Resize image to thumbnail size

resizer.js

function resize( imagewidth, imageheight, thumbwidth, thumbheight ) {
    var w = 0, h = 0, x = 0, y = 0,
        widthratio  = imagewidth / thumbwidth,
        heightratio = imageheight / thumbheight,
        maxratio    = Math.max( widthratio, heightratio );
    if ( maxratio > 1 ) {
        w = imagewidth / maxratio;
        h = imageheight / maxratio;
    } else {
        w = imagewidth;
        h = imageheight;
    }
    x = ( thumbwidth - w ) / 2;
    y = ( thumbheight - h ) / 2;
    return { w:w, h:h, x:x, y:y };
  };