asp中背景图片的切换
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发布时间：2022-05-17 01:47
共4个回答
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时间：2022-05-17 06:08
鼠标滑过上面的导航链接时 下面框中图片进行流畅的切换，左右移动的效果
html结构如下：
代码如下:
Web Design
These are the things you should know.
-
Structure -
Presentation -
Behavior
实在是很简单啊。下面我们直接来看js代码，先给出两个辅助函数：
addLoadEvent
代码如下:
function addLoadEvent(func) {
var oldonload = window.onload;
if(typeof window.onload != "function") {
window.onload = func;
} else {
window.onload = function() {
oldonload();
func();
}
}
}
这个函数顾名思义就是加载window的onload事件所要处理的方法
insertAfter
代码如下:
function insertAfter(newElement, targetElement) {
var parent = targetElement.parentNode;
if(parent.lastChild == targetElement) {
parent.appendChild(newElement);
} else {
parent.insertBefore(newElement, targetElement.nextSibling);
}
}
在DOM API中有个insertBefore但是没有insertAfter，所以这里自定义一个insertAfter方法，只要清楚appendChild和insertBefore这个函数很好理解，把newElement插入到targetElement之前。
接下来moveElement函数很核心：
moveElement
代码如下:
function moveElement(elementID, final_x, final_y, interval) {
if(!document.getElementById) return false;
if(!document.getElementById(elementID)) return false;
var elem = document.getElementById(elementID);
if(elem.movement) {
clearTimeout(elem.movement);
}
if(!elem.style.left) {
elem.style.left = "0px";
}
if(!elem.style.top) {
elem.style.top = "0px";
}
var xpos = parseInt(elem.style.left);
var ypos = parseInt(elem.style.top);
if(xpos == final_x && ypos == final_y) {
return true;
}
if(xpos < final_x) {
var dist = Math.ceil((final_x - xpos)/10);
xpos = xpos + dist;
}
if(xpos > final_x) {
var dist = Math.ceil((xpos - final_x)/10);
xpos = xpos - dist;
}
if(ypos < final_y) {
var dist = Math.ceil((final_y - ypos)/10);
ypos = ypos + dist;
}
if(ypos > final_y) {
var dist = Math.ceil((ypos - final_y)/10);
ypos = ypos - dist;
}
elem.style.left = xpos + "px";
elem.style.top = ypos + "px";
var repeat = "moveElement( + elementID + ," + final_x + "," + final_y + "," + interval + ")";
elem.movement = setTimeout(repeat, interval);
}
final_x, final_y 分别为元素移动终止的left和top值，所以被移动元素要设置position属性（"relative"或是"position"）,这样它的left，top属性才会起作用，这个函数也不难，就是取得元素当前的left和top值然后和final_x,final_y做比较，接着对其left和top按照一定的步长改变，每次的步长就是每个if中的dist变量，因为每次dist都会根据被移动元素的最新left，top计算，所以有一种先加速后减速的移动效果，参数interval，和setTimeout配合让moveElement自我调用，直到元素移动到final_x和final_y.
