aXLabelPositionArray - an array containing all the
X-coordinates of the visible main profile points.
aStartPointIndex - the index of the first visible main profile point.
aLength - the number of visible main profile points, note here that
aXLabelPositionArray.length must not be used. aLength should be used
aBounds - 1) the location of this rectangle (x,y) corresponds to the
most left point on the lowest visible grid-line line.
2) the width corresponds to the whole width of the x-axis
3) the height corresponds to the distance between x-axis and the
bottom of the graphics