🖨️ Barcode & QR Code Printer

A modern, production-ready desktop application for generating and printing Code128 barcodes and QR codes on Windows. Built with Python and Flet for a beautiful native experience with threaded printing and atomic file operations.

✨ Features

Core Features

• 🎯 Simple Interface - Clean, Material Design 3 interface for quick barcode printing
• 📱 Dual Code Support - Generate both Code128 barcodes and QR codes
• ⌨️ Barcode Scanner Support - Scan barcodes directly with USB/Bluetooth scanners
• 🖨️ Multi-Printer Support - Select from any installed Windows printer
• 👁️ Preview - See your barcode/QR code before printing with async generation
• 📊 Print History - Track all printed codes with timestamps and type indicators
• 🔁 One-Click Reprint - Tap any history entry to copy it to the clipboard and text field, ready to reprint instantly
• 🗑️ Clear History - Contextual floating action button appears when history has entries to clear it in one tap
• 🏷️ Dynamic Print Button - Button label updates to "Print Barcode" or "Print QR Code" based on the selected code type
• 🎨 Dark/Light Mode - Choose your preferred theme with persistent settings
• 💾 Settings Persistence - Remembers your printer and theme preferences with atomic file writes

Technical Features

• ⚡ Performance Optimized - LRU cache with thread-safe access for instant code generation
• 🎯 Auto-Focus - Automatically re-focuses the input field on window focus and background click, always ready for the next scan
• 🧵 Threaded Printing - Non-blocking print operations keep UI responsive
• 📐 Smart Scaling - Auto-scales to 4 inches or page width, handles both dimensions
• 🔒 Thread-Safe - Proper locking for concurrent operations
• 💪 Robust Error Handling - Graceful handling of printer failures and invalid input with backward-compatible history entries
• 🎚️ Progress Indicator - Visual indeterminate progress bar during print with delayed auto-hide via threading.Timer
• 📐 DPI Aware Printing - Adapts to any printer resolution (300, 600, 1200+ DPI)
• 🖥️ Per-Monitor DPI Aware - Display renders sharply on high-DPI and multi-monitor setups via SetProcessDpiAwareness
• 🪟 Minimum Window Size - Enforces a 700×700px minimum to prevent layout breakage
• 🚫 Zero pywin32 Dependency - All printer access, clipboard, and GDI printing handled natively via ctypes

📸 Screenshots

🚀 Quick Start

Download the Installer

The easiest way to get started is to download the pre-built installer directly from the Releases page. Run BarcodePrinter_Setup.exe and follow the prompts — no Python required.

Build from Source

Prerequisites: Python 3.10+

1. Clone the repository and install dependencies:

   git clone https://github.com/dannyphamv/flet-barcode-printer.git
   cd flet-barcode-printer
   pip install -r requirements.txt

2. Build the standalone Windows executable:

   flet build windows

3. Create the installer with Inno Setup:

   Download and install Inno Setup, then double-click installer.iss to open it in Inno Setup Compiler and click the Compile button.

   Your installer will be output to installer_output\BarcodePrinter_Setup.exe.

💡 Usage

1. Select Code Type - Choose between Barcode or QR Code
2. Enter/Scan Data - Type or scan your barcode data
3. Preview (Optional) - Click Preview to see the generated code
4. Select Printer - Choose your target printer from the dropdown
5. Print - Click Print or press Enter
6. Reprint - In the History tab, tap any row to copy the data to your clipboard and jump back to the Print tab ready to go

The app automatically:

• Generates high-quality codes optimized for 4-inch printing
• Scales to fit smaller label sizes
• Centers the code on the page
• Maintains aspect ratio
• Saves to print history

🔧 Dependencies

Package	Version	Purpose
flet[all]	>=0.80.5	Modern GUI framework
flet-datatable2	>=0.80.5	Enhanced data tables
python-barcode[images]	>=0.16.1	Code128 barcode generation
qrcode[pil]	>=8.2	QR code generation
Pillow	>=12.1.1	Image processing & LANCZOS resampling

pywin32 is not required. Printer enumeration, GDI printing, and clipboard access are all handled through Python's built-in ctypes module.

See requirements.txt for exact versions.

🏗️ Technical Architecture

Threading Model

• Main Thread: Flet UI event loop
• Background Threads: Print operations run in daemon threads
• Thread Safety: threading.Lock protects LRU cache, page.run_thread() for UI updates
• Non-blocking: threading.Timer for delayed progress bar hide instead of time.sleep()

Data Persistence

• Atomic Writes: Uses tempfile.mkstemp() + os.replace() to prevent corruption
• JSON Storage: Settings and history stored in %APPDATA%/BarcodePrinter/
• Graceful Degradation: Handles corrupted files by returning defaults
• Backward-Compatible History: Old entries without a code_type field default to barcode automatically

Print Quality

• DPI Detection: Queries printer capabilities via GetDeviceCaps() through ctypes
• Dynamic Scaling: Calculates exact pixel dimensions based on printer DPI
• High-Quality Resampling: Uses Pillow's LANCZOS algorithm
• Overflow Protection: Checks both width and height constraints

📝 License

This project is licensed under the MIT License - see the LICENSE file for details.