IE下png图形的另一种处理方法

IE下png图形的另一种处理方法(2)  *          2004-04-25  Fixed PNG image printing, eliminated need for external
 *                      GIF file, fixed intermittent uninitialised variable
 *                      error [by AG, <http://www.scss.com.au/family/andrew/> ]
 *          2004-09-30  Reverted inline Javascript image to transparent GIF. The
 *                      new XP SP2 'security' measures prevented the JS image
 *                      from working. [by AG]
 *          2004-10-22  Rewrote fixImage() to try and work around some reported
 *                      problems with PNGs vanishing! [by AG]
 *
 */
 
var IS_PNG = /.png$/i; /* <-- NOTE: remove the "\-trans" to process *all* PNGs */
var supported = /MSIE (5\.5)[6789]/.test(navigator.userAgent) && navigator.platform == 'Win32';
var realSrc;
var blankSrc = 'images/blank.gif';
if (supported) fixImage();
function propertyChanged() {
  if (supported && event.propertyName == 'src' && element.src != blankSrc) {
    fixImage();
  }
}
function fixImage() {
  if (realSrc && element.src == realSrc) {