Print lamp ID labels on the Brother QL-820NWB

label_printer.py renders a DK-11221 23x23 mm label (QR code linking to the lamp's buildfor.life page plus the ID) and sends it over the network backend (brother-ql-next). The station prints two after each successful measurement, one for the box and one for the lamp; printer failures never lose a run, and any lamp can be reprinted with uv run label_printer.py <ID>. Printer address via HPCS_LABEL_PRINTER or --printer.
2026-07-09 18:15:01 +07:00
parent 7ef2960254
commit 719ddcf04a
4 changed files with 141 additions and 1 deletions
@@ -0,0 +1,109 @@
+"""
+Lamp ID labels on the Brother QL-820NWB (DK-11221, 23x23 mm die-cut).
+
+Each label carries a QR code linking to the lamp's page on buildfor.life and
+the lamp ID as text. The station prints two per lamp: one for the box, one
+for the lamp itself.
+
+Printer address comes from --printer or the HPCS_LABEL_PRINTER environment
+variable, e.g. tcp://192.168.1.50 (the QL-820NWB listens on port 9100).
+
+Usage:
+    uv run label_printer.py L0006                     # print 2 labels
+    uv run label_printer.py L0006 --copies 1
+    uv run label_printer.py L0006 --preview out.png   # render only, no printer
+"""
+
+import argparse
+import os
+import sys
+
+import qrcode
+from PIL import Image, ImageDraw, ImageFont
+
+LABEL_ID = "23x23"  # DK-11221
+DOTS = (202, 202)  # printable area of the 23x23 label
+MODEL = "QL-820NWB"
+URL_BASE = "https://buildfor.life/comparisons/lamps/"
+TEXT_HEIGHT = 52  # bottom strip for the ID text
+
+
+def _font(size):
+    for name in ("arialbd.ttf", "arial.ttf", "DejaVuSans-Bold.ttf"):
+        try:
+            return ImageFont.truetype(name, size)
+        except OSError:
+            continue
+    return ImageFont.load_default(size)
+
+
+def render_label(lamp_id: str) -> Image.Image:
+    """202x202 1-bit label: QR to the lamp page on top, ID text below."""
+    image = Image.new("1", DOTS, 1)
+
+    qr = qrcode.QRCode(
+        error_correction=qrcode.constants.ERROR_CORRECT_M,
+        box_size=1,
+        border=2,  # quiet zone; tight but fine for close-range scanning
+    )
+    qr.add_data(f"{URL_BASE}{lamp_id.lower()}/")
+    qr.make(fit=True)
+    modules = len(qr.get_matrix())
+    qr_size = DOTS[1] - TEXT_HEIGHT
+    qr.box_size = max(1, qr_size // modules)
+    qr_img = qr.make_image().get_image().convert("1")
+    image.paste(qr_img, ((DOTS[0] - qr_img.width) // 2, (qr_size - qr_img.height) // 2))
+
+    draw = ImageDraw.Draw(image)
+    size = 44
+    while size > 10:
+        font = _font(size)
+        box = draw.textbbox((0, 0), lamp_id, font=font)
+        if box[2] - box[0] <= DOTS[0] - 8:
+            break
+        size -= 2
+    draw.text(
+        ((DOTS[0] - (box[2] - box[0])) // 2 - box[0], DOTS[1] - TEXT_HEIGHT + (TEXT_HEIGHT - (box[3] - box[1])) // 2 - box[1]),
+        lamp_id,
+        font=font,
+        fill=0,
+    )
+    return image
+
+
+def print_labels(lamp_id: str, printer: str, copies: int = 2) -> None:
+    """Render and send `copies` labels to the QL-820NWB."""
+    from brother_ql.backends.helpers import send
+    from brother_ql.conversion import convert
+    from brother_ql.raster import BrotherQLRaster
+
+    image = render_label(lamp_id)
+    raster = BrotherQLRaster(MODEL)
+    instructions = convert(qlr=raster, images=[image] * copies, label=LABEL_ID, cut=True)
+    send(instructions=instructions, printer_identifier=printer, backend_identifier="network", blocking=True)
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Print lamp ID labels (QR + ID)")
+    parser.add_argument("lamp_id", help="e.g. L0006")
+    parser.add_argument("--printer", default=os.environ.get("HPCS_LABEL_PRINTER", ""),
+                        help="tcp://<ip> of the QL-820NWB (default: HPCS_LABEL_PRINTER env)")
+    parser.add_argument("--copies", type=int, default=2)
+    parser.add_argument("--preview", metavar="PNG",
+                        help="Write the rendered label to a PNG instead of printing")
+    args = parser.parse_args()
+
+    lamp_id = args.lamp_id.upper()
+    if args.preview:
+        render_label(lamp_id).save(args.preview)
+        print(f"Wrote {args.preview}")
+        return
+    if not args.printer:
+        print("ERROR: no printer configured. Pass --printer tcp://<ip> or set HPCS_LABEL_PRINTER.")
+        sys.exit(1)
+    print_labels(lamp_id, args.printer, args.copies)
+    print(f"Printed {args.copies} label(s) for {lamp_id} on {args.printer}")
+
+
+if __name__ == "__main__":
+    main()