I develope new program but i need to allow user to highlighting word in pdf file then i want to process the file to get list of highlighted words with place
how can do that by java
thank in advance
PDF files are PostScript, which is very difficult to process. I doubt there's an easy way.
Take a look at http://java-source.net/open-source/pdf-libraries , but be aware you might have some difficulty.
Also, read http://partners.adobe.com/public/developer/en/pdf/HighlightFileFormat.pdf for the specs of the highlight format. Depending on what "place" information you need, that might be enough.
How are you displaying the PDF? If you are displaying the image, you just need the word co-ordinates. Something like PdfBox or JPedal or maybe IText can do this.
Related
I want to make a program that is able to read PDF files and parse it's contents.
Thus I need to extract the text using some kind of library. I found 3 ways to do so.
OCR libraries (like Tesseract)
ScanPdf libraries (like iText)
Converters from PDF to text.
I fail to understand the big differences between them since all of them will produce in the end a text file from the PDF. So which is the best way to go about this?
PDF is a complex format. If you open a PDF and you're staring at a bunch of text, that doesn't really tell you much. It could be that you're staring at an image file someone decided to wrap into a PDF file. This is 99%+ certain what you have if someone scanned a document and told their scanner to 'scan to PDF', and 100% certain what you got if you have a PNG or JPG and 'save as PDF', or try to 'print to PDF' such a thing.
There is no text in the PDF then. There are pixels.
To turn pixels into text, that's where OCR libraries come in. That's what they do. That is all they do. It's an AI bonanza and error prone. No guarantees.
However, PDF is more complex than that, it isn't like PNG/JPG: It's more like HTML. You can put actual text in there.
This has different issues, though. You can place text blobs (i.e. a 'rectangle', with coordinates, and then the text that is supposed to go inside). Again a lot like HTML: You can do something like:
<p class="foo">
World!
</p>
<p class="bar">
Hello,
</p>
and then create CSS so that the foo is rendered after the bar block (can be as simple as .foo, .bar { display: block; } .foo {float: right}).
Turning that HTML into "World! Hello," is not all that tricky. Realizing that during a render, you end up seeing "Hello, World!", and thus writing code that returns "Hello, World!", that's way more complicated.
The same problem applies to PDF. For simple PDFs, extracting the raw text inside is not too difficult, but be aware that for even mildly complex PDFs, the text can arrive in a jumbled mess.
iText is trying to give you enough power, at least, to provide the latter: To give you a full hierarchical breakdown. It returns 'here is a text box, here is its positioning, and here is the text inside. and now here is another text box, etc'. It does not return a big string.
In other words: The answer depends a lot on what PDFs you have / what PDFs you expect to be able to read, and how complex they are. If they are scans, you need an OCR library. If they are simple, a basic pdf2text converter will do fine. If you want to attempt to take into account fancily positioned PDFs with forms inside and 'popups' that can be opened and closed, oof. Probably all these tools are insufficient and you're signing up to many personweeks worth of effort.
There definitely IS text embedded PDFs, it is NOT just pixels.
It depends on if the PDF is a "true" PDF (ie you can highlight the text and copy and paste it elsewhere) or if the PDF is a scanned image.
With scanned images, you'll have to use an OCR API. All of the major cloud providers have OCR APIs (ie Amazon Textract, Google Document AI, Microsoft Form Recognizer, etc). If it's a true PDF, then I've found the pdf.js library (https://mozilla.github.io/pdf.js/) quite helpful in doing a direct text extraction.
Just know that doing this only gets you the text that is literally on the page, and there's quite a bit of work still to do to get key/value data fields programmatically across many documents.
This is something that my startup is working on (www.sensible.so/) too if you're interested in something more powerful!
I am writing a code that calculates how many words in a file
And my problem is: when I input the file, there will have more word than the original file...For example, in the file, the content is abcdabcd, but when I run the code, the console shows Total no. of letters: 194
I am using netbeans IDE and mac, when I click the blank space instead of directly open the file, I found there are many words in front of abcdabcd, I guess perhaps this is the reason... But I don't know how to fix this problem on my code
[![enter image description here][1]][1]
Can anyone help me solve this problem?
Thanks!
The input file is encoded with rtf (Rich Text Format), despite it being saved with a .txt extension. This encoding is commonly used to do many things plain text cannot do, such as bold and italic etc. However, to accomplish this, the file is filled with all sorts of other things to accompany the normal text, in your case "abcdef". Of course, java reads all of this as if it were a plain text file, and ends up counting all of the rtf formatting as well.
I assume you're using TextEdit, so look at this tutorial to see how to use only plain text, so all of the extra formatting is not included in the final file.
Hope this helped :)
first of all: My goal is to just load a PDF, highlight words from that PDF (Page) and show that Page / PDF to the user as Image.
Till now i parse the PDF with a custom Text-Stripper to get all word-positions with their coordinates ( needed to generate a rectangle for highlighting later)
After that i started to generate PDAnnotationTextMarkup's so. Now i'm at this point where i can see my annotations well if i save the pdf to a file and view it with a PDFReader by choice. But if i use the convertToImage Method given by PDFBox, i only get a normal page rendered without annotations.
After a little time on google i found: PDFBOX-2019 which was mentioned in another stackoverflow question
Now im looking for a workaround because i think the ticket history is showing that no one will fix that issue in about a year.
Anybody a good idea to fix that and achieve my goal?
thanks in advance
ben
I am using iText to extract text from PDF to a String but I have encountered a problem
with some PDF. When I tried to extract text, the reader extract only blanks/destroyed text
on SOME pdfs.
Example of destroyed text:
"th isbe long to t he t est fo r extr act ion tex t"
What is the cause of this problem?
I am thinking of removing the fonts and change the font to a suitable one to be read by
the reader. I have tried researching about this, but what I found does not help me.
This is caused by the way text is stored in the PDF file. It just puts letters with information for rendering and location. The text extraction algorithm is smart in that it finds letters that seem to be close together and, if so, it puts them together. If they aren't that close, it puts in some space.
I can't tell you what to do about it, though.
I am using iText library for writing a PDF file.
I want to give page numbers and page header on every page of file
How can I do that?
If you don't break lines manually then it's really hard almost impossible to precisely get the line count. This number depends on font measurement and the text layout on a page. iText is a great tool for PDF generation not for parsing.
I suggest you buy the iText book "iText in Action" which is very helpful. If you don't generate your page breaks yourself, you could checkout the PdfPageEvent methods such as onStartPage() and the getPageNumber() method.