jqueryui: Light Box

1> create index.html

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Light-box</title>

#lightbox{
 background-color:#eee;
 padding: 10px;
 border-bottom: 2px solid #666;
 border-right: 2px solid #666;
 }
#lightboxDetails{
 font-size: 0.8em;
 padding-top: 0.4em;
 } 
#lightboxCaption{ float: left; }
#keyboardMsg{ float: right; }
#closeButton{ top: 5px; right: 5px; }

#lightbox img{ border: none; clear: both;} 
#overlay img{ border: none; }

#overlay{ background-image: url(overlay.png); }

* html #overlay{
 background-color: #333;
 back\ground-color: transparent;
 filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(src="../overlay.png", sizingMethod="scale");
 }
</style>
</head>

</div>
</div>
</body>
</html>

2> create lightbox.js

var loadingImage = 'loading.gif';  
var closeButton = 'close.gif';

function getPageScroll(){

var yScroll;

if (self.pageYOffset) {
  yScroll = self.pageYOffset;
 } else if (document.documentElement && document.documentElement.scrollTop){  // Explorer 6 Strict
  yScroll = document.documentElement.scrollTop;
 } else if (document.body) {// all other Explorers
  yScroll = document.body.scrollTop;
 }

arrayPageScroll = new Array('',yScroll) 
 return arrayPageScroll;
}

// for small pages with total width less then width of the viewport
 if(xScroll < windowWidth){ 
  pageWidth = windowWidth;
 } else {
  pageWidth = xScroll;
 }

arrayPageSize = new Array(pageWidth,pageHeight,windowWidth,windowHeight) 
 return arrayPageSize;
}

function pause(numberMillis) {
 var now = new Date();
 var exitTime = now.getTime() + numberMillis;
 while (true) {
  now = new Date();
  if (now.getTime() > exitTime)
   return;
 }
}

//
// listenKey()
//
function listenKey () { document.onkeypress = getKey; }

//
// showLightbox()
// Preloads images. Pleaces new image in lightbox then centers and displays.
//
function showLightbox(objLink)
{
 // prep objects
 var objOverlay = document.getElementById('overlay');
 var objLightbox = document.getElementById('lightbox');
 var objCaption = document.getElementById('lightboxCaption');
 var objImage = document.getElementById('lightboxImage');
 var objLoadingImage = document.getElementById('loadingImage');
 var objLightboxDetails = document.getElementById('lightboxDetails');

var arrayPageSize = getPageSize();
 var arrayPageScroll = getPageScroll();

// center loadingImage if it exists
 if (objLoadingImage) {
  objLoadingImage.style.top = (arrayPageScroll[1] + ((arrayPageSize[3] - 35 - objLoadingImage.height) / 2) + 'px');
  objLoadingImage.style.left = (((arrayPageSize[0] - 20 - objLoadingImage.width) / 2) + 'px');
  objLoadingImage.style.display = 'block';
 }

// set height of Overlay to take up whole page and show
 objOverlay.style.height = (arrayPageSize[1] + 'px');
 objOverlay.style.display = 'block';

// preload image
 imgPreload = new Image();

imgPreload.onload=function(){
  objImage.src = objLink.href;

// center lightbox and make sure that the top and left values are not negative
  // and the image placed outside the viewport
  var lightboxTop = arrayPageScroll[1] + ((arrayPageSize[3] - 35 - imgPreload.height) / 2);
  var lightboxLeft = ((arrayPageSize[0] - 20 - imgPreload.width) / 2);
  
  objLightbox.style.top = (lightboxTop < 0) ? "0px" : lightboxTop + "px";
  objLightbox.style.left = (lightboxLeft < 0) ? "0px" : lightboxLeft + "px";

objLightboxDetails.style.width = imgPreload.width + 'px';
  
  if(objLink.getAttribute('title')){
   objCaption.style.display = 'block';
   //objCaption.style.width = imgPreload.width + 'px';
   objCaption.innerHTML = objLink.getAttribute('title');
  } else {
   objCaption.style.display = 'none';
  }
  
  // A small pause between the image loading and displaying is required with IE,
  // this prevents the previous image displaying for a short burst causing flicker.
  if (navigator.appVersion.indexOf("MSIE")!=-1){
   pause(250);
  }

if (objLoadingImage) { objLoadingImage.style.display = 'none'; }
  objLightbox.style.display = 'block';

// After image is loaded, update the overlay height as the new image might have
  // increased the overall page height.
  arrayPageSize = getPageSize();
  objOverlay.style.height = (arrayPageSize[1] + 'px');
  
  // Check for 'x' keypress
  listenKey();

return false;
 }

imgPreload.src = objLink.href;
 
}

//
// hideLightbox()
//
function hideLightbox()
{
 // get objects
 objOverlay = document.getElementById('overlay');
 objLightbox = document.getElementById('lightbox');

