flutter_usb_printer 0.3.2

This plugin will allow develop send data and work with usb printer on android

0.3.2

New Features

• sendData(vendorId, productId, data): New method that selects the device and writes to it in a single native call, reusing an already-open connection when possible. Prefer this over separate connect() + write() calls for actual printing — two separate method-channel calls left a window where a concurrent print job could steal the underlying USB connection in between

Bug Fixes

• Concurrent print jobs: All device I/O (connect, write, printText, printRawText, sendData, close) is now serialized behind a mutex, so concurrent print jobs (e.g. split-ticket printing to multiple printers via Future.wait) can no longer steal or close each other's connection mid-transfer
• Receiver leak: The USB broadcast receiver is no longer re-registered on every onAttachedToActivity (e.g. rotation, config change); it registers once and is unregistered on engine detach
• Frozen-printer UX: Bulk-transfer timeout reduced from 100s × 3 attempts (~5 min worst case) to 6s × 2 attempts, so an offline or stalled printer fails fast instead of appearing frozen

0.3.1

New Features

• setChunkDelay(int ms): New method to insert a configurable delay (in milliseconds) between USB bulk-transfer chunks. Increase to 20–50 ms if large payloads print intermittently on slower printers

Bug Fixes

• User-facing errors: USB error messages (uninitialized device, uninitialized manager, permission errors) are now shown as Toasts instead of silent logcat entries
• Toast on uninitialized: Toasts are now shown when USB device is not initialized or USB Manager is not initialized rather than failing silently

0.3.0+1

Breaking Changes

• minSdk raised from 16 to 24

New Features

• USB permission dialog is now shown automatically when a device is plugged in (via USB_DEVICE_ATTACHED intent-filter and device_filter.xml)

New Features

• isConnected(): New method that returns true only when a device is selected, the USB connection is open, and the bulk-out endpoint is ready

Bug Fixes

• Large print jobs: write(), printText(), and printRawText() now send data in 16 KB chunks instead of a single bulk transfer, eliminating JNI critical lock warnings on large payloads
• Transfer retry: Bulk transfers are retried up to 3 times with increasing backoff (100ms/200ms/300ms) before failing
• Endpoint stall: A USB CLEAR_FEATURE / ENDPOINT_HALT control transfer is sent after claimInterface to clear any stale stall condition on the bulk-out endpoint, fixing -1 transfer failures on first write after fresh connection
• Power-cycle reconnect: mUsbDevice is now cleared on USB_DEVICE_DETACHED and when openDevice() fails, so power-cycling the printer no longer causes a RemoteException — the next write triggers a proper re-select and permission request with the fresh device reference
• Permission flow: connect() now waits for the user to respond to the USB permission dialog before resolving — previously it returned true immediately before the user even saw the dialog
• Permission check: hasPermission() is checked before calling requestPermission() — no redundant dialog when permission is already granted
• Connection reliability: openConnection() now scans all USB interfaces (not just index 0) to find the BULK OUT endpoint, fixing printers that expose the print interface at index 1+
• Silent failure fixed: openConnection() previously returned true even when no endpoint was found, causing a silent NPE on bulkTransfer; it now returns false with a clear log message
• Transfer result: write(), printText(), and printRawText() now return the actual transfer result (b >= 0) instead of always returning true
• Null crash: Fixed NullPointerException in the USB permission broadcast receiver when EXTRA_DEVICE is absent on permission denial
• UI null crash: Fixed crash in device list when manufacturer or productName fields are null

Maintenance

• Migrated Android build to AGP 8.11.1, Gradle 8.14, Kotlin 2.2.20
• Migrated to Kotlin DSL (build.gradle.kts) and new Flutter Gradle plugin DSL
• Fixed deprecated getParcelableExtra API (Android 13+)
• Fixed deprecated buildDir setter/getter (replaced with layout.buildDirectory)
• Replaced raw Thread{} with Kotlin Coroutines for proper error propagation
• Migrated test mocking to TestDefaultBinaryMessengerBinding API
• Added flutter_lints and analysis_options.yaml
• Added android:exported="true" to MainActivity (required for Android 12+)

0.2.0

• Upgraded to Flutter 3.41.9 / Dart 3.9.2+
• Migrated Android build to AGP 8.11.1, Gradle 8.14, Kotlin 2.2.20
• Migrated to Kotlin DSL (build.gradle.kts) and new Flutter Gradle plugin DSL
• Raised minSdk from 16 to 24 (breaking change)
• Fixed deprecated getParcelableExtra API (Android 13+)
• Replaced raw Thread{} with Kotlin Coroutines for proper error propagation
• Fixed printText/printRawText always returning true regardless of actual result
• Fixed non-true singleton pattern in USBPrinterAdapter
• Migrated test mocking to TestDefaultBinaryMessengerBinding API
• Added flutter_lints and analysis_options.yaml

0.1.0+1

• fixed Future

0.1.0

• null safety

0.0.1

• first release