Is there a Java Library that converts a PostScrpit File ".ps" into a String or TextFile (or something I can read with an InputStream)?
I have these Files and need to read them and handle them accourding to the Text in it. They allway contain only Text and usually its just one line like
date:SWYgeW91IHJlYWQgdGhpcyB5b3UncmUgcHJvYmFibGUgdG8gY3VyaW91cyAgYnV0IG5pY2UgdHJ5IGFueXdheS4gUGxlYXNlIEhlbHA=
in it.
Right now I convert it into a PDF and "read" it with an OCR Engine. But it seems a litte bit over the top for just one line.
Is there an other way to do it?
If you could point me in the right direction, that would be great.
PostScript is a language to define graphical output on paper, to a printer device. As such it does not really contain plaintext, and "extracting" text from it poses problems. It could for instance be programmatically determined in places, or it could be interspersed with PS code making the text data useless.
Normally you would output a modified PS to a printer (real or virtual) with a specific config that leads the result to be output as a standard text sequence (without the graphical formatting).
This is often done by altering the PS code file, to alter the text output command.
A desciption of this method can be found in part 3 of following Waikato Uni PM
http://www.cs.waikato.ac.nz/~ihw/papers/98NM-Reed-IHW-Extract-Text.pdf
If you convert the PostScript file to PDF (for example, with Ghostscript ps2pdf or with Acrobat Distiller), you could then read this file using iText (http://itextpdf.com). You could also convert the PDF into a more readable form using RUPS, one of the iText tools.
Related
I'm pretty sure the answer i'm going to get is: "why don't you just have the text files all be the same or follow some set format". Unfortunately i do not have this option but, i was wondering if there is a way to take any text file and translate it over to another text or xml file that will always look the same?
The text files pretty much have the same data just arranged differently.
The closest i can come up with is to have an XSLT sheet for each text file but, then i have to turn around and read the file that was just created, delete it, and repeat for each text file.
So, is there a way to grab the data off text files that essentially have the same data just stored differently; and store this data in an object that i could then re-use later on in some process?
If it was up to me, i would push for every text file to follow some predefined format since they all pretty much contain the same data but, it's not up to me.
Odd question... You say they are text files yet mention XSLT as a possible solution. XSLT will only work if the source is XML, if that is so, please redefine the question. If you say text files I assume delimiter separated (e.g. csv), fixed length,...
There are some parsers (like smooks) out there that allow you to parse multiple formats, but it will still require you to perform the "mapping" yourself of course.
This is a typical problem in the integration world so any integration tool should offer you a solution (e.g. wso2, fuse,...).
I have a program which will be used for building questions database. I'm making it for a site that want user to know that contet was donwloaded from that site. That's why I want the output be PDF - almost everyone can view it, almost nobody can edit it (and remove e.g. footer or watermark, unlike in some simpler file types). That explains why it HAS to be PDF.
This program will be used by numerous users which will create new databases or expand existing ones. That's why having output formed as multple files is extremly sloppy and inefficient way of achieving what I want to achieve (it would complicate things for the user).
And what I want to do is to create PDF files which are still editable with my program once created.
I want to achieve this by implementing my custom file type readable with my program into the output PDF.
I came up with three ways of doing that:
Attach the file to PDF and then corrupting the part of PDF which contains it in a way it just makes the PDF unaware that it contains the file, thus making imposible for user to notice it (easely). Upon reading the document I'd revert the corruption and extract file using one of may PDF libraries.
Hide the file inside an image which would be added to the PDF somwhere on the first or last page, somehow (that is still need to work out) hidden from the public eye. Knowing it's location, it should be relativley easy to retrieve it using PDF library.
I have learned that if you add "%" sign as a first character in line inside a PDF, the whole line will be ignored (similar to "//" in Java) by the PDF reader (atleast Adobe reader), making possible for me to add as many lines as I want to the PDF (if I know where, and I do) whitout the end user being aware of that. I could implement my whole custom file into PDF that way. The problem here is that I actually have to read the PDF using one of the Java's input readers, but I'm not sure which one. I understand that PDF can't be read like a text file since it's a binary file (Right?).
In the end, I decided to go with the method number 3.
Unless someone has any better ideas, and the conditions are:
1. One file only. And that file is PDF.
2. User must not be aware of the addition.
The problem is that I don't know how to read the PDF as a file (I'm not trying to read it as a PDF, which I would do using a PDF library).
