function imgadapter(obj,width,height)
{
//alert('缩放前');
var max_height = height;    //减去图片外加的边框和Pdding值
var max_width = width;      
var real_height = obj.height;
var real_width = obj.width;
var img_pdding;

//产品图片按比例缩放

if(obj.width>max_width)
{
   obj.width = max_width;
   obj.height = Math.round(obj.width*(real_height/real_width));
}
if(obj.height>max_height)
{
   obj.height = max_height;
   obj.width = Math.round(obj.height*(real_width/real_height));
}
//产品图片上下居中---(1)没有按比例缩放时,图片的实际高度小于传入参数width. (2)按比例缩放后,图片的高度小于传入参数
/*if(obj.height<max_height)
{
   img_padding = Math.round((max_height-obj.height)/2);
   obj.style.paddingTop=img_padding;
   obj.style.paddingBottom=img_padding;
}*/

//产品图片左右居中
if(obj.width<max_width)
{
   img_padding = Math.round((max_width-obj.width)/2);
   obj.style.paddingLeft=img_padding;
   obj.style.paddingRight=img_padding;
}

obj.style.visibility ='visible' ;
//alert('缩放后');
}