LX-D02 BLE thermal printer: PC, Windows printer, Home Assistant

- printer.py: protocol with flow control (pause / resend / done)
- lxd02.py: print text or pictures from the command line
- windows/: POS-58 driver + local ESC/POS server = a regular Windows printer,
  Explorer menu for pictures
- custom_components/lxd02: Home Assistant integration with a persistent queue

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitignore

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+__pycache__/
+*.log
+*.bin

LICENSE

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+MIT License
+
+Copyright (c) 2026 Alex Cube
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# lx-d02
+
+Печать на Bluetooth-термопринтере **LX-D02** (он же Funny Print, Xiqi, DOLEWA и другие
+бренды) без приложения на смартфоне:
+
+- **как на обычном принтере Windows**: из Блокнота, браузера, Word, из меню «Печать»;
+- **картинки правым кликом** в проводнике, растянутые на всю ширину ленты;
+- **из командной строки**: `python lxd02.py "Привет"`;
+- **из Home Assistant**: действие `lxd02.print_text` с очередью, которая переживает
+  выключенный принтер и перезапуск HA.
+
+Принтер работает только по BLE (Bluetooth Low Energy): USB-порт у него лишь для зарядки,
+и Windows без этого проекта его как принтер не видит.
+
+Протокол разобран в [ValdikSS/printer-driver-funnyprint](https://github.com/ValdikSS/printer-driver-funnyprint),
+управление потоком сделано по образцу [klimromanyuk/funnyprint](https://github.com/klimromanyuk/funnyprint).
+Подробный рассказ, как это сделано: [блог «Доктор Лексиум»](https://www.lexium.ru/).
+
+## Что нужно
+
+- Python 3.9+ и Bluetooth на компьютере.
+- `pip install -r requirements.txt`
+- Принтер включён и **не подключён к телефону**: LX-D02 держит только одно соединение,
+  и пока открыто Funny Print, компьютер его не найдёт.
+
+Проверка: `python lxd02.py "Привет"` должен напечатать строку.
+
+На Python 3.9 bleak 1.x падает при импорте, поэтому в `requirements.txt` стоит `bleak<1.0`.
+На более новом Python ограничение можно снять.
+
+## Печать из командной строки
+
+```
+python lxd02.py "Первая строка" "Вторая строка"
+python lxd02.py фото.jpg скриншот.png
+```
+
+Текст печатается шрифтом DejaVu Sans (кириллица есть). Картинки растягиваются на ширину
+ленты (48 мм, 384 точки), альбомные поворачиваются вдоль ленты, чтобы выйти крупнее,
+полутона передаются растром.
+
+Принтер ищется по имени `LX-D02`. Чтобы не тратить на поиск несколько секунд, задайте MAC:
+`set LXD02_MAC=AA:BB:CC:DD:EE:FF` (MAC покажет любой BLE-сканер, например nRF Connect
+на телефоне).
+
+## Принтер в Windows
+
+Как это устроено: Windows печатает на принтер с драйвером **POS-58** (стандартный драйвер
+58-мм чековых принтеров), драйвер раскладывает страницу на ленту 58 мм и отдаёт её
+командами ESC/POS в порт `127.0.0.1:9100`. Там их принимает `windows/print_server.py`
+и печатает по Bluetooth.
+
+Почему не встроенные драйверы Windows: «Microsoft Print to PDF» знает только офисные
+форматы, и лист A4, ужатый до 48 мм, нечитаем. IPP Class Driver принимает только
+стандартные названия бумаги, самое узкое из которых A6.
+
+### Драйвер
+
+Драйвер POS-58 обычно идёт с любым дешёвым 58-мм чековым принтером, ищите
+«POS-58 driver» на сайте Xprinter или продавца. Проверено с `POS-58 11.2.0.0`
+(Zjiang, `pos58.inf`). Сам принтер POS-58 не нужен, нужен только драйвер.
+
+### Установка
+
+В PowerShell **от имени администратора**:
+
+```powershell
+Set-ExecutionPolicy -Scope Process Bypass
+.\windows\install.ps1
+```
+
+Скрипт:
+
+- добавляет принтер **LX-D02** на драйвере POS-58 и порту `127.0.0.1:9100`;
+- ставит в Планировщик задание «LX-D02 print server» (сервер стартует при входе в систему);
+- добавляет в меню картинок пункт «Print on LX-D02» и ярлык в «Отправить».
+
+Удаление: `.\windows\install.ps1 -Uninstall`. Журнал: `windows\print_server.log`.
