="Mars" id="map-mars" />
<area shape="circle" coords="396,212,67" href="#jupiter" alt="Jupiter" id="map-jupiter" />
<area shape="circle" coords="504,151,45" href="#saturn" alt="Saturn" id="map-saturn" />
<area shape="poly" coords="550,180,580,180,580,240,550,240" nohref="nohref" alt="X" id="map-extra">
</map>
<dl id="menu-earth" class="menu">
<dt>Name</dt>
<dd>Earth</dd>
<dt>Mean radius</dt>
<dd>6,371.0 km</dd>
</dl>
<dl id="menu-venus" class="menu">
<dt>Name</dt>
<dd>Venus</dd>
<dt>Mean radius</dt>
<dd>6,051.8 km</dd>
</dl>
<dl id="menu-mercury" class="menu">
<dt>Name</dt>
<dd>Mercury</dd>
<dt>Mean radius</dt>
<dd>2,439.7 km</dd>
</dl>
<dl id="menu-mars" class="menu">
<dt>Name</dt>
<dd>Mars</dd>
<dt>Mean radius</dt>
<dd>3,396.2 km</dd>
</dl>
<dl id="menu-jupiter" class="menu">
<dt>Name</dt>
<dd>Jupiter</dd>
<dt>Mean radius</dt>
<dd>71,492 km</dd>
</dl>
<dl id="menu-saturn" class="menu">
<dt>Name</dt>
<dd>Saturn</dd>
<dt>Mean radius</dt>
<dd>60,268 km</dd>
</dl>
<dl id="menu-extra" class="menu">
<dt>Name</dt>
<dd>Dust in space</dd>
</dl>
<img src="http://www.vtaide.com/png/images/planets3.jpg" alt="Solar system" longdesc="http://www.vtaide.com/png/images/planets3.jpg" usemap="#planetmap" id="planetimage" />
</nav>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
<script type="text/javascript" src="jquery.areaoffset.js"></script>
<script type="text/javascript">
jQuery(function ($) {
var planetImage = $('#planetimage'),
imageOffset = planetImage.position();
$('#planetmap').children('area').each(function () {
var menu = $(this.id.replace(/^map-/, '#menu-')),
area = $(this),
offset = $(this).areaOffset(true),
menuOffset = {
left : imageOffset.left + offset.left,
top : imageOffset.top + offset.top
};
if (menu.length) {
menu.offset(menuOffset).bind('mouseleave', function () {
menu.removeClass('menu-show');
})
}
$.data(this, 'menu', menu);
}).bind('mouseenter', function () {
var menu = $.data(this, 'menu');
if (menu) {
$('dl.menu').removeClass('menu-show');
menu.addClass('menu-show');
}
});
});
</script>
</body>
</html>