CAM::PDF(3pm) | User Contributed Perl Documentation | CAM::PDF(3pm) |
CAM::PDF - PDF manipulation library
Copyright 2002-2006 Clotho Advanced Media, Inc., <http://www.clotho.com/>
Copyright 2007-2008 Chris Dolan
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
use CAM::PDF; my $pdf = CAM::PDF->new('test1.pdf'); my $page1 = $pdf->getPageContent(1); [ ... mess with page ... ] $pdf->setPageContent(1, $page1); [ ... create some new content ... ] $pdf->appendPageContent(1, $newcontent); my $anotherpdf = CAM::PDF->new('test2.pdf'); $pdf->appendPDF($anotherpdf); my @prefs = $pdf->getPrefs(); $prefs[$CAM::PDF::PREF_OPASS] = 'mypassword'; $prefs[$CAM::PDF::PREF_UPASS] = 'mypassword'; $pdf->setPrefs(@prefs); $pdf->cleanoutput('out1.pdf'); print $pdf->toPDF();
Many example programs are included in this distribution to do useful tasks. See the "bin" subdirectory.
This package reads and writes any document that conforms to the PDF specification generously provided by Adobe at <http://partners.adobe.com/public/developer/pdf/index_reference.html> (link last checked Oct 2005).
The file format through PDF 1.5 is well-supported, with the exception of the "linearized" or "optimized" output format, which this module can read but not write. Many specific aspects of the document model are not manipulable with this package (like fonts), but if the input document is correctly written, then this module will preserve the model integrity.
The PDF writing feature saves as PDF 1.4-compatible. That means that we cannot write compressed object streams. The consequence is that reading and then writing a PDF 1.5+ document may enlarge the resulting file by a fair margin.
This library grants you some power over the PDF security model. Note that applications editing PDF documents via this library MUST respect the security preferences of the document. Any violation of this respect is contrary to Adobe's intellectual property position, as stated in the reference manual at the above URL.
Technical detail regarding corrupt PDFs: This library adheres strictly to the PDF specification. Adobe's Acrobat Reader is more lenient, allowing some corrupted PDFs to be viewable. Therefore, it is possible that some PDFs may be readable by Acrobat that are illegible to this library. In particular, files which have had line endings converted to or from DOS/Windows style (i.e. CR-NL) may be rendered unusable even though Acrobat does not complain. Future library versions may relax the parser, but not yet.
$self = CAM::PDF->new(content | filename | '-') $self->toPDF() $self->needsSave() $self->save() $self->cleansave() $self->output(filename | '-') $self->cleanoutput(filename | '-') $self->previousRevision() $self->allRevisions() $self->preserveOrder() $self->appendObject(olddoc, oldnum, [follow=(1|0)]) $self->replaceObject(newnum, olddoc, oldnum, [follow=(1|0)]) (olddoc can be undef in the above for adding new objects) $self->numPages() $self->getPageText(pagenum) $self->getPageDimensions(pagenum) $self->getPageContent(pagenum) $self->setPageContent(pagenum, content) $self->appendPageContent(pagenum, content) $self->deletePage(pagenum) $self->deletePages(pagenum, pagenum, ...) $self->extractPages(pagenum, pagenum, ...) $self->appendPDF(CAM::PDF object) $self->prependPDF(CAM::PDF object) $self->wrapString(string, width, fontsize, page, fontlabel) $self->getFontNames(pagenum) $self->addFont(page, fontname, fontlabel, [fontmetrics]) $self->deEmbedFont(page, fontname, [newfontname]) $self->deEmbedFontByBaseName(page, basename, [newfont]) $self->getPrefs() $self->setPrefs() $self->canPrint() $self->canModify() $self->canCopy() $self->canAdd() $self->getFormFieldList() $self->fillFormFields(fieldname, value, [fieldname, value, ...]) or $self->fillFormFields(%values) $self->clearFormFieldTriggers(fieldname, fieldname, ...)