// hide lightbox and overlay
 objOverlay.style.display = 'none';
 objLightbox.style.display = 'none';
 
 // disable keypress listener
 document.onkeypress = '';
}

//
// initLightbox()
// Function runs on window load, going through link tags looking for rel="lightbox".
// These links receive onclick events that enable the lightbox display for their targets.
// The function also inserts html markup at the top of the page which will be used as a
// container for the overlay pattern and the inline image.
//
function initLightbox()
{
 
 if (!document.getElementsByTagName){ return; }
 var anchors = document.getElementsByTagName("a");

// loop through all anchor tags
 for (var i=0; i<anchors.length; i++){
  var anchor = anchors[i];

if (anchor.getAttribute("href") && (anchor.getAttribute("rel") == "lightbox")){
   anchor.onclick = function () {showLightbox(this); return false;}
  }
 }

var objBody = document.getElementsByTagName("body").item(0);
 
 // create overlay div and hardcode some functional styles (aesthetic styles are in CSS file)
 var objOverlay = document.createElement("div");
 objOverlay.setAttribute('id','overlay');
 objOverlay.onclick = function () {hideLightbox(); return false;}
 objOverlay.style.display = 'none';
 objOverlay.style.position = 'absolute';
 objOverlay.style.top = '0';
 objOverlay.style.left = '0';
 objOverlay.style.zIndex = '90';
  objOverlay.style.width = '100%';
 objBody.insertBefore(objOverlay, objBody.firstChild);
 
 var arrayPageSize = getPageSize();
 var arrayPageScroll = getPageScroll();

// preload and create loader image
 var imgPreloader = new Image();
 
 // if loader image found, create link to hide lightbox and create loadingimage
 imgPreloader.onload=function(){

var objLoadingImageLink = document.createElement("a");
  objLoadingImageLink.setAttribute('href','#');
  objLoadingImageLink.onclick = function () {hideLightbox(); return false;}
  objOverlay.appendChild(objLoadingImageLink);
  
  var objLoadingImage = document.createElement("img");
  objLoadingImage.src = loadingImage;
  objLoadingImage.setAttribute('id','loadingImage');
  objLoadingImage.style.position = 'absolute';
  objLoadingImage.style.zIndex = '150';
  objLoadingImageLink.appendChild(objLoadingImage);

imgPreloader.onload=function(){}; // clear onLoad, as IE will flip out w/animated gifs

return false;
 }

imgPreloader.src = loadingImage;

// create lightbox div, same note about styles as above
 var objLightbox = document.createElement("div");
 objLightbox.setAttribute('id','lightbox');
 objLightbox.style.display = 'none';
 objLightbox.style.position = 'absolute';
 objLightbox.style.zIndex = '100'; 
 objBody.insertBefore(objLightbox, objOverlay.nextSibling);
 
 // create link
 var objLink = document.createElement("a");
 objLink.setAttribute('href','#');
 objLink.setAttribute('title','Click to close');
 objLink.onclick = function () {hideLightbox(); return false;}
 objLightbox.appendChild(objLink);

// preload and create close button image
 var imgPreloadCloseButton = new Image();

// if close button image found, 
 imgPreloadCloseButton.onload=function(){

var objCloseButton = document.createElement("img");
  objCloseButton.src = closeButton;
  objCloseButton.setAttribute('id','closeButton');
  objCloseButton.style.position = 'absolute';
  objCloseButton.style.zIndex = '200';
  objLink.appendChild(objCloseButton);

return false;
 }

imgPreloadCloseButton.src = closeButton;

// create image
 var objImage = document.createElement("img");
 objImage.setAttribute('id','lightboxImage');
 objLink.appendChild(objImage);
 
 // create details div, a container for the caption and keyboard message
 var objLightboxDetails = document.createElement("div");
 objLightboxDetails.setAttribute('id','lightboxDetails');
 objLightbox.appendChild(objLightboxDetails);

// create caption
 var objCaption = document.createElement("div");
 objCaption.setAttribute('id','lightboxCaption');
 objCaption.style.display = 'none';
 objLightboxDetails.appendChild(objCaption);

// create keyboard message
 var objKeyboardMsg = document.createElement("div");
 objKeyboardMsg.setAttribute('id','keyboardMsg');
 objKeyboardMsg.innerHTML = 'press <kbd>x</kbd> to close';
 objLightboxDetails.appendChild(objKeyboardMsg);

}

//
// addLoadEvent()
// Adds event to window.onload without overwriting currently assigned onload functions.
//
function addLoadEvent(func)
{ 
 var oldonload = window.onload;
 if (typeof window.onload != 'function'){
     window.onload = func;
 } else {
  window.onload = function(){
  oldonload();
  func();
  }
 }

}

addLoadEvent(initLightbox); // run initLightbox onLoad

Tuesday 24 March 2015

Light Box

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