ohbrother 0.1.1

Rootless Brother QL-800 label printing without proprietary software

ohbrother

Brother QL-800 label printing on Linux without proprietary software.

Requires Python 3.11+. Dependencies: pyusb for USB I/O, Pillow for image handling. Rasterization is implemented in-house.

Background

The QL-800 presents as USB class 8 (Mass Storage / BOT) in all modes, including printer mode. The standard brother_ql pyusb backend only scans for class-7 devices and never finds it. This library talks directly to the bulk endpoints and handles two QL-800-specific quirks:

• Mid-stream status response. The raster stream embeds ESC i S; the printer sends a 32-byte response mid-write. Not draining it before the next status read returns stale data.
• Zero-length packets. The IN endpoint sends ZLPs when idle instead of timing out.

Installation

pip install ohbrother
sudo ohbrother-install-udev

Reconnect the printer after installing the udev rules.

Editor Lite mode

If the printer enumerates as PID 0x209e, it is in Editor Lite (virtual disk) mode. Hold the Editor Lite button until the green LED turns off, then reconnect. It re-enumerates as 0x209b. ohbrother raises EditorLiteModeError on 0x209e.

Usage

ohbrother detect
ohbrother status
ohbrother list-labels                              # shows pixel dimensions too

# Endless tape
ohbrother print "Hello World"
ohbrother print --label 29 "narrow 29mm label"

# Die-cut labels — image is sized to exact label dimensions
ohbrother print --label 29x90 "Jane Smith\n123 Main St\nSpringfield IL"
ohbrother print --label 62x100 --image shipping.png

# Two-color tape (DK-22251)
ohbrother print --label 62red --red "black text"
ohbrother print --label 62red --red --text-color red "red text"

# Utilities
ohbrother cut                                      # feed and cut without printing
ohbrother print --dry-run "test"

Python API

from ohbrother import Printer, PrintOptions, render_for_label, label_dims

# Endless tape, black text
opts = PrintOptions(label="62")
with Printer("usb://0x04f9:0x209b", opts) as p:
    img = render_for_label("Hello World", "62")
    p.print_images([img])

# Die-cut label (29x90mm standard address label)
# render_for_label sizes the canvas to exactly (306, 991)px as required
opts = PrintOptions(label="29x90")
with Printer("usb://0x04f9:0x209b", opts) as p:
    img = render_for_label("Jane Smith\n123 Main St", "29x90", font_size=50)
    p.print_images([img])

# Two-color tape — red text
opts = PrintOptions(label="62red", red=True)
with Printer("usb://0x04f9:0x209b", opts) as p:
    img = render_for_label("URGENT", "62red", text_color=(255, 0, 0), font_size=140)
    p.print_images([img])

# Feed and cut without printing
with Printer("usb://0x04f9:0x209b", opts) as p:
    p.cut()

# Recover from a stuck state
with Printer("usb://0x04f9:0x209b") as p:
    p.reset()

Auto-detect the first available printer:

from ohbrother.detect import discover

identifier = next(d["identifier"] for d in discover() if d["usable"])

Die-cut labels

Die-cut labels require the image to be exactly (width_px, height_px) — any mismatch raises a ValueError. render_for_label() handles this automatically. If you construct images manually, use label_dims(label_id) to get the required pixel dimensions.

Two-color tape (DK-22251)

Always use label="62red" and red=True, even for black-only prints. Single-color mode against two-color tape produces a generic error with no error bits; validate_preflight() catches this before the write and raises TapeMismatchError.

Red vs black separation uses HSV: hue < 40 or > 210, saturation > 100, value > 80. (255, 0, 0) renders as red ink; (0, 0, 0) renders as black. Both can appear in the same image.

License

MIT