Swizzle support for colors

arcade/types.py

@@ -3,8 +3,6 @@
 """
 from __future__ import annotations
 
-from __future__ import annotations
-
 import sys
 from array import array
 import ctypes
@@ -419,6 +417,42 @@ def random(
 
         return cls(r, g, b, a)
 
+    def swizzle(self, swizzle_string: str) -> Tuple[int, ...]:
+        """
+        Get a tuple of channel values in the same order as the passed string.
+
+        This imitates swizzling `as implemented in GLSL <https://www.khronos.org/opengl/wiki/Data_Type_(GLSL)#Swizzling>`_
+
+        .. code-block:: python
+
+           >>> from arcade.types import Color
+           >>> color = Color(180, 90, 0, 255)
+           >>> color.swizzle("abgr")
+           (255, 0, 90, 180)
+
+        You can also use any length of swizzle string and use capital
+        letters. Any capitals will be treated as lower case equivalents.
+
+        .. code-block: python
+
+           >>> from arcade.types import Color
+           >>> color = Color(180, 90, 0, 255)
+           >>> color.swizzle("ABGR")
+           (255, 0, 90, 180)
+
+
+        :param swizzle_string:
+            A string of channel names as letters in ``"RGBArgba"``.
+        :return:
+            A tuple in the same order as the input string.
+        """
+        ret = []
+        for c in swizzle_string.lower():
+            if c not in 'rgba':
+                raise ValueError(f"Swizzle string must only contain characters in [RGBArgba], not {c}.")
+            ret.append(getattr(self, c))
+        return tuple(ret)
+
 
 ColorLike = Union[RGB, RGBA255]
 

tests/unit/color/test_color_type.py

@@ -201,6 +201,29 @@ def test_deepcopy_color_inheritance():
     assert isinstance(deep, ColorSubclass)
 
 
+@pytest.mark.parametrize("klass", [Color, ColorSubclass])
+def test_swizzle(klass):
+    color_instance = klass(1, 2, 3, a=4)
+
+    # Edge case
+    assert color_instance.swizzle("") == tuple()
+
+    assert color_instance.swizzle("r") == (1,)
+    assert color_instance.swizzle("g") == (2,)
+    assert color_instance.swizzle("b") == (3,)
+    assert color_instance.swizzle("a") == (4,)
+    assert color_instance.swizzle("R") == (1,)
+    assert color_instance.swizzle("G") == (2,)
+    assert color_instance.swizzle("B") == (3,)
+    assert color_instance.swizzle("A") == (4,)
+
+    assert color_instance.swizzle("ra") == (1, 4)
+    assert color_instance.swizzle("RA") == (1, 4)
+
+    assert color_instance.swizzle("aabbggrr") == (4, 4, 3, 3, 2, 2, 1, 1)
+    assert color_instance.swizzle("AABBGGRR") == (4, 4, 3, 3, 2, 2, 1, 1)
+
+
 RANDINT_RETURN_RESULT = 128