[evince/wip/gpoo/128-xmpRights] backend: Add support for checking xmpRights:UsageTerms in PDF

[Germán Poo-Caamaño <gpoo src gnome org>]

commit ecea2b511b94ae32054e56d3164da516f104e6e0
Author: Juanjo Marín <juanj marin juntadeandalucia es>
Date:   Fri Jan 15 13:52:00 2010 +0000

    backend: Add support for checking xmpRights:UsageTerms in PDF
    
    The Creative Commons instructions about how to get the license
    information it's ambiguous about the human readable statement
    about the license. The current method for checking this
    information is using xmpRights:UsageTerms, and Evince only
    checks dc:rights, the previous recommended method (tough it
    is present on the template and applications recommended by CC) .
    
    Fixes #128

 backend/pdf/ev-poppler.cc | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)
---
diff --git a/backend/pdf/ev-poppler.cc b/backend/pdf/ev-poppler.cc
index 911894b9..294124da 100644
--- a/backend/pdf/ev-poppler.cc
+++ b/backend/pdf/ev-poppler.cc
@@ -68,12 +68,25 @@
 #define HAVE_CAIRO_PRINT
 #endif
 
-/* fields from the XMP Rights Management Schema, XMP Specification Sept 2005, pag. 45 */
+/* Fields for checking the license info suggested by Creative Commons 
+ * Main reference: http://wiki.creativecommons.org/XMP */
+
+/* fields from the XMP Rights Management Schema, XMP Specification Sept 2005, pag. 42 */
 #define LICENSE_MARKED "/rdf:RDF/rdf:Description/xmpRights:Marked"
-#define LICENSE_TEXT "/rdf:RDF/rdf:Description/dc:rights/rdf:Alt/rdf:li[lang('%s')]"
+#define LICENSE_TEXT "/x:xmpmeta/rdf:RDF/rdf:Description/xmpRights:UsageTerms[lang('%s')]"
 #define LICENSE_WEB_STATEMENT "/rdf:RDF/rdf:Description/xmpRights:WebStatement"
 /* license field from Creative Commons schema, http://creativecommons.org/ns */
 #define LICENSE_URI "/rdf:RDF/rdf:Description/cc:license/@rdf:resource"
+
+/* alternative field from the Dublic Core Schema for checking the informal rights statement 
+ * as suggested by the Creative Commons template [1]. This field has been replaced or 
+ * complemented by its XMP counterpart [2].
+ * References: 
+ *    [1] http://wiki.creativecommons.org/XMP_help_for_Adobe_applications 
+ *    [2] http://code.creativecommons.org/issues/issue505 */
+#define LICENSE_TEXT_ALT "/x:xmpmeta/rdf:RDF/rdf:Description/dc:rights/rdf:Alt/rdf:li[lang('%s')]"
+#define GET_LICENSE_TEXT(a) ( (a < 1) ? LICENSE_TEXT : LICENSE_TEXT_ALT )
+
 /* fields for authors and keywords */
 #define AUTHORS "/rdf:RDF/rdf:Description/dc:creator/rdf:Seq/rdf:li"
 #define KEYWORDS "/rdf:RDF/rdf:Description/dc:subject/rdf:Bag/rdf:li"
@@ -921,7 +934,11 @@ pdf_document_get_license_from_metadata (xmlXPathContextPtr xpathCtx)
                 * Schema. This field is recomended to be checked by Creative
                 * Commons */
                /* 1) checking for a suitable localized string */
-               license->text = pdf_document_get_localized_object_from_metadata (xpathCtx, LICENSE_TEXT);
+               int lt;
+
+               for (lt = 0; !license->text && lt < 2; lt++)
+                       license->text = pdf_document_get_localized_object_from_metadata (xpathCtx,
+                                                                                        GET_LICENSE_TEXT 
(lt));
 
                /* Checking the license URI as defined by the Creative Commons
                 * Schema. This field is recomended to be checked by Creative