// canvas document.body의 DOCTYPE 표준 모드 대응
var canvas = document[ 'CSS1Compat' == document.compatMode ? 'documentElement' : 'body'];

//마우스 X좌표 취득
function getMouseX(e) {
  if(document.all) return canvas.scrollLeft+event.clientX;
  else if(document.getElementById) return e.pageX;
}

//마우스 Y좌표 취득
function getMouseY(e) {
  if(document.all) return canvas.scrollTop+event.clientY;
  else if(document.getElementById) return e.pageY;
}