js按比例缩放图片并显示图片的一部分

$(document).ready(function(){  
	//取得图片外层div的宽度  
	var boxwidth = $(‘.media-object’).parent().width();  
	var boxheight = boxwidth*9/16;  
	var imgarray = $(‘.media-object’);  
	for(var i=0;i<imgarray.length;i++){  
		//获取图片原始长、宽  
		var width = imgarray[i].width ;  
		var height = imgarray[i].height;  
		//判断图片长宽比例  
		if( width*9/16 > boxheight ){  
			//使用宽度按16：9的比例缩放后高度不够，转而使用高度  
			//此时图片高度应该设为div高 boxheight  
			var imgheight = boxheight;  
			$(imgarray[i]).css(‘height’,imgheight);  
			//此高度下等比例的图片宽度为 imgwidth  
			var imgwidth = imgheight*width/height;  
			$(imgarray[i]).css(‘width’,imgwidth);  
			//计算此时图片宽度与div宽度的差值  
			var difference = imgwidth-boxwidth;  
			//计算图片应该裁剪的位置  
			var stratX = difference/2;  
			var startY = 0;  
			var endX = imgwidth – difference/2;  
			var endY = imgheight;  
			//使用css clip:rect(top, right, bottom, left)属性裁剪  
			$(imgarray[i]).css(‘clip’,’rect(‘+stratX+’px ‘+endX+’px ‘+endY+’px ‘+startY+’px)’);  
		}else{  
			//使用宽度按照16：9缩放，多余的高度去除  
			//此时图片宽度应该设为div宽 boxwidth  
			var imgwidth = boxwidth;  
			$(imgarray[i]).css(‘width’,imgwidth);  
			//此宽度下等比例的图片高度为 imgheight  
			var imgheight = imgwidth*height/width;  
			$(imgarray[i]).css(‘height’,imgheight);  
			//计算此时图片高度与div高度的差值  
			var difference = imgheight-boxheight;  
			//计算图片应该裁剪的位置  
			var stratX = 0;  
			var startY = difference/2;  
			var endX = imgwidth;  
			var endY = imgheight – difference/2;  
			//使用css clip:rect(top, right, bottom, left)属性裁剪  
			$(imgarray[i]).css(‘clip’,’rect(‘+stratX+’px ‘+endX+’px ‘+endY+’px ‘+startY+’px)’);  
		}  
	}  
});