Scan image files.

This just scans for the image mime types; it doesn't parse the images
themselves yet.

Addresses #61.

pepper_music_player/library/scan.py

@@ -49,6 +49,16 @@ class AudioFile(File):
     track: entity.Track
 
 
+@dataclasses.dataclass(frozen=True)
+class ImageFile(File):
+    """An image file.
+
+    Attributes:
+        image: The image in the file.
+    """
+    image: entity.Image
+
+
 def _read_audio_tags(dirname: str, basename: str, filename: str) -> tag.Tags:
     """Returns tags read from an audio file."""
     file_info = mutagen.File(filename, easy=True)
@@ -61,6 +71,17 @@ def _read_audio_tags(dirname: str, basename: str, filename: str) -> tag.Tags:
     }).derive()
 
 
+def _read_image_tags(dirname: str, basename: str, filename: str) -> tag.Tags:
+    """Returns tags read from an image file."""
+    # TODO(#61): Actually read more tags (e.g., width and height) from the file
+    # itself.
+    return tag.Tags({
+        tag.BASENAME: (basename,),
+        tag.DIRNAME: (dirname,),
+        tag.FILENAME: (filename,),
+    }).derive()
+
+
 def scan(root_dirname: str) -> Iterable[File]:
     """Scans a directory."""
     # TODO: Keep track of errors with os.walk(onerror=...)
@@ -81,6 +102,17 @@ def scan(root_dirname: str) -> Iterable[File]:
                                               basename=basename,
                                               filename=str(filepath))),
                 )
+            elif mime_major == 'image':
+                yield ImageFile(
+                    filename=str(filepath),
+                    dirname=dirname,
+                    basename=basename,
+                    image=entity.Image(tags=_read_image_tags(
+                        dirname=dirname,
+                        basename=basename,
+                        filename=str(filepath),
+                    )),
+                )
             else:
                 yield File(filename=str(filepath),
                            dirname=dirname,

pepper_music_player/library/scan_test.py

@@ -109,6 +109,24 @@ def test_parses_flac(self):
             scan.scan(str(self._root_dirpath)),
         )
 
+    def test_parses_image(self):
+        # TODO(#61): Write a real image, and test tags parsed from that.
+        self._root_dirpath.joinpath('foo.png').write_bytes(b'')
+        self.assertCountEqual(
+            (scan.ImageFile(
+                filename=str(self._root_dirpath.joinpath('foo.png')),
+                dirname=str(self._root_dirpath),
+                basename='foo.png',
+                image=entity.Image(tags=tag.Tags({
+                    tag.BASENAME: ('foo.png',),
+                    tag.DIRNAME: (str(self._root_dirpath),),
+                    tag.FILENAME:
+                        (str(self._root_dirpath.joinpath('foo.png')),),
+                }).derive()),
+            ),),
+            scan.scan(str(self._root_dirpath)),
+        )
+
 
 if __name__ == '__main__':
     unittest.main()