NAME
SVG::Metadata - Perl module to capture metadata info about an SVG file
SYNOPSIS
use SVG::Metadata;
$svgmeta->parse($filename)
or die "Could not parse $filename: " . $svgmeta->errormsg();
$svgmeta2->parse($filename2)
or die "Could not parse $filename: " . $svgmeta->errormsg();
# Do the files have the same metadata (author, title, license)?
if (! $svgmeta->compare($svgmeta2) ) {
print "$filename is different than $filename2\n";
}
if ($svgmeta->title() eq '') {
$svgmeta->title('Unknown');
}
if ($svgmeta->author() eq '') {
$svgmeta->author('Unknown');
}
if ($svgmeta->license() eq '') {
$svgmeta->license('Unknown');
}
if (! $svgmeta->keywords()) {
$svgmeta->addKeyword('unsorted');
} elsif ($svgmeta->hasKeyword('unsorted') && $svgmeta->keywords()>1) {
$svgmeta->removeKeyword('unsorted');
}
print $svgmeta->to_text();DESCRIPTION
This module provides a way of extracting, browsing and using RDF metadata embedded in an SVG file.
The SVG spec itself does not provide any particular mechanisms for handling metadata, but instead relies on embedded, namespaced RDF sections, as per XML philosophy. Unfortunately, many SVG tools don't support the concept of RDF metadata; indeed many don't support the idea of embedded XML "islands" at all. Some will even ignore and drop the rdf data entirely when encountered.
The motivation for this module is twofold. First, it provides a mechanism for accessing this metadata from the SVG files. Second, it provides a means of validating SVG files to detect if they have the metadata.
The motivation for this script is primarily for the Open Clip Art Library (http://www.openclipart.org), as a way of filtering out submissions that lack metadata from being included in the official distributions. A secondary motivation is to serve as a testing tool for SVG editors like Inkscape (http://www.inkscape.org).
FUNCTIONS
new()
Creates a new SVG::Metadata object. Optionally, can pass in arguments 'title', 'author', 'license', etc..
my $svgmeta = new SVG::Metadata;
my $svgmeta = new SVG::Metadata(title=>'My title', author=>'Me', license=>'Public Domain');author()
Alias for creator()
errormsg()
Returns the last encountered error message. Most of the error messages are encountered during file parsing.
print $svgmeta->errormsg();parse($filename)
Extracts RDF metadata out of an existing SVG file.
$svgmeta->parse($filename) || die "Error: " . $svgmeta->errormsg();This routine looks for a field in the rdf:RDF section of the document named 'ns:Work' and then attempts to load the following keys from it: 'dc:title', 'dc:rights'->'ns:Agent', and 'ns:license'. If any are missing, it
The $filename parameter can be a filename, or a text string containing the XML to parse, or an open 'IO::Handle', or a URL.
Returns undef if there was a problem parsing the file, and sets an error message appropriately. The conditions under which it will return undef are as follows:
* No 'filename' parameter given.
* Filename does not exist.
* Document is not parseable SVG.
* No rdf:RDF element was found in the document.
* The rdf:RDF element did not have a ns:Work sub-elementtitle()
Gets or sets the title.
$svgmeta->title('My Title');
print $svgmeta->title();description()
Gets or sets the description
subject()
Gets or sets the subject
publisher()
Gets or sets the publisher name. E.g., 'Open Clip Art Library'
publisher_url()
Gets or sets the web URL for the publisher. E.g., 'http://www.openclipart.org'
creator()
Gets or sets the creator.
$svgmeta->creator('Bris Geek');
print $svgmeta->creator();creator_url()
Gets or sets the URL for the creator.
author()
Alias for creator() - does the same thing
$svgmeta->author('Bris Geek');
print $svgmeta->author();owner()
Gets or sets the owner.
$svgmeta->owner('Bris Geek');
print $svgmeta->owner();owner_url()
Gets or sets the owner URL for the item
license()
Gets or sets the license.
$svgmeta->license('Public Domain');
print $svgmeta->license();license_date()
Gets or sets the date that the item was licensed
language()
Gets or sets the language for the metadata. This should be in the two-letter lettercodes, such as 'en', etc.
strict_validation()
Gets or sets the strict validation option.
keywords()
Gets or sets an array of keywords. Keywords are a categorization mechanism, and can be used, for example, to sort the files topically.
addKeywords($kw1 [, $kw2 ...])
Adds one or more a new keywords. Note that the keywords are stored internally as a set, so only one copy of a given keyword will be stored.
$svgmeta->addKeyword('Fruits and Vegetables');
$svgmeta->addKeyword('Fruit','Vegetable','Animal','Mineral');removeKeyword($kw)
Removes a given keyword
$svgmeta->removeKeyword('Fruits and Vegetables');Return value: The keyword removed.
hasKeyword($kw)
Returns true if the metadata includes the given keyword
compare($meta2)
Compares this metadata to another metadata for equality.
Two SVG file metadata objects are considered equivalent if they have exactly the same author, title, and license. Keywords can vary, as can the SVG file itself.
to_text()
Creates a plain text representation of the metadata, suitable for debuggery, emails, etc. Example output:
Title: SVG Road Signs
Author: John Cliff
License: http://web.resource.org/cc/PublicDomain
Keywords: unsortedReturn value is a string containing the title, author, license, and keywords, each value on a separate line. The text always ends with a newline character.
to_rdf()
Generates an RDF snippet to describe the item. This includes the author, title, license, etc. The text always ends with a newline character.
PREREQUISITES
XML::Twig
AUTHOR
Bryce Harrington <bryce@bryceharrington.com>
COPYRIGHT
Copyright (C) 2004 Bryce Harrington. All Rights Reserved.
This script is free software; you can redistribute it and/or modify it under the same terms as Perl itself.