How to add paragraph and then a line? - itext

Question

All of the examples I have seen so far using ITextSharp start from scratch and create a new document, add something to it and close it.
What if I need to do multiple things to a PDF for example I want to add a paragraph and then add a line.
For example if I run this simple console app in which I just create a PDF and add a paragraph and then close it everything runs fine.
class Program
{
static void Main(string[] args)
{
Document pdfDoc = new Document();
PdfWriter.GetInstance(pdfDoc, new FileStream("TestPDF.pdf", FileMode.Create));
pdfDoc.Open();
pdfDoc.Add(new Paragraph("Some Text added"));
pdfDoc.Close();
Console.WriteLine("The file was created.");
Console.ReadLine();
}
}
However if I need to do something else like draw a line like this
class Program
{
static void Main(string[] args)
{
Document pdfDoc = new Document();
PdfWriter.GetInstance(pdfDoc, new FileStream("TestPDF.pdf", FileMode.Create));
pdfDoc.Open();
pdfDoc.Add(new Paragraph("Some Text added"));
PdfWriter writer = PdfWriter.GetInstance(pdfDoc, new FileStream("TestPDF.pdf", FileMode.OpenOrCreate));
PdfContentByte cb = writer.DirectContent;
cb.MoveTo(pdfDoc.PageSize.Width / 2, pdfDoc.PageSize.Height / 2);
cb.LineTo(pdfDoc.PageSize.Width / 2, pdfDoc.PageSize.Height);
cb.Stroke();
writer.Close();
pdfDoc.Close();
Console.WriteLine("The file was created.");
Console.ReadLine();
}
}
I get an error when trying to open the file because it is already opened by pdfDoc.
If I put the highlighted code after the pdfDoc.Close() I get an error saying "The Document is not opened"
How do I switch from adding text to adding a line?
Do I need to close the doc and then re-open it again with the PDFReader and modify it there or can I do it all at once?

Answer 1

You're getting an error because you're trying to request a second instance of a PDFWriter when you already have one. The second PdfWriter.GetInstance(pdfDoc, new FileStream("TestPDF.pdf", FileMode.OpenOrCreate)); is not needed. I made a small edit to your code and this now seems to work
Document pdfDoc = new Document();
PdfWriter writer = PdfWriter.GetInstance(pdfDoc, new FileStream("TestPDF.pdf", FileMode.OpenOrCreate));
pdfDoc.Open();
pdfDoc.Add(new Paragraph("Some Text added"));
PdfContentByte cb = writer.DirectContent;
cb.MoveTo(pdfDoc.PageSize.Width / 2, pdfDoc.PageSize.Height / 2);
cb.LineTo(pdfDoc.PageSize.Width / 2, pdfDoc.PageSize.Height);
cb.Stroke();
pdfDoc.Close();
Console.WriteLine("The file was created.");
Console.ReadLine();