UsbConnection class

USB Connection backed by a native platform channel for lifecycle and libusb FFI for bulk I/O.

Platform status in this release: not yet tested on hardware on macOS or Android (Android also lacks a bundled libusb-1.0.so); fails in testing on Windows (cause not yet confirmed, see the README's "Known issues"); not possible on iOS, where open throws UsbUnsupportedOnPlatformException.

Lifecycle flow:

1. open checks platform support, requests permission (Android) if needed, calls openForFfi to get a handle, verifies identity, claims the interface, and makes the handle available for I/O.
2. writeRaw / read delegate through UsbPlatform — in production those methods route to a per-connection worker isolate that owns libusb calls (Task 18). Stall recovery is bounded by config.usbStallRetries; unplug surfaces UsbDeviceUnpluggedException and closes the connection.
3. close is idempotent; releases the interface, closes the libusb handle, and notifies native side.

Inheritance

• Object
• Connection
• UsbConnection

Constructors

UsbConnection(UsbDeviceAddress address, {ConnectionConfig? config})

UsbConnection.withPlatform(UsbDeviceAddress address, UsbPlatform _platform, {ConnectionConfig? config})

Test seam — production code should use the default constructor.

Properties

address → UsbDeviceAddress

final

config ↔ ConnectionConfig

getter/setter pair, inherited

connectionDescription → String

Human-readable description (e.g. "TCP:192.168.1.10:9100").

no setter, override

hashCode → int

The hash code for this object.

no setter, inherited

isConnected → bool

Whether the connection is currently open.

no setter, override

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

bytesAvailable() → Future<int>

libusb bulk endpoints can't be peeked, so this does a short read and buffers whatever arrives. The base class's request/response loop only calls read while this returns > 0.

override

close() → Future<void>

Close the connection.

override

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

open() → Future<void>

Open the connection to the printer.

override

read() → Future<Uint8List?>

Read all available bytes from the connection. Returns null if none.

override

sendAndWaitForResponse(Uint8List data, {int? initialTimeout, int? readTimeout, String? endOfResponseMarker}) → Future<Uint8List>

Send data and wait for response, optionally checking for an end-of-response marker. Matches SDK's ConnectionA.sendAndWaitForResponse. Outer deadline prevents infinite hang when printer trickles data.

inherited

sendAndWaitForValidResponse(Uint8List data, {int? initialTimeout, int? readTimeout, required ResponseValidator validator}) → Future<Uint8List>

Send data and wait for a valid response as determined by validator. Matches SDK's ConnectionA.sendAndWaitForValidResponse. Outer deadline prevents infinite hang when printer trickles data.

inherited

toString() → String

A string representation of this object.

inherited

waitForData(int timeoutMs) → Future<void>

Wait until data is available or timeout expires. Polls every 50ms matching SDK's Sleeper.sleep(50L).

inherited

write(Uint8List data) → Future<void>

Write data with chunking matching SDK's ConnectionA behavior. Splits into config.maxChunkSize byte chunks with config.interChunkDelayMs delay.

inherited

writeRaw(Uint8List data) → Future<void>

Write raw bytes to the underlying transport (single chunk, no splitting).

override

Operators

operator ==(Object other) → bool

The equality operator.

inherited