问JCrop检查是否选择了区域

EN

var jcrop_api;
var selected;
$('#profile_crop').Jcrop({onSelect: showCoords, onRelease: releaseCoords, setSelect: [0, 542, 671, 0], boxWidth: 542, boxHeight: 671, aspectRatio: 542/671},
  function() {
    jcrop_api = this; 
  }
);

function showCoords(c){
  selected = true;
  // variables can be accessed here as
  // c.x, c.y, c.x2, c.y2, c.w, c.h
};

function releaseCoords(c){
  selected = false;
  // variables can be accessed here as
  // c.x, c.y, c.x2, c.y2, c.w, c.h
};