Using PNG, and the cross-browser hack!

12/15/2005 11:55 AM by Chris Toohey

I'm doing a lot of web-work as of late (some using Domino and some not). As a result of this, I've been working with Photoshop moreso now than ever before, as the majority of my work has been marketing-related.

This being said, I'm really starting to push the usage of the PNG format for my images. Before going any further, here's some information on the PNG format:

PNG (Portable Network Graphics) Home Site
Intro to PNG Features
Why should I use PNG images on my webpage? - Overclock.net
To PNG or not to PNG | evolt.org

Now, in order to use this cross-browser, you'll need to use the following javascript hack for IE issues.

I only have but a minor enhancement to this, marked below in bold!

function correctPNG() // correctly handle PNG transparency in Win IE 5.5 or higher.
 {
  for(var i=0; i    {     var img = document.images[i]
    var imgName = img.src.toUpperCase()
    if (imgName.substring(imgName.length-3, imgName.length) == "PNG")
     {
      var imgID = (img.id) ? "id='" + img.id + "' " : ""
      var imgClass = (img.className) ? "class='" + img.className + "' " : ""
      var imgTitle = (img.title) ? "title='" + img.title + "' " : "title='" + img.alt + "' "
      var imgStyle = "display:inline-block;" + img.style.cssText
      if (img.align == "left") imgStyle = "float:left;" + imgStyle
       if (img.align == "right") imgStyle = "float:right;" + imgStyle
        if (img.parentElement.href) imgStyle = "cursor:hand;" + imgStyle
         var strNewHTML = "          + " style=\"" + "width:" + img.width + "px; height:" + img.height + "px;" + imgStyle + ";"
         + "filter:progid:DXImageTransform.Microsoft.AlphaImageLoader"
         + "(src=\'" + img.src + "\', sizingMethod='scale');\">"
         img.outerHTML = strNewHTML
         i = i-1
        }
       }
 }
if (window.attachEvent) window.attachEvent("onload", correctPNG);

This checks to see if window.attachEvent can be ran (if so, the browser's IE-based) and then sets to correctPNG() function to run onload of the body!

With this code in your common javascript library, it's easy enough to add PNG files to your web-based solutions, while ensuring that the format works across all browsers as intended!