缩略图自适应宽和高

控制缩略图常见的是JS来控制，还有就是最直接的方法定义img的宽高；
下面两种方法自适应宽和高，zhenzhai推荐使用CSS方法；
一、CSS方法；
主要是在CSS设置最小值和最大值(max- 100px; max-height: 100px; expression(this.width >100 && this.height < this.width ? 100: true); height: expression(this.height > 100 ? 100: true);)

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

a img{border:0;}

.imgthumblist { margin: 0 3px; padding: 0; list-style: none; }

/*\*/ * html .imgthumblist { height: 1%; }/**/ *>.imgthumblist { overflow: hidden; }

.imgthumblist li { float: left; display: inline; text-align: center; background: #F0F9FF; 108px; height: 163px; w\idth: 100px; he\ight: 155px; overflow: hidden; border: 1px solid #B9D0ED; padding: 3px; margin: 3px; }

.imgthumblist li.list1line { height: 123px; he\ight: 115px; }

.imgthumblist li.list2line { height: 143px; he\ight: 135px; }

.contentL .imgthumblist li { margin: 0 1px 3px; }

.imgthumblist p { margin: 0; line-height: 18px; font-size:12px}

.imgthumblist div { line-height: 90px; font-size: 90px; height: 100px; display: table; }

.imgthumblist div a { display: table-cell !important; display: block; 100px; vertical-align: middle; }

.imgthumblist div img { vertical-align: middle; max- 100px; max-height: 100px; expression(this.width >100 && this.height < this.width ? 100: true); height: expression(this.height > 100 ? 100: true); font-size: 10px; }

@media all and (min- 0px){ .imgthumblist div img { 100px; height: 100px; } } /*for Opera Only*/

</style>

</li>

</li>

</li>

</ul>

</div>

二、JS方法
我就不说了代码写的很清楚

//改变透明度参数：图片对象，透明度：1-100的值

function setAlpha(imgObj,opacityValue){

imgObj.filters.alpha.opacity=parseInt(opacityValue);

}

//图片的显示大小[以宽度来限制]

function DrawImageW(imgObj,widthValue){

var image=new Image();

image.src=imgObj.src;

if(image.width>0 && image.height>0){

if(image.width>=widthValue){

imgObj.width=widthValue;

imgObj.height=(image.height*widthValue)/image.width;

}else{

imgObj.width=image.width;

imgObj.height=image.height;

}

//图片的显示大小[以高度来限制]

function DrawImageH(imgObj,heightValue){

var image=new Image();

image.src=imgObj.src;

if(image.width>0 && image.height>0){

if(image.height>=heightValue){

imgObj.height=heightValue;

imgObj.width=(image.width*heightValue)/image.height;

}else{

imgObj.width=image.width;

imgObj.height=image.height;

}

//图片的显示大小[宽高同时限制]

function DrawImage(imgObj,widthValue,heightValue){

var image=new Image();

image.src=imgObj.src;

if(image.width>0 && image.height>0){

if(image.height>heightValue||image.width>widthValue){

var h=0,w,wflg=false;

if(image.height>heightValue)

wflg=true;

if(wflg){

w=widthValue;

h=(image.height*widthValue)/image.width;

}

if(h==0||h>heightValue){

h=heightValue;

w=(image.width*heightValue)/image.height;

}

//alert(w)

//alert(h)

imgObj.width=w;

imgObj.height=h;

}else{

imgObj.width=image.width;

imgObj.height=image.height;

}

function zoomImg(imgObj){

var zoom=parseInt(imgObj.style.zoom, 10)||100;zoom+=event.wheelDelta/12;if (zoom>0) imgObj.style.zoom=zoom+'%';

return false;

}

</script>