code: function (startX, startY, endX, endY) {
              var context = this.backBufferContext2D;
  
              if (context < 1 / 255) {
                  // Fast path: don't draw fully transparent
                  return;
              }
  
              context.beginPath();
              context.moveTo(startX, startY);
              context.lineTo(endX, endY);
              context.stroke();
          }
docs: Stroke a line of the given two points
  @name strokeLine
  @memberOf me.CanvasRenderer.prototype
  @function
  @param {Number} startX the start x coordinate
  @param {Number} startY the start y coordinate
  @param {Number} endX the end x coordinate
  @param {Number} endY the end y coordinate