ie6下png图片背景不透明的解决办法使用js实现

/**
* DD_belatedPNG: Adds IE6 support: PNG images for CSS background-image and HTML <IMG/>.
* Author: Drew Diller
* Email: drew.diller@gmail.com
* URL: http://www.dillerdesign.com/experiment/DD_belatedPNG/
* Version: 0.0.8a
* Licensed under the MIT License: http://dillerdesign.com/experiment/DD_belatedPNG/#license
*
* Example usage:
* DD_belatedPNG.fix(.png_bg); // argument is a CSS selector
* DD_belatedPNG.fixPng( someNode ); // argument is an HTMLDomElement
**/
/*
PLEASE READ:
Absolutely everything in this script is SILLY. I know this. IEs rendering of certain pixels doesnt make sense, so neither does this code!
*/
/** rewrite by waitingbar 2012.1.12
为了解决IE6下透明的png图片缩小时不能完全显示问题
el.vml.image.fill.type = tile; 改为：
el.vml.image.fill.type = frame;
*/

var DD_belatedPNG = {
ns: DD_belatedPNG,
imgSize: {},
delay: 10,
nodesFixed: 0,
createVmlNameSpace: function () { /* enable VML */
if (document.namespaces && !document.namespaces[this.ns]) {
document.namespaces.add(this.ns, urn:schemas-microsoft-com:vml);
}
},
createVmlStyleSheet: function () { /* style VML, enable behaviors */
/*
Just in case lots of other developers have added
lots of other stylesheets using document.createStyleSheet
and hit the 31-limit mark, lets not use that method!
further reading: http://msdn.microsoft.com/en-us/library/ms531194(VS.85).aspx
*/
var screenStyleSheet, printStyleSheet;
screenStyleSheet = document.createElement(style);
screenStyleSheet.setAttribute(media, screen);
document.documentElement.firstChild.insertBefore(screenStyleSheet, document.documentElement.firstChild.firstChild);
if (screenStyleSheet.styleSheet) {
screenStyleSheet = screenStyleSheet.styleSheet;
screenStyleSheet.addRule(this.ns + \\:*, {behavior:url(#default#VML)});
screenStyleSheet.addRule(this.ns + \\:shape, position:absolute;);
screenStyleSheet.addRule(img. + this.ns + _sizeFinder, behavior:none; border:none; position:absolute; z-index:-1; top:-10000px; visibility:hidden;); /* large negative top value for avoiding vertical scrollbars for large images, suggested by James OBrien, http://www.thanatopsic.org/hendrik/ */
this.screenStyleSheet = screenStyleSheet;
/* Add a print-media stylesheet, for preventing VML artifacts from showing up in print (including preview). */
/* Thanks to R閙i Pr関ost for automating this! */
printStyleSheet = document.createElement(style);
printStyleSheet.setAttribute(media, print);
document.documentElement.firstChild.insertBefore(printStyleSheet, document.documentElement.firstChild.firstChild);
printStyleSheet = printStyleSheet.styleSheet;
printStyleSheet.addRule(this.ns + \\:*, {display: none !important;});
printStyleSheet.addRule(img. + this.ns + _sizeFinder, {display: none !important;});
}
},
readPropertyChange: function () {
var el, display, v;
el = event.srcElement;
if (!el.vmlInitiated) {
return;
}
if (event.propertyName.search(background) != -1 || event.propertyName.search(border) != -1) {
DD_belatedPNG.applyVML(el);
}
if (event.propertyName == style.display) {
display = (el.currentStyle.display == none) ? none : block;
for (v in el.vml) {
if (el.vml.hasOwnProperty(v)) {
el.vml[v].shape.style.display = display;
}
}
}
if (event.propertyName.search(filter) != -1) {
DD_belatedPNG.vmlOpacity(el);
}
},
vmlOpacity: function (el) {
if (el.currentStyle.filter.search(lpha) != -1) {
var trans = el.currentStyle.filter;
trans = parseInt(trans.substring(trans.lastIndexOf(=)+1, trans.lastIndexOf())), 10)/100;
el.vml.color.shape.style.filter = el.currentStyle.filter; /* complete guesswork */
el.vml.image.fill.opacity = trans; /* complete guesswork */
}
},
handlePseudoHover: function (el) {
setTimeout(function () { /* wouldnt work as intended without setTimeout */
DD_belatedPNG.applyVML(el);
}, 1);
},
/**
* This is the method to use in a document.
