fixed printing of j2k files with "-c 0", closes #294

It's kind of meaningless to supply that option with a raw codestream,
but if it's what the user wanted to do, then it's what the user wanted
to do.

glymur/command_line.py

@@ -2,9 +2,11 @@
 Entry point for console script jp2dump.
 """
 import argparse
+import os
 import sys
 import warnings
-from . import Jp2k, set_printoptions
+
+from . import Jp2k, set_printoptions, lib
 
 def main():
     """
@@ -55,11 +57,13 @@ def main():
 
         # JP2 metadata can be extensive, so don't print any warnings until we
         # are done with the metadata.
-        j = Jp2k(filename)
-        if print_full_codestream:
-            print(j.get_codestream(header_only=False))
+        jp2 = Jp2k(filename)
+        if jp2._codec_format == lib.openjp2.CODEC_J2K and codestream_level == 0:
+            print('File:  {0}'.format(os.path.basename(filename)))
+        elif print_full_codestream:
+            print(jp2.get_codestream(header_only=False))
         else:
-            print(j)
+            print(jp2)
 
         # Re-emit any warnings that may have been suppressed.
         if len(wctx) > 0:

glymur/test/test_printing.py

@@ -1102,3 +1102,12 @@ class TestJp2dump(unittest.TestCase):
         actual = self.run_jp2dump(['', '-x', self.jp2file])
 
         self.assertEqual(actual, fixtures.nemo_dump_no_codestream_no_xml)
+
+    def test_codestream_0_with_j2k_file(self):
+        """-c 0 should print just a single line when used on a codestream."""
+        sys.argv = ['', '-c', '0', self.j2kfile]
+        with patch('sys.stdout', new=StringIO()) as fake_out:
+            command_line.main()
+            actual = fake_out.getvalue().strip()
+        self.assertRegex(actual, "File:  .*")
+