ie6下实现png透明

update：最近发现一个更好的解决方案，使用VML替换AlphaImageLoader，可以解决被替换元素hover状态不起作用的问题。详见：http://www.dillerdesign.com/experiment/DD_belatedPNG/。我使用VML方式做的页面：http://fang.kuwo.cn/p/Radio

 

// Universal transparent-PNG enabler for MSIE/Win 5.5+
// http://dsandler.org
// From original code: http://www.youngpup.net/?request=/snippets/sleight.xml
// and background-image code: http://www.allinthehead.com/retro/69
// also:
//  * use sizingMethod=crop to avoid scaling PNGs (who would do such a thing?)
//  * only do this once, to make it compatible with CSS rollovers

if (navigator.platform == "Win32" && navigator.appName == "Microsoft Internet Explorer" && window.attachEvent) {
	window.attachEvent("onload", enableAlphaImages);
}

function enableAlphaImages(){
	var rslt = navigator.appVersion.match(/MSIE (\d+\.\d+)/, '');
	var itsAllGood = (rslt != null && Number(rslt[1]) >= 5.5);
	if (itsAllGood) {
		for (var i=0; i<document.all.length; i++){
			var obj = document.all[i];
			var bg = obj.currentStyle.backgroundImage;
			var img = document.images[i];
			if (bg && bg.match(/\.png/i) != null) {
				var img = bg.substring(5,bg.length-2);
				var offset = obj.style["background-position"];
				obj.style.filter =
				"progid:DXImageTransform.Microsoft.AlphaImageLoader(src='"+img+"', sizingMethod='crop')";
				obj.style.backgroundImage = "url('/images/spacer.gif')";
				obj.style["background-position"] = offset; // reapply
			} else if (img && img.src.match(/\.png$/i) != null) {
				var src = img.src;
				img.style.width = img.width + "px";
				img.style.height = img.height + "px";
				img.style.filter =
				"progid:DXImageTransform.Microsoft.AlphaImageLoader(src='"+src+"', sizingMethod='crop')"
				img.src = "/images/spacer.gif";
			}

		}
	}
}

注意，需要将png图片设置为元素的背景图片，并且添加一个图片“spacer.gif”。

示例见：http://blog.gulu77.com/demo/200809/test_PNGTransparncyinIE/

 

转自：http://blog.gulu77.com/?p=147