图片等比例缩放，图片资源加载完，才获取。

 

<a class="miniImg artZoom miniSPicID" href="" rel="">
<img src="" id="img_SPicID" class="img_SPicID" runat="server" style=" margin:0px auto; display:inherit;" />
</a>

<script type="text/javascript">
$(function () {
$(window).load(function () {//图片资源加载完才获取

$(".miniSSketch").attr("href", $(".img_SSketch").attr("src")).attr("rel", $(".img_SSketch").attr("src"));
$(".miniSPicID").attr("href", $(".img_SPicID").attr("src")).attr("rel", $(".img_SPicID").attr("src"));

var imgWidth2 = $(".img_SPicID").width();
var imgHeight2 = $(".img_SPicID").height();
if (imgWidth2 == 0)
imgWidth2 = 1000;
if (imgHeight2 == 0)
imgHeight2 = 1000;
//图片缩列图
if (imgWidth2 > boxWidth && imgHeight2 > boxHeight) {
if ((boxWidth / boxHeight) >= (imgWidth2 / imgHeight2)) {
//重新设置img的width和height
$(".img_SPicID").width((boxHeight * imgWidth2) / imgHeight2);
$(".img_SPicID").height(boxHeight);
//让图片居中显示
var margin = (boxWidth - $(".img_SPicID").width()) / 2;
$(".img_SPicID").css("margin-left", margin);
}
else {
//重新设置img的width和height
$(".img_SPicID").width(boxWidth);
$(".img_SPicID").height((boxWidth * imgHeight2) / imgWidth2);
//让图片居中显示
var margin = (boxHeight - $(".img_SPicID").height()) / 2;
$(".img_SPicID").css("margin-top", margin);
}
}

//alert($(".img_SSketch").attr("src"));
var boxWidth = 500, boxHeight = 500;
//图片缩列图
var imgWidth = $(".img_SSketch").width();
var imgHeight = $(".img_SSketch").height();

//比较imgBox的长宽比与img的长宽比大小
if (imgWidth > boxWidth && imgHeight > boxHeight) {
if ((boxWidth / boxHeight) >= (imgWidth / imgHeight)) {
//重新设置img的width和height
$(".img_SSketch").width((boxHeight * imgWidth) / imgHeight);
$(".img_SSketch").height(boxHeight);
//让图片居中显示
var margin = (boxWidth - $(".img_SSketch").width()) / 2;
$(".img_SSketch").css("margin-left", margin);
}
else {
//重新设置img的width和height
$(".img_SSketch").width(boxWidth);
$(".img_SSketch").height((boxWidth * imgHeight) / imgWidth);
//让图片居中显示
var margin = (boxHeight - $(".img_SSketch").height()) / 2;
$(".img_SSketch").css("margin-top", margin);
}
}
});

});
</script>