In iText5, we can get the PdfPTable's height when we need "public float calculateHeights(boolean firsttime)".
But in iText7, how can we get current table height value (especially before adding the table to its parent element)?
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.
Cause sometimes we need this value for calculation to decide the "y-axis" value.
In iText5, elements and information about their position/size were a bit mixed together, which allowed you to call calculateWidths on a PdfPTable element.
In iText7, this functionality is separated, which allows different kind of flexibility for rendering/layouting elements.
Thus, model elements, which a Table instance is an example of, do not know anything about their position or size. And calling table.getHeight results in null because table did not have HEIGHT property previously set to it.
To calculate table height, one would have to make use of the rendering functionality.
For a model element, you can get the subtree of renderers representing this model element and all its children, and layout it in any given area. To really know the height of a table, you would want to create an area which knowingly will be sufficient to place the whole contents of the element.
PdfDocument pdfDoc = ...
Document doc = ...
Table table = new Table(2)
.addCell(new Cell().add(new Paragraph("cell 1, 1")))
.addCell(new Cell().add(new Paragraph("cell 1, 2")));
LayoutResult result = table.createRendererSubTree().setParent(doc.getRenderer()).layout(
new LayoutContext(new LayoutArea(1, new Rectangle(0, 0, 400, 1e4f))));
System.out.println(result.getOccupiedArea().getBBox().getHeight());
The code above prints 22.982422O for me, but the results may vary depending on the configuration and properties of elements.
I would like to point out two important parts of the code:
We pass 1e4f as the height of the LayoutArea, considering that this will be sufficient to place the whole table. Note that if the table cannot be placed into that height, the result will never exceed this given height and thus it will not be correct for your usecase (know the total height of the table). So make sure to pass the height which will be sufficient for placement of the whole table.
.setParent(doc.getRenderer()) part is important here and is used for retrieving inheritant properties. Note that we did not set a lot of properties to table element, even font, but this information is essential to know the area this element would occupy. So this information will be inherited from the parent chain during layout. You can test this by changing the document's font: document.setFont(newFont);, or font size: document.setFontSize(24); and watching the resultant height change