How to adapt the position of the first line in ColumnText?

I'm dealing with a situation where I have a Phrase added to a ColumnText object.

The title in black is where iText is placing the text of the Phrase within the ColumnText. The title in pink is the desired placement. Is there anything I can do to tell iText not to put any space between the top of the highest glyphs (D and Z in this case) and the top of the ColumnText box?

Posted on StackOverflow on January 12, 2015 by Locriansax

Please take a look at the ColumnTextAscender example. Here is how it works in iText 7. I have drawn red rectangles at first:

Rectangle[] areas = new Rectangle[]{new Rectangle(50, 750, 200, 50), new Rectangle(300, 750, 200, 50)};
        // for canvas usage one should create a page
        pdfDoc.addNewPage();
        for (Rectangle rect : areas) {
            new PdfCanvas(pdfDoc.getFirstPage()).setLineWidth(0.5f).setStrokeColor(ColorConstants.RED).rectangle(rect).stroke();
        }

Then I set ColumnDocumentRenderer for the current document, so that new data will appear in the specified areas:

doc.setRenderer(new ColumnDocumentRenderer(doc, areas));

To add a paragraph to the desired placement in iText 7 you should set margin value to 0 and leading to 1:

public void addColumn(Document doc, boolean useAscender) {
        Paragraph p = new Paragraph("This text is added at the top of the column.");
        // No setUseAscender(boolean). We can change leading instead. This is a bit different, but
        // for now we do not see the need to implement this method in iText7
        if (useAscender) {
            p.setMargin(0);
            p.setMultipliedLeading(1);
        }

        doc.add(p);
    }

And then just execute this method with different useAscender parameters for each column:

addColumn(doc, false);
addColumn(doc, true);

The result looks like this:

Click this link if you want to see how to answer this question in iText 5.