Palettes are selected by matricizer

Matricizers select color palettes now. This is motivated by the fact
that the gradient palettes don't really look good for openssh randomart
based art, and rainbows do look good.

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

colorhash/__main__.py

@@ -154,13 +154,6 @@ def main() -> None:
         case _:
             assert False, f"unknown input type {args.input_type}"
 
-    # Choose the palette
-    palette: list[str]
-    if args.palette == "auto":
-        palette = list(DEFAULT_PALETTES.values())[sum(hashdata) % len(DEFAULT_PALETTES)]
-    else:
-        palette = PALETTES[args.palette]
-
     # Choose the dimensions and the matricizer
     matricizer: Matricizer
     match args.matrix:
@@ -170,10 +163,17 @@ def main() -> None:
         case "randomart":
             # 17x9 is what openssh uses
             # TODO - allow configuring dimensions, maybe
-            matricizer = RandomartMatricizer(17, 9)
+            matricizer = RandomartMatricizer(11, 6)
         case _:
             assert False, f"invalid args.matrix: {args.matrix}"
 
+    # Choose the palette
+    palette: list[str]
+    if args.palette == "auto":
+        palette = matricizer.choose_palette(hashdata, PALETTES)
+    else:
+        palette = PALETTES[args.palette]
+
     # Choose the colorizer
     colorizer = PaletteColorizer(palette)
 

colorhash/matricizer.py

@@ -1,6 +1,8 @@
 "All things that turn a hash into a matrix."
 import abc
-from typing import Sequence
+from typing import Mapping, Sequence
+
+from .palettes import Palette, DEFAULT_PALETTES
 
 
 Matrix = Sequence[Sequence[int]]
@@ -33,6 +35,12 @@ class Matricizer(metaclass=abc.ABCMeta):
         :returns: the matrix converted from the hash data.
         """
 
+    @abc.abstractmethod
+    def choose_palette(self, data: bytes, palettes: Mapping[str, Palette]) -> Palette:
+        """
+        Choose a palette based on the give data and palettes.
+        """
+
 
 class NibbleMatricizer(Matricizer):
     """
@@ -81,6 +89,9 @@ class NibbleMatricizer(Matricizer):
 
         return cols
 
+    def choose_palette(self, data: bytes, palettes: Mapping[str, Palette]) -> Palette:
+        return list(palettes.values())[sum(data) % len(palettes)]
+
 
 class RandomartMatricizer(Matricizer):
     """
@@ -127,3 +138,6 @@ class RandomartMatricizer(Matricizer):
                 if rows[r][c] < 0xF:
                     rows[r][c] += 1
         return rows
+
+    def choose_palette(self, _data: bytes, _palettes: Mapping[str, Palette]) -> Palette:
+        return DEFAULT_PALETTES['rainbow']