jQuery第三十一天练习

DD_belatedPNG.js

/**
* DD_belatedPNG: Adds IE6 support: PNG images for CSS background-image and HTML .
* 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.  IE's rendering of certain pixels doesn't make sense, so neither does this code!
*/

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, let's 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 O'Brien, 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 mi Pr vost 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 () { /* wouldn't 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 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'; /* Don't show blank white shapeangle when waiting for image to load. */
		el.vml.image.fill.type = 'tile'; /* Makes image show up. */
		el.vml.color.fill.on = false; /* Actually going to apply vml element's 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 doesn't like this, so try{} it */
} catch(r) {}
DD_belatedPNG.createVmlNameSpace();
DD_belatedPNG.createVmlStyleSheet();

效果图：