preview reader

1 files changed, 66 insertions, 0 deletions

diff --git a/bsie/reader/preview/_rawpy.py b/bsie/reader/preview/_rawpy.py
new file mode 100644
index 0000000..2c20a48
--- /dev/null
+++ b/bsie/reader/preview/_rawpy.py
@@ -0,0 +1,66 @@
+"""
+
+Part of the bsie module.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+from functools import partial
+import typing
+
+# external imports
+import PIL.Image
+import rawpy
+
+# bsie imports
+from bsie.utils import errors, filematcher
+
+# inner-module imports
+from . import utils
+from .. import base
+
+# constants
+MATCH_RULE = 'mime={image/x-nikon-nef} | extension={nef}'
+
+# exports
+__all__: typing.Sequence[str] = (
+    'RawpyPreviewReader',
+    )
+
+
+## code ##
+
+class RawpyPreviewReader(base.Reader):
+    """Produce previews for raw image files using the rawpy library."""
+
+    # file matcher
+    _match: filematcher.Matcher
+
+    # additional kwargs to rawpy's postprocess
+    _rawpy_kwargs: typing.Dict[str, typing.Any]
+
+    def __init__(self, **rawpy_kwargs):
+        match_rule = rawpy_kwargs.pop('file_match_rule', MATCH_RULE)
+        self._match = filematcher.parse(match_rule)
+        self._rawpy_kwargs = rawpy_kwargs
+
+    def __call__(self, path: str) -> typing.Callable[[int], PIL.Image.Image]:
+        # perform quick checks first
+        if not self._match(path):
+            raise errors.UnsupportedFileFormatError(path)
+
+        try:
+            # open file with rawpy
+            ary = rawpy.imread(path).postprocess(**self._rawpy_kwargs)
+            # convert to PIL.Image
+            img = PIL.Image.fromarray(ary)
+            # return callback
+            return partial(utils.resize, img)
+
+        except (rawpy.LibRawFatalError, # pylint: disable=no-member # pylint doesn't find the errors
+                rawpy.NotSupportedError, # pylint: disable=no-member
+                rawpy.LibRawNonFatalError, # pylint: disable=no-member
+               ) as err:
+            raise errors.ReaderError(path) from err
+
+## EOF ##