extract code into utils, cleanup

my/photos/utils.py

@@ -0,0 +1,84 @@
+from typing import Dict
+
+import PIL.Image # type: ignore
+from PIL.ExifTags import TAGS, GPSTAGS # type: ignore
+
+
+Exif = Dict
+
+
+class ExifTags:
+    DATETIME = "DateTimeOriginal"
+    LAT      = "GPSLatitude"
+    LAT_REF  = "GPSLatitudeRef"
+    LON      = "GPSLongitude"
+    LON_REF  = "GPSLongitudeRef"
+    GPSINFO  = "GPSInfo"
+
+
+# TODO there must be something more standard for this...
+def get_exif_from_file(path: str) -> Exif:
+    # TODO exception handler?
+    with PIL.Image.open(path) as fo:
+        return get_exif_data(fo)
+
+
+def get_exif_data(image):
+    """Returns a dictionary from the exif data of an PIL Image item. Also converts the GPS Tags"""
+    exif_data = {}
+    info = image._getexif()
+    if info:
+        for tag, value in info.items():
+            decoded = TAGS.get(tag, tag)
+            if decoded == ExifTags.GPSINFO:
+                gps_data = {}
+                for t in value:
+                    sub_decoded = GPSTAGS.get(t, t)
+                    gps_data[sub_decoded] = value[t]
+
+                exif_data[decoded] = gps_data
+            else:
+                exif_data[decoded] = value
+
+    return exif_data
+
+
+def to_degree(value):
+    """Helper function to convert the GPS coordinates
+    stored in the EXIF to degress in float format"""
+    d0 = value[0][0]
+    d1 = value[0][1]
+    d = float(d0) / float(d1)
+    m0 = value[1][0]
+    m1 = value[1][1]
+    m = float(m0) / float(m1)
+
+    s0 = value[2][0]
+    s1 = value[2][1]
+    s = float(s0) / float(s1)
+
+    return d + (m / 60.0) + (s / 3600.0)
+
+
+def convert_ref(cstr, ref: str):
+    val = to_degree(cstr)
+    if ref == 'S' or ref == 'W':
+        val = -val
+    return val
+
+
+
+import re
+from datetime import datetime
+from pathlib import Path
+from typing import Optional
+
+# TODO surely there is a library that does it??
+_DT_REGEX = re.compile(r'\D(\d{8})\D*(\d{6})\D')
+def dt_from_path(p: Path) -> Optional[datetime]:
+    name = p.stem
+    mm = _DT_REGEX.search(name)
+    if mm is None:
+        return None
+    dates = mm.group(1) + mm.group(2)
+    return datetime.strptime(dates, "%Y%m%d%H%M%S")