feat: add hsl/hsla properties to colours (#21)

Author: backwardspy

catppuccin/colour.py

@@ -7,6 +7,8 @@
 from dataclasses import dataclass
 from typing import Any, Tuple
 
+from catppuccin.hsl import rgb_to_hsl
+
 
 @dataclass(frozen=True)
 class Colour:
@@ -27,6 +29,16 @@ def rgba(self) -> Tuple[int, int, int, int]:
         """Get the colour as a 4-tuple of red, green, blue, and alpha."""
         return self.red, self.green, self.blue, self.alpha
 
+    @property
+    def hsl(self) -> Tuple[float, float, float]:
+        """Get the colour as a 3-tuple of hue, saturation, and lightness."""
+        return rgb_to_hsl(*self.rgb)
+
+    @property
+    def hsla(self) -> Tuple[float, float, float, float]:
+        """Get the colour as a 4-tuple of hue, saturation, lightness, and alpha."""
+        return (*self.hsl, self.alpha)
+
     @property
     def hex(self) -> str:
         """Get the colour as a lowercase hex string."""

catppuccin/hsl.py

@@ -0,0 +1,40 @@
+"""
+Utilities for working with HSL colours.
+"""
+from __future__ import annotations
+
+from typing import Tuple
+
+
+# pylint: disable=invalid-name
+def rgb_to_hsl(r: int, g: int, b: int) -> Tuple[int, float, float]:
+    """Convert RGB to HSL."""
+    r1 = r / 255
+    g1 = g / 255
+    b1 = b / 255
+
+    cmax = max(r1, g1, b1)
+    cmin = min(r1, g1, b1)
+    delta = cmax - cmin
+
+    if delta == 0:
+        h = 0.0
+    elif cmax == r1:
+        h = ((g1 - b1) / delta) % 6
+    elif cmax == g1:
+        h = (b1 - r1) / delta + 2
+    else:
+        h = (r1 - g1) / delta + 4
+
+    h = round(h * 60)
+    if h < 0:
+        h += 360
+
+    l = (cmax + cmin) / 2
+
+    if delta == 0:
+        s = 0.0
+    else:
+        s = delta / (1 - abs(2 * l - 1))
+
+    return h, round(s, 2), round(l, 2)

tests/test_colour.py

@@ -15,6 +15,18 @@ def test_colour_to_rgba_default():
     assert Colour(12, 123, 234).rgba == (12, 123, 234, 255)
 
 
+def test_colour_to_hsl():
+    assert Colour(12, 123, 234).hsl == (210, 0.90, 0.48)
+
+
+def test_colour_to_hsla():
+    assert Colour(12, 123, 234, 35).hsla == (210, 0.90, 0.48, 35)
+
+
+def test_colour_to_hsla_default():
+    assert Colour(12, 123, 234).hsla == (210, 0.90, 0.48, 255)
+
+
 def test_rgb_colour_to_hex():
     assert Colour(0x12, 0xEB, 0x77).hex == "12eb77"
 

tests/test_hsl.py

@@ -0,0 +1,13 @@
+from catppuccin import Flavour
+from catppuccin.hsl import rgb_to_hsl
+
+mocha = Flavour.mocha()
+latte = Flavour.latte()
+
+
+def test_rgb_to_hsl():
+    hsl = rgb_to_hsl(*mocha.mauve.rgb)
+    assert hsl == (267, 0.84, 0.81)
+
+    hsl = rgb_to_hsl(*latte.text.rgb)
+    assert hsl == (234, 0.16, 0.35)