feat: Add Fichero D11s thermal label printer support with REST API and CLI

- Implemented a new module for the Fichero D11s thermal label printer, including BLE and Classic Bluetooth interfaces.
- Created a REST API using FastAPI to manage printer status, info, and printing tasks (text and images).
- Developed a CLI for direct printer interaction, allowing users to print text and images, check status, and modify settings.
- Added image processing capabilities for converting text and images to the required format for printing.
- Introduced error handling for printer operations and connection management.
- Included a shell script for running the API server with configurable parameters.
- Added English translations for configuration options.
- Created a repository metadata file for project management.

fichero_printer/fichero/imaging.py

@@ -0,0 +1,97 @@
+"""Image processing for Fichero D11s thermal label printer."""
+
+import logging
+
+import numpy as np
+from PIL import Image, ImageDraw, ImageFont, ImageOps
+
+from fichero.printer import PRINTHEAD_PX
+
+log = logging.getLogger(__name__)
+
+
+def floyd_steinberg_dither(img: Image.Image) -> Image.Image:
+    """Floyd-Steinberg error-diffusion dithering to 1-bit.
+
+    Same algorithm as PrinterImageProcessor.ditherFloydSteinberg() in the
+    decompiled Fichero APK: distributes quantisation error to neighbouring
+    pixels with weights 7/16, 3/16, 5/16, 1/16.
+    """
+    arr = np.array(img, dtype=np.float32)
+    h, w = arr.shape
+
+    for y in range(h):
+        for x in range(w):
+            old = arr[y, x]
+            new = 0.0 if old < 128 else 255.0
+            arr[y, x] = new
+            err = old - new
+            if x + 1 < w:
+                arr[y, x + 1] += err * 7 / 16
+            if y + 1 < h:
+                if x - 1 >= 0:
+                    arr[y + 1, x - 1] += err * 3 / 16
+                arr[y + 1, x] += err * 5 / 16
+                if x + 1 < w:
+                    arr[y + 1, x + 1] += err * 1 / 16
+
+    arr = np.clip(arr, 0, 255).astype(np.uint8)
+    return Image.fromarray(arr, mode="L")
+
+
+def prepare_image(
+    img: Image.Image, max_rows: int = 240, dither: bool = True
+) -> Image.Image:
+    """Convert any image to 96px wide, 1-bit, black on white.
+
+    When *dither* is True (default), uses Floyd-Steinberg error diffusion
+    for better quality on photos and gradients.  Set False for crisp text.
+    """
+    img = img.convert("L")
+    w, h = img.size
+    new_h = int(h * (PRINTHEAD_PX / w))
+    img = img.resize((PRINTHEAD_PX, new_h), Image.LANCZOS)
+
+    if new_h > max_rows:
+        log.warning("Image height %dpx exceeds max %dpx, cropping bottom", new_h, max_rows)
+        img = img.crop((0, 0, PRINTHEAD_PX, max_rows))
+
+    img = ImageOps.autocontrast(img, cutoff=1)
+
+    if dither:
+        img = floyd_steinberg_dither(img)
+
+    # Pack to 1-bit.  PIL mode "1" tobytes() uses 0-bit=black, 1-bit=white,
+    # but the printer wants 1-bit=black.  Mapping dark->1 via point() inverts
+    # the PIL convention so the final packed bits match what the printer needs.
+    img = img.point(lambda x: 1 if x < 128 else 0, "1")
+    return img
+
+
+def image_to_raster(img: Image.Image) -> bytes:
+    """Pack 1-bit image into raw raster bytes, MSB first."""
+    if img.mode != "1":
+        raise ValueError(f"Expected mode '1', got '{img.mode}'")
+    if img.width != PRINTHEAD_PX:
+        raise ValueError(f"Expected width {PRINTHEAD_PX}, got {img.width}")
+    return img.tobytes()
+
+
+def text_to_image(text: str, font_size: int = 30, label_height: int = 240) -> Image.Image:
+    """Render crisp 1-bit text, rotated 90 degrees for label printing."""
+    canvas_w = label_height
+    canvas_h = PRINTHEAD_PX
+    img = Image.new("L", (canvas_w, canvas_h), 255)
+    draw = ImageDraw.Draw(img)
+    draw.fontmode = "1"  # disable antialiasing - pure 1-bit glyph rendering
+
+    font = ImageFont.load_default(size=font_size)
+
+    bbox = draw.textbbox((0, 0), text, font=font)
+    tw, th = bbox[2] - bbox[0], bbox[3] - bbox[1]
+    x = (canvas_w - tw) // 2 - bbox[0]
+    y = (canvas_h - th) // 2 - bbox[1]
+    draw.text((x, y), text, fill=0, font=font)
+
+    img = img.rotate(90, expand=True)
+    return img