var invertedCells = {};

jQuery('#logo_mask').live('mousemove', function(e){
  var target = jQuery(this).prev();
  var targetNode = target[0];

	var sizeX = 9;
	var sizeY = 9;

	var offsetX = 7;
	var offsetY = 6;

	var offset = target.offset();
	var x = e.pageX - offset.left - offsetX;
	var y = e.pageY - offset.top - offsetY;

	var cellX = Math.floor(x / sizeX);
	var cellY = Math.floor(y / sizeY);
  if (cellX in invertedCells)
  {
    if (cellY in invertedCells[cellX])
      return false;
  }
  else {
    invertedCells[cellX] = {}
  }

  invertedCells[cellX][cellY] = true;

	x = cellX*sizeX+offsetX;
	y = cellY*sizeY+offsetY;

	if (x + sizeX > target.width)
		sizeX = target.width - x;
	if (y + sizeY > target.height)
		sizeY = target.height - y;

	Pixastic.process(targetNode, 'invert', {
	  rect: { left: x, top: y, width: sizeX, height: sizeY }
	});
});