javascript 特效之代码解释

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">

<html>

<head>

<title>1</title>

<meta http-equiv="imagetoolbar" content="no">

<style type="text/css">

	html {

		overflow: hidden;

	}

	body {

		margin: 0px;

		padding: 0px;

		background: #000;

		width: 100%;

		height: 100%;

	}

	#imageFlow {

		position: absolute;

		width: 100%;

		height: 80%;

		left: 0%;

		top: 10%;

		background: #000;

	}

	#imageFlow .diapo {

		position: absolute;

		left: -1000px;

		cursor: pointer;

		-ms-interpolation-mode: nearest-neighbor;

	}

	#imageFlow .link {

		border: dotted #fff 1px;

		margin-left: -1px;

		margin-bottom: -1px;

	}

	#imageFlow .bank {

		visibility: hidden;

	}

	#imageFlow .top {

		position: absolute;

		width: 100%;

		height: 40%;

		background: #181818;

	}

	#imageFlow .text {

		position: absolute;

		left: 0px;

		width: 100%;

		bottom: 16%;

		text-align: center;

		color: #FFF;

		font-family: verdana, arial, Helvetica, sans-serif;

		z-index: 1000;

	}

	#imageFlow .title {

		font-size: 0.9em;

		font-weight: bold;

	}

	#imageFlow .legend {

		font-size: 0.8em;

	}

	#imageFlow .scrollbar {

		position: absolute;

		left: 10%;

		bottom: 10%;

		width: 80%;

		height: 16px;

		z-index: 1000;

	}

	#imageFlow .track {

		position: absolute;

		left: 1%;

		width: 98%;

		height: 16px;

		filter: alpha(opacity=30);

		opacity: 0.3;

	}

	#imageFlow .arrow-left {

		position: absolute;

	}

	#imageFlow .arrow-right {

		position: absolute;

		right: 0px;

	}

	#imageFlow .bar {

		position: absolute;

		height: 16px;

		left: 25px;

	}

</style>



<script type="text/javascript">



var imf = function () {

	var lf = 0;

	var instances = [];

	function getElementsByClass (object, tag, className) {

		var o = object.getElementsByTagName(tag);

		for ( var i = 0, n = o.length, ret = []; i < n; i++)

			if (o[i].className == className) ret.push(o[i]);

		if (ret.length == 1) ret = ret[0];

		return ret;

	}

	function addEvent (o, e, f) {

		if (window.addEventListener) o.addEventListener(e, f, false);

		else if (window.attachEvent) r = o.attachEvent('on' + e, f);

	}

	function createReflexion (cont, img) {

		var flx = false;

		if (document.createElement("canvas").getContext) {

			flx = document.createElement("canvas");

			flx.width = img.width;

			flx.height = img.height;

			var context = flx.getContext("2d");

			context.translate(0, img.height);

			context.scale(1, -1);

			context.drawImage(img, 0, 0, img.width, img.height);

			context.globalCompositeOperation = "destination-out";

			var gradient = context.createLinearGradient(0, 0, 0, img.height * 2);

			gradient.addColorStop(1, "rgba(255, 255, 255, 0)");

			gradient.addColorStop(0, "rgba(255, 255, 255, 1)");

			context.fillStyle = gradient;

			context.fillRect(0, 0, img.width, img.height * 2);

		} else {

			/* ---- DXImageTransform ---- */

			flx     = document.createElement('img');

			flx.src = img.src;

			flx.style.filter = 'flipv progid:DXImageTransform.Microsoft.Alpha(' +

			                   'opacity=50, style=1, finishOpacity=0, startx=0, starty=0, finishx=0, finishy=' +

							   (img.height * .25) + ')';

		}

		/* ---- insert Reflexion ---- */

		flx.style.position = 'absolute';

		flx.style.left     = '-1000px';

		cont.appendChild(flx);

		return flx;

