I have a list of text data containing links (PDActions) that might need to be rendered on more than one page. (see below)
**Table of Contents**
document1 link 5
document2 link 8
document3 link 11
Is there a simple way to just print all these content and let PDFBox decide to wrap the text and fit them in multiple pages as needed. And just give me the final PDDocument?
There are multiple answers on this topic such as this one. However, the answers are quite old, and I'm checking if there is a newer and simpler way to do it.
PDFBox version: 2.0.26
PDFBox essentially still only has that very low-level text drawing API but there are projects built on top of PDFBox offering automatic layout.
Allow me to quote the PDFBox FAQs
Can I use PDFBox to create complex layouts?
I'd like to use PDFBox to create a complex layout containing several paragraphs, tables, images etc. Is PDFBox fit for that purpose?
PDFBox being a low level PDF library provides the APIs to create page content such as text, images etc. But at this point in time it doesn't provide a higher level API to do page layout, paragraph handling, automatic line wrapping or create tables and such.
But PDFBox is the foundation of some projects which might help in that case. This includes projects such as
Boxable
BoxTable
easytable
pdfbox-layout
PdfLayoutManager
ph-pdf-layout
You may also want to consider using Apache FOP which allows to create complex documents from XML data and templates-
Related
We are converting a sizeable document for hosting on ReadTheDocs. We weren't happy with the simple presentation enabled by Markdown table syntax, so we coded our tables as HTML. Very nice in the HTML viewer (e.g., the end of http://manual.cytoscape.org/en/latest/Command_Line_Arguments.html).
In the PDF version generated by ReadTheDocs, each of our tables is completely missing (see page 9 on https://media.readthedocs.org/pdf/cytoscape-working-copy/latest/cytoscape-working-copy.pdf).
Have we made a mistake by coding tables as HTML? Could we have taken a different route and gotten nice tables in both HTML and PDF?
Any advice would be helpful ...
Thanks!
I have not used ReadTheDocs myself, but from reading their Getting Started guide, I assume you are using Sphinx? While Markdown supports embedding raw HTML, Sphinx does not support converting it to other formats.
You should consider moving to reStructuredText (Sphinx's native markup format), as it is much more advanced than Markdown. It can even be extended with custom directives and roles, should you need this. But be sure to first check whether reStructuredText tables offer the flexibility you require. Pandoc can convert your Markdown files to reStructuredText.
I see you are using a table to document command line options. reStructuredText supports documenting command line options using option lists. In theory, you could change how option lists are represented in the output document, but this might not be easy to accomplish, especially for PDF output using LaTeX (shameless plug: using rinohtype for PDF output should make this much easier in the future).
I am writing an application that has to read and interpret data stored in some PDF files. The reading part is done but I am only able to get a dump of all the words on a page and not the format of the words. What I mean is that if I have to extract a table, I am getting the numbers in the table but not the markup which defines the table.
Further, there is some formatting used which displays a few of these numbers within parentheses (meaning that those numbers are negative) but the parentheses themselves are not part of the text. Hence, I am not able to distinguish between positive and negative numbers present in the PDF table!
How do you get the PDF markup along with the text? Is a PDF similar in structure to an XML with tags used to markup tables etc.? If not, then, is there a resource which describes the salient features of the PDF DOM?
I am using VBA and the Acrobat library (AcroExch etc.)
There is no such thing as "PDF markup" in the sense of HTML etc. A table in PDF cannot be distinguished from line art, other than by using OCR, which can be error-prone if the layout is complex. It is simply drawn using geometrical shapes, like in a vector-based graphics program.
"Is a PDF similar in structure to an XML with tags used to markup tables etc.?"
No, not at all.
And there is no such thing as a 'DOM' either. Google for a file named *PDF32000_2008.pdf*. The current PDF specification for v1.7 (ISO spec) is that file. You should be able to locate it on the Adobe website.
