Allow configuration of crop gravity when using crop option. Fixed #7.

README.rst

@@ -110,3 +110,21 @@ To resize static images, just prefix the path with ``static:``, for example:
 
 There are many other options/parameters to pass to the templatetag. Please refer
 to the codebase until the documentation is more complete.
+
+
+Options
+-------
+
+You can pass some options to the thumbnail tag:
+
+* upscale: Configures if the input should be upscaled if requested sizes are larger than source.
+* retina: Option to enable retina support (by providing both url and url_2x)
+* crop: Deside if images should be cropped if requested sizes doesn't fit source aspect ratio.
+* quality: Configures quality for image compression
+* pngquant: Configures the pngquant compression factor
+
+.. hint::
+
+    The `crop` option can be set to True for default gravity when cropping (which is `Center`).
+    You can also pass valid GraphicsMagick gravities (North, NorthEeast, East, SouthEast, ...)
+    or their abbreviation (N, NE, E, SE, ...)

ultimatethumb/tests/test_thumbnail.py

@@ -148,6 +148,37 @@ def test_gm_options_crop(self):
             ('quality', 90),
         ]
 
+    @pytest.mark.parametrize('crop,expected', [
+        (True, 'Center'),
+        (1, 'Center'),
+        ('C', 'Center'),
+        ('N', 'North'),
+        ('NW', 'NorthWest'),
+        ('NE', 'NorthEast'),
+        ('W', 'West'),
+        ('E', 'East'),
+        ('S', 'South'),
+        ('SW', 'SouthWest'),
+        ('SE', 'SouthEast'),
+        ('Center', 'Center'),
+        ('North', 'North'),
+        ('NorthWest', 'NorthWest'),
+        ('NorthEast', 'NorthEast'),
+        ('West', 'West'),
+        ('East', 'East'),
+        ('South', 'South'),
+        ('SouthWest', 'SouthWest'),
+        ('SouthEast', 'SouthEast'),
+        (0, None),
+        (False, None),
+        (None, None),
+        ('invalid', None),
+    ])
+    def test_gm_options_crop_gravities(self, crop, expected):
+        image = ImageModelFactory.create()
+        thumbnail = Thumbnail(image.file.path, {'size': ['100', '50'], 'crop': crop})
+        assert thumbnail.get_gm_options().get('gravity', None) == expected
+
     def test_gm_options_quality(self):
         image = ImageModelFactory.create()
         thumbnail = Thumbnail(image.file.path, {'size': ['100', '50'], 'quality': 5})

ultimatethumb/thumbnail.py

@@ -10,10 +10,35 @@
 from .utils import build_url, factor_size, get_size_for_path, get_thumb_data, get_thumb_name
 
 
+CROP_GRAVITY = {
+    True: 'Center',
+    1: 'Center',
+    'C': 'Center',
+    'N': 'North',
+    'NW': 'NorthWest',
+    'NE': 'NorthEast',
+    'W': 'West',
+    'E': 'East',
+    'S': 'South',
+    'SW': 'SouthWest',
+    'SE': 'SouthEast',
+    'Center': 'Center',
+    'North': 'North',
+    'NorthWest': 'NorthWest',
+    'NorthEast': 'NorthEast',
+    'West': 'West',
+    'East': 'East',
+    'South': 'South',
+    'SouthWest': 'SouthWest',
+    'SouthEast': 'SouthEast',
+}
+
+
 Size = namedtuple('Size', ('width', 'height'))
 
 
 class Thumbnail(object):
+
     def __init__(self, source, opts):
         self.source = source
 
@@ -170,8 +195,9 @@ def get_gm_options(self, factor=1):
             resize_attrs
         )
 
-        if self.options['crop']:
-            gm_options['gravity'] = 'Center'
+        crop = CROP_GRAVITY.get(self.options['crop'], False)
+        if crop:
+            gm_options['gravity'] = crop
             gm_options['crop'] = '{0}x{1}+0+0'.format(
                 factor_size(size[0], factor),
                 factor_size(size[1], factor)