//等比率缩放图片大小

function DrawImage(ImgD,FitWidth,FitHeight){  
var image=new Image();  
image.src=ImgD.src;  
if(image.width>0 && image.height>0)  
{  
if(image.width/image.height>= FitWidth/FitHeight)  
{  
if(image.width>FitWidth)  
{  
ImgD.width=FitWidth;  
ImgD.height=(image.height*FitWidth)/image.width;  
}  
else  
{  
ImgD.width=image.width;  
ImgD.height=image.height;  
}  
}  
else  
{  
if(image.height>FitHeight)  
{  
ImgD.height=FitHeight;  
ImgD.width=(image.width*FitHeight)/image.height;  
}  
else  
{  
ImgD.width=image.width;  
ImgD.height=image.height;  
}  
}  
}  
}