florilegia
v7.0.0
Published
Extract annotations from PDF files and convert them to RDF using the [Web Annotation Vocabulary](https://www.w3.org/TR/annotation-vocab/).
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pdf2oac
Extract annotations from PDF files and convert them to RDF using the Web Annotation Vocabulary.
Requires C compiler that supports C++11.
Installation
pdf2oac requires running a patched version of libpoppler that is built from source. The patches allow handling stamp annotations and rendering annotations to images. They can be found in the libpoppler/patches
directory. To successfully build the project, you must have a C compiler that supports C++11, as well several packages that should be installed through your operating system's package manager:
- libcairo
- libglib2.0
- libpixman
- libfreetype2
- libpng
Somewhat ridiculously, it also relies on a system-provided package for libpoppler's glib bindings (libpoppler-glib).
On Ubuntu 18.04, all of these requirements can be installed by running the command:
sudo apt install libcairo2-dev libglib2.0-dev libpixman-1-dev libfreetype6-dev libpng-dev libpoppler-glib-dev
Installation is done through npm, using the command npm install
.
Node.js library
Example
const pdf2oac = require('pdf2oac')
pdf2oac('~/Documents/annotated_document.pdf')
.on('data', triple => {
console.log(triple);
})
.on('close', () => {
console.log('No more annotations');
})
Methods
const pdf2oac = require('pdf2oac')
pdf2oac(pdfFilename, options={})
Returns a ReadableStream that will extract annotations from the given pdf and stream objects with subject
, predicate
, object
, and possibly graph
attributes.
Available options:
pdfURI
: The URI that will be used as the RDF resource representing the PDF file. Defaults tofile://$pdfFilename
.baseURI
: The base URI for all generated triples. Defaults tohttp://example.org/#
.graphURI
: If provided, the returned stream will emit quads ({ subject, predicate, object, graph }
) with the given graph URI rather than triples ({ subject, predicate, object }
).
Command line utility
pdf2oac ~/Documents/annotated_document.pdf --format turtle > annotations.ttl
Available options:
--pdf-uri
: Same as pdfURI, above.--baseURI
: Same as baseURI, above.--graphURI
: Same as graphURI, above.-f
,--format
: The output format. One ofturtle
,trig
,n-triples
,n-quads
, orjson
. Default istrig
if graph URI is provided, orturtle
if not.json
does not return JSON-LD. Rather, it outputs{ subject, predicate, object, ?graph }
triples/quads.