+
+### Советы
+
+- **Бумага.** У драйвера по умолчанию лента 3276 мм. Пусть вас не пугает превью: сервер
+  срезает белое сверху и снизу и сжимает пустые промежутки до 6 мм. Для удобного превью
+  выберите в настройках печати размер 58×210.
+- **Поля.** Ставьте поля «Минимальные» (в браузере) или 0 (в редакторах). Левое поле
+  сервер убирает сам, но правое срежет драйвер: печатная полоса 48 мм начинается
+  от левого края листа, а браузер с обычными полями сдвигает текст вправо.
+- **Картинки** лучше печатать правым кликом, а не из браузера или «Фотографий»:
+  те раскладывают картинку по листу, и она выходит мелкой или обрезанной.
+- Странный результат? Последнее задание сохраняется в `windows\last_job.bin`,
+  `python windows\print_server.py --test windows\last_job.bin` покажет его картинкой.
+
+## Home Assistant
+
+Нужен Bluetooth на хосте HA (встроенный адаптер или прокси ESPHome).
+
+Скопируйте `custom_components/lxd02` в `/config/custom_components/`, добавьте
+в `configuration.yaml` и перезапустите HA:
+
+```yaml
+lxd02:
+  mac: AA:BB:CC:DD:EE:FF
+```
+
+Действие:
+
+```yaml
+action: lxd02.print_text
+data:
+  text: "Привет из Home Assistant"
+  size: 28         # размер шрифта, 10..120
+  density: 3       # плотность, 0..7
+  feed: 40         # прогон ленты после текста
+  separator: true  # линия под текстом
+```
+
+Задания попадают в очередь на диске (`/config/.storage/lxd02`). Если принтер выключен,
+вне зоны или занят телефоном, задание ждёт, и очередь печатается, как только HA снова
+увидит принтер. Пока очередь не пуста, HA пробует раз в минуту. Действие не падает,
+если принтера нет: ищите `LX-D02` в журнале HA.
+
+### Пример: чат MeshCore на ленте
+
+Печатает входящие сообщения канала `my_channel` из интеграции MeshCore: отправитель
+и время, ниже текст, под ним черта. Свои исходящие пропускаются: интеграция присылает
+их заново на каждое обновление статуса доставки.
+
+```yaml
+triggers:
+- trigger: event
+  event_type: meshcore_message
+  event_data:
+    message_type: channel
+conditions:
+- condition: template
+  value_template: "{{ trigger.event.data.channel | lower == 'my_channel' and not trigger.event.data.outgoing | default(false) }}"
+actions:
+- action: lxd02.print_text
+  continue_on_error: true
+  data:
+    size: 24
+    separator: true
+    text: "{{ trigger.event.data.sender_name }} · {{ now().strftime('%d.%m %H:%M') }}\n{{ trigger.event.data.message }}"
+mode: queued
+max: 20
+```
+
+### Если Bluetooth на хосте зависает
+
+На ТВ-приставках встроенный чип раз в несколько недель может зависнуть
+(`hci0: Opcode 0x0c03 failed: -110` в `dmesg`, HA пишет `NotReady`). Помогает
+перепривязать чип к драйверу. Пример сторожа на systemd для чипа на UART (`hci_uart_bcm`):
+
+```sh
+#!/bin/sh
+# /usr/local/sbin/bt-watchdog.sh: run every minute by bt-watchdog.timer
+D=/sys/bus/serial/drivers/hci_uart_bcm
+up() { hciconfig hci0 2>/dev/null | grep -q "UP RUNNING"; }
+up && exit 0
+sleep 20  # HA/BlueZ may be resetting the adapter itself
+up && exit 0
+logger -t bt-watchdog "hci0 down, rebinding serial0-0"
+echo serial0-0 > $D/unbind 2>/dev/null
+sleep 2
+echo serial0-0 > $D/bind
+sleep 8
+timeout 5 bluetoothctl power on >/dev/null 2>&1
+```
+
+Имена драйвера и устройства у вас могут отличаться: смотрите `/sys/bus/serial/drivers/`.
+
+## Протокол коротко
+
+| | |
+|---|---|
+| Имя в BLE-рекламе | `LX-D02` |
+| Сервис / запись / уведомления | `FFE6` / `FFE1` / `FFE2` |
+| Ширина печати | 384 точки, 48 байт на строку, по две строки в пакете из 96 байт |
+| Рукопожатие | принтер шлёт вызов `5a0a`, ответ `5a0b` + байт CRC16 от MAC × 10 |
+| Управление потоком | `5a08` пауза (буфер полон), `5a05` + номер строки (дослать с неё), `5a06` готово |
+
+Весь протокол: `custom_components/lxd02/printer.py`, самопроверка `python printer.py`.
+
+## Лицензия
+
+MIT, см. `LICENSE`.

