Implement minimal EXIF and IPTC tag support

docs/README.md

@@ -24,6 +24,9 @@ The following options are available in the ``hugophotoswipe.yml`` file:
 | jpeg_progressive | False | Output progressive JPEGs |
 | jpeg_optimize | False | Optimize JPEG output |
 | jpeg_quality | 75 | JPEG quality factor |
+| tag_map | None | Dictionary map of exif/iptc tags to photo properties |
+| exif | None | List of tags to be included or excluded |
+| iptc | None | List of tags to be included or excluded |
 
 Naturally, the jpeg options are only applied when ``output_format`` is 
 ``jpg``.
@@ -42,6 +45,50 @@ unchanged. When a single number is given, the *maximum* dimension of the photo
 will be reduced to the given number, and the other dimension is chosen 
 according to the aspect ratio.
 
+EXIF/IPTC Tags
+--------------
+
+You can use the metadata embedded in the photos as a starter to fill out captions
+and copyright information. HugoPhotoSwipe will use this information when you run 
+`hps update` in the following manner:
+1. Prefer the information already specified in the album file
+2. Use the information in the metadata
+
+Using metadata requires a mapping for each field you want to be populated. Currently
+only caption and copyright are supported. In the configuration file, add the `tag_map`
+setting as follows:
+
+```yaml
+tag_map:
+  caption: exif.ImageDescription
+  copyright: exif.Artist
+```
+
+Caption will be saved to the album yaml file with the photo information. You can then
+edit it there if you wish. Because the album file is given priority, your changes will
+not be overridden, even after an update. Copyright is not yet used as this is currently 
+an album-level property.
+
+The format of the option is: `property: iptc/exif.tag`. Tag may include spaces. A full
+list of tags can be found here:
+* [IPTC tags](https://github.com/jamesacampbell/iptcinfo3/blob/a9cea6cb1981e4ad29cf317d44419e4fd45c2170/iptcinfo3.py#L445)
+* [EXIF tags](https://github.com/python-pillow/Pillow/blob/master/src/PIL/ExifTags.py)
+
+The following two configuration file options allow you more granular control over what
+metadata HugoPhotoSwipe loads from the file. The intended use is to reduce the number of
+tags that are saved. If you want to use a tag in the `tag_map`, it must included or 
+not be excluded. Specifying `include: []` will result in no data being loaded. 
+Not specifying either option will result in all tags being loaded.
+
+```yaml
+iptc:
+  include: ['tag1', 'tag2', ...]
+  exclude: ['tag1', 'tag2', ...]
+exif:
+  include: ['tag1', 'tag2', ...]
+  exclude: ['tag1', 'tag2', ...]
+```
+
 Shortcodes
 ==========
 

hugophotoswipe/config.py

@@ -53,6 +53,9 @@
     "jpeg_quality": 75,
     "fast": False,
     "verbose": False,
+    "exif": None,
+    "iptc": None,
+    "tag_map": None,
 }
 
 DONT_DUMP = ["verbose", "fast"]

hugophotoswipe/photo.py

@@ -17,8 +17,10 @@
 import smartcrop
 import tempfile
 
+from PIL.TiffImagePlugin import IFDRational
 from PIL import Image
-from PIL import ExifTags
+from PIL.ExifTags import TAGS, GPSTAGS
+import iptcinfo3 as iptc3
 from functools import total_ordering
 from textwrap import wrap
 from textwrap import indent
@@ -50,11 +52,13 @@ def __init__(
         # names
         self.name = name
         self.alt = alt
-        self.caption = caption
+        self._caption = caption
 
         # other
-        self.copyright = copyright
+        self._copyright = copyright
         self.cover_path = None
+        self._exif = None
+        self._iptc = None
 
         # caching
         self._original_img = None
@@ -78,14 +82,13 @@ def original_image(self):
     def _load_original_image(self):
         img = Image.open(self.original_path)
         # if there is no exif data, simply return the image
-        exif = img._getexif()
+        self._load_exif(img)
+        exif = self._exif
         if exif is None:
             return img
 
         # get the orientation tag code from the ExifTags dict
-        orientation = next(
-            (k for k, v in ExifTags.TAGS.items() if v == "Orientation"), None
-        )
+        orientation = exif.get('Orientation')
         if orientation is None:
             print("Couldn't find orientation tag in ExifTags.TAGS")
             return img
@@ -105,13 +108,105 @@ def _load_original_image(self):
         # fallback for unhandled rotation tags
         return img
 
