#!/usr/bin/env python3
"""B9B: 128x128 test frames for /dev/fb0, in RGB565 (little-endian u16, fb native) and XRGB8888, plus PNG previews.
Frames: red, green, blue, white, black, and 'geo' = geometry/orientation/colour chart:
  - 1-px white border on the outermost rows/columns (all 4 edges must be visible -> no crop/offset error),
  - 2nd row/column inside the border black (a 1-px shift shows up as a doubled or missing line),
  - corner blocks 24x24: top-left RED, top-right GREEN, bottom-left BLUE, bottom-right WHITE,
  - centre: 3 vertical bars R | G | B (rows 40..87), and a yellow arrow pointing UP above them.
usage: gen-patterns.py outdir"""
import os, struct, sys, zlib

W = H = 128
O = sys.argv[1]; os.makedirs(O, exist_ok=True)
R, G, B, Wh, K, Y = (255, 0, 0), (0, 255, 0), (0, 0, 255), (255, 255, 255), (0, 0, 0), (255, 255, 0)

def solid(c): return [[c] * W for _ in range(H)]

def geo():
    p = solid(K)
    for y in range(H):
        for x in range(W):
            if x in (0, W - 1) or y in (0, H - 1):
                p[y][x] = Wh
            elif 2 <= x < 26 and 2 <= y < 26:
                p[y][x] = R
            elif W - 26 <= x < W - 2 and 2 <= y < 26:
                p[y][x] = G
            elif 2 <= x < 26 and H - 26 <= y < H - 2:
                p[y][x] = B
            elif W - 26 <= x < W - 2 and H - 26 <= y < H - 2:
                p[y][x] = Wh
            elif 40 <= y < 88 and 28 <= x < 100:
                p[y][x] = (R, G, B)[(x - 28) // 24]
            elif 6 <= y < 34 and abs(x - 63.5) <= (y - 6) * 0.5 and y < 22:   # arrow head
                p[y][x] = Y
            elif 22 <= y < 34 and 58 <= x < 70:                                 # arrow shaft
                p[y][x] = Y
    return p

def rgb565(p):  return b''.join(struct.pack('<H', (r >> 3) << 11 | (g >> 2) << 5 | b >> 3) for row in p for (r, g, b) in row)
def xrgb8888(p): return b''.join(struct.pack('<I', r << 16 | g << 8 | b) for row in p for (r, g, b) in row)

def png(path, p, s=2):
    def ch(t, b): return struct.pack('>I', len(b)) + t + b + struct.pack('>I', zlib.crc32(t + b) & 0xffffffff)
    rows = []
    for row in p:
        line = b'\0' + b''.join(bytes(c) * s for c in row)
        rows += [line] * s
    open(path, 'wb').write(b'\x89PNG\r\n\x1a\n' + ch(b'IHDR', struct.pack('>IIBBBBB', W * s, H * s, 8, 2, 0, 0, 0))
                           + ch(b'IDAT', zlib.compress(b''.join(rows))) + ch(b'IEND', b''))

frames = {'red': solid(R), 'green': solid(G), 'blue': solid(B), 'white': solid(Wh), 'black': solid(K), 'geo': geo()}
for n, p in frames.items():
    open(f'{O}/{n}.565', 'wb').write(rgb565(p))
    open(f'{O}/{n}.8888', 'wb').write(xrgb8888(p))
png(f'{O}/geo-expected.png', frames['geo'], 3)
print('ok', sorted(os.listdir(O)))