morse_print.py

#!/usr/bin/env python3
"""Print a message in Morse code on the S01 thermal printer.

Encodes text into graphical dots and dashes (laid out with proper letter/word
spacing) and prints an A-Z reference key underneath.

Examples:
    python morse_print.py                       # a random phrase
    python morse_print.py --text "HELLO WORLD"
    python morse_print.py --no-print
"""
from __future__ import annotations

import argparse
from pathlib import Path
import random

from PIL import Image, ImageDraw

from print_common import ROOT, Card

MORSE = {
    "A": ".-", "B": "-...", "C": "-.-.", "D": "-..", "E": ".", "F": "..-.",
    "G": "--.", "H": "....", "I": "..", "J": ".---", "K": "-.-", "L": ".-..",
    "M": "--", "N": "-.", "O": "---", "P": ".--.", "Q": "--.-", "R": ".-.",
    "S": "...", "T": "-", "U": "..-", "V": "...-", "W": ".--", "X": "-..-",
    "Y": "-.--", "Z": "--..", "0": "-----", "1": ".----", "2": "..---",
    "3": "...--", "4": "....-", "5": ".....", "6": "-....", "7": "--...",
    "8": "---..", "9": "----.", ".": ".-.-.-", ",": "--..--", "?": "..--..",
    "!": "-.-.--", "/": "-..-.", "'": ".----.",
}
PHRASES = ["HELLO WORLD", "STAY CURIOUS", "WHAT HATH GOD WROUGHT", "KEEP IT SIMPLE",
           "SOS", "HELLO FROM THE PRINTER", "NICE WORK", "TO THE STARS", "GOOD LUCK"]

H = 9            # symbol height unit (px)
INTRA = H        # gap between symbols in a letter
LETTER_GAP = 3 * H
WORD_GAP = 6 * H
LINE_H = round(H * 2.4)


def letter_width(code: str) -> int:
    w = sum((H if s == "." else 3 * H) for s in code)
    return w + INTRA * (len(code) - 1)


def render_morse(text: str, width: int) -> Image.Image:
    words = text.upper().split()
    rows: list[list] = [[]]  # each row: list of (kind, code) where kind='L'
    x = 0
    for wi, word in enumerate(words):
        letters = [(c, MORSE[c]) for c in word if c in MORSE]
        wpx = sum(letter_width(code) for _, code in letters) + LETTER_GAP * (len(letters) - 1)
        gap = WORD_GAP if rows[-1] else 0
        if x + gap + wpx > width and rows[-1]:
            rows.append([])
            x = 0
            gap = 0
        x += gap
        for li, (ch, code) in enumerate(letters):
            lw = letter_width(code)
            if x + lw > width and rows[-1]:
                rows.append([])
                x = 0
            rows[-1].append((x, code))
            x += lw + LETTER_GAP
    h = len(rows) * LINE_H
    img = Image.new("L", (width, h + 4), 255)
    d = ImageDraw.Draw(img)
    for ri, row in enumerate(rows):
        y = ri * LINE_H + 2
        for start_x, code in row:
            cx = start_x
            for s in code:
                if s == ".":
                    d.ellipse((cx, y, cx + H, y + H), fill=0)
                    cx += H + INTRA
                else:
                    d.rounded_rectangle((cx, y, cx + 3 * H, y + H), radius=H // 2, fill=0)
                    cx += 3 * H + INTRA
    return img


def main() -> int:
    parser = argparse.ArgumentParser(description="Print a message in Morse code on the S01 thermal printer.")
    parser.add_argument("--text", default=None, help="Message to encode (default: random phrase).")
    parser.add_argument("--no-key", action="store_true", help="Skip the A-Z reference key.")
    parser.add_argument("--out", type=Path, default=ROOT / "morse.png")
    parser.add_argument("--darkness", type=int, choices=range(1, 6), default=3)
    parser.add_argument("--bottom-feed", type=int, default=24)
    parser.add_argument("--no-print", action="store_true")
    args = parser.parse_args()

    text = args.text or random.choice(PHRASES)
    print(f"Encoding: {text}")

    card = Card()
    card.title("MORSE CODE")
    card.para(text.upper(), size=17, bold=True, center=True)
    card.gap(6).image(render_morse(text, card.inner_w), border=False)
    if not args.no_key:
        card.gap(6).divider().line("KEY", size=13, bold=True, center=True)
        letters = [(c, MORSE[c]) for c in "ABCDEFGHIJKLMNOPQRSTUVWXYZ"]
        width = 13
        for i in range(0, len(letters), 3):
            row = "".join(f"{c} {code}".ljust(width) for c, code in letters[i:i + 3])
            card.line(row.rstrip(), size=13, bold=False)
    card.footer("morse code", "- . -")
    return card.finish(args.out, args.bottom_feed, args.darkness, do_print=not args.no_print)


if __name__ == "__main__":
    raise SystemExit(main())