Functions in the xmp module to register and unregister custom namespaces.

5 files changed, 137 insertions, 1 deletions

diff --git a/src/exiv2wrapper.cpp b/src/exiv2wrapper.cpp
index 0d80e05..4512222 100644
--- a/src/exiv2wrapper.cpp
+++ b/src/exiv2wrapper.cpp
@@ -34,6 +34,9 @@
 #define NON_REPEATABLE 102
 #define KEY_NOT_FOUND 103
 #define INVALID_VALUE 104
+#define EXISTING_PREFIX 105
+#define BUILTIN_NS 106
+#define NOT_REGISTERED 107
 
 // Custom macros
 #define CHECK_METADATA_READ \
@@ -1279,6 +1282,15 @@ void translateExiv2Error(Exiv2::Error const& error)
         case INVALID_VALUE:
             PyErr_SetString(PyExc_ValueError, "Invalid value");
             break;
+        case EXISTING_PREFIX:
+            PyErr_SetString(PyExc_KeyError, "A namespace with this prefix already exists");
+            break;
+        case BUILTIN_NS:
+            PyErr_SetString(PyExc_KeyError, "Cannot unregister a builtin namespace");
+            break;
+        case NOT_REGISTERED:
+            PyErr_SetString(PyExc_KeyError, "No namespace registered under this name");
+            break;
 
         // Default handler
         default:
@@ -1286,5 +1298,52 @@ void translateExiv2Error(Exiv2::Error const& error)
     }
 }
 
+
+void registerXmpNs(const std::string& name, const std::string& prefix)
+{
+    try
+    {
+        const std::string& ns = Exiv2::XmpProperties::ns(prefix);
+    }
+    catch (Exiv2::Error& error)
+    {
+        // No namespace exists with the requested prefix, it is safe to
+        // register a new one.
+        Exiv2::XmpProperties::registerNs(name, prefix);
+        return;
+    }
+    throw Exiv2::Error(EXISTING_PREFIX, prefix);
+}
+
+void unregisterXmpNs(const std::string& name)
+{
+    const std::string& prefix = Exiv2::XmpProperties::prefix(name);
+    if (prefix != "")
+    {
+        Exiv2::XmpProperties::unregisterNs(name);
+        try
+        {
+            const Exiv2::XmpNsInfo* info = Exiv2::XmpProperties::nsInfo(prefix);
+        }
+        catch (Exiv2::Error& error)
+        {
+            // The namespace has been successfully unregistered.
+            return;
+        }
+        // The namespace hasn’t been unregistered because it’s builtin.
+        throw Exiv2::Error(BUILTIN_NS, name);
+    }
+    else
+    {
+        throw Exiv2::Error(NOT_REGISTERED, name);
+    } 
+}
+
+void unregisterAllXmpNs()
+{
+    // Unregister all custom namespaces.
+    Exiv2::XmpProperties::unregisterNs();
+}
+
 } // End of namespace exiv2wrapper
 
diff --git a/src/exiv2wrapper.hpp b/src/exiv2wrapper.hpp
index 5058d56..3c87628 100644
--- a/src/exiv2wrapper.hpp
+++ b/src/exiv2wrapper.hpp
@@ -272,6 +272,12 @@ private:
 // Translate an Exiv2 generic exception into a Python exception
 void translateExiv2Error(Exiv2::Error const& error);
 
+
+// Functions to manipulate custom XMP namespaces
+void registerXmpNs(const std::string& name, const std::string& prefix);
+void unregisterXmpNs(const std::string& name);
+void unregisterAllXmpNs();
+
 } // End of namespace exiv2wrapper
 
