Points of Interests

The following is a list of common steps executed by pdftotext to extract text from a PDF file, and in which file the corresponding code is located. Note that the stated locations refer to commit 065dca3 and may have changed by now.

• Opening and reading the PDF file
     PDFDoc::PDFDoc(), line 144ff

• Parsing the PDF version number from the PDF file header
     PDFDoc::checkHeader(), line 350

• Parsing startxref
     PDFDoc::getStartXRef(), line 1999ff

• Parsing the xref table and the trailer dictionary
     XRef::readXRefTable(), line 535

• Parsing the document catalog
     Catalog::Catalog(), line 76

• Extracting the PDF subtype
     PDFDoc::extractPDFSubtype(), line 516

• Parsing a page (i.e., a page object node from the page tree)
     Catalog::cachePageTree(), line 315

• Parsing the commands of a page's content stream
     Gfx::display(), line 644

• Executing the commands of a page's content stream
     Gfx::go(), line 650

  • Executing a BT command (begin text)
       Gfx::opBeginText(), line 3585

  • Executing a Tj command (showing text)
       Gfx::opShowText(), line 3709

  • Executing a TJ command (showing text with individual glyph positioning)
       Gfx::opShowSpaceText(), line 3779

  • Executing a ' command (moving to next line and showing text)
       Gfx::opMoveShowText(), line 3727

  • Executing a " command (moving to next line, setting the word and character spacing, and showing text)
       Gfx::opMoveSetShowText(), line 3751

  • Executing a Tf command (setting font)
       Gfx::opSetFont(), line 3610

  • Executing a ET command (end text)
       Gfx::opEndText(), line 3595

• Combining diacritical marks
     TextPage::addChar(), line 2699

• Detecting words
     TextPage::addChar(), line 2648

• Detecting text blocks
     TextPage::coalesce(), line 3017

• Detecting text lines in each text block
     TextBlock::coalesce(), line 1725

• Detecting tables
     TextPage::coalesce, line 3487ff

• Detecting reading order
     TextPage::coalesce, line 3720ff

• Detecting text flows
     TextPage::coalesce, line 3753ff

HOWTOs

Create a PDF with human-readable objects + content streams

Put the following in the preamble of your TeX file (between \documentclass{} and \begin{document}):

   1 \pdfobjcompresslevel=0 
   2 \pdfcompresslevel=0

Create a PDF with specified crop box

Put the following in the preamble of your TeX file (between \documentclass{} and \begin{document}):

   1 \pdfpageattr{
   2   /CropBox [50 50 100 100]
   3 }

Create A PDF without page numbering

Put the following in the preamble of your TeX file:

   1 \thispagestyle{empty}