Note: 'clean' as in cleansave() and cleanobject() means write a fresh PDF document. The alternative (e.g. save()) reuses the existing doc and just appends to it. Also note that 'clean' functions sort the objects numerically. If you prefer that the new PDF docs more closely resemble the old ones, call preserveOrder() before cleansave() or cleanobject().
$self->toString() $self->getPage(pagenum) $self->getFont(pagenum, fontname) $self->getFonts(pagenum) $self->getStringWidth(fontdict, string) $self->getFormField(fieldname) $self->getFormFieldDict(object) $self->isLinearized() $self->decodeObject(objectnum) $self->decodeAll(any-node) $self->decodeOne(dict-node) $self->encodeObject(objectnum, filter) $self->encodeOne(any-node, filter) $self->changeString(obj-node, hashref)
$self->pageAddName(pagenum, name, objectnum) $self->getPageObjnum(pagenum) $self->getPropertyNames(pagenum) $self->getProperty(pagenum, propname) $self->getValue(any-node) $self->dereference(objectnum) or $self->dereference(name,pagenum) $self->deleteObject(objectnum) $self->copyObject(obj-node) $self->cacheObjects() $self->setObjNum(obj-node, num) $self->getRefList(obj-node) $self->changeRefKeys(obj-node, hashref)
$self->getObjValue(objectnum)
$self->_startdoc() $self->delinearlize() $self->build*() $self->parse*() $self->write*() $self->*CB() $self->traverse() $self->fixDecode() $self->abbrevInlineImage() $self->unabbrevInlineImage() $self->cleanse() $self->clean() $self->createID()
This constructor takes an optional final argument which is a hash reference. This hash can contain any of the following optional parameters:
(all of these functions are intended for internal only)
Given a fragment of PDF page content, parse it and return an object Node. This can be called as a class method in most circumstances, but is intended as an instance method.
Given a fragment of PDF page content, parse it and return a stream Node. This can be called as a class method in most circumstances, but is intended as an instance method.
The dictionary Node argument is typically the body of the object Node that precedes this stream.
Given a fragment of PDF page content, parse it and return an dictionary Node. This can be called as a class method in most circumstances, but is intended as an instance method.
Given a fragment of PDF page content, parse it and return an array Node. This can be called as a class or instance method.
Given a fragment of PDF page content, parse it and return a label Node. This can be called as a class or instance method.
Given a fragment of PDF page content, parse it and return a reference Node. This can be called as a class or instance method.
Given a fragment of PDF page content, parse it and return a number Node. This can be called as a class or instance method.
Given a fragment of PDF page content, parse it and return a string Node. This can be called as a class or instance method.
Given a fragment of PDF page content, parse it and return a hex string Node. This can be called as a class or instance method.
Given a fragment of PDF page content, parse it and return a boolean Node. This can be called as a class or instance method.
Given a fragment of PDF page content, parse it and return a null Node. This can be called as a class or instance method.
Dereference a data object, return a value. Given an node object of any kind, returns raw scalar object: hashref, arrayref, string, number. This function follows all references, and descends into all objects.
Dereference a data object, and return a value. Behaves just like the getValue() function, but used when all you know is the object number.
Dereference a data object, return a PDF object as a node. This function makes heavy use of the internal object cache. Most (if not all) object requests should go through this function.
$name should look something like '/R12'.
Returns a dictionary for a given font identified by its label, referenced by page.
Returns a list of fonts for a given page.
Returns an array of font objects for a given page.
Returns a dictionary for a given font, referenced by page and the name of the base font.
Returns a data structure representing the font metrics for the named font. The property list is the results of something like the following:
$self->_buildNameTable($pagenum); my $properties = $self->{Names}->{$pagenum};
Alternatively, if you know the page number, it might be easier to do:
my $font = $self->dereference($fontlabel, $pagenum); my $fontmetrics = $font->{value}->{value};
where the $fontlabel is something like '/Helv'. The getFontMetrics() method is useful in the cases where you've forgotten which page number you are working on (e.g. in CAM::PDF::GS), or if your property list isn't part of any page (e.g. working with form field annotation objects).
