jcrop.js

  $('.jcrop').on('load', function(){
    image = $(this);
    ratio = image.data('ratio').split('x');
    ratio = parseFloat(ratio[0]) / parseFloat(ratio[1]);

    x1     = image.data('x1');
    y1     = image.data('y1');
    x2     = image.data('x2');
    y2     = image.data('y2');
    width  = image.data('width');
    height = image.data('height');

    image.Jcrop({
      setSelect: [ x1, y1, x2, y2 ],
      aspectRatio: ratio,
      trueSize: [width, height],
      onChange: $.proxy( showCoords, this ),
      onSelect: $.proxy( showCoords, this )
    });

    function showCoords(c)
    {
      var image = $(this);
      var ratio = image.data('ratio');

      $('#'+ratio+" .x1").val(c.x);
      $('#'+ratio+" .y1").val(c.y);
      $('#'+ratio+" .crop_width").val(c.w);
    };