+    def _load_exif(self, image):
+        if settings.exif:
+            tags = set(_filter_tags(TAGS.values(),
+                                    settings.exif.get('include'),
+                                    settings.exif.get('exclude')))
+            tags.add('Orientation')  # always need this for resize
+        else:
+            tags = TAGS.values()
+
+        exif_data = {}
+        exif = image._getexif() or {}
+        for k, v in exif.items():
+            decoded = TAGS.get(k)
+            if decoded in tags and not isinstance(v, IFDRational):  # Filter complex data values
+                exif_data[decoded] = v
+        for k, v in exif_data.pop('GPSInfo', {}).items():
+            decoded = GPSTAGS.get(k, k)
+            exif_data[decoded] = v
+        self._exif = exif_data
+
     def free(self):
         """Manually clean up the cached image"""
         if hasattr(self, "_original_img") and self._original_img:
             self._original_img.close()
             del self._original_img
         self._original_img = None
 
+    @property
+    def iptc(self):
+        if self._iptc is None:
+            if settings.iptc:
+                tags = _filter_tags(iptc3.c_datasets_r.keys(),
+                                    settings.iptc.get('include'),
+                                    settings.iptc.get('exclude'))
+            else:
+                tags = iptc3.c_datasets_r.keys()
+
+            info = iptc3.IPTCInfo(self.original_path)
+            iptc = {}
+            for k in tags:
+                if type(info[k]) is bytes:
+                    iptc[k] = info[k].decode('utf-8')
+                elif type(info[k]) is list:
+                    l = []
+                    for v in info[k]:
+                        l.append(v.decode('utf-8'))
+                    iptc[k] = l
+                else:
+                    iptc[k] = info[k]
+            self._iptc = iptc
+
+        return self._iptc
+
+    @property
+    def exif(self):
+        if not self._exif:
+            _ = self.original_image  # Trigger loading image and exif data
+        return self._exif
+
+    def _get_tag_value(self, tag):
+        assert tag is not None
+        try:
+            obj, t = tag.split('.')
+        except Exception as e:
+            logging.warning(e)
+            raise ValueError(f"Tag improperly formatted. Should be of format (exif/iptc).tag Provided: ({tag})")
+        if obj.lower() not in ['exif', 'iptc']:
+            raise ValueError(f"Tags can only reference iptc or exif data. ({tag})")
+        o = getattr(self, obj.lower(), {})
+        if o is None:
+            logging.warning(f'Tag "{tag}" specified but {obj} not loaded. Returning "".')
+            o = {}
+        return o.get(t, "")
+
+    @property
+    def caption(self):
+        if self._caption:
+            return self._caption
+        elif settings.tag_map and settings.tag_map.get('caption'):
+            return str(self._get_tag_value(settings.tag_map.get('caption')))
+        return ""
+
+    @property
+    def copyright(self):
+        if self._copyright:
+            return self._copyright
+        elif settings.tag_map and settings.tag_map.get('copyright'):
+            return str(self._get_tag_value(settings.tag_map.get('copyright')))
+        return ""
+
+    def __getattribute__(self, attr):
+        """ Allow property style access to all tags defined in settings.tag_map """
+        try:
+            return super().__getattribute__(attr)
+        except AttributeError as e:
+            if settings.tag_map and settings.tag_map.get(attr):
+                return self._get_tag_value(settings.tag_map.get(attr))
+            raise e
+
     def has_sizes(self):
         """ Check if all necessary sizes exist on disk """
         if self.name is None:
@@ -435,3 +530,10 @@ def __eq__(self, other):
 
     def __del__(self):
         self.free()
+
+
+def _filter_tags(tags, include=None, exclude=None):
+    exc = lambda k: True if not exclude else k not in exclude
+    inc = lambda k: True if not include else k in include
+    return filter(exc, filter(inc, tags))
+

setup.py

@@ -27,6 +27,7 @@
     "pyyaml",
     "tqdm",
     "smartcrop",
+    "iptcinfo3",
 ]
 
 docs_require = []