If a font metrics hash is supplied (it is required for a font other than the 14 core fonts), then it is cloned and inserted into the new font structure. Note that if those font metrics contain references (e.g. to the "FontDescriptor"), the referred objects are not copied -- you must do that part yourself.
For Type1 fonts, the font metrics must minimally contain the following fields: "Subtype", "FirstChar", "LastChar", "Widths", "FontDescriptor".
The optional $basefont parameter allows you to change the font. This is useful when some applications embed a standard font (see below) and give it a funny name, like "SYLXNP+Helvetica". In this example, it's important to change the basename back to the standard "Helvetica" when de-embedding.
De-embedding the font does NOT remove it from the PDF document, it just removes references to it. To get a size reduction by throwing away unused font data, you should use the following code sometime after this method.
$self->cleanse();
For reference, the standard fonts are "Times-Roman", "Helvetica", and "Courier" (and their bold, italic and bold-italic forms) plus "Symbol" and "Zapfdingbats". (Adobe PDF Reference v1.4, p.319)
Returns the width of the string, using the font metrics if possible.
Returns a dictionary for a given numbered page.
Return the number of the PDF object in which the specified page occurs.
For example, given a simple 8.5 by 11 inch page, this method will return "(0,0,612,792)".
This method will die() if the specified page number does not exist.
Given a PDF object reference, return it's name, if it has one. This is useful for indirect references to images in particular.
owner password user password print boolean modify boolean copy boolean add boolean
See the PDF reference for the intended use of the latter four booleans.
This module publishes the array indices of these values for your convenience:
$CAM::PDF::PREF_OPASS $CAM::PDF::PREF_UPASS $CAM::PDF::PREF_PRINT $CAM::PDF::PREF_MODIFY $CAM::PDF::PREF_COPY $CAM::PDF::PREF_ADD
So, you can retrieve the value of the Copy boolean via:
my ($canCopy) = ($self->getPrefs())[$CAM::PDF::PREF_COPY];
Return the object containing the form field definition for the specified field name. $name can be either the full name or the "short/alternate" name.
Return a hash reference representing the accumulated property list for a form field, including all of it's inherited properties. This should be treated as a read-only hash! It ONLY retrieves the properties it knows about.
Important Note: Most PDF readers (Acrobat, Preview.app) only offer one password field for opening documents. So, if the $ownerpass and $userpass are different, those applications cannot read the documents. (Perhaps this is a bug in CAM::PDF?)
Note: any omitted booleans default to false. So, these two are equivalent:
$doc->setPrefs('password', 'password'); $doc->setPrefs('password', 'password', 0, 0, 0, 0);
Change the name of a PDF object structure.
Delete the name of a PDF object structure.
Append a named object to the metadata for a given page.
If your content is a parsed tree (i.e. the result of getPageContentTree) then you should serialize it via toString first.
Note that this can break documents with annotations. See the appendpdf.pl script for a workaround.
If $leaveblank is true, the new page does not get any content. Thus, the document is broken until you subsequently call setPageContent().
Create a new Stream object. This object is NOT added to the document. Use the appendObject() function to do that after calling this function.
Like replaceObject(), the second form allows you to append a newly-created block to the PDF.
If the other document is undefined, then the object to copy is taken to be an anonymous object that is not part of any other document. This is useful when you've just created that anonymous object.
Generate a new document ID. Contrary the Adobe recommendation, this is a random number.
my %fields = (fname => 'John', lname => 'Smith', state => 'WI'); $field{zip} = 53703; $self->fillFormFields(%fields);
If the first argument is a hash reference, it is interpreted as options for how to render the filled data:
Undo the tweaks used to make the document 'optimized'. This function is automatically called on every save or output since this library does not yet support linearized documents.
This function operates solely in memory. It DOES NOT write the document to a file. See the output() function for that.