As omz stated, text inside PDF does not really have a structure. You can take a look on the specification here. However, for some very specific files, there is something called PDF Tags, or PDF Marked Content, which is fairly new, and it aims to give PDF documents some kind of structure. If you target this kind of files specifically, you might be able to achieve something. Take a look on chapter 10 (Document Interchange) of the Adobe's specification for further details.
Maybe what you want to achieve can be done with less effort and faster by using TET, the Text Extraction Toolkit made by the fine folks from pdflib.com ( http://www.pdflib.com/products/tet/ ) ??
AFAIR, the TET has some (limited) support for table detection as well....
I want to generate a technical report from lisp (AllegroCL in my case) and I studied various packages/project to help me do this.
Requirements:
Need to generate a PDF
May create an intermediate format like RTF, Restructured TEXT, HTML, Word DOC or Latex
Need to be flexible to be able to add content throughout my application
Need to handle Multi-Page, Headers, Footers, Tables, inclusion of Images.
Possibilities:
cl-pdf and cl-typesetting: I checked this one out and it works for now, but is there a better alternative?
Some Latex generator, but ???
Question:
Do you know alternatives to easily generate (PDF) reports from lisp. What is the best workflow to go for?
we are using cl-pdf and cl-typesetting for the last 3 years and it has numerous issues... (like its confusion around encodings, or silently not rendering things that don't fit, or...) so, i don't recommend new development based on them.
currently we are in the process of moving all our export mechanisms to open document format. openoffice is all happy with it, and there's a plugin for ms office, too.
there's .fodt, the so called flat open document text format, which is a mere xml file describing a document. generating it is as easy as generating xml files.
you can also make parts of your document read-only with a password (insert a section and mark it read-only and protected by a password. when generating the xml, you can generate random hashes as password...).
My objective is to extract the text and images from a PDF file while parsing its structure. The scope for parsing the structure is not exhaustive; I only need to be able to identify headings and paragraphs.
I have tried a few of different things, but I did not get very far in any of them:
Convert PDF to text. It does not work for me as I lose images and the structure of the document.
Convert PDF to HTML. I found a few tools that helped me with this, and the best one so far is pdftohtml. The tool is really good presentation wise, but I haven't been able to successfully parse the HTML.
Convert PDF to XML. Same as above.
Anyone has any suggestions on how to tackle this problem?
There is essentially not an easy cut-and-paste solution because PDF isn't really very interested in structure. There are many other answers on this site that will tell you things in much more detail, but this one should give you the main points:
If identifying text structure in PDF documents is so difficult, how do PDF readers do it so well?
If you want to do this in PDF itself (where you would have the majority of control over the process), you'll have to loop over all text on pages and identify headers by looking at their text properties (fonts used, size relative to the other text on the page, etc...).
On top of that you'll also have to identify paragraphs by looking at the positioning of text fragments, white space on the page, closeness of certain letters, words and lines... PDF by itself doesn't even have a concept for a "word", let alone "lines" or "paragraphs".
To complicate things even more, the way text is drawn on the page (and thus the order in which it appears in the PDF file itself) doesn't even have to be the proper reading order (or what us humans would consider to be proper reading order).
PDF parsing for headers and its sub contents are really very difficult (It doesn't mean its impossible ) as PDF comes in various formats. But I recently encountered with tool named GROBID which can helps in this scenario. I know it's not perfect but if we provide proper training it can accomplish our goals.
Grobid available as a opensource on github.
https://github.com/kermitt2/grobid
You may do use the following approach like this with iTextSharp or other open source libraries:
Read PDF file with with iTextSharp or similar open source tools and collect all text objects into an array (or convert PDF to HTML using the tool like pdftohtml and then parse HTML)
Sort all text objects by coordinates so you will have them all together
Then iterate through objects and check the distance between them to see if 2 or more objects can be merged into one paragraph or not
Or you may use the commercial tool like ByteScout PDF Extractor SDK that is capable of doing exactly this:
extract text and images along with analyzing the layout of the text
XML or CSV where text objects are merged or splitted into paragraphs inside a virtual layout grid
access objects via special API that makes it possible to address each object via its "virtual" row and column index disregarding how it is stored inside the original PDF.