tests/test_config.py

@@ -32,6 +32,8 @@ def test_config_1(self):
             self.assertEqual(line(fp), "dirname_large: large")
             self.assertEqual(line(fp), "dirname_small: small")
             self.assertEqual(line(fp), "dirname_thumb: thumb")
+            self.assertEqual(line(fp), "exif:")
+            self.assertEqual(line(fp), "iptc:")
             self.assertEqual(line(fp), "jpeg_optimize: False")
             self.assertEqual(line(fp), "jpeg_progressive: False")
             self.assertEqual(line(fp), "jpeg_quality: 75")
@@ -40,6 +42,7 @@ def test_config_1(self):
             self.assertEqual(line(fp), "output_format: jpg")
             self.assertEqual(line(fp), "photo_dir: photos")
             self.assertEqual(line(fp), "smartcrop_js_path:")
+            self.assertEqual(line(fp), "tag_map:")
             self.assertEqual(line(fp), "url_prefix:")
             self.assertEqual(line(fp), "use_smartcrop_js: False")
 
@@ -65,6 +68,8 @@ def test_config_2(self):
             self.assertEqual(line(fp), "dirname_large: large")
             self.assertEqual(line(fp), "dirname_small: small")
             self.assertEqual(line(fp), "dirname_thumb: thumb")
+            self.assertEqual(line(fp), "exif:")
+            self.assertEqual(line(fp), "iptc:")
             self.assertEqual(line(fp), "jpeg_optimize: False")
             self.assertEqual(line(fp), "jpeg_progressive: True")
             self.assertEqual(line(fp), "jpeg_quality: 75")
@@ -73,6 +78,7 @@ def test_config_2(self):
             self.assertEqual(line(fp), "output_format: jpg")
             self.assertEqual(line(fp), "photo_dir: photo_files")
             self.assertEqual(line(fp), "smartcrop_js_path:")
+            self.assertEqual(line(fp), "tag_map:")
             self.assertEqual(line(fp), "url_prefix:")
             self.assertEqual(line(fp), "use_smartcrop_js: False")
 

tests/test_photo.py

@@ -196,7 +196,47 @@ def test_thumb(self):
 
     def test_sha256sum(self):
         self.assertEqual(self.photo.sha256sum(),
-"c2fdf14c548a08032fd06e6036197fc7e9c262e6d06fac40e54ec5dd2ce6912f")
+                         "c2fdf14c548a08032fd06e6036197fc7e9c262e6d06fac40e54ec5dd2ce6912f")
+
+
+class PhotoTagsTestCase(unittest.TestCase):
+    def setUp(self):
+        here = os.path.dirname(os.path.realpath(__file__))
+        test_file = os.path.join(here, "data", "dogs", "dog-2.jpg")
+        self.photo = Photo(
+            album_name="test_album",
+            original_path=test_file,
+            name="dog_2",
+            alt="Alt text",
+            caption="caption text",
+            copyright=None,
+        )
+        self._tmpdir = tempfile.mkdtemp(prefix="hps_photo_")
+        # Reset settings after each test
+        settings.__init__(**dict())
+
+    def tearDown(self):
+        shutil.rmtree(self._tmpdir)
+
+    def test_iptc_tags_retain_default_behaviour(self):
+        setattr(settings, "tag_map", {"caption": "iptc.headline"})
+        self.assertEqual("caption text", self.photo.caption)
+
+    def test_iptc_tags_backfill(self):
+        setattr(self.photo, "_caption", None)
+        setattr(settings, "tag_map", {"caption": "iptc.headline"})
+        self.assertEqual("A photo by Andrew Branch. unsplash.com/photos/owWHkSUmCCQ", self.photo.caption)
+
+    def test_exif_tags_retain_default_behaviour(self):
+        setattr(settings, "tag_map", {"copyright": "exif.Copyright"})
+        setattr(self.photo, "_copyright", "The other dog")
+        self.assertEqual("The other dog", self.photo.copyright)
+
+    def test_exif_tags_backfill(self):
+        # Configure Tag Map to point copyright to a filled-out EXIF tag.
+        setattr(settings, "tag_map", {"copyright": "exif.Copyright"})
+        self.assertEqual("Free (do whatever you want) high-resolution photos. unsplash.com/license",
+                         self.photo.copyright)
 
 
 if __name__ == "__main__":