custom_components/lxd02/__init__.py

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+"""LX-D02 thermal printer: service lxd02.print_text.
+
+Jobs go to a persistent queue (.storage/lxd02). If the printer is off, they wait
+and print when it shows up in Bluetooth again.
+
+configuration.yaml:
+    lxd02:
+      mac: AA:BB:CC:DD:EE:FF
+"""
+import asyncio
+from datetime import timedelta
+import logging
+
+from bleak.exc import BleakError
+import voluptuous as vol
+from bleak_retry_connector import BleakClientWithServiceCache, establish_connection
+
+from homeassistant.components import bluetooth
+from homeassistant.core import HomeAssistant, ServiceCall, callback
+from homeassistant.exceptions import HomeAssistantError
+import homeassistant.helpers.config_validation as cv
+from homeassistant.helpers.event import async_track_time_interval
+from homeassistant.helpers.storage import Store
+
+from .printer import print_payloads, render, to_payloads
+
+DOMAIN = "lxd02"
+_LOGGER = logging.getLogger(__name__)
+RETRY = timedelta(seconds=60)
+
+CONFIG_SCHEMA = vol.Schema(
+    {DOMAIN: vol.Schema({vol.Required("mac"): cv.string})}, extra=vol.ALLOW_EXTRA
+)
+
+PRINT_SCHEMA = vol.Schema(
+    {
+        vol.Required("text"): cv.string,
+        vol.Optional("size", default=28): vol.All(vol.Coerce(int), vol.Range(min=10, max=120)),
+        vol.Optional("density", default=3): vol.All(vol.Coerce(int), vol.Range(min=0, max=7)),
+        vol.Optional("feed", default=40): vol.All(vol.Coerce(int), vol.Range(min=0, max=500)),
+        vol.Optional("separator", default=False): cv.boolean,
+    }
+)
+
+
+async def async_setup(hass: HomeAssistant, config) -> bool:
+    mac = config[DOMAIN]["mac"].upper()
+    lock = asyncio.Lock()
+    store = Store(hass, 1, DOMAIN)
+    queue = await store.async_load() or []
+
+    async def print_job(device, job):
+        img = await hass.async_add_executor_job(
+            render, job["text"], job["size"], job["separator"]
+        )
+        payloads = to_payloads(img)
+        try:
+            client = await establish_connection(BleakClientWithServiceCache, device, "LX-D02")
+        except BleakError as err:
+            raise HomeAssistantError(f"LX-D02 connect failed: {err!r}") from err
+        try:
+            await print_payloads(client, mac, payloads, job["density"], job["feed"])
+        except (asyncio.TimeoutError, RuntimeError, BleakError) as err:
+            raise HomeAssistantError(f"LX-D02 print failed: {err!r}") from err
+        finally:
+            await client.disconnect()
+
+    async def flush():
+        async with lock:
+            while queue:
+                device = bluetooth.async_ble_device_from_address(hass, mac, connectable=True)
+                if device is None:
+                    _LOGGER.info("LX-D02 not in range, %d job(s) queued", len(queue))
+                    return
+                try:
+                    await print_job(device, queue[0])
+                except HomeAssistantError as err:
+                    _LOGGER.warning("%s; %d job(s) stay queued", err, len(queue))
+                    return
+                except Exception:  # bad job (render etc.): drop it, don't block the queue
+                    _LOGGER.exception("LX-D02 job dropped: %r", queue[0])
+                queue.pop(0)
+                await store.async_save(queue)
+
+    async def print_text(call: ServiceCall) -> None:
+        queue.append(dict(call.data))
+        await store.async_save(queue)
+        await flush()
+
+    @callback
+    def seen(service_info, change) -> None:
+        if queue and not lock.locked():
+            hass.async_create_task(flush())
+
+    # HA calls `seen` only when the advert changes or the printer comes back after
+    # being marked unavailable, not on every packet. So a failed attempt (or a replay
+    # of stale history right after HA restart) is never retried by adverts alone:
+    # the timer retries while the queue is not empty.
+    async_track_time_interval(hass, callback(lambda _: seen(None, None)), RETRY)
+    bluetooth.async_register_callback(
+        hass,
+        seen,
+        bluetooth.BluetoothCallbackMatcher(address=mac, connectable=True),
+        bluetooth.BluetoothScanningMode.ACTIVE,
+    )
+    hass.services.async_register(DOMAIN, "print_text", print_text, schema=PRINT_SCHEMA)
+    return True

