How to set the line space between two chunks in itextsharp - pdf

Question

I am creating a PDF using iTextSharp. This is a reporting tool. Everything is working fine, only the space between two chunks is slighly greater that what I want. I tried to find some help on StackOverflow and got to know SetLeading(fixed, multiplied); but it is not coming with chunk in case.
The reason I need it in chunk is that I have multiple chunks which I am adding into paragraph proceeding to which adding all into Document at a single shot.
public static void createPDF(Paragraph para)
{
string imagepath = "12.pdf";
Document doc = new Document();
try
{
Paragraph p = para;
Rectangle[] COLUMNS = {
new Rectangle(36, 36, 290, 806),
new Rectangle(305, 36, 559, 806)
};
//This is what i have tried
// p.SetLeading(0.4f,0.8f);
p.SpacingBefore = 0.0f;
p.SpacingAfter = 0.1f;
PdfReader inputPdf = new PdfReader(#"");
PdfWriter writer2 = PdfWriter.GetInstance(doc, new FileStream(imagepath, FileMode.Create));
doc.Open();
PdfContentByte canvas = writer2.DirectContent;
for (int ij = 1; ij <= 3; ij++)
{
doc.SetPageSize(inputPdf.GetPageSizeWithRotation(ij));
doc.NewPage();
PdfImportedPage page = writer2.GetImportedPage(inputPdf, ij);
int rotation = inputPdf.GetPageRotation(ij);
if (rotation == 90 || rotation == 270)
{
canvas.AddTemplate(page, 0, -1f, 1f, 0, 0, inputPdf.GetPageSizeWithRotation(ij).Height);
}
else
{
canvas.AddTemplate(page, 1f, 0, 0, 1f, 0, 0);
}
}
doc.NewPage();
ColumnText ct = new ColumnText(canvas);
int side_of_the_page = 0;
ct.SetSimpleColumn(COLUMNS[side_of_the_page]);
int paragraphs = 0;
int i = 0;
while (paragraphs < p.Count-1)
{
string TEXT = p[i].ToString();
ct.AddElement(p[i]);
while (ColumnText.HasMoreText(ct.Go()))
{
if (side_of_the_page == 0)
{
side_of_the_page = 1;
canvas.MoveTo(297.5f, 36);
canvas.LineTo(297.5f, 806);
canvas.Stroke();
}
else
{
side_of_the_page = 0;
doc.NewPage();
}
ct.SetSimpleColumn(COLUMNS[side_of_the_page]);
}
i++;
paragraphs++;
}
doc.Close();
}
catch {
}
}

Answer 1

Please read chapter 2 of my book. The Chunk object is called the atomic building block among iText's high-level objects. By design, you cannot define a leading on the level of a Chunk.
I quote from page 23:
A Chunk isn't aware of the space that is needed between two lines.
The leading is defined at the level of a Phrase (and, of course, its superclasses, such as Paragraph). If you want to change the spacing between Chunk objects, you need to wrap Chunks in Phrases or Paragraphs (as you already indicate) and define the leading for those phrases or paragraphs.
Note that the documentation also states:
In normal circumstances you'll use Chunk objects to compose other text objects, such as Phrases and Paragraphs. Typically, you won't add Chunk objects directly to a Document.
Which special circumstance do you have that requires making an exception to this rule?
Extra remarks
You are importing an existing PDF in a way that throws away all existing interactivity. This is suboptimal.
You first compose a paragraph p, you set the leading for p, then you decompose p throwing away the leading you've defined and then you complain that there's no leading.
This is what you are doing wrong:
while (paragraphs < p.Count-1)
{
ct.AddElement(p[i]);
...
}
The object p knows its leading; the separate components of this object (p[0], p[1],...), don't know anything about the leading.
Hence you should do something like this:
ColumnText ct = new ColumnText(canvas);
int side_of_the_page = 0;
ct.SetSimpleColumn(COLUMNS[side_of_the_page]);
ct.AddElement(p);
while (ColumnText.HasMoreText(ct.Go()))
{
if (side_of_the_page == 0)
{
side_of_the_page = 1;
canvas.MoveTo(297.5f, 36);
canvas.LineTo(297.5f, 806);
canvas.Stroke();
}
else
{
side_of_the_page = 0;
doc.NewPage();
}
ct.SetSimpleColumn(COLUMNS[side_of_the_page]);
}
As you have defined the leading at the level of the p object, you must add the p object as an element to the ColumnText.
Regarding the wrong way you're copying the original document: The AddLongTable example shows how to do it correctly. You get a PdfReader object for the existing document. You create a PdfStamper to create a new document. You get the number of pages in the existing document, and then you use insertPage() as many time as needed to add extra content.