接着是pepareSlideshow函数，动态的创建所需的dom元素：
prepareSlideshow
代码如下:
function prepareSlideshow() {
//确保浏览器能理解DOM API
if(!document.getElementsByTagName) return false;
if(!document.getElementById) return false;
//确保该元素已存在
if(!document.getElementById("linklist")) return false;
var slideshow = document.createElement("div");
/*如果在css中设置这些属性，此处可省
slideshow.style.position = "relative";
slideshow.style.overflow = "hidden";
slideshow.style.width = "100px";
slideshow.style.height = "100px";
*/
slideshow.setAttribute("id", "slideshow");
var preview = document.createElement("img");
/*如果在css中设置，此处可省
preview.style.position = "absolute";
*/
preview.setAttribute("src", "slideshow/topics.gif");
preview.setAttribute("alt", "building blocks of web design");
preview.setAttribute("id", "preview");
slideshow.appendChild(preview);
var list = document.getElementById("linklist");
insertAfter(slideshow, list);
//获得ol中所有的a元素
var links = list.getElementsByTagName("a");
//给每个a的mouseover事件附加上moveElement方法
links[0].onmouseover = function() {
moveElement("preview",-100, 0, 10);
}
links[1].onmouseover = function() {
moveElement("preview",-200, 0, 10);
}
links[2].onmouseover = function() {
moveElement("preview",-300, 0, 10);
}
}
这里也就涉及到一些元素的创建，元素属性的设置等基本的DOM API运用，然后给ol[id="linklist"]中的a元素附加鼠标moveover事件对应的moveElement方法，最后用addLoadEvent（prepareSlideshow）就行了，结合html和效果图看，这个函数也是很好理解的。
代码打包下载 http://www.gxlcms.com/jiaoben/27501.html
热心网友
时间：2022-05-17 03:16
<center>
<script language="JavaScript1.2">var slideshow_width=140 //SET IMAGE WIDTH
var slideshow_height=225 //SET IMAGE HEIGHT
var pause=3000 //SET PAUSE BETWEEN SLIDE (3000=3 seconds)var fadeimages=new Array()
//SET IMAGE PATHS. Extend or contract array as needed
fadeimages[0]="photo/photo1.jpg"
fadeimages[1]="photo/photo2.jpg"
fadeimages[2]="photo/photo3.jpg"////NO need to edit beyond here/////////////var preloadedimages=new Array()
for (p=0;p<fadeimages.length;p++){
preloadedimages[p]=new Image()
preloadedimages[p].src=fadeimages[p]
}var ie4=document.all&&navigator.userAgent.indexOf("Opera")==-1
var dom=document.getElementById&&navigator.userAgent.indexOf("Opera")==-1if (ie4||dom)
document.write('<div style="position:relative;width:'+slideshow_width+';height:'+slideshow_height+';overflow:hidden"><div id="canvas0" style="position:absolute;width:'+slideshow_width+';height:'+slideshow_height+';top:0;filter:alpha(opacity=10);-moz-opacity:10"></div><div id="canvas1" style="position:absolute;width:'+slideshow_width+';height:'+slideshow_height+';top:0;filter:alpha(opacity=10);-moz-opacity:10"></div></div>')
else
document.write('<img name="defaultslide" src="'+fadeimages[0]+'">')var curpos=10
var degree=10
var curcanvas="canvas0"
var curimageindex=0
var nextimageindex=1
function fadepic(){
if (curpos<100){
curpos+=10
if (tempobj.filters)
tempobj.filters.alpha.opacity=curpos
else if (tempobj.style.MozOpacity)
tempobj.style.MozOpacity=curpos/100
}
else{
clearInterval(dropslide)
nextcanvas=(curcanvas=="canvas0")? "canvas0" : "canvas1"
tempobj=ie4? eval("document.all."+nextcanvas) : document.getElementById(nextcanvas)
tempobj.innerHTML='<img src="'+fadeimages[nextimageindex]+'">'
nextimageindex=(nextimageindex<fadeimages.length-1)? nextimageindex+1 : 0
setTimeout("rotateimage()",pause)
}
}function rotateimage(){
if (ie4||dom){
resetit(curcanvas)
var crossobj=tempobj=ie4? eval("document.all."+curcanvas) : document.getElementById(curcanvas)
crossobj.style.zIndex++
var temp='setInterval("fadepic()",50)'
dropslide=eval(temp)
curcanvas=(curcanvas=="canvas0")? "canvas1" : "canvas0"
}
else
document.images.defaultslide.src=fadeimages[curimageindex]
curimageindex=(curimageindex<fadeimages.length-1)? curimageindex+1 : 0
}function resetit(what){
curpos=10
var crossobj=ie4? eval("document.all."+what) : document.getElementById(what)
if (crossobj.filters)
crossobj.filters.alpha.opacity=curpos
else if (crossobj.style.MozOpacity)
crossobj.style.MozOpacity=curpos/100
}function startit(){
var crossobj=ie4? eval("document.all."+curcanvas) : document.getElementById(curcanvas)
crossobj.innerHTML='<img src="'+fadeimages[curimageindex]+'">'
rotateimage()
}if (ie4||dom)
window.onload=startit
else
setInterval("rotateimage()",pause)</script>
热心网友
时间：2022-05-17 04:34
热心网友
时间：2022-05-17 06:09