So, does anyone have a better idea?
If not, how do I read PDF as a FILE, so the output is array of characters (with newline detection), and then rewrite the whole file with my content addition?
In Java, there is no real difference between text and binary files, you can read them both as an inputstream. The difference is that for binary files, you can't really create a Reader for it, because that assumes there's a way to convert the byte stream to unicode characters, and that won't work for PDF files.
So in your case, you'd need to read the files in byte buffers and possibly loop over them to scan for bytes representing the '%' and end-of-line character in PDF.
A better way is to use another existing way of encoding data in a PDF: XMP tags. This is allows any sort of complex Key-Value pairs to be encoded in XML and embedded in PDF's, JPEGs etc. See http://partners.adobe.com/public/developer/en/xmp/sdk/XMPspecification.pdf.
There's an open source library in Java that allows you to manipulate that: http://pdfbox.apache.org/userguide/metadata.html. See also a related question from another guy who succeeded in it: custom schema to XMP metadata or http://plindenbaum.blogspot.co.uk/2010/07/pdfbox-insertextract-metadata-frominto.html
It's all just 1's and 0's - just use RandomAccessFile and start reading. The PDF specification defines what a valid newline character(s) is/are (there are several). Grab a hex editor and open a PDF and you can at least start getting a feel for things. Be careful of where you insert your lines though - you'll need to add them towards the end of the file where they won't screw up the xref table offsets to the obj entries.
Here's a related question that may be of interest: PDF parsing file trailer
I would suggest putting your comment immediately before the startxref line. If you put it anywhere else, you could wind up shifting things around and breaking the xref table pointers.
So a simple algorithm for inserting your special comment will be:
Go to the end of the file
Search backwards for startxref
Insert your special comment immediately before startxref - be sure to insert a newline character at the end of your special comment
Save the PDF
You can (and should) do this manually in a hex editor.
Really important: are your users going to be saving changes to these files? i.e. if they fill in the form field, are they going to hit save? If they are, your comment lines may be removed during the save (and different versions of different PDF viewers could behave differently in this regard).
XMP tags are the correct way to do what you are trying to do - you can embed entire XML segments, and I think you'd be hard pressed to come up with a data structure that couldn't be expressed as XML.
I personally recommend using iText for this, but I'm biased (I'm one of the devs). The iText In Action book has an excellent chapter on embedding XMP data into PDFs. Here's some sample code from the book (which I definitely recommend): http://itextpdf.com/examples/iia.php?id=217
I have created a program that should one day become a PDF editor
It's purpose will be saving GUI's textual content to the PDF, and loading it from it. GUI resembles text editor, but it only has certain fields(JTextAreas, actually).
It can look like this (this is only one page, it can have many more, also upper and lower margins are cut out of the picture) It should actually resemble A4 in pixel size.
I have looked around for a bit for PDF libraries and found out that iText could suit my PDF creating needs, however, if I understood it correct, it retirevs text from a whole page as a string which won't work for me, because I will need to detect diferent fields/paragaphs/orsomething to be able to load them back into the program.
Now, I'm a bit lazy, but I don't want to spend hours going trough numerus PDF libraries just to find out that they won't work for me.
Instead, I'm asking someone with a bit more Java PDF handling experience to recommend me one according to my needs.
Or maybe recommend me how to add invisible parts to PDF which will help my program to determine where is it exactly situated insied a PDF file...
Just to be clear (I formed my question wrong before), only thing I need to put in my PDF is text, and that's all I need to later be able to get out. My program should be able to read PDF's which he created himself...
Also, because of the designated use of files created with this program, they need to be in the PDF format.
Short Answer: Use an intermediate format like JSON or XML.
Long Answer: You're using PDF's in a manner that they wasn't designed for. PDF's were not designed to store data; they were designed to present and format data in an portable form. Furthermore, a PDF is a very "heavy" way to store data. I suggest storing your data in another manner, perhaps in a format like JSON or XML.
The advantage now is that you are not tied to a specific output-format like PDF. This can come in handy later on if you decide that you want to export your data into another format (like a Word document, or an image) because you now have a common representation.
I found this link and another link that provides examples that show you how to store and read back metadata in your PDF. This might be what you're looking for, but again, I don't recommend it.
If you really insist on using PDF to store data, I suggest that you store the actual data in either XML or RDF and then attach that to the PDF file when you generate it. Then you can read the XML back for the data.
