Allowing DataReferenceBoxes to be empty. #175

glymur/jp2box.py

@@ -915,9 +915,12 @@ class DataReferenceBox(Jp2kBox):
     DR : list
         Data Entry URL boxes.
     """
-    def __init__(self, data_entry_url_boxes, length=0, offset=-1):
+    def __init__(self, data_entry_url_boxes=None, length=0, offset=-1):
         Jp2kBox.__init__(self, box_id='dtbl', longname='Data Reference')
-        self.DR = data_entry_url_boxes
+        if data_entry_url_boxes is None:
+            self.DR = []
+        else:
+            self.DR = data_entry_url_boxes
         self.length = length
         self.offset = offset
 

glymur/test/test_jp2box_jpx.py

@@ -127,6 +127,19 @@ class TestJPXWrap(unittest.TestCase):
             self.assertEqual(jpx.box[-1].box[2].box_id, 'lbl ')
             self.assertEqual(jpx.box[-1].box[2].label, label)
 
+    def test_empty_data_reference(self):
+        """Data reference boxes can be empty."""
+        jp2 = Jp2k(self.jp2file)
+        boxes = [jp2.box[idx] for idx in [0, 1, 2, 4]]
+
+        dref = glymur.jp2box.DataReferenceBox()
+        boxes.append(dref)
+
+        with tempfile.NamedTemporaryFile(suffix=".jpx") as tfile:
+            jpx = jp2.wrap(tfile.name, boxes=boxes)
+        self.assertEqual(jpx.box[-1].box_id, 'dtbl')
+        self.assertEqual(len(jpx.box[-1].box), 0)
+
     def test_only_one_data_reference(self):
         """Data reference boxes cannot be inside a superbox ."""
         jp2 = Jp2k(self.jp2file)