On Fri, Apr 24, 2009 at 07:08:05PM +0100, David Gerard wrote:
There was a spec in earlier versions of HTML to put a low-res
thumbnail up while the full image dribbled through your dialup - <img
lowsrc="image-placeholder.gif" src="image.gif"> - but it was so
little
used (I know of no cases) that I don't know if it's even supported in
browsers any more.
http://www.htmlcodetutorial.com/images/_IMG_LOWSRC.html
I tried it with FireFox 3.0.9 and IE 7.0.6001.18000; neither paid any
attention to it. IE 6.0.2800.1106 under Wine also ignored it. Too bad,
that would have been nice if it worked.
I don't know that we need fancy AJAX if we know at page rendering time
whether the image is available, though. We might be able to get away
with a simple script like this:
var ImageCache={};
function loadImage(id, url){
var i = document.getElementById(id);
if(i){
var img = new Image();
ImageCache[id] = img;
img.onload=function(){ i.src = url; ImageCache[id]=null; };
img.src = url;
}
}
And then generate the <img> tag with the placeholder and some id, and
call that function onload for it. Of course, if there are a lot of these
images on one page then we might run into the browser's concurrent
connection limit, which an AJAX solution might be able to overcome.