custom_components/lxd02/manifest.json

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+{
+  "domain": "lxd02",
+  "name": "LX-D02 Thermal Printer",
+  "version": "0.2.0",
+  "documentation": "https://git.08h.ru/alex/lx-d02",
+  "dependencies": ["bluetooth"],
+  "requirements": [],
+  "codeowners": [],
+  "iot_class": "local_push"
+}

custom_components/lxd02/printer.py

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+"""LX-D02 (FunnyPrint) protocol. No Home Assistant imports: also used by ../../lxd02.py.
+
+Protocol from github.com/ValdikSS/printer-driver-funnyprint.
+"""
+import asyncio
+from pathlib import Path
+
+from PIL import Image, ImageDraw, ImageFont
+
+WRITE = "0000ffe1-0000-1000-8000-00805f9b34fb"
+NOTIFY = "0000ffe2-0000-1000-8000-00805f9b34fb"
+WIDTH = 384  # dots, 48 bytes per row
+FONT = Path(__file__).with_name("DejaVuSans.ttf")
+
+
+def crc16(data):
+    crc = 0
+    for b in data:
+        for i in range(8):
+            if ((crc >> 15) & 1) ^ ((b >> (7 - i)) & 1):
+                crc = ((crc << 1) & 0xFFFF) ^ 0x1021
+            else:
+                crc = (crc << 1) & 0xFFFF
+    return crc
+
+
+def handshake_reply(mac):
+    r = crc16(b"\x00" + bytes.fromhex(mac.replace(":", ""))) >> 8
+    return b"\x5a\x0b" + bytes([r]) * 10
+
+
+def wrap(text, font, width):
+    out = []
+    for para in text.split("\n"):
+        line = ""
+        for word in para.split(" "):
+            cand = f"{line} {word}" if line else word
+            if line and font.getlength(cand) > width:
+                out.append(line)
+                line = word
+            else:
+                line = cand
+        out.append(line)
+    return out
+
+
+def render(text, size=28, separator=False):
+    font = ImageFont.truetype(str(FONT), size)
+    lines = wrap(text, font, WIDTH - 8)
+    text_h = (size + 6) * len(lines) + 4
+    h = text_h + (16 if separator else 0)
+    img = Image.new("1", (WIDTH, h + h % 2), 1)
+    d = ImageDraw.Draw(img)
+    for i, line in enumerate(lines):
+        d.text((4, 2 + i * (size + 6)), line, font=font, fill=0)
+    if separator:
+        d.rectangle((0, text_h + 6, WIDTH - 1, text_h + 9), fill=0)
+    return img
+
+
+def to_payloads(img):
+    """1-bit image, WIDTH wide -> 96-byte payloads, two rows each, 1 = black."""
+    if img.height % 2:
+        img = img.crop((0, 0, WIDTH, img.height + 1))  # pads with 0 = black
+        img.paste(1, (0, img.height - 1, WIDTH, img.height))
+    raw = bytes(b ^ 0xFF for b in img.tobytes())
+    rows = [raw[i:i + 48] for i in range(0, len(raw), 48)]
+    return [rows[i] + rows[i + 1] for i in range(0, len(rows), 2)]
+
+
+async def print_payloads(client, mac, payloads, density=3, feed=40):
+    """Handshake and print on an already connected BleakClient."""
+    payloads = payloads + [bytes(96)] * feed
+    events = asyncio.Queue()
+
+    def w(data):
+        return client.write_gatt_char(WRITE, data, response=False)
+
+    async def wait_for(prefix, timeout=5):
+        while True:
+            data = await asyncio.wait_for(events.get(), timeout)
+            if data[:2] == prefix:
+                return data
+
+    await client.start_notify(NOTIFY, lambda _, data: events.put_nowait(bytes(data)))
+    await w(b"\x5a\x01" + bytes(10))  # device info
+    await asyncio.sleep(0.5)
+    await w(b"\x5a\x0a" + bytes(10))  # challenge