	}

	/* //////////// ==== ImageFlow Constructor ==== //////////// */

	function ImageFlow(oCont, size, zoom, border) {

		this.diapos     = [];

		this.scr        = false;

		this.size       = size;

		this.zoom       = zoom;

		this.bdw        = border;

		this.oCont      = oCont;

		this.oc         = document.getElementById(oCont);

		this.scrollbar  = getElementsByClass(this.oc,   'div', 'scrollbar');

		this.text       = getElementsByClass(this.oc,   'div', 'text');

		this.title      = getElementsByClass(this.text, 'div', 'title');

		this.legend     = getElementsByClass(this.text, 'div', 'legend');

		this.bar        = getElementsByClass(this.oc,   'img', 'bar');

		this.arL        = getElementsByClass(this.oc,   'img', 'arrow-left');

		this.arR        = getElementsByClass(this.oc,   'img', 'arrow-right');

		this.bw         = this.bar.width;

		this.alw        = this.arL.width - 5;

		this.arw        = this.arR.width - 5;

		this.bar.parent = this.oc.parent  = this;

		this.arL.parent = this.arR.parent = this;

		this.view       = this.back       = -1;

		this.resize();

		this.oc.onselectstart = function () { return false; }

		/* ---- create images ---- */

		var img   = getElementsByClass(this.oc, 'div', 'bank').getElementsByTagName('a');

		this.NF = img.length;

		for (var i = 0, o; o = img[i]; i++) {

			this.diapos[i] = new Diapo(this, i,

										o.rel,

										o.title || '- ' + i + ' -',

										o.innerHTML || o.rel,

										o.href || '',

										o.target || '_self'

			);

		}

		/* ==== add mouse wheel events ==== */

		if (window.addEventListener)

			this.oc.addEventListener('DOMMouseScroll', function(e) {

				this.parent.scroll(-e.detail);

			}, false);

		else this.oc.onmousewheel = function () {

			this.parent.scroll(event.wheelDelta);

		}

		/* ==== scrollbar drag N drop ==== */

		this.bar.onmousedown = function (e) {

			if (!e) e = window.event;

			var scl = e.screenX - this.offsetLeft;

			var self = this.parent;

			/* ---- move bar ---- */

			this.parent.oc.onmousemove = function (e) {

				if (!e) e = window.event;

				self.bar.style.left = Math.round(Math.min((self.ws - self.arw - self.bw), Math.max(self.alw, e.screenX - scl))) + 'px';

				self.view = Math.round(((e.screenX - scl) ) / (self.ws - self.alw - self.arw - self.bw) * self.NF);

				if (self.view != self.back) self.calc();

				return false;

			}

			/* ---- release scrollbar ---- */

			this.parent.oc.onmouseup = function (e) {

				self.oc.onmousemove = null;

				return false;

			}

			return false;

		}

		/* ==== right arrow ==== */

		this.arR.onclick = this.arR.ondblclick = function () {

			if (this.parent.view < this.parent.NF - 1)

				this.parent.calc(1);

		}

		/* ==== Left arrow ==== */

		this.arL.onclick = this.arL.ondblclick = function () {

			if (this.parent.view > 0)

				this.parent.calc(-1);

		}

	}

	/* //////////// ==== ImageFlow prototype ==== //////////// */

	ImageFlow.prototype = {

		/* ==== targets ==== */

		calc : function (inc) {

			if (inc) this.view += inc;

			var tw = 0;

			var lw = 0;

			var o = this.diapos[this.view];

			if (o && o.loaded) {

				/* ---- reset ---- */

				var ob = this.diapos[this.back];

				if (ob && ob != o) {

					ob.img.className = 'diapo';

					ob.z1 = 1;

				}

				/* ---- update legend ---- */

				this.title.replaceChild(document.createTextNode(o.title), this.title.firstChild);

				this.legend.replaceChild(document.createTextNode(o.text), this.legend.firstChild);