ie-css3.htc 可以让IE低版本浏览器支持CSS3 的一个小工具

ie-css3.htc
先说道说道这斯是弄啥嘞
ie-css3.htc是一个可以让IE浏览器支持部份CSS3属性的htc文件，不只是box-shadow，它还可以让你的IE浏览器支持圆角属性border-radius和文字阴影属性text-shadow
复制保存下面的代码并命名为ie-css.htc,放在你认为比较好的位置中去，然后在CSS中调用，就像使用背景图片那样，只要能找得到他就可以了。

/***************以下内容为 ie css3.htc 内容****************/

--Do not remove this if you are using--
Original Author: Remiz Rahnas
Original Author URL: http://www.htmlremix.com Published date: 2008/09/24

Changes by Nick Fetchak:
- IE8 standards mode compatibility
- VML elements now positioned behind original box rather than inside of it - should be less prone to breakage
- Added partial support for 'box-shadow' style
- Checks for VML support before doing anything
- Updates VML element size and position via timer and also via window resize event
- lots of other small things
Published date : 2010/03/14 http://fetchak.com/ie-css3 
Thanks to TheBrightLines.com (http://www.thebrightlines.com/2009/12/03/using-ies-filter-in-a-cross-browser-way) for enlightening me about the DropShadow filter

<public:attach event="ondocumentready" onevent="ondocumentready('v08vnSVo78t4JfjH')" />
<script type="text/javascript">

timer_length = 200; // Milliseconds
border_opacity = false; // Use opacity on borders of rounded-corner elements? Note: This causes antialiasing issues

// supportsVml() borrowed from http://stackoverflow.com/questions/654112/how-do-you-detect-support-for-vml-or-svg-in-a-browser function supportsVml() {
if (typeof supportsVml.supported == "undefined") {
var a = document.body.appendChild(document.createElement('div'));
a.innerHTML = '<v:shape id="vml_flag1" adj="1" />';
var b = a.firstChild;
b.style.behavior = "url(#default#VML)";
supportsVml.supported = b ? typeof b.adj == "object": true;
a.parentNode.removeChild(a);
}
return supportsVml.supported
}

// findPos() borrowed from http://www.quirksmode.org/js/findpos.html function findPos(obj) {
var curleft = curtop = 0;

if (obj.offsetParent) {
do {
curleft += obj.offsetLeft;
curtop += obj.offsetTop;
} while (obj = obj.offsetParent);
}

return({
'x': curleft,
'y': curtop
});
}

function createBoxShadow(element, vml_parent) {
var style = element.currentStyle['iecss3-box-shadow'] || element.currentStyle['-moz-box-shadow'] || element.currentStyle['-webkit-box-shadow'] || element.currentStyle['box-shadow'] || '';
var match = style.match(/^(\d+)px (\d+)px (\d+)px/);
if (!match) { return(false); }

var shadow = document.createElement('v:roundrect');
shadow.userAttrs = {
'x': parseInt(RegExp.$1 || 0),
'y': parseInt(RegExp.$2 || 0),
'radius': parseInt(RegExp.$3 || 0) / 2
};
shadow.position_offset = {
'y': (0 - vml_parent.pos_ieCSS3.y - shadow.userAttrs.radius + shadow.userAttrs.y),
'x': (0 - vml_parent.pos_ieCSS3.x - shadow.userAttrs.radius + shadow.userAttrs.x)
};
shadow.size_offset = {
'width': 0,
'height': 0
};
shadow.arcsize = element.arcSize +'px';
shadow.style.display = 'block';
shadow.style.position = 'absolute';
shadow.style.top = (element.pos_ieCSS3.y + shadow.position_offset.y) +'px';
shadow.style.left = (element.pos_ieCSS3.x + shadow.position_offset.x) +'px';
shadow.style.width = element.offsetWidth +'px';
shadow.style.height = element.offsetHeight +'px';
shadow.style.antialias = true;
shadow.className = 'vml_box_shadow';
shadow.style.zIndex = element.zIndex - 1;
shadow.style.filter = 'progid:DXImageTransform.Microsoft.Blur(pixelRadius='+ shadow.userAttrs.radius +',makeShadow=true,shadowOpacity='+ element.opacity +')';

element.parentNode.appendChild(shadow);
//element.parentNode.insertBefore(shadow, element.element);

