code: function(x1, y1, x2, y2, px, py)
      {
  		return Math.abs((y2 - y1) * px - (x2 - x1) * py + x2 * y1 - y2 * x1) /
  			Math.sqrt((y2 - y1) * (y2 - y1) + (x2 - x1) * (x2 - x1));
      }
docs: Function: ptLineDist
  
  Returns the distance between a line defined by two points and a point.
  To get the distance between a point and a segment (with a specific
  length) use <mxUtils.ptSeqDistSq>.
  
  Parameters:
  
  x1 - X-coordinate of point 1 of the line.
  y1 - Y-coordinate of point 1 of the line.
  x2 - X-coordinate of point 1 of the line.
  y2 - Y-coordinate of point 1 of the line.
  px - X-coordinate of the point.
  py - Y-coordinate of the point.