public  void tableLayout(PdfPTable table,
    float[][] widths,
    float[] heights,
    int headerRows,
    int rowStart,
    PdfContentByte[] canvases)
This method is called at the end of the table rendering. The text or graphics are added to
one of the 4 PdfContentByte contained in
canvases.

The indexes to canvases are:


PdfPTable.BASECANVAS - the original PdfContentByte. Anything placed here
will be under the table.
PdfPTable.BACKGROUNDCANVAS - the layer where the background goes to.
PdfPTable.LINECANVAS - the layer where the lines go to.
PdfPTable.TEXTCANVAS - the layer where the text go to. Anything placed here
will be over the table.

The layers are placed in sequence on top of each other.

The widths and heights have the coordinates of the cells.

The size of the widths array is the number of rows.
Each sub-array in widths corresponds to the x column border positions where
the first element is the x coordinate of the left table border and the last
element is the x coordinate of the right table border. 
If colspan is not used all the sub-arrays in widths
are the same.

For the heights the first element is the y coordinate of the top table border and the last
element is the y coordinate of the bottom table border.