// For window resizing
element.vml.push(shadow);

return(true);
}

function createBorderRect(element, vml_parent) {
if (isNaN(element.borderRadius)) { return(false); }

element.style.background = 'transparent';
element.style.borderColor = 'transparent';

var rect = document.createElement('v:roundrect');
rect.position_offset = {
'y': (0.5 * element.strokeWeight) - vml_parent.pos_ieCSS3.y,
'x': (0.5 * element.strokeWeight) - vml_parent.pos_ieCSS3.x
};
rect.size_offset = {
'width': 0 - element.strokeWeight,
'height': 0 - element.strokeWeight
};
rect.arcsize = element.arcSize +'px';
rect.strokeColor = element.strokeColor;
rect.strokeWeight = element.strokeWeight +'px';
rect.stroked = element.stroked;
rect.className = 'vml_border_radius';
rect.style.display = 'block';
rect.style.position = 'absolute';
rect.style.top = (element.pos_ieCSS3.y + rect.position_offset.y) +'px';
rect.style.left = (element.pos_ieCSS3.x + rect.position_offset.x) +'px';
rect.style.width = (element.offsetWidth + rect.size_offset.width) +'px';
rect.style.height = (element.offsetHeight + rect.size_offset.height) +'px';
rect.style.antialias = true;
rect.style.zIndex = element.zIndex - 1;

if (border_opacity && (element.opacity < 1)) {
rect.style.filter = 'progid:DXImageTransform.Microsoft.Alpha(Opacity='+ parseFloat(element.opacity * 100) +')';
}

var fill = document.createElement('v:fill');
fill.color = element.fillColor;
fill.src = element.fillSrc;
fill.className = 'vml_border_radius_fill';
fill.type = 'tile';
fill.opacity = element.opacity;

// Hack: IE6 doesn't support transparent borders, use padding to offset original element
isIE6 = /msie|MSIE 6/.test(navigator.userAgent);
if (isIE6 && (element.strokeWeight > 0)) {
element.style.borderStyle = 'none';
element.style.paddingTop = parseInt(element.currentStyle.paddingTop || 0) + element.strokeWeight;
element.style.paddingBottom = parseInt(element.currentStyle.paddingBottom || 0) + element.strokeWeight;
}

rect.appendChild(fill);
element.parentNode.appendChild(rect);
//element.parentNode.insertBefore(rect, element.element);

// For window resizing
element.vml.push(rect);

return(true);
}

function createTextShadow(element, vml_parent) {
if (!element.textShadow) { return(false); }

var match = element.textShadow.match(/^(\d+)px (\d+)px (\d+)px (#?\w+)/);
if (!match) { return(false); }

//var shadow = document.createElement('span');
var shadow = element.cloneNode(true);
var radius = parseInt(RegExp.$3 || 0);
shadow.userAttrs = {
'x': parseInt(RegExp.$1 || 0) - (radius),
'y': parseInt(RegExp.$2 || 0) - (radius),
'radius': radius / 2,
'color': (RegExp.$4 || '#000')
};
shadow.position_offset = {
'y': (0 - vml_parent.pos_ieCSS3.y + shadow.userAttrs.y),
'x': (0 - vml_parent.pos_ieCSS3.x + shadow.userAttrs.x)
};
shadow.size_offset = {
'width': 0,
'height': 0
};
shadow.style.color = shadow.userAttrs.color;
shadow.style.position = 'absolute';
shadow.style.top = (element.pos_ieCSS3.y + shadow.position_offset.y) +'px';
shadow.style.left = (element.pos_ieCSS3.x + shadow.position_offset.x) +'px';
shadow.style.antialias = true;
shadow.style.behavior = null;
shadow.className = 'ieCSS3_text_shadow';
shadow.innerHTML = element.innerHTML;
// For some reason it only looks right with opacity at 75%
shadow.style.filter = '\
progid:DXImageTransform.Microsoft.Alpha(Opacity=75)\
progid:DXImageTransform.Microsoft.Blur(pixelRadius='+ shadow.userAttrs.radius +',makeShadow=false,shadowOpacity=100)\
';

var clone = element.cloneNode(true);
clone.position_offset = {
'y': (0 - vml_parent.pos_ieCSS3.y),
'x': (0 - vml_parent.pos_ieCSS3.x)
};
clone.size_offset = {
'width': 0,
'height': 0
};
clone.style.behavior = null;
clone.style.position = 'absolute';
clone.style.top = (element.pos_ieCSS3.y + clone.position_offset.y) +'px';
clone.style.left = (element.pos_ieCSS3.x + clone.position_offset.x) +'px';
clone.className = 'ieCSS3_text_shadow';

element.parentNode.appendChild(shadow);
element.parentNode.appendChild(clone);

element.style.visibility = 'hidden';

// For window resizing
element.vml.push(clone);
element.vml.push(shadow);

return(true);
}

function ondocumentready(classID) {
if (!supportsVml()) { return(false); }

if (this.className.match(classID)) { return(false); }
this.className = this.className.concat(' ', classID);

// Add a namespace for VML (IE8 requires it)
if (!document.namespaces.v) { document.namespaces.add("v", "urn:schemas-microsoft-com:vml"); }

// Check to see if we've run once before on this page
if (typeof(window.ieCSS3) == 'undefined') {
// Create global ieCSS3 object
window.ieCSS3 = {
'vmlified_elements': new Array(),
'update_timer': setInterval(updatePositionAndSize, timer_length)
};

if (typeof(window.onresize) == 'function') { window.ieCSS3.previous_onresize = window.onresize; }

