img: add _AsciiIfdEntry._parse_value()

Steve Canny · Steve Canny · commit f95caff6eae4 · 2014-02-27T12:08:36.000-08:00
diff --git a/docx/image/tiff.py b/docx/image/tiff.py
@@ -286,6 +286,14 @@ class _AsciiIfdEntry(_IfdEntry):
     """
     IFD entry having the form of a NULL-terminated ASCII string
     """
+    @classmethod
+    def _parse_value(cls, stream_rdr, offset, value_count, value_offset):
+        """
+        Return the ASCII string parsed from *stream_rdr* at *value_offset*.
+        The length of the string, including a terminating '\x00' (NUL)
+        character, is in *value_count*.
+        """
+        return stream_rdr.read_str(value_count-1, value_offset)
 
 
 class _ShortIfdEntry(_IfdEntry):
diff --git a/tests/image/test_tiff.py b/tests/image/test_tiff.py
@@ -14,8 +14,8 @@
 from docx.image.constants import MIME_TYPE, TIFF_TAG
 from docx.image.helpers import BIG_ENDIAN, LITTLE_ENDIAN, StreamReader
 from docx.image.tiff import (
-    _IfdEntries, _IfdEntry, _IfdEntryFactory, _IfdParser, _LongIfdEntry,
-    _RationalIfdEntry, _ShortIfdEntry, Tiff, _TiffParser
+    _AsciiIfdEntry, _IfdEntries, _IfdEntry, _IfdEntryFactory, _IfdParser,
+    _LongIfdEntry, _RationalIfdEntry, _ShortIfdEntry, Tiff, _TiffParser
 )
 
 from ..unitutil import (
@@ -423,6 +423,15 @@ def value_(self, request):
         return loose_mock(request)
 
 
+class Describe_AsciiIfdEntry(object):
+
+    def it_can_parse_an_ascii_string_IFD_entry(self):
+        bytes_ = b'foobar\x00'
+        stream_rdr = StreamReader(BytesIO(bytes_), BIG_ENDIAN)
+        val = _AsciiIfdEntry._parse_value(stream_rdr, None, 7, 0)
+        assert val == 'foobar'
+
+
 class Describe_ShortIfdEntry(object):
 
     def it_can_parse_a_short_int_IFD_entry(self):