+    await wait_for(b"\x5a\x0a")
+    await w(handshake_reply(mac))
+    if (await wait_for(b"\x5a\x0b"))[2] != 1:
+        raise RuntimeError("LX-D02 handshake failed")
+
+    await w(b"\x5a\x0c" + bytes([max(0, min(7, density))]))
+    await asyncio.sleep(0.3)
+    n = len(payloads)
+    await w(b"\x5a\x04" + n.to_bytes(2, "big") + b"\x00\x00")
+    await asyncio.sleep(0.1)
+
+    # Flow control as in klimromanyuk/funnyprint: the printer's buffer is small.
+    # 5a08 = "pause, buffer full"; 5a05 + row number = "lost rows, resend from here";
+    # 5a06 = "done". Without this, long prints (pictures) come out cut short.
+    cur, paused, rests = 0, False, 0
+    try:
+        while True:
+            if paused or cur >= n:
+                data = await asyncio.wait_for(events.get(), 90 if paused else max(60, n * 0.5))
+            elif not events.empty():
+                data = events.get_nowait()
+            else:
+                await w(b"\x55" + cur.to_bytes(2, "big") + payloads[cur] + b"\x00")
+                cur += 1
+                await asyncio.sleep(0.025)
+                continue
+            kind = data[:2]
+            if kind == b"\x5a\x06":
+                return
+            if kind == b"\x5a\x08":
+                paused = True
+            elif kind == b"\x5a\x05":
+                lost = int.from_bytes(data[2:4], "big")
+                if paused:  # let the printer print out its buffer, then resend
+                    rests += 1
+                    await asyncio.sleep(min(8.0, 2.0 + rests * 0.5))
+                    while not events.empty():
+                        more = events.get_nowait()
+                        if more[:2] == b"\x5a\x06":
+                            return
+                        if more[:2] == b"\x5a\x05":
+                            lost = int.from_bytes(more[2:4], "big")
+                    paused = False
+                cur = lost
+    finally:
+        await w(b"\x5a\x04" + n.to_bytes(2, "big") + b"\x01\x00")
+
+
+if __name__ == "__main__":
+    assert handshake_reply("00:00:00:00:00:00") == b"\x5a\x0b" + bytes(10)
+    assert to_payloads(Image.new("1", (WIDTH, 2), 0)) == [b"\xff" * 96]
+    assert to_payloads(Image.new("1", (WIDTH, 1), 0)) == [b"\xff" * 48 + bytes(48)]
+    assert render("x", separator=True).height == render("x").height + 16
+    assert len(wrap("a " * 200, ImageFont.truetype(str(FONT), 28), WIDTH)) > 1
+    print("ok")

custom_components/lxd02/services.yaml

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+print_text:
+  name: Print text
+  description: Print text on the LX-D02 thermal printer.
+  fields:
+    text:
+      name: Text
+      required: true
+      example: "Temperature: 21.5 °C"
+      selector:
+        text:
+          multiline: true
+    size:
+      name: Font size
+      default: 28
+      selector:
+        number:
+          min: 10
+          max: 120
+    density:
+      name: Density
+      default: 3
+      selector:
+        number:
+          min: 0
+          max: 7
+    separator:
+      name: Separator line
+      description: Draw a horizontal line under the text.
+      default: false
+      selector:
+        boolean:
+    feed:
+      name: Feed after (rows of 2 dots)
+      default: 40
+      selector:
+        number:
+          min: 0
+          max: 500

