Replace PyGame dependency with pillow

PyGame is used to load manipulate and save image data idependently
of their file format.

The PyGame project is fairly big and has caused various unexpected
logging in the tools, so replace it with pillow, which is sufficient
for our use case.

Also expose OOP and functional API for tiletool, so it can be
consumed programatically by 3rd customized tools.

Author: dciabrin

tools/paltool.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-# Copyright (c) 2018-2019 Damien Ciabrini
+# Copyright (c) 2018-2026 Damien Ciabrini
 # This file is part of ngdevkit
 #
 # ngdevkit is free software: you can redistribute it and/or modify
@@ -20,18 +20,10 @@
 Extract palette from a 2D image and convert it to C or ASM data.
 """
 
-from __future__ import print_function
-import struct
-import os
-import sys
 import argparse
-from random import randint
-
-os.environ['PYGAME_HIDE_SUPPORT_PROMPT'] = '1'
-os.environ['SDL_VIDEODRIVER'] = 'dummy'
-os.environ['SDL_AUDIODRIVER'] = 'dummy'
-import pygame
 
+from PIL import Image
+from itertools import batched
 
 def rgb24_to_packed15(col):
     r, g, b = [c >> 2 for c in col]
@@ -62,15 +54,18 @@ def main():
 
     arguments = parser.parse_args()
 
-    img = pygame.image.load(arguments.FILE)
+    img = Image.open(arguments.FILE)
 
-    # only keep the first 16 colors, even if palette has other
-    # colors initialized but unused.
-    pal = img.get_palette()[:16]
+    # extract the palette as a 24bits RGB
+    pal_ints = img.getpalette()
+    pal_rgb = list(batched(pal_ints, 3))
+    # make sure the palette has 16colors
+    if len(pal_rgb) > 16:
+        pal_rgb = pal_rgb[:16]
+    elif len(pal_rgb) < 16:
+        pal_rgb.extend([(0, 0, 0)] * (16 - len(pal_rgb)))
 
-    # for the time being, do not the 16th bit available in
-    # the Neo Geo hardware
-    ngpal = [rgb24_to_packed15(c) for c in pal]
+    ngpal = [rgb24_to_packed15(c) for c in pal_rgb]
 
     out = open(arguments.output, "w")
     output_c_anonymous_palette(ngpal, out)