webp: add compression (lossless/lossy) to image info

PIL/WebPImagePlugin.py

@@ -153,6 +153,7 @@ class WebPImageFile(ImageFile.ImageFile):
 
         self.mode = mode
         self.size = size
+        self.info['compression'] = 'lossy' if lossy else 'lossless'
         self.tile = [('webp', (0, 0) + size, 0,
                       # Decoder params: rawmode, has_alpha, width, height.
                       (mode, 1 if 'RGBA' == mode else 0, size[0], size[1]))]

Tests/test_file_webp.py

@@ -72,6 +72,18 @@ class TestFileWebp(PillowTestCase):
         target = hopper("RGB")
         self.assert_image_similar(image, target, 12)
 
+    def test_info_compression(self):
+        for name, compression in (
+            ('flower2'           , 'lossy'),
+            ('flower'            , 'lossy'),
+            ('hopper'            , 'lossy'),
+            ('lossless-no-vp8x'  , 'lossless'),
+            ('lossless-with-vp8x', 'lossless'),
+            ('transparent'       , 'lossy'),
+        ):
+            image = Image.open('Tests/images/%s.webp' % name)
+            self.assertEqual(image.info['compression'], compression)
+
 
 if __name__ == '__main__':
     unittest.main()

Tests/test_file_webp_lossless.py

@@ -31,6 +31,7 @@ class TestFileWebpLossless(PillowTestCase):
         self.assertEqual(image.mode, "RGB")
         self.assertEqual(image.size, (128, 128))
         self.assertEqual(image.format, "WEBP")
+        self.assertEqual(image.info['compression'], 'lossless')
         image.load()
         image.getdata()