ruby-avm-library/lib/avm/xmp.rb
2011-03-11 13:27:17 -05:00

79 lines
1.9 KiB
Ruby

require 'nokogiri'
module AVM
class XMP
attr_reader :doc
def initialize(doc = nil)
@doc = doc || empty_xml_doc
ensure_namespaces!
ensure_descriptions_findable!
end
def get_refs
yield Hash[[ :dublin_core, :iptc ].collect { |key| [ key, send(key) ] }]
end
def self.from_string(string)
new(Nokogiri::XML(string))
end
private
def ensure_namespaces!
{
:x => "adobe:ns:meta/",
:rdf => "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
:dc => "http://purl.org/dc/elements/1.1/",
:photoshop => "http://ns.adobe.com/photoshop/1.0/",
:avm => "http://www.communicatingastronomy.org/avm/1.0/",
:Iptc4xmpCore => "http://iptc.org/std/Iptc4xmpCore/1.0/xmlns/"
}.each do |namespace, url|
doc.root.add_namespace_definition(namespace.to_s, url)
end
end
def ensure_descriptions_findable!
doc.search('//rdf:Description').each do |description|
if first_child = description.first_element_child
if first_child.namespace
case first_child.namespace.prefix
when 'dc'
description['about'] = 'Dublin Core'
when 'Iptc4xmpCore'
description['about'] = 'IPTC'
end
end
end
end
end
def dublin_core
at_rdf_description "Dublin Core"
end
def iptc
at_rdf_description "IPTC"
end
def at_rdf_description(about)
@doc.at_xpath(%{//rdf:Description[@about="#{about}"]})
end
def empty_xml_doc
Nokogiri::XML(<<-XML)
<x:xmpmeta xmlns:x="adobe:ns:meta/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<rdf:RDF>
<rdf:Description about="Dublin Core">
</rdf:Description>
<rdf:Description about="IPTC">
</rdf:Description>
</rdf:RDF>
</x:xmpmeta>
XML
end
end
end