Add rotation option

Fixes #72

Add slot for auto_stretch option

rawkit/options.py

@@ -220,7 +220,9 @@ class Options(object):
         '_colorspace',
         '_cropbox',
         '_gamma',
-        '_interpolation'
+        '_interpolation',
+        '_auto_stretch',
+        '_rotation',
     ]
     """The options which are supported by this class."""
 
@@ -562,6 +564,41 @@ def auto_stretch(self):
         """
         return True
 
+    @option
+    def rotation(self):
+        """
+        Rotates the image by the given number of degrees. Must be a multiple of
+        90 (0, 90, 180, 270, etc).
+
+        The default (None) is to use the rotation provided by the camera.
+
+        :type: :class:`int`
+        :default: None
+        :dcraw: ``-t``
+        :libraw: :class:`libraw.structs.libraw_output_params_t.user_flip`
+        """
+        return None
+
+    @rotation.setter
+    def rotation(self, value):
+        if value is not None and value > 0:
+            value = ((value + 3600) % 360)
+
+        if value in (None, 0, 90, 180, 270):
+            self._rotation = value
+        else:
+            raise ValueError('Rotation must be None (use camera rotation) or '
+                             'a multiple of 90')
+
+    @rotation.param_writer
+    def rotation(self, params):
+        params.user_flip = ctypes.c_int({
+            270: 5,
+            180: 3,
+            90: 6,
+            0: 0
+        }[self._rotation])
+
     def _map_to_libraw_params(self, params):
         """
         Internal method that writes rawkit options into the libraw options
@@ -575,3 +612,6 @@ def _map_to_libraw_params(self, params):
             opt = getattr(Options, prop)
             if type(opt) is option and getattr(self, prop) is not None:
                 opt.write_param(self, params)
+
+        # This generally isn't needed, except for testing.
+        return params

tests/unit/options_test.py

@@ -43,25 +43,21 @@ def test_option_from_class_should_return_decorator():
 
 
 def test_custom_wb_param_writer_writes_rgbg_and_greybox(options):
-    params = Mock()
-    options.white_balance = WhiteBalance(greybox=(0, 0, 0, 0),
-                                         rgbg=(0, 0, 0, 0))
-    options._map_to_libraw_params(params)
-    assert params.greybox is not None
-    assert params.rgbg is not None
+    options.white_balance = WhiteBalance(greybox=(7, 7, 7, 7),
+                                         rgbg=(42, 42, 42, 42))
+    params = options._map_to_libraw_params(Mock())
+
+    for v in params.greybox:
+        assert v == 7
+    for v in params.user_mul:
+        assert v == 42
 
 
 def test_bps_must_be_8_or_16(options):
     with pytest.raises(ValueError):
         options.bps = 5
 
 
-def test_map_params_fails_on_invalid(options):
-    # with pytest.raises(AttributeError):
-    params = Mock()
-    options._map_to_libraw_params(params)
-
-
 def test_options_are_iterable(options):
     options.half_size = True
     assert 'half_size' in options
@@ -84,3 +80,37 @@ def test_options_values(options):
     options.half_size = True
 
     assert options.values() == [True]
+
+
+def test_set_rotation_invalid_type(options):
+    with pytest.raises(TypeError):
+        options.rotation = 'fish'
+
+
+def test_set_rotation_value_is_reduced(options):
+    options.rotation = 270 + 90
+    assert options.rotation == 0
+
+    options.rotation = 270 + 180
+    assert options.rotation == 90
+
+    options.rotation = None
+    assert options.rotation is None
+
+
+def test_set_rotation_invalid_value(options):
+    with pytest.raises(ValueError):
+        options.rotation = 93.5
+
+
+def test_rotation_param_writer_values(options):
+    values = {
+        270: 5,
+        180: 3,
+        90: 6,
+        0: 0
+    }
+    for value in values.keys():
+        options.rotation = value
+        params = options._map_to_libraw_params(Mock())
+        assert params.user_flip.value == values[value]