// Attach window resize event
window.onresize = updatePositionAndSize;
}

// These attrs are for the script and have no meaning to the browser:
this.borderRadius = parseInt(this.currentStyle['iecss3-border-radius'] ||
this.currentStyle['-moz-border-radius'] ||
this.currentStyle['-webkit-border-radius'] ||
this.currentStyle['border-radius'] ||
this.currentStyle['-khtml-border-radius']);
this.arcSize = Math.min(this.borderRadius / Math.min(this.offsetWidth, this.offsetHeight), 1);
this.fillColor = this.currentStyle.backgroundColor;
this.fillSrc = this.currentStyle.backgroundImage.replace(/^url\("(.+)"\)$/, '$1');
this.strokeColor = this.currentStyle.borderColor;
this.strokeWeight = parseInt(this.currentStyle.borderWidth);
this.stroked = 'true';
if (isNaN(this.strokeWeight) || (this.strokeWeight == 0)) {
this.strokeWeight = 0;
this.strokeColor = fillColor;
this.stroked = 'false';
}
this.opacity = parseFloat(this.currentStyle.opacity || 1);
this.textShadow = this.currentStyle['text-shadow'];

this.element.vml = new Array();
this.zIndex = parseInt(this.currentStyle.zIndex);
if (isNaN(this.zIndex)) { this.zIndex = 0; }

// Find which element provides position:relative for the target element (default to BODY)
vml_parent = this;
var limit = 100, i = 0;
do {
vml_parent = vml_parent.parentElement;
i++;
if (i >= limit) { return(false); }
} while ((typeof(vml_parent) != 'undefined') && (vml_parent.currentStyle.position != 'relative') && (vml_parent.tagName != 'BODY'));

vml_parent.pos_ieCSS3 = findPos(vml_parent);
this.pos_ieCSS3 = findPos(this);

var rv1 = createBoxShadow(this, vml_parent);
var rv2 = createBorderRect(this, vml_parent);
var rv3 = createTextShadow(this, vml_parent);
if (rv1 || rv2 || rv3) { window.ieCSS3.vmlified_elements.push(this.element); }

if (typeof(vml_parent.document.ieCSS3_stylesheet) == 'undefined') {
vml_parent.document.ieCSS3_stylesheet = vml_parent.document.createStyleSheet();
vml_parent.document.ieCSS3_stylesheet.addRule("v\\:roundrect", "behavior: url(#default#VML)");
vml_parent.document.ieCSS3_stylesheet.addRule("v\\:fill", "behavior: url(#default#VML)");
// Compatibility with IE7.js
vml_parent.document.ieCSS3_stylesheet.ie7 = true;
}
}

function updatePositionAndSize() {
if (typeof(window.ieCSS3.vmlified_elements) != 'object') { return(false); }

for (var i in window.ieCSS3.vmlified_elements) {
var el = window.ieCSS3.vmlified_elements[i];

if (typeof(el.vml) != 'object') { continue; }

for (var z in el.vml) {
//var parent_pos = findPos(el.vml[z].parentNode);
var new_pos = findPos(el);
new_pos.x = (new_pos.x + el.vml[z].position_offset.x) + 'px';
new_pos.y = (new_pos.y + el.vml[z].position_offset.y) + 'px';
if (el.vml[z].style.left != new_pos.x) { el.vml[z].style.left = new_pos.x; }
if (el.vml[z].style.top != new_pos.y) { el.vml[z].style.top = new_pos.y; }

var new_size = {
'width': parseInt(el.offsetWidth + el.vml[z].size_offset.width),
'height': parseInt(el.offsetHeight + el.vml[z].size_offset.height)
}
if (el.vml[z].offsetWidth != new_size.width) { el.vml[z].style.width = new_size.width +'px'; }
if (el.vml[z].offsetHeight != new_size.height) { el.vml[z].style.height = new_size.height +'px'; }
}
}

if (event && (event.type == 'resize') && typeof(window.ieCSS3.previous_onresize) == 'function') { window.ieCSS3.previous_onresize(); }
}
</script>

使用方法

.box {
-moz-border-radius: 15px; /* Firefox */
-webkit-border-radius: 15px; /* Safari 和 Chrome */
border-radius: 15px; /* Opera 10.5+, 以及使用了IE-CSS3的IE浏览器 */

-moz-box-shadow: 10px 10px 20px #000; /* Firefox */
-webkit-box-shadow: 10px 10px 20px #000; /* Safari 和 Chrome */
box-shadow: 10px 10px 20px #000; /* Opera 10.5+, 以及使用了IE-CSS3的IE浏览器 */

behavior: url(ie-css3.htc); /* 通知IE浏览器调用脚本作用于'box'类 */
}