What libraries, extensions etc. would be required to render a portion of a PDF document to an image file?
Most PHP PDF libraries that I have found center around creating PDF documents, but is there a simple way to render a document to an image format suitable for web use?
Our environment is a LAMP stack.
AFAIK, there is no PHP module to do it. There is a command line tool, pdfimages (part of xpdf). For reference, here's how that works:
pdfimages -j source.pdf image
Which will extract all images from source.pdf as image-000.jpg, image-001.jpg, etc. Note the output format is always Jpeg.
Possible Options
Being a command line tool, you need exec (or system, passthru, any of the command executing functions built into PHP). As your environment doesn't have that, I see four options:
pdfimages as a modelpdfimages do the heavy lifting, by running it on a remote host you do controlRegarding #3, rolling your own, I don't think rolling your own, to solve a very narrow definition of requirements, would be too difficult. I seem to recall that the image boundaries in PDF are well defined: just read in the file to a boundary, cut to the end of the boundary, base64_decode, and write to a file -- repeat. However, that may be too much...
If rolling your own is too complicated, then option #4 is kind of like what Joel Spolsky describes for working with complicated Excel objects (see the numbered list under the bold heading "Let Office do the heavy work for you").
exec and curlpdfimagesAn example exchange could look like this:
GET http://www.cheaphost.com/pdfimages.php?extract=http://www.limitedhost.com/path/to/uploaded.pdf
Content-type: text/html
<html>
<body>
<ul>
<li>http://www.cheaphost.com/pdfimages.php?retrieve=ab9895v/image-000.jpg</li>
<li>http://www.cheaphost.com/pdfimages.php?retrieve=ab9895v/image-001.jpg</li>
</ul>
</body>
</html>
So your single pdfimages.php script (running on the host with the exec functionality) can both extract images, and give you access to the extracted images. When extracting, it reads a PDF you tell it, runs pdfimages on it, and gives you back a list of URL to call to retrieve the extracted images. When retrieving, it just gives you back a straight image.
You would need to deal with cleanup, perhaps the thing to do would be to delete the image after retrieval. You would also need to handle security -- don't know what's in these images, but the content might need to be wrapped in SSL and other precautions taken.
Try the below code. I am using this code for opening a PDF file. You can use it for other files also.
File file = new File(Environment.getExternalStorageDirectory(),
"Report.pdf");
Uri path = Uri.fromFile(file);
Intent pdfOpenintent = new Intent(Intent.ACTION_VIEW);
pdfOpenintent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
pdfOpenintent.setDataAndType(path, "application/pdf");
try {
startActivity(pdfOpenintent);
}
catch (ActivityNotFoundException e) {
}
If you want to open files, you can change the setDataAndType(path, "application/pdf"). If you want to open different files with the same intent, you can use Intent.createChooser(intent, "Open in...");. For more information, look at How to make an intent with multiple actions.
Google pdf2html, pdftohtml looks to be the only viable one. and it's based on a command line program, not PHP. so it may not be useful to you. Google is capable of converting, so there may be a way to do it with GDocs as well. though I'm not sure of that. At any rate, I hope this gets you on the proper path at least.
djvu2pdf should fit the bill, it's a small script that makes use of the djvulibre toolset. If not, there are other methods that require multiple command-line tools.
You need
ImageMagickandGhostScriptThe
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