img: add Image.sha1

Steve Canny · Steve Canny · commit fcba2bf93c1e · 2014-03-01T01:35:31.000-08:00
diff --git a/docx/image/image.py b/docx/image/image.py
@@ -7,9 +7,11 @@
 
 from __future__ import absolute_import, division, print_function
 
+import hashlib
 import os
 
 from ..compat import BytesIO, is_string
+from ..shared import lazyproperty
 from .exceptions import UnrecognizedImageError
 
 
@@ -81,6 +83,13 @@ def vert_dpi(self):
         """
         return self._image_header.vert_dpi
 
+    @lazyproperty
+    def sha1(self):
+        """
+        SHA1 hash digest of the image blob
+        """
+        return hashlib.sha1(self._blob).hexdigest()
+
     @classmethod
     def _from_stream(cls, stream, blob, filename=None):
         """
diff --git a/tests/image/test_image.py b/tests/image/test_image.py
@@ -70,6 +70,11 @@ def it_knows_the_horz_and_vert_dpi_of_the_image(self, dpi_fixture):
         assert image.horz_dpi == horz_dpi
         assert image.vert_dpi == vert_dpi
 
+    def it_knows_the_sha1_of_its_image(self):
+        blob = b'fO0Bar'
+        image = Image(blob, None, None)
+        assert image.sha1 == '4921e7002ddfba690a937d54bda226a7b8bdeb68'
+
     # fixtures -------------------------------------------------------
 
     @pytest.fixture
