JavaScript Image Popup

• Download source code - 17.6 KB

Introduction

Many a times, developers require to show larger popup images when users hover their mouse pointer over a thumbnail image. I will explain here a very simple JavaScript that can be used to show a popup image. The script is tested, and works fine in IE 7.0 and Mozilla Firefox 3.0.

Steps for the implementation

1. Create a DIV named "imgbox" on the HTML page on which your thumbnail images will be shown. The DIV and the CSS element ID associated with the DIV is shown below:
HTML

<div id="imgbox"></div>

The CSS element:

CSS

#imgbox 
{
    vertical-align : middle;
    position : absolute;
    border: 1px solid #999;
    background : #FFFFFF; 
    filter: Alpha(Opacity=100);
    visibility : hidden;
    height : 200px;
    width : 200px;
    z-index : 50;
    overflow : hidden;
    text-align : center;
}

2. Here is the JavaScript code to show the popup image:
1. Get the left and top positions of the thumbnail image:
JavaScript

function getElementLeft(elm) 
{
    var x = 0;

    //set x to elm’s offsetLeft
    x = elm.offsetLeft;

    //set elm to its offsetParent
    elm = elm.offsetParent;

    //use while loop to check if elm is null
    // if not then add current elm’s offsetLeft to x
    //offsetTop to y and set elm to its offsetParent

    while(elm != null)
    {
        x = parseInt(x) + parseInt(elm.offsetLeft);
        elm = elm.offsetParent;
    }
    return x;
}

function getElementTop(elm) 
{
    var y = 0;

    //set x to elm’s offsetLeft
    y = elm.offsetTop;

    //set elm to its offsetParent
    elm = elm.offsetParent;

    //use while loop to check if elm is null
    // if not then add current elm’s offsetLeft to x
    //offsetTop to y and set elm to its offsetParent

    while(elm != null)
    {
        y = parseInt(y) + parseInt(elm.offsetTop);
        elm = elm.offsetParent;
    }

    return y;
}

2. Get the thumbnail image source, make the DIV visible, increase the height and width to the required size, and attach the image to the DIV.
JavaScript

function Large(obj)
{
    var imgbox=document.getElementById("imgbox");
    imgbox.style.visibility='visible';
    var img = document.createElement("img");
    img.src=obj.src;
    img.style.width='200px';
    img.style.height='200px';
    
    if(img.addEventListener){
        img.addEventListener('mouseout',Out,false);
    } else {
        img.attachEvent('onmouseout',Out);
    }             
    imgbox.innerHTML='';
    imgbox.appendChild(img);
    imgbox.style.left=(getElementLeft(obj)-50) +'px';
    imgbox.style.top=(getElementTop(obj)-50) + 'px';
}

3. Hide the DIV at mouse out.
JavaScript

function Out()
{
    document.getElementById("imgbox").style.visibility='hidden';
}

3. Add a OnMouseOver client-side event call for the thumbnail images to show the popup image on mouse-over.
HTML

<img id='img1' src='images/Sample.jpg' onmouseover="Large(this)" />

Comments

Hope this JavaScript would solve your popup image requirement. If you have implemented a popup image feature in some other way, or developed a feature-rich script, please put a link to your CodeProject article so that others can refer it too.