* @param {String} selector - REQUIRED - a CSS selector, such as #doc .container
**/
fix: function (selector) {
if (this.screenStyleSheet) {
var selectors, i;
selectors = selector.split(,); /* multiple selectors supported, no need for multiple calls to this anymore */
for (i=0; i<selectors.length; i++) {
this.screenStyleSheet.addRule(selectors[i], behavior:expression(DD_belatedPNG.fixPng(this))); /* seems to execute the function without adding it to the stylesheet - interesting... */
}
}
},
applyVML: function (el) {
el.runtimeStyle.cssText = ;
this.vmlFill(el);
this.vmlOffsets(el);
this.vmlOpacity(el);
if (el.isImg) {
this.copyImageBorders(el);
}
},
attachHandlers: function (el) {
var self, handlers, handler, moreForAs, a, h;
self = this;
handlers = {resize: vmlOffsets, move: vmlOffsets};
if (el.nodeName == A) {
moreForAs = {mouseleave: handlePseudoHover, mouseenter: handlePseudoHover, focus: handlePseudoHover, blur: handlePseudoHover};
for (a in moreForAs) {
if (moreForAs.hasOwnProperty(a)) {
handlers[a] = moreForAs[a];
}
}
}
for (h in handlers) {
if (handlers.hasOwnProperty(h)) {
handler = function () {
self[handlers[h]](el);
};
el.attachEvent(on + h, handler);
}
}
el.attachEvent(onpropertychange, this.readPropertyChange);
},
giveLayout: function (el) {
el.style.zoom = 1;
if (el.currentStyle.position == static) {
el.style.position = relative;
}
},
copyImageBorders: function (el) {
var styles, s;
styles = {borderStyle:true, borderWidth:true, borderColor:true};
for (s in styles) {
if (styles.hasOwnProperty(s)) {
el.vml.color.shape.style[s] = el.currentStyle[s];
}
}
},
vmlFill: function (el) {
if (!el.currentStyle) {
return;
} else {
var elStyle, noImg, lib, v, img, imgLoaded;
elStyle = el.currentStyle;
}
for (v in el.vml) {
if (el.vml.hasOwnProperty(v)) {
el.vml[v].shape.style.zIndex = elStyle.zIndex;
}
}
el.runtimeStyle.backgroundColor = ;
el.runtimeStyle.backgroundImage = ;
noImg = true;
if (elStyle.backgroundImage != none || el.isImg) {
if (!el.isImg) {
el.vmlBg = elStyle.backgroundImage;
el.vmlBg = el.vmlBg.substr(5, el.vmlBg.lastIndexOf("))-5);
}
else {
el.vmlBg = el.src;
}
lib = this;
if (!lib.imgSize[el.vmlBg]) { /* determine size of loaded image */
img = document.createElement(img);
lib.imgSize[el.vmlBg] = img;
img.className = lib.ns + _sizeFinder;
img.runtimeStyle.cssText = behavior:none; position:absolute; left:-10000px; top:-10000px; border:none; margin:0; padding:0;; /* make sure to set behavior to none to prevent accidental matching of the helper elements! */
imgLoaded = function () {
this.width = this.offsetWidth; /* weird cache-busting requirement! */
this.height = this.offsetHeight;
lib.vmlOffsets(el);
};
img.attachEvent(onload, imgLoaded);
img.src = el.vmlBg;
img.removeAttribute(width);
img.removeAttribute(height);
document.body.insertBefore(img, document.body.firstChild);
}
el.vml.image.fill.src = el.vmlBg;
noImg = false;
}
el.vml.image.fill.on = !noImg;
el.vml.image.fill.color = none;
el.vml.color.shape.style.backgroundColor = elStyle.backgroundColor;
el.runtimeStyle.backgroundImage = none;
el.runtimeStyle.backgroundColor = transparent;
},
/* IE cant figure out what do when the offsetLeft and the clientLeft add up to 1, and the VML ends up getting fuzzy... so we have to push/enlarge things by 1 pixel and then clip off the excess */
vmlOffsets: function (el) {
var thisStyle, size, fudge, makeVisible, bg, bgR, dC, altC, b, c, v;
thisStyle = el.currentStyle;
size = {W:el.clientWidth+1, H:el.clientHeight+1, w:this.imgSize[el.vmlBg].width, h:this.imgSize[el.vmlBg].height, L:el.offsetLeft, T:el.offsetTop, bLW:el.clientLeft, bTW:el.clientTop};
fudge = (size.L + size.bLW == 1) ? 1 : 0;
/* vml shape, left, top, width, height, origin */
