/*
功能：图片等比例缩放
目标:ImgTag
图片宽度:FitWidth
图片高度:FitHeight
*/
var FitWidth = 445;
var FitHeight = 225;
function FoucsImage(ImgTag)
{
    var image = new Image();
 image.src = ImgTag.src;
 if(image.width>0 && image.height>0){
  if(image.width/image.height >= FitWidth/FitHeight){
   if(image.width > FitWidth){
    ImgTag.width = FitWidth;
    ImgTag.height = (image.height*FitWidth)/image.width;
   }
   else{ 
    ImgTag.width = image.width;
    ImgTag.height = image.height;
   }
  }
  else{
   if(image.height > FitHeight){
    ImgTag.height = FitHeight;
    ImgTag.width = (image.width*FitHeight)/image.height;
   }
   else{
    ImgTag.width = image.width; 
    ImgTag.height = image.height;
   }
  }
 }
}