lxd02.py

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+"""Print on the LX-D02 thermal printer from the PC.
+
+Usage: python lxd02.py "text" [more lines...]
+       python lxd02.py picture.jpg [more pictures...]   (stretched to the tape width)
+Set LXD02_MAC=AA:BB:CC:DD:EE:FF to skip the Bluetooth search.
+"""
+import asyncio
+import os
+import sys
+from pathlib import Path
+
+from bleak import BleakClient, BleakScanner
+from PIL import Image, ImageOps
+
+sys.path.insert(0, str(Path(__file__).resolve().parent / "custom_components" / "lxd02"))
+from printer import WIDTH, print_payloads, render, to_payloads  # noqa: E402
+
+PICTURES = {".jpg", ".jpeg", ".png", ".bmp", ".gif", ".webp", ".tif", ".tiff"}
+
+
+def picture(path):
+    """Any picture -> 1-bit image WIDTH wide. Landscape ones are turned to run
+    along the tape, so they come out bigger."""
+    img = ImageOps.exif_transpose(Image.open(path)).convert("RGBA")
+    white = Image.new("RGBA", img.size, "white")
+    img = Image.alpha_composite(white, img).convert("L")  # transparent -> white, not black
+    if img.width > img.height:
+        img = img.rotate(90, expand=True)
+    img = img.resize((WIDTH, max(2, round(img.height * WIDTH / img.width))), Image.LANCZOS)
+    return ImageOps.autocontrast(img, cutoff=1).convert("1")  # dithering for halftones
+
+
+async def send(img, mac=None):
+    mac = mac or os.environ.get("LXD02_MAC")
+    if not mac:
+        device = await BleakScanner.find_device_by_name("LX-D02", timeout=20)
+        if device is None:
+            raise RuntimeError("LX-D02 not found: is it on and not connected to a phone?")
+        mac = device.address
+    for attempt in range(3):  # Windows often fails the first connect to a sleeping printer
+        try:
+            client = BleakClient(mac, timeout=20)
+            await client.connect()
+            break
+        except Exception:
+            if attempt == 2:
+                raise
+            await asyncio.sleep(2)
+    try:
+        await print_payloads(client, mac, to_payloads(img))
+    finally:
+        await client.disconnect()
+
+
+def main(args):
+    if args and all(Path(a).suffix.lower() in PICTURES and Path(a).is_file() for a in args):
+        for a in args:
+            print("printing", a)
+            asyncio.run(send(picture(a)))
+    else:
+        asyncio.run(send(render("\n".join(args) or "Hello, LX-D02!\nПривет с ПК")))
+    print("ok")
+
+
+if __name__ == "__main__":
+    try:
+        main(sys.argv[1:])
+    except Exception as err:  # started from "Send to": keep the window open to show why
+        print("ERROR:", err)
+        if sys.stdin and sys.stdin.isatty():
+            input("Press Enter to close")
+        sys.exit(1)

