Split out color palettes to their own file

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

colorhash/__main__.py

@@ -7,24 +7,14 @@ import sys
 
 from .colorizer import PaletteColorizer
 from .matricizer import Matricizer, NibbleMatricizer, RandomartMatricizer
+from .palettes import DEFAULT_PALETTES, PALETTES
 from .svg import gensvg
 
 
 # TODO - WASM compile for embedding directly in HTML
 # TODO - option to add a caption based on the filename
-# TODO - palettes defined by JSON
-
-
-PALETTES = {
-    "red": [f"#{0x110000 * i:06x}" for i in range(0x10)],
-    "green": [f"#{0x001100 * i:06x}" for i in range(0x10)],
-    "blue": [f"#{0x000011 * i:06x}" for i in range(0x10)],
-    "black": [f"#{0x111111 * i:06x}" for i in range(0x10)],
-    "cyan": [f"#{0x001111 * i:06x}" for i in range(0x10)],
-    "yellow": [f"#{0x111100 * i:06x}" for i in range(0x10)],
-    "magenta": [f"#{0x110011 * i:06x}" for i in range(0x10)],
-    "white": [f"#{0x111111 * (0xF - i):06x}" for i in range(0x10)],
-}
+# TODO - load palettes from a file
+# TODO - HSV color
 
 
 def main() -> None:

colorhash/palettes.py

@@ -0,0 +1,56 @@
+"Base color palette definitions."
+import abc
+from typing import Sequence, Self
+
+
+class Palette(metaclass=abc.ABCMeta):
+    """
+    A 16-color palette.
+
+    All colors must be HTML color strings.
+    """
+
+    @abc.abstractmethod
+    def choose(self, color: int) -> str:
+        """
+        Chooses the given color in this palette.
+        """
+
+    def __getitem__(self, color: int) -> str:
+        return self.choose(color)
+
+
+class StaticPalette(Palette):
+    """
+    A static color palette with discrete colors.
+    """
+
+    def __init__(self, colors: Sequence[str]) -> None:
+        """
+        Creates a new static color palette.
+
+        :param colors: the colors for this palette. Must be exactly 16 colors.
+        """
+        if len(colors) != 16:
+            raise ValueError(f"palette must have exactly 16 colors (got {len(colors)})")
+        self.colors = colors
+
+    def choose(self, color: int) -> str:
+        if not isinstance(color, int):
+            raise KeyError("palette color indices must be an integer")
+        return self.colors[color]
+
+
+DEFAULT_PALETTES = {
+    "red": StaticPalette([f"#{0x110000 * i:06x}" for i in range(0x10)]),
+    "green": StaticPalette([f"#{0x001100 * i:06x}" for i in range(0x10)]),
+    "blue": StaticPalette([f"#{0x000011 * i:06x}" for i in range(0x10)]),
+    "black": StaticPalette([f"#{0x111111 * i:06x}" for i in range(0x10)]),
+    "cyan": StaticPalette([f"#{0x001111 * i:06x}" for i in range(0x10)]),
+    "yellow": StaticPalette([f"#{0x111100 * i:06x}" for i in range(0x10)]),
+    "magenta": StaticPalette([f"#{0x110011 * i:06x}" for i in range(0x10)]),
+    "white": StaticPalette([f"#{0x111111 * (0xF - i):06x}" for i in range(0x10)]),
+}
+
+
+PALETTES = {**DEFAULT_PALETTES}