ekran (X,Y):<input type=text id=Ex size=2>
<input type=text id=Ey size=2>
canvas (X,Y):<input type=text id=Cx size=2>
<input type=text id=Cy size=2>
<br>

<canvas width="400" height="400" id="can"></canvas>

<script>
  var c = can.getContext("2d");
  var w = c.canvas.width;
  var h = c.canvas.height;

var MYSZKA = {x: 0, y: 0};
c.canvas.onmousemove =  function(evt) {	
  MYSZKA.x = evt.clientX - 8;
  MYSZKA.y = evt.clientY - 8;
  Cx.value = MYSZKA.x;
  Cy.value = MYSZKA.y;
  Ex.value = evt.screenX;
  Ey.value = evt.screenY;
};

c.strokeStyle="black";
  c.strokeRect(0, 0, w, h);

</script>