requirements.txt

@@ -0,0 +1,2 @@
+bleak<1.0
+pillow

windows/install.ps1

@@ -0,0 +1,60 @@
+# Adds the "LX-D02" printer to Windows, starts print_server.py at every logon and adds
+# "Print on LX-D02" for pictures to the Explorer menu and to "Send to".
+# Needs the POS-58 driver (stock driver for 58 mm receipt printers), see README.
+#
+# Run in PowerShell as administrator:   .\install.ps1            (printer found by name)
+#                                      .\install.ps1 AA:BB:CC:DD:EE:FF
+# Remove: .\install.ps1 -Uninstall
+param([string]$Mac = "", [switch]$Uninstall)
+$ErrorActionPreference = "Stop"
+$Name = "LX-D02"
+$Port = "LX-D02-9100"
+$Task = "LX-D02 print server"
+$Root = Split-Path $PSScriptRoot
+$Menu = "HKCU:\Software\Classes\SystemFileAssociations\image\shell\LXD02"
+$SendTo = Join-Path ([Environment]::GetFolderPath("SendTo")) "LX-D02.lnk"
+
+# Clean up first, so running it again simply reinstalls
+Stop-ScheduledTask -TaskName $Task -ErrorAction SilentlyContinue
+Unregister-ScheduledTask -TaskName $Task -Confirm:$false -ErrorAction SilentlyContinue
+Get-CimInstance Win32_Process -Filter "Name like 'python%.exe'" |
+    Where-Object { $_.CommandLine -like "*print_server.py*" } |
+    ForEach-Object { Stop-Process -Id $_.ProcessId -Force }
+Remove-Printer -Name $Name -ErrorAction SilentlyContinue
+Remove-PrinterPort -Name $Port -ErrorAction SilentlyContinue
+Remove-Item $Menu -Recurse -ErrorAction SilentlyContinue
+Remove-Item $SendTo -ErrorAction SilentlyContinue
+if ($Uninstall) { "Removed."; return }
+
+$driver = Get-PrinterDriver | Where-Object Name -like "POS-58*" | Select-Object -First 1
+if (-not $driver) { throw "POS-58 driver is not installed. See README: 'Driver'." }
+$py = (Get-Command python.exe).Source
+$pyw = (Get-Command pythonw.exe).Source
+
+# The printer: the POS-58 driver sends ESC/POS to our server instead of a COM port
+Add-PrinterPort -Name $Port -PrinterHostAddress 127.0.0.1 -PortNumber 9100
+Add-Printer -Name $Name -DriverName $driver.Name -PortName $Port
+
+# The server, started at logon
+$action = New-ScheduledTaskAction -Execute $pyw -Argument "`"$PSScriptRoot\print_server.py`" $Mac" -WorkingDirectory $PSScriptRoot
+$trigger = New-ScheduledTaskTrigger -AtLogOn -User $env:USERNAME
+$settings = New-ScheduledTaskSettingsSet -ExecutionTimeLimit 0 -AllowStartIfOnBatteries -DontStopIfGoingOnBatteries
+Register-ScheduledTask -TaskName $Task -Action $action -Trigger $trigger -Settings $settings -Force | Out-Null
+Start-ScheduledTask -TaskName $Task
+
+# Pictures: right click -> "Print on LX-D02", or several at once via "Send to"
+$cmd = "`"$py`" `"$Root\lxd02.py`""
+New-Item -Path "$Menu\command" -Force | Out-Null
+Set-ItemProperty -Path $Menu -Name "(default)" -Value "Print on LX-D02"
+Set-ItemProperty -Path $Menu -Name "Icon" -Value "$env:SystemRoot\System32\imageres.dll,46"
+Set-ItemProperty -Path $Menu -Name "MultiSelectModel" -Value "Single"  # one Bluetooth connection at a time
+Set-ItemProperty -Path "$Menu\command" -Name "(default)" -Value "$cmd `"%1`""
+$link = (New-Object -ComObject WScript.Shell).CreateShortcut($SendTo)
+$link.TargetPath = $py
+$link.Arguments = "`"$Root\lxd02.py`""
+$link.WorkingDirectory = $Root
+$link.IconLocation = "$env:SystemRoot\System32\imageres.dll,46"
+$link.Save()
+
+"Done: printer '$Name' (driver '$($driver.Name)'), print server, Explorer menu."
+"Log: $PSScriptRoot\print_server.log"

