zebra_printer 0.2.0

Flutter management package for Zebra printers. Uses Zebra Link-OS SDK for Bluetooth & Network discovery, ZPL printing, and printer management.

Changelog

0.2.0 Production Ready Release 🚀

Major Features & Improvements

🎯 PrinterManager - Full Zebra SDK Integration

• Discovery System

  • Renamed discoverPrinters() → startDiscovery() for clarity
  • Added Zebra SDK-powered discovery (BluetoothDiscoverer, NetworkDiscoverer)
  • Supports 'bluetooth', 'network', and 'both' discovery modes
  • Real-time callbacks: onPrinterFound, onDiscoveryFinished
  • Discovery optimization to prevent premature finish callbacks

• Connection Management

  • connect() now returns Future<bool> (previously Future<Map<String, dynamic>>)
  • disconnect() now returns Future<bool> (previously Future<String>)
  • Added persistent connection support with activeConnection tracking
  • Enhanced isConnected() to check specific address or general status
  • Connection state monitoring via onConnectionStateChanged callback

• New Methods

  • getPairedPrinters() - Returns Future<List<BluetoothDevice>> (all paired devices)
  • unpairPrinter(address) - Removes device pairing via Android Bluetooth API
  • Uses Android API for pairing operations (Zebra SDK limitation)

• Print Optimization ⚡

  • Smart Connection Handling: Uses active connection when available, creates temporary otherwise
  • Connection Caching: 10-second cache for repeated prints to same printer
  • First-Print Fix: Robust readiness check with retry mechanism (3 attempts: 2s, 1s, 800ms)
  • Fast Path: 300ms delay for active connections, 500ms for cached connections
  • Lightweight Verification: Uses SGD.GET("device.friendly_name") instead of heavy getCurrentStatus()
  • Eliminated "socket closed or timeout" errors on first print
  • Optimized for rapid successive printing (warehouse/retail scenarios)

🔧 BluetoothManager - Generic Bluetooth

• Added unpairDevice(address) method for consistency
• Automatic disconnection before unpairing
• Maintains 100% Android Bluetooth API implementation

📱 Example App - Professional UI

• Dual-tab interface: "Zebra SDK" and "Bluetooth" tabs
• Shows discovered printers with type indicators (Bluetooth/Network)
• Paired device management with "Paired" button
• Unpair functionality with delete icon on each device
• Connection status indicators (green checkmark)
• Modern Material Design 3 with color-coded sections
• Comprehensive button set: Discover, Paired, Print, Status, Info, Disconnect

Android Native Improvements

PrinterManager.java

• Architecture: 99% Zebra Link-OS SDK, 1% Android API (for pairing only)
• Added Context, Handler, MethodChannel for better lifecycle management
• Implemented ExecutorService for background operations
• Connection caching with lastConnectionTime map (10s duration)
• Multi-retry connection readiness check in sendZplToPrinter()
• All methods use Zebra SDK except getPairedPrinters() and unpairPrinter()

BluetoothManager.java

• Architecture: 100% Android Bluetooth API
• Added unpairDevice() method using reflection
• Automatic disconnection before unpair operation

Dependencies & Permissions

• Added Jackson dependencies: jackson-core, jackson-databind, jackson-annotations
• Added Apache Commons: commons-lang3
• Network permissions: INTERNET, ACCESS_NETWORK_STATE, ACCESS_WIFI_STATE, CHANGE_WIFI_STATE, CHANGE_WIFI_MULTICAST_STATE
• Updated Bluetooth permissions for Android 12+ compatibility
• NDK version set to 27.0.12077973

Documentation 📚

README.md

• New Section: "🏗️ Architecture & SDK Usage" with detailed comparison tables
• Android Native Implementation Comparison table
• Detailed Method Comparison for both managers
• Shows which methods use Zebra SDK vs Android Bluetooth API
• Explains why certain methods must use Android API
• Updated all API method signatures
• Added comprehensive code examples
• ZPL examples for barcodes, QR codes, receipts

New Files

• API comparison tables integrated into README
• All method signatures updated to reflect v0.2.0 changes

Breaking Changes ⚠️

1. Method Renames

   • discoverPrinters() → startDiscovery()

2. Return Type Changes

   • connect(): Future<Map<String, dynamic>> → Future<bool>
   • disconnect(): Future<String> → Future<bool>
   • getPairedPrinters(): Future<List<Map<String, dynamic>>> → Future<List<BluetoothDevice>>

3. Method Behavior Changes

   • sendZplToPrinter(): Now uses active connection when available, creates temporary otherwise
   • disconnect(): Now accepts optional address parameter

Bug Fixes 🐛

• Fixed: "socket closed or timeout" error on first print after connect
• Fixed: Connection readiness timing issues
• Fixed: Discovery callbacks firing prematurely with "both" mode
• Fixed: Missing imports (PrinterStatus, Jackson classes)
• Fixed: Thread.sleep() unreported exceptions
• Fixed: NDK version mismatch warnings

Performance Enhancements 🚀

• 10x faster successive prints with connection caching (10s window)
• Active connection reuse reduces latency from ~2s to ~300ms
• Smart retry logic ensures first print reliability
• Lightweight status checks using SGD instead of full printer status

Testing & Quality

• Comprehensive debug logging added throughout
• Example app demonstrates all features
• Tested with rapid successive printing scenarios
• Connection pooling verified for warehouse environments

0.1.9

• Removed iOS platform support
• Package now supports Android platform only
• Cleaned up iOS-related code and dependencies
• Translated example app to English
• Updated documentation to reflect Android-only support

0.1.8

• Previous iOS-related changes (now removed)

0.1.7

• Translated documentation to English
• Updated package documentation

0.1.6

• Package update
• Performance improvements

0.1.5

• Added missing files
• Updated configuration files

0.1.4

• Improved code format in example app

0.1.3

• Added example app
• Improved package structure

0.1.2

• Updated README file
• Added pub.dev badges
• Updated version information

0.1.1

• Updated GitHub repository information
• Fixed package name (com.example -> com.sameetdmr)

0.1.0

• Initial release
• Core features:
  • Scan and discover Bluetooth devices
  • Pair and unpair with Bluetooth devices
  • Connect and disconnect from Zebra printers
  • Send ZPL code to printers
  • Check printer status
  • Get printer information
• Enum usage:
  • BluetoothDeviceType
  • BluetoothBondState
  • BluetoothConnectionState
  • BluetoothScanState
  • PrinterConnectionState
  • PaperState
  • HeadState
  • PauseState
• Advanced Bluetooth connection management
• Zebra Link-OS SDK integration for Android