Assuming that your application will only consume PDF files generated by the same application, there is one part of the PDF specification called Marked Content, that was introduced precisely for this purpose. Using Marked Content you can specify the structure of the text in your document (chapter, paragraph, etc).
Read Chapter 14 - Document Interchange of the PDF Reference Document for more details.
I have an xml file with which i want to print as a PDF using PCL. I am new to PCL. Can i use PCL to get the xml printed in PDF format directly or should i have some intermediate process to create a PDF file and then use PCL to get it printed as PDF?
If you have a xml, there are two ways to recieve PDF file.
1. Create stylesheet for your xml, and use XEP
or
2. use just your xml and VisualXSL, which will help you create your pdf for print.
More additional: If you will create your xsl stylsheet, you can format by XEP many type of PDFs, for example PDF/1A, or another levels
Both XEP and VisualXSL are Renderx products(http://www.renderx.com/tools/index.html) and they have trial versions, that you can use:). I have used both products many times, and was satisfied.
You can also visit the forum where you can find answers about how to use and how usefull are products described above. http://cooltools.renderx.com
PCL is a printer control language. In other words command bytes you send to a (usually HP) printer which is then converted to ink on a page. This is normally not the way you will generate a PDF since too much information from the original will be lost.
You will normally want to convert your XML to something describing the actual print you want to have. A reasonable choice for this is the XSL-FO XML dialect which, however, is not very nice to do by hand. You can then choose to convert your XML into DocBook XML which in turn has very nice style sheets for converting further on to XSL-FO and other formats.
You can then use Apache FOP to convert XSL-FO into many formats, one being PDF. This allows you to - if FOP gets too small - to replace with one of several commercial XSL_FO rendering engines at a later date.
In a current project i need to display PDFs in a webpage. Right now we are embedding them with the Adobe PDF Reader but i would rather have something more elegant (the reader does not integrate well, it can not be overlaid with transparent regions, ...).
I envision something close google documents, where they display PDFs as image but also allow text to be selected and copied out of the PDF (an requirement we have).
Does anybody know how they do this? Or of any library we could use to obtain a comparable result?
I know we could split the PDFs into images on server side, but this would not allow for the selection of text ...
Thanks in advance for any help
PS: Java based project, using wicket.
I have some suggestions, but it'll be definitely hard to implement this stuff. Good luck!
First approach:
First, use a library like pdf-renderer (https://pdf-renderer.dev.java.net/) to convert the PDF into an image. Store these images on your server or use a caching-technique. Converting PDF into an image is not hard.
Then, use the Type Select JavaScript library (http://www.typeselect.org/) to overlay textual data over your text. This text is selectable, while the real text is still in the original image. To get the original text, see the next approach, or do it yourself, see the conclusion.
The original text then must be overlaid on the image, which is a pain.
Second approach:
The PDF specifications allow textual information to be linked to a Font. Most documents use a subset of Type-3 or Type-1 fonts which (often) use a standard character set (I thought it was Unicode, but not sure). If your PDF document does not contain a standard character set, (i.e. it has defined it's own) it's impossible to know what characters are which glyphs (symbols) and thus are you unable to convert to a textual representation.
Read the PDF document, read the graphics-objects, parse the instructions (use the PDF specification for more insight in this process) for rendering text, converting them to HTML. The HTML conversion can select appropriate tags (like <H1> and <p>, but also <b> and <i>) based on the parameters of the fonts (their names and attributes) used and the instructions (letter spacing, line spacing, size, face) in the graphics-objects.
You can use the pdf-renderer library for reading and parsing the PDF files and then code a HTML translator yourself. This is not easy, and it does not cover all cases of PDF documents.
In this approach you will lose the original look of the document. There are some PDF generation libraries which do not use the Adobe Font techniques. This also is a problem with the first approach, even you can see it you can not select it (but equal behavior with the official Adobe Reader, thus not a big deal you'd might say).
Conclusion:
You can choose the first approach, the second approach or both.
I wouldn't go in the direction of Optical Character Recognition (OCR) since it's really overkill in such a problem, since it also has several drawbacks. This approach is Google using. If there are characters which are unrecognized, a human being does the processing.
If you are into the human-processing thing; you can only use the Type Select library and PDF to Image conversion and do the OCR yourself, which is probably the easiest (human as a machine = intelligently cheap, lol) way to solve the problem.