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Published 46 days ago
SDKFlutter
PlatformAndroid
β†’

Metadata

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

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Changelog #

0.2.4 Connection Validity Check & Broken Pipe Fix πŸ›‘οΈ #

  • Critical Bug Fix

    • Fixed "Broken pipe" error when calling sendZplToPrinter() after getPrinterInfo()
    • Added connection validity check before reusing activeConnection
    • Resolved socket state corruption issue caused by SGD commands

  • Connection Management Improvements

    • activeConnection now verified with isConnected() before use
    • Automatic connection recovery when active connection is closed
    • Stale connections automatically detected and recreated
    • All three methods now include connection validity checks:
      • sendZplToPrinter()
      • getPrinterInfo()
      • checkPrinterStatus()

  • Reliability Enhancements

    • Connection state validation in all reuse scenarios
    • Graceful handling of closed connections
    • 10-second connection cache still active for fast reconnection
    • Better error logging for connection state issues

  • Technical Details

    • Added isConnected() check before using activeConnection
    • Automatic cleanup of stale connection references
    • Connection state verified in real-time, not just by reference
    • Fast path (500ms) for recent connections still applies

  • Flow Example

    connect() β†’ getPrinterInfo() β†’ sendZplToPrinter()
βœ… No "Broken pipe" error
βœ… Automatic recovery if connection breaks
βœ… Fast execution with connection cache

Upgrade Impact: Non-breaking - Critical reliability fix for production use.

0.2.3 Connection Reuse & Reliability Fix πŸ”§ #

  • Bug Fixes

    • Fixed socket timeout error when calling getPrinterInfo() or checkPrinterStatus() after connect()
    • Resolved "read failed, socket might closed or timeout" error caused by multiple simultaneous connections

  • Performance Improvements

    • getPrinterInfo() now reuses active connection when available (300ms vs 800ms)
    • checkPrinterStatus() now reuses active connection when available (300ms vs 800ms)
    • Reduced connection overhead for consecutive info/status queries

  • New Features

    • Smart connection management: automatically detects and reuses active connections
    • Connection state awareness: methods intelligently switch between active and temporary connections
    • Enhanced logging for connection lifecycle debugging

  • Technical Details

    • Added shouldCloseConnection flag to prevent closing active connections
    • Both getPrinterInfo() and checkPrinterStatus() now check for activeConnection
    • Temporary connections created only when no active connection exists or address differs
    • Connection stabilization: 300ms for active connections, 800ms for new connections

  • Developer Experience

    • Detailed debug logging added (Dart + Android) for troubleshooting
    • Better error messages with full exception stack traces
    • Null-safe parameter validation

Upgrade Impact: Non-breaking - existing code continues to work with improved reliability and performance.

0.2.2 PrinterInfo Model Update 🎯 #

  • Breaking Changes

    • getPrinterInfo() now returns PrinterInfo model instead of raw String

  • New Features

    • Added PrinterInfo model class with structured printer information
      • model: Printer model name (e.g., "ZD421")
      • serialNumber: Printer serial number
      • firmware: Firmware version
      • language: PrinterLanguage enum (ZPL/CPCL/Unknown)
      • rawInfo: Original raw string (for debugging)
    • Added PrinterLanguage enum for type-safe language detection
    • Type-safe access to printer information with autocomplete support

  • Improvements

    • Better type safety for printer information
    • Improved example app with formatted printer info dialog
    • Added helper methods: toCompactString(), toJson(), fromMap()

  • Developer Experience

    • IDE autocomplete support for printer info fields
    • Null-safe implementation
    • Clean, structured data instead of string parsing
    • Better testability

0.2.1 Documentation Update πŸ“ #

  • Documentation Improvements
    • Moved Architecture & SDK Usage section before Installation for better flow
    • Removed detailed method comparison tables for cleaner documentation
    • Removed API Reference section (redundant with inline documentation)
    • Kept essential comparison tables: Implementation Comparison + Why Two Managers
    • README.md reduced from 18 KB to 14 KB for faster loading

0.2.0 Production Ready Release πŸš€ #

Major Features & Improvements #

🎯 PrinterManager - Full Zebra SDK Integration

  • Discovery System

    • Renamed discoverPrinters() β†’ 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)

πŸ”§ BluetoothManager - Generic Bluetooth

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

πŸ“± 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 πŸ“š #

README.md

  • New Section: "πŸ—οΈ 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() β†’ startDiscovery()

  2. Return Type Changes

    • connect(): Future<Map<String, dynamic>> β†’ Future<bool>
    • disconnect(): Future<String> β†’ Future<bool>
    • getPairedPrinters(): Future<List<Map<String, dynamic>>> β†’ 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 πŸ› #

  • 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 πŸš€ #

  • 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.flutter-io.cn 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

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Metadata

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

Repository (GitHub)
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Topics

#zebra #printer #bluetooth #zpl #label-printing

Documentation

Documentation
API reference

License

MIT (license)

Dependencies

flutter

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