add rgba property

grapefruit.py

@@ -1530,6 +1530,16 @@ def rgb(self, value):
     self.__rgb = tuple([float(v) for v in value])
     self.__hsl = rgb_to_hsl(*self.__rgb)
 
+  @property
+  def rgba(self):
+    """The RGBA values of this Color."""
+    return (self.__rgb + (self.__a,))
+  @rgba.setter
+  def rgba(self, value):
+    self.__rgb = tuple([float(v) for v in value[:3]])
+    self.__a = float(value[3])
+    self.__hsl = rgb_to_hsl(*self.__rgb)
+
   @property
   def red(self):
     return self.__rgb[0]

grapefruit_test.py

@@ -244,6 +244,16 @@ def test_set_rgb(self):
     assert_equal(col.rgb, (0.1, 0.2, 0.3))
     assert_equal(col.hsl, grapefruit.rgb_to_hsl(0.1, 0.2, 0.3))
 
+  def test_get_rgba(self):
+    col = grapefruit.Color.from_rgb(1.0, 0.5, 0.0)
+    assert_equal(col.rgba, (1, 0.5, 0, 1))
+  def test_set_rgba(self):
+    col = grapefruit.Color.from_rgb(1.0, 0.5, 0.0)
+    col.rgba = (0.1, 0.2, 0.3, 0.5)
+    assert_equal(col.rgb, (0.1, 0.2, 0.3))
+    assert_equal(col.alpha, 0.5)
+    assert_equal(col.hsl, grapefruit.rgb_to_hsl(0.1, 0.2, 0.3))
+
   def test_get_red(self):
     col = grapefruit.Color.from_rgb(0.1, 0.2, 0.3)
     assert_equal(col.red, 0.1)