/* l a r g e i m g s . j s
author: Andrew Purdam webmaster @ hallvet . com . au
Creation date: 7/12/05
Implementation of download of large imgs to replace other imgs
when a window is deemed large enough
Requires:
Definition of global variable "browser" to be
"Safari", "OmniWeb", "Opera", "WebTV", "iCab", "Internet Explorer", "FireFox", "Netscape Navigator", or "An Unknown Browser"
(actually, just need to know if it is Internet Explorer)
Two entry points are needed per document:
In header
*/
var largeimgs = new Array() ; // imgs to use when over the window size threshhold
var smallimgs = new Array() ; // imgs to use then under. These get filled in on first call to resizeimgs
function altimg(srcuri, w, h) // constructor for alternative img object
{
this.srcuri = srcuri ;
this.width = w ;
this.height = h ;
}
var firsttime = true ;
function resizeimgs(mw, mh) // called with minimum width and height to trigger use of larger images
{
if (firsttime)
{
firsttime = false ;
// set the small (original) images, and if IE, doctor the large img names
for (var imgname in largeimgs)
{
var imgobj = document.images[imgname] ;
if (imgobj)
smallimgs[imgname] = new altimg(imgobj.src, imgobj.width, imgobj.height) ;
// if internetexplorer, need to reparse the largeimgs relative to the document root
if (browser == "Internet Explorer")
{ // IE doesn't interpret relative uris, so I need to parse the srcuri
// into the src root
var url = new String(document.URL) ; // got the URL, now get the root
root1 = url.lastIndexOf("/") ; // either in Unix or
root2 = url.lastIndexOf("\\") ; // Windows notation
if (root1 > root2) root = url.substring(0,root1+1) ; // include the slash
else if (root2 > root1) root = url.substring(0,root2+1) ;
else root = url + "/" ; // couldn't find any slashes, so append one
largeimgs[imgname].srcuri = root + largeimgs[imgname].srcuri ;
}
}
}
width = window.innerWidth ? window.innerWidth : document.body.offsetWidth ;
height = window.innerHeight ? window.innerHeight : document.body.offsetHeight ;
if (width < mw || height < mh) for (var imgname in largeimgs)
{
var imgobj = document.images[imgname] ;
if (imgobj)
{
imgobj.src = smallimgs[imgname].srcuri ;
imgobj.width = smallimgs[imgname].width ;
imgobj.height = smallimgs[imgname].height ;
}
}
else for (var imgname in largeimgs)
{
var imgobj = document.images[imgname] ;
if (imgobj)
{
imgobj.src = largeimgs[imgname].srcuri ;
imgobj.width = largeimgs[imgname].width ;
imgobj.height = largeimgs[imgname].height ;
}
}
}