label_printer/documentation/README_GUI.md

Label Printer GUI Application

A modern Kivy-based graphical interface for printing labels with barcodes, featuring real-time preview and printer selection.

Features

✓ Two-Column Layout

• Left: Data entry form with input fields
• Right: Real-time label preview

✓ Input Fields

• SAP-Nr. Articol (SAP Number/Article)
• Cantitate (Quantity)
• ID rola cablu (Cable Reel ID)

✓ Live Preview

• Real-time preview of label as you type
• Label size: 11.5 cm × 8 cm
• Shows barcode and all entered information

✓ Printer Management

• Dropdown to select from available system printers
• Automatic detection of installed CUPS printers

✓ Printing

• Direct printing to selected printer
• Background printing with status notifications
• Error handling and user feedback

Installation

Prerequisites

• Python 3.7 or higher
• CUPS (Common Unix Printing System) - usually pre-installed on Linux
• System printer configured and installed

Setup Steps

1. Install dependencies:

pip install -r requirements_gui.txt

2. Install Kivy garden dependencies (if using matplotlib preview):

garden install matplotlib

3. Ensure system printer is configured:

# Check available printers
lpstat -p -d

# Or using CUPS web interface
# Open: http://localhost:631

Usage

Run the GUI Application

python label_printer_gui.py

Operation

1. Enter Label Data:

   • Type the SAP Number in the first field
   • Enter the quantity (numbers only)
   • Enter the Cable Reel ID

2. Monitor Preview:

   • The preview updates automatically as you type
   • Shows combined barcode with all entered data

3. Select Printer:

   • Use the dropdown to select your target printer
   • Default is "PDF" if no other printers available

4. Print:

   • Click "PRINT LABEL" button
   • Wait for confirmation message
   • Label will print to selected printer

Label Format

The label contains:

• Row 1: SAP Number | Quantity | Cable ID (combined in barcode)
• Barcode: Code128 format encoding the combined information
• Size: 11.5 cm width × 8 cm height
• DPI: 300 DPI for high-quality printing

File Structure

/srv/Label-design/
├── print_label.py           # Core printing functions
├── label_printer_gui.py      # Kivy GUI application
├── requirements.txt          # Original dependencies
├── requirements_gui.txt      # GUI-specific dependencies
└── how_to.txt               # Original documentation

Troubleshooting

No printers detected

• Check CUPS service: sudo systemctl status cups
• List printers: lpstat -p
• Restart CUPS if needed: sudo systemctl restart cups

Preview not updating

• Ensure all input fields are properly connected
• Check console for error messages
• Verify PIL/Pillow installation: python -c "from PIL import Image; print('OK')"

Print fails

• Verify printer name is correct
• Check printer status: lpstat -p -d
• Test direct print: echo "test" | lp -d printername
• Ensure CUPS daemon is running

Kivy window sizing issues

• The app defaults to 1600×900 window
• Can be resized freely after launch
• Modify Window.size = (1600, 900) in code to change default

Code Integration

To integrate the printing function into other applications:

from print_label import print_label_standalone

# Print a label
success = print_label_standalone(
    value="YOUR_TEXT",
    printer="printername", 
    preview=0  # 0=no preview, 1-3=3s preview, >3=5s preview
)

Requirements

• kivy: GUI framework
• python-barcode: Barcode generation
• pillow: Image processing
• pycups: CUPS printer interface
• matplotlib: (Optional) For advanced visualization

License

Based on the existing print_label.py printing framework.

Notes

• All data is combined into a single barcode for easy scanning
• Labels are printed at 300 DPI for sharp quality
• Temporary files are cleaned up automatically
• Printing happens in background threads to prevent UI blocking

Support

For issues or questions, check:

1. Console output for error messages
2. CUPS printer configuration
3. System printer availability
4. Required dependencies installation