问从零开始编码jQuery/javascript中的图像裁剪器和大小器(同时)？

EN

function changeZoom(percent){
    var minWidth=viewport.width();
    var newWidth= (orgWidth-minWidth)*percent/100+minWidth;
    var newHeight= newWidth/orgRatio;
    var oldSize=[img.width(),img.height()];

    img.css({ width: newWidth+"px", height: newHeight+"px" });

    adjustDimensions();

    //ugly hack :(
    if (img.offset().left+img.width()>dragcontainer.offset().left+dragcontainer.width()){
        img.css({ left: dragcontainer.width()-img.width() +"px" });  
    }
    if (img.offset().top+img.height()>dragcontainer.offset().top+dragcontainer.height()){
        img.css({ top: dragcontainer.height()-img.height() +"px" });  
    } 
}