windows/print_server.py

@@ -0,0 +1,123 @@
+"""LX-D02 as a regular Windows printer.
+
+Windows prints to the "LX-D02" printer: the stock POS-58 driver for 58 mm receipt
+printers, on a TCP port 127.0.0.1:9100 (see install.ps1). The driver turns the page into
+ESC/POS raster; this server takes it from the port and prints it over Bluetooth.
+
+Usage: python print_server.py [MAC]       (without MAC the printer is found by name)
+       python print_server.py --test FILE  (saved job -> FILE.png, no printing)
+       python print_server.py --selftest
+"""
+import asyncio
+import logging
+import queue
+import socketserver
+import sys
+import threading
+from pathlib import Path
+
+from PIL import Image, ImageOps
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+from lxd02 import WIDTH, send  # noqa: E402
+
+PORT = 9100
+MAX_GAP = 48  # dots: longer white gaps are cut down to this (6 mm)
+LAST_JOB = Path(__file__).with_name("last_job.bin")
+log = logging.getLogger("lx-d02")
+
+
+def render(data):
+    """ESC/POS from the POS-58 driver -> 1-bit image WIDTH wide, ready to print.
+
+    The driver sends the page as GS v 0 raster bands. Its ESC J feeds between the bands
+    only move the paper by the band height, so the bands are just stacked."""
+    rows, pos = [], 0
+    while True:
+        pos = data.find(b"\x1dv0", pos)
+        if pos < 0 or pos + 8 > len(data):
+            break
+        w = data[pos + 4] | data[pos + 5] << 8
+        h = data[pos + 6] | data[pos + 7] << 8
+        band = data[pos + 8:pos + 8 + w * h]
+        rows += [band[r * w:(r + 1) * w].ljust(WIDTH // 8, b"\0")[:WIDTH // 8] for r in range(h)]
+        pos += 8 + w * h
+    if not rows:
+        raise ValueError(f"no ESC/POS raster in the job: {data[:16]!r} (is the driver POS-58?)")
+    img = ImageOps.invert(Image.frombytes("1", (WIDTH, len(rows)), b"".join(rows)).convert("L"))
+    box = ImageOps.invert(img).getbbox()
+    if not box:
+        raise ValueError("blank page")
+    # Apps keep their page margins: drop the left one and the white above and below
+    shift = max(0, box[0] - 4)
+    img = img.crop((shift, max(0, box[1] - 4), WIDTH + shift, min(img.height, box[3] + 4)))
+    img.paste(255, (WIDTH - shift, 0, WIDTH, img.height))  # the crop past the right edge is black
+    return squeeze(img).convert("1")
+
+
+def squeeze(img, gap=MAX_GAP):
+    """Shorten white gaps longer than `gap` rows: page layouts put the footer a whole
+    page below the text, and the tape is not a page."""
+    raw = img.tobytes()
+    keep, blank = [], 0
+    for y in range(img.height):
+        row = raw[y * img.width:(y + 1) * img.width]
+        blank = blank + 1 if min(row) == 255 else 0
+        if blank <= gap:
+            keep.append(row)
+    return Image.frombytes("L", (img.width, len(keep)), b"".join(keep))
+
+
+class Job(socketserver.BaseRequestHandler):
+    jobs = queue.Queue()
+
+    def handle(self):
+        chunks = []
+        while True:
+            chunk = self.request.recv(65536)
+            if not chunk:
+                break
+            chunks.append(chunk)
+        if chunks:  # an empty connection is Windows checking the port
+            self.jobs.put(b"".join(chunks))
+
+
+def printer_loop(mac):
+    """One job at a time: the printer takes a single Bluetooth connection."""
+    while True:
+        data = Job.jobs.get()
+        LAST_JOB.write_bytes(data)  # for debugging a strange print: --test last_job.bin
+        try:
+            img = render(data)
+            log.info("job: %d bytes, %d dots long", len(data), img.height)
+            asyncio.run(send(img, mac))
+            log.info("printed")
+        except Exception:
+            log.exception("job failed")
+
+
+def main(mac):
+    threading.Thread(target=printer_loop, args=(mac,), daemon=True).start()
+    server = socketserver.ThreadingTCPServer(("127.0.0.1", PORT), Job)
+    log.info("waiting for jobs on 127.0.0.1:%d", PORT)
+    server.serve_forever()
+
+
+if __name__ == "__main__":
+    handlers = [logging.FileHandler(Path(__file__).with_name("print_server.log"), encoding="utf-8")]
+    if sys.stderr:  # None under pythonw
+        handlers.append(logging.StreamHandler())
+    logging.basicConfig(level=logging.INFO, format="%(asctime)s %(message)s", handlers=handlers)
+    if sys.argv[1:2] == ["--selftest"]:
+        # one blank row, then one row with a single dot at x = 7: comes out shifted left
+        job = b"\x1b@\x1dv0\x00" + bytes([48, 0, 2, 0]) + bytes(48) + b"\x01" + bytes(47) + b"\x1bJ\x15"
+        img = render(job)
+        assert img.width == WIDTH and img.getpixel((4, 1)) == 0 and img.getpixel((7, 1)) == 255
+        assert squeeze(Image.new("L", (8, 100), 255), 10).height == 10
+        print("ok")
+    elif sys.argv[1:2] == ["--test"]:
+        src = Path(sys.argv[2])
+        render(src.read_bytes()).save(src.with_suffix(".png"))
+        print("ok", src.with_suffix(".png"))
+    else:
+        main(sys.argv[1] if len(sys.argv) > 1 else None)