New three-column label format for Brother P-touch EDGE PT-E560BT asset tags:
logo | three static lines + variable field | QR code.
Layout and rendering
- ptouch_label.py: geometry engine with PDF and preview renderers. Both
consume the same geometry, so the preview matches the print exactly.
- Code symbols are snapped to whole printer dots per module. Fractional
modules are the usual reason a small QR code will not scan.
- QR is maximised to the printable height by default (16.4 mm, 4 dots per
module) instead of a fixed 16 mm box (12.3 mm, 3 dots per module).
- Code payload is composed as prefix + inventory + suffix. A legacy
{inventory} template is migrated on first save.
Hardware handling
- print_area.py reads the driver's real printable area via GetDeviceCaps.
The PT-E560BT head is 128 dots at 180 dpi, so the maximum print height is
18.06 mm even on 24 mm tape; the driver reports media as 65x24 mm but only
about 61x18 mm is reachable. Content is fitted to the reachable area,
otherwise the driver silently crops it.
- set_printer_resolution.py reads/switches the driver's resolution mode. The
driver offers 180x180 (symmetric) and 180x360 (anisotropic, 2x across the
tape); the anisotropic mode scaled output incorrectly.
GUI
- label_printer_ptouch_gui.py: 600x300 two-column panel - controls on the
left, live preview on the right. Advanced settings for logo, static lines,
code prefix/suffix and error correction.
- native_file_dialog.py: the standard Windows file picker, run in a
subprocess because Tk and Kivy both want the main event loop.
Printing
- Print failures are reported honestly. print_to_printer previously returned
True unconditionally, so a failed print claimed success and was logged as
SUCCESS.
- SumatraPDF exit codes are now checked (4 = no printer, 5 = driver error).
- The PDF is sent with noscale so driver-side scaling cannot distort the QR
module pitch.
Tests
- validate_ptouch_layout.py decodes the QR back out of the rendered preview
module by module, proving the preview and PDF are the same layout.
- test_ptouch_pipeline.py writes to a temp config so it cannot overwrite
operator settings.
- test_gui_layout.py exercises the real app class headlessly.
- test_print_reporting.py covers the failure paths.
Diagnostics: check_print_area.py, check_print_geometry.py, check_devmode.py,
print_calibration.py, print_measure_scale.py, capture_print_job.py.
ske087
Quality App Developer