Modified ImageSequence Iterator class to be an iterator

PIL/ImageSequence.py

@@ -32,6 +32,7 @@ class Iterator(object):
         if not hasattr(im, "seek"):
             raise AttributeError("im must have seek method")
         self.im = im
+        self.position = 0
 
     def __getitem__(self, ix):
         try:
@@ -40,3 +41,17 @@ class Iterator(object):
             return self.im
         except EOFError:
             raise IndexError  # end of sequence
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        try:
+            self.im.seek(self.position)
+            self.position += 1
+            return self.im
+        except EOFError:
+            raise StopIteration
+
+    def next(self):
+        return self.__next__()

Tests/test_imagesequence.py

@@ -24,6 +24,14 @@ class TestImageSequence(PillowTestCase):
 
         self.assertRaises(AttributeError, lambda: ImageSequence.Iterator(0))
 
+    def test_iterator(self):
+        im = Image.open('Tests/images/multipage.tiff')
+        i = ImageSequence.Iterator(im)
+        for index in range(0, im.n_frames):
+            self.assertEqual(i[index], next(i))
+        self.assertRaises(IndexError, lambda: i[index+1])
+        self.assertRaises(StopIteration, lambda: next(i))
+
     def _test_multipage_tiff(self):
         im = Image.open('Tests/images/multipage.tiff')
         for index, frame in enumerate(ImageSequence.Iterator(im)):