Добавленный щелчком прямоугольник исчезает в скрипте холста html5

$("#Add").on("click", function() {
  $("#first_text").show();
  $("#resetInput").show();
  var rheight = 20;
  ctx.fillStyle = '#E1FFC7';
  ctx.fillRect(20, rheight, 300, 50);
});

var canvas = document.getElementById('cv');
ctx = canvas.getContext('2d');

// core drawing function
var drawMe = function() {
  var img = document.getElementById('bg');
  ctx.drawImage(img, 0, 0, 364, 662, 0, 0, 364, 662);
  ctx.fillStyle = '#E1FFC7';
  if ($('#first_text:visible').length > 0) {
    ctx.fillRect(20, 20, 300, 50);
  }

  text = $("#first_text").val();
  ctx.fillStyle = 'black';
  ctx.fillText(text, 20, 20)
}

$("#resetInput").on("click", function() {
  $("#first_text").val("");
  drawMe();
});

$("#first_text").on("change keypress keyup keydown ", function() {
  drawMe();
});

drawMe();

canvas {
  margin: 40px;
}

#first_text,
#resetInput {
  display: none;
}

<script src = "https://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<p>
  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor
  in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum
</p>
<button id = "Add">add text</button>
<br/>

<input type = "text" id = "first_text"> <button id = "resetInput">reset</button>


<br>
<canvas id = "cv"></canvas>
<img id = "bg" src = "https://cloud.githubusercontent.com/assets/398893/15136779/4e765036-1639-11e6-9201-67e728e86f39.jpg" style = "opacity:0;" />