Metadata support

wand/api.py

@@ -129,6 +129,19 @@ class MagickPixelPacket(ctypes.Structure):
     library.MagickGetImageSignature.argtypes = [ctypes.c_void_p]
     library.MagickGetImageSignature.restype = ctypes.c_char_p
 
+    library.MagickGetImageProperty.argtypes = [ctypes.c_void_p, ctypes.c_char_p]
+    library.MagickGetImageProperty.restype = ctypes.c_char_p
+
+    library.MagickGetImageProperties.argtypes = [ctypes.c_void_p,
+                                                 ctypes.c_char_p,
+                                                 ctypes.POINTER(ctypes.c_size_t)]
+    library.MagickGetImageProperties.restype = ctypes.POINTER(ctypes.c_char_p)
+
+    library.MagickSetImageProperty.argtypes = [ctypes.c_void_p, ctypes.c_char_p,
+                                               ctypes.c_char_p]
+
+    library.MagickDeleteImageProperty.argtypes = [ctypes.c_void_p,
+                                                  ctypes.c_char_p]
     library.MagickGetImageBackgroundColor.argtypes = [ctypes.c_void_p,
                                                       ctypes.c_void_p]
 

wand/image.py

@@ -460,6 +460,7 @@ def __init__(self, image=None, blob=None, file=None, filename=None,
                     read = True
                 if not read:
                     raise TypeError('invalid argument(s)')
+            self.metadata = Metadata(self)
         self.raise_exception()
 
     @property
@@ -1422,9 +1423,50 @@ def clone(self):
         return type(self)(iterator=self)
 
 
+class Metadata(collections.Mapping):
+    """Class that implements dict-like read-only access to image metadata like
+    EXIF or IPTC headers.
+
+    :param image: An `Image` instance
+    :type image: :class:`Image`
+    """
+    def __init__(self, image):
+        if not isinstance(image, Image):
+            raise TypeError('expected a wand.image.Image instance, '
+                            'not ' + repr(image))
+        self.image = image
+
+    def __getitem__(self, k):
+        """
+        :param k: Metadata header name string.
+        :type k: :class:`basestring`
+        :returns: a header value string
+        :rtype: :class:`str`
+        """
+        if not isinstance(k, basestring):
+            raise TypeError('k must be a string, not ' + repr(format))
+
+        v = library.MagickGetImageProperty(self.image.wand, k)
+        if v is None:
+            raise KeyError
+        return v
+
+    def __iter__(self):
+        num = ctypes.c_size_t()
+        props_p = library.MagickGetImageProperties(self.image.wand, '', num)
+        props = [props_p[i] for i in xrange(num.value)]
+        library.MagickRelinquishMemory(props_p)
+        return iter(props)
+
+    def __len__(self):
+        num = ctypes.c_size_t()
+        props_p = library.MagickGetImageProperties(self.image.wand, '', num)
+        library.MagickRelinquishMemory(props_p)
+        return num.value
+
+
 class ClosedImageError(DestroyedResourceError):
     """An error that rises when some code tries access to an already closed
     image.
 
     """
-

wandtests/image.py

@@ -773,3 +773,14 @@ def reset_coords():
             msg = 'img = {0!r}, control = {1!r}'.format(
                 img.signature, sig)
             assert img.signature == sig, msg
+
+
+@tests.test
+def metadata():
+    """Test metadata api"""
+    with Image(filename=asset('beach.jpg')) as img:
+        assert len(img.metadata) == 52
+        assert 'exif:ApertureValue' in img.metadata
+        assert 'exif:UnknownValue' not in img.metadata
+        assert img.metadata['exif:ApertureValue'] == '192/32'
+        assert img.metadata.get('exif:UnknownValue', "IDK") == "IDK"