 #endif
diff --git a/src/exiv2wrapper_python.cpp b/src/exiv2wrapper_python.cpp
index 5b793f7..bd20774 100644
--- a/src/exiv2wrapper_python.cpp
+++ b/src/exiv2wrapper_python.cpp
@@ -153,5 +153,9 @@ BOOST_PYTHON_MODULE(libexiv2python)
         .def("_setExifThumbnailFromFile", &Image::setExifThumbnailFromFile)
         .def("_setExifThumbnailFromData", &Image::setExifThumbnailFromData)
     ;
+
+    def("_registerXmpNs", registerXmpNs, args("name", "prefix"));
+    def("_unregisterXmpNs", unregisterXmpNs, args("name"));
+    def("_unregisterAllXmpNs", unregisterAllXmpNs);
 }
 
diff --git a/src/pyexiv2/__init__.py b/src/pyexiv2/__init__.py
index 54d7ebe..9aa3185 100644
--- a/src/pyexiv2/__init__.py
+++ b/src/pyexiv2/__init__.py
@@ -62,7 +62,8 @@ import libexiv2python
 from pyexiv2.metadata import ImageMetadata
 from pyexiv2.exif import ExifValueError, ExifTag, ExifThumbnail
 from pyexiv2.iptc import IptcValueError, IptcTag
-from pyexiv2.xmp import XmpValueError, XmpTag
+from pyexiv2.xmp import XmpValueError, XmpTag, register_namespace, \
+                        unregister_namespace, unregister_namespaces
 from pyexiv2.preview import Preview
 from pyexiv2.utils import FixedOffset, Rational, NotifyingList, \
                           undefined_to_string, string_to_undefined, \
diff --git a/src/pyexiv2/xmp.py b/src/pyexiv2/xmp.py
index 2142c41..c6488a1 100644
--- a/src/pyexiv2/xmp.py
+++ b/src/pyexiv2/xmp.py
@@ -440,6 +440,18 @@ class XmpTag(object):
             else:
                 raise XmpValueError(value, type)
 
+        elif type == '':
+            # Unknown type, assume string
+            if isinstance(value, unicode):
+                try:
+                    return value.encode('utf-8')
+                except UnicodeEncodeError:
+                    raise XmpValueError(value, type)
+            elif isinstance(value, str):
+                return value
+            else:
+                raise XmpValueError(value, type)
+
         raise NotImplementedError('XMP conversion for type [%s]' % type)
 
     def __str__(self):
@@ -454,3 +466,57 @@ class XmpTag(object):
              right = self._raw_value
         return '<%s = %s>' % (left, right)
 
+
+def register_namespace(name, prefix):
+    """
+    Register a custom XMP namespace.
+
+    Overriding the prefix of a known or previously registered namespace is not
+    allowed.
+
+    :param name: the name of the custom namespace (ending with a ``/``),
+                 typically a URL (e.g. http://purl.org/dc/elements/1.1/)
+    :type name: string
+    :param prefix: the prefix for the custom namespace (keys in this namespace
+                   will be in the form ``Xmp.{prefix}.{something}``)
+    :type prefix: string
+
+    :raise ValueError: if the name doesn’t end with a ``/``
+    :raise KeyError: if a namespace already exist with this prefix
+    """
+    if not name.endswith('/'):
+        raise ValueError('Name should end with a /')
+    libexiv2python._registerXmpNs(name, prefix)
+
+
+def unregister_namespace(name):
+    """
+    Unregister a custom XMP namespace.
+
+    A custom namespace is identified by its name, **not** by its prefix.
+
+    Attempting to unregister an unknown namespace raises an error, as does
+    attempting to unregister a builtin namespace.
+
+    :param name: the name of the custom namespace (ending with a ``/``),
+                 typically a URL (e.g. http://purl.org/dc/elements/1.1/)
+    :type name: string
+
+    :raise ValueError: if the name doesn’t end with a ``/``
+    :raise KeyError: if the namespace is unknown or a builtin namespace
+    """
+    if not name.endswith('/'):
+        raise ValueError('Name should end with a /')
+    libexiv2python._unregisterXmpNs(name)
+
+
+def unregister_namespaces():
+    """
+    Unregister all custom XMP namespaces.
+
+    Builtin namespaces are not unregistered.
+
+    This function always succeeds.
+    """
+    libexiv2python._unregisterAllXmpNs()
+