title: In iText7, is there a way like iText5's calculateHeights method?
body: <p>In iText5, we can get the PdfPTable's height when we need "public float calculateHeights(boolean firsttime)".</p>
  
  <p>But in iText7, how can we get current table height value (especially before adding  the table to its parent element)?</p>
  
  <p>I already tested "table.getHeight()" method, but it returns null.
  And I also found that in a table render object I can get this value, but the limitation is that the render need to be triggered when the table is adding into its parent element, so the time is not my need.</p>
  
  <p>Cause sometimes we need this value for calculation to decide the "y-axis" value.</p>