Disclaimer: I am affiliated with ByteScout
PDF files can be parsed with tabula-py, or tabula-java.
I made a full tutorial on how to use tabula-py on this article. You can tabula in a web-browser too as long as you have installed Java.
Unless its is Marked Content, PDF does not have a structure.... You have to 'guess' it which is what the various tools are doing. There is a good blog post explaining the issues at http://blog.idrsolutions.com/2010/09/the-easy-way-to-discover-if-a-pdf-file-contains-structured-content/
As mentioned in the answers above, PDF's aren't very easy to parse. However, if you have certain additional information regarding the text that you want to parse, you can pull it off.
If your headings are positioned at specific parts of the page, you can parse the PDF file and sort the parsed output by coordinates.
If you have prior knowledge of the spacing between headings and paragraphs, you could also leverage this information to parse the file.
PDFBox is a PDF parsing tool that you can use for extracting text and images on top of which you can define your custom rules for parsing.
However, for parsing PDFs you need to have some prior knowledge of the general format of the PDF file. You can check out the following blogpost Document parsing for more information regarding document parsing.
Disclaimer:I was involved in writing the blogpost.
iText api:
PdfReader pr=new PdfReader("C:\test.pdf");
References:
PDFReader
I'd like to write some (java) code that takes a PDF document, and creates named destinations from all of the bookmarks. I think the iText API is the easiest way of doing this, but I have never used the API before.
How would you go about writing this sort of code with the iText API? Can iText do the parsing needed to manipulate existing PDFs by itself? The kind of manipulations I am thinking of are:
Open,
Find bookmarks,
Create destinations,
Save,
Close.
Or is there a different API that would be better?
Followup: I submitted a patch to iText a few months ago (it has now been accepted and is part of HEAD) that adds text parsing capabilities to iText. PdfBox (mentioned below) has (had?) problems with reading newer PDFs that use xref streams instead of the older xref table format.
Another library that is very good at parsing existing PDF files is PdfBox It can also be used for modifying an existing PDF. FYI - this is the text parser that Lucene uses.
I will also mention that iText does have the ability to parse a PDF file, it's just not great at parsing the text content on each page. If you are looking at accessing the PDF higher level constructs (Dictionaries, etc...) that are used for storing bookmarks, etc... and you don't mind getting your hands a little dirty with reading the PDF spec, you can absolutely do what you are asking about (we do it quite a bit ourselves).
The PDF Spec is big, but readable for the most part, and you don't have to worry about the bulk of it (which is geared towards actual page content and rendering) if all you are trying to do is extract bookmarks.
I'll just warn you up front that you may be disappointed with this. iText isn't really intended to be used as a parser. It's really more for creating entirely new PDF documents, but you can take a whack at it.
To start, using iText, you won't be able to modify the existing PDF document. What you can do, though, is to make a copy with the additional features that you want. (If somebody else knows better, please let me know, this drives me crazy.)
What you will want to do is create a PdfReader object from an input stream on your source file. Then create a PdfCopy object (which is just an extended PdfWriter that makes getting data from an existing source more convenient) for your destination.
As far as I can tell, the bookmarks cannot be obtained from iText at all. Another library may be needed. I think jpedal may have the ability to extract them (it can get them as an XML document, which you may then have to parse to get what you want.) However you get them, you can then add them to a java.util.List, and set that list as outline on the PDFCopy. The bookmarks themselves are just HashMaps with a particular set of keys. I'm not sure what all of the values are, but they include "Title", "Action" (which seems to be where you'd specify that this is a named destination, though I don't know what that value would be), and "URI" (which is used if this is an external link -- I suspect that this would specify the name of the named destination that you're linking to). Again, the specifics are hard to find.
Then iterate over the pages of the reader, importing each page to the PdfCopy. this page may help you.
Sorry I'm not more helpful to you. Good luck.
P.S. If anybody else knows of a better tool that's either (L)GPL or BSD licensed, I'd love to hear about it.