makeVisible = function (vml, l, t, w, h, o) {
vml.coordsize = w+,+h;
vml.coordorigin = o+,+o;
vml.path = m0,0l+w+,0l+w+,+h+l0,+h+ xe;
vml.style.width = w + px;
vml.style.height = h + px;
vml.style.left = l + px;
vml.style.top = t + px;
};
makeVisible(el.vml.color.shape, (size.L + (el.isImg ? 0 : size.bLW)), (size.T + (el.isImg ? 0 : size.bTW)), (size.W-1), (size.H-1), 0);
makeVisible(el.vml.image.shape, (size.L + size.bLW), (size.T + size.bTW), (size.W), (size.H), 1 );
bg = {X:0, Y:0};
if (el.isImg) {
bg.X = parseInt(thisStyle.paddingLeft, 10) + 1;
bg.Y = parseInt(thisStyle.paddingTop, 10) + 1;
}
else {
for (b in bg) {
if (bg.hasOwnProperty(b)) {
this.figurePercentage(bg, size, b, thisStyle[backgroundPosition+b]);
}
}
}
el.vml.image.fill.position = (bg.X/size.W) + , + (bg.Y/size.H);
bgR = thisStyle.backgroundRepeat;
dC = {T:1, R:size.W+fudge, B:size.H, L:1+fudge}; /* these are defaults for repeat of any kind */
altC = { X: {b1: L, b2: R, d: W}, Y: {b1: T, b2: B, d: H} };
if (bgR != repeat || el.isImg) {
c = {T:(bg.Y), R:(bg.X+size.w), B:(bg.Y+size.h), L:(bg.X)}; /* these are defaults for no-repeat - clips down to the image location */
if (bgR.search(repeat-) != -1) { /* now lets revert to dC for repeat-x or repeat-y */
v = bgR.split(repeat-)[1].toUpperCase();
c[altC[v].b1] = 1;
c[altC[v].b2] = size[altC[v].d];
}
if (c.B > size.H) {
c.B = size.H;
}
el.vml.image.shape.style.clip = rect(+c.T+px +(c.R+fudge)+px +c.B+px +(c.L+fudge)+px);
}
else {
el.vml.image.shape.style.clip = rect(+dC.T+px +dC.R+px +dC.B+px +dC.L+px);
}
},
figurePercentage: function (bg, size, axis, position) {
var horizontal, fraction;
fraction = true;
horizontal = (axis == X);
switch(position) {
case left:
case top:
bg[axis] = 0;
break;
case center:
bg[axis] = 0.5;
break;
case right:
case bottom:
bg[axis] = 1;
break;
default:
if (position.search(%) != -1) {
bg[axis] = parseInt(position, 10) / 100;
}
else {
fraction = false;
}
}
bg[axis] = Math.ceil( fraction ? ( (size[horizontal?W: H] * bg[axis]) - (size[horizontal?w: h] * bg[axis]) ) : parseInt(position, 10) );
if (bg[axis] % 2 === 0) {
bg[axis]++;
}
return bg[axis];
},
fixPng: function (el) {
el.style.behavior = none;
var lib, els, nodeStr, v, e;
if (el.nodeName == BODY || el.nodeName == TD || el.nodeName == TR) { /* elements not supported yet */
return;
}
el.isImg = false;
if (el.nodeName == IMG) {
if(el.src.toLowerCase().search(/\.png$/) != -1) {
el.isImg = true;
el.style.visibility = hidden;
}
else {
return;
}
}
else if (el.currentStyle.backgroundImage.toLowerCase().search(.png) == -1) {
return;
}
lib = DD_belatedPNG;
el.vml = {color: {}, image: {}};
els = {shape: {}, fill: {}};
for (v in el.vml) {
if (el.vml.hasOwnProperty(v)) {
for (e in els) {
if (els.hasOwnProperty(e)) {
nodeStr = lib.ns + : + e;
el.vml[v][e] = document.createElement(nodeStr);
}
}
el.vml[v].shape.stroked = false;
el.vml[v].shape.appendChild(el.vml[v].fill);
el.parentNode.insertBefore(el.vml[v].shape, el);
}
}
el.vml.image.shape.fillcolor = none; /* Dont show blank white shapeangle when waiting for image to load. */
//el.vml.image.fill.type = tile; /* Makes image show up. */
el.vml.image.fill.type = frame; /* 2012.1.12 */
el.vml.color.fill.on = false; /* Actually going to apply vml elements style.backgroundColor, so hide the whiteness. */
lib.attachHandlers(el);
lib.giveLayout(el);
lib.giveLayout(el.offsetParent);
el.vmlInitiated = true;
lib.applyVML(el); /* Render! */
}
};
try {
document.execCommand("BackgroundImageCache", false, true); /* TredoSoft Multiple IE doesnt like this, so try{} it */
} catch(r) {}
DD_belatedPNG.createVmlNameSpace();
DD_belatedPNG.createVmlStyleSheet();

< !--[if IE 6]><script src="DD_belatedPNG.js"></script><script> DD_belatedPNG.fix(.png_bg);</script><![endif]-->