Note: it is the responsibility of the application to ensure that the PDF document has either the Modify or Add permission. You can do this like the following:
if ($self->canModify()) { $self->output($outfile); } else { die "The PDF file denies permission to make modifications\n"; }
In many cases, it's useful to apply one action to every node in an object tree. The routines below all use this traverse() function. One of the most important parameters is the first: the $dereference boolean. If true, the traversal follows reference Nodes. If false, it does not descend into reference Nodes.
Optionally, you can pass in a hashref as a final argument to reduce redundant traversing across multiple calls. Just pass in an empty hashref the first time and pass in the same hashref each time. See "changeRefKeys()" for an example.
Remove any filters (like compression, etc) from a data stream indicated by the object number.
Remove any filters from any data stream in this object or any object referenced by it.
Remove any filters from an object. The boolean flag $save (defaults to false) indicates whether this removal should be permanent or just this once. If true, the function returns success or failure. If false, the function returns the defiltered content.
Return an array all of objects referred to in this object.
Renumber all references in an object.
CAM::PDF->rangeToArray(1, 15, '1,3-5,12,9', '14-', '8 - 6, -2');
becomes
(1,3,4,5,12,9,14,15,8,7,6,1,2)
This library was primarily developed against the 3rd edition of the reference (PDF v1.4) with several important updates from 4th edition (PDF v1.5). This library focuses most deeply on PDF v1.2 features. Nonetheless, it should be forward and backward compatible in the majority of cases.
This module is written with good speed and flexibility in mind, often at the expense of memory consumption. Entire PDF documents are typically slurped into RAM. As an example, simply calling "new('PDFReference15_v15.pdf')" (the 13.5 MB Adobe PDF Reference V1.5 document) pushes Perl to consume 89 MB of RAM on my development machine.
There are several other PDF modules on CPAN. Below is a brief description of a few of them. If these comments are out of date, please inform me.
This is the leading PDF library, in my opinion.
Excellent text and font support. This is the highest level library of the bunch, and is the most complete implementation of the Adobe PDF spec. The author is amazingly responsive and patient.
Excellent compression support (CAM::PDF cribs off this Text::PDF feature). This has not been developed since 2003.
This library is not object oriented, so it can only process one PDF at a time, while storing all data in global variables. I'm not fond of it, but it's quite popular, so don't take my word for it!
CAM::PDF is the only one of these that has regression tests. Currently, CAM::PDF has test coverage of about 50%, as reported by "Build testcover".
Additionally, PDFLib is a commercial package not on CPAN (www.pdflib.com). It is a C-based library with a Perl interface. It is designed for PDF creation, not for reuse.
The data structure used to represent the PDF document is composed primarily of a hierarchy of Node objects. Every node in the document tree has this structure:
type => <type> value => <value> objnum => <object number> gennum => <generation number>
where the <value> depends on the <type>, and <type> is one of
Type Value ---- ----- object Node stream byte string string byte string hexstring byte string number number reference integer (object number) boolean "true" | "false" label string array arrayref of Nodes dictionary hashref of (string => Node) null undef
All of these except "stream" are directly related to the PDF data types of the same name. Streams are treated as special cases in this library since the have a non-general syntax and placement in the document body. Internally, streams are very much like strings, except that they have filters applied to them.
All objects are referenced indirectly by their numbers, as defined in the PDF document. In all cases, the dereference() function should be used to deserialize objects into their internal representation. This function is also useful for looking up named objects in the page model metadata. Every node in the hierarchy contains its object and generation number. You can think of this as a sort of a pointer back to the root of each node tree. This serves in place of a "parent" link for every node, which would be harder to maintain.
The PDF document itself is represented internally as a hash reference with many components, including the document content, the document metadata (index, trailer and root node), the object cache, and several other caches, in addition to a few assorted bookkeeping structures.
The core of the document is represented in the object cache, which is only populated as needed, thus avoiding the overhead of parsing the whole document at read time.
Chris Dolan
This module was originally developed by me at Clotho Advanced Media Inc. Now I maintain it in my spare time.
Thanks to all the people who have submitted bug reports over the years! I've belatedly started crediting people in the CHANGES file. Apologies to contributors I've overlooked...
2022-12-08 | perl v5.36.0 |