hid4flutter

https://pub.dev/packages/hid4flutter
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hid4flutter is a Flutter plugin that enables communication with HID (Human Interface Device) devices...
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### Install hidapi on Linux

Source: https://pub.dev/packages/hid4flutter

On Linux, you need to manually install the hidapi library before using the hid4flutter plugin.

```bash
sudo apt-get install libhidapi-hidraw0

```

--------------------------------

### Install Dependencies

Source: https://pub.dev/packages/hid4flutter

Run this command in your project's root directory after updating pubspec.yaml to fetch the new dependency.

```bash
flutter pub get

```

--------------------------------

### Get all connected devices

Source: https://pub.dev/packages/hid4flutter

Retrieves a list of all currently connected HID devices.

```APIDOC
## Get all connected devices list

```dart
List<HidDevice> devices = await Hid.getDevices();

// Do something with the list
```
```

--------------------------------

### Get device by vendorId and productId

Source: https://pub.dev/packages/hid4flutter

Retrieves a list of HID devices matching the specified vendor ID and product ID.

```APIDOC
## Get device by vendorId and productId

```dart
List<HidDevice> devices = await Hid.getDevices(vendorId: 0x55, productId: 0x13);

// Since multiple devices can match the same vendorId 
// and productId, get the first device or null.
HidDevice? device = devices.firstOrNull;

// Do something with the device
```
```

--------------------------------

### Flutter App for HID Device Interaction

Source: https://pub.dev/packages/hid4flutter/example

This is the main application widget for the HID4Flutter example. It sets up the MaterialApp with a theme and navigates to the DeviceListScreen.

```dart
import 'dart:typed_data';
import 'package:flutter/material.dart';
import 'package:hid4flutter/hid4flutter.dart';

class _ReportPayload {
  final int reportId;
  final Uint8List bytes;
  const _ReportPayload(this.reportId, this.bytes);
}

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
          colorScheme: ColorScheme.fromSeed(seedColor: Colors.blue),
          useMaterial3: true),
      home: const DeviceListScreen(),
    );
  }
}

class DeviceListScreen extends StatefulWidget {
  const DeviceListScreen({super.key});

  @override
  DeviceListScreenState createState() => DeviceListScreenState();
}

class DeviceListScreenState extends State<DeviceListScreen> {
  List<HidDevice> devices = [];

  @override
  void initState() {
    super.initState();
    _loadConnectedDevices();
  }

  Future<void> _loadConnectedDevices() async {
    try {
      List<HidDevice> connectedDevices = await Hid.getDevices();
      setState(() {
        devices = connectedDevices;
      });
    } catch (e) {
      // ignore: avoid_print
      print('Error getting connected devices: $e');
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: const Text('Connected Devices'),
      ),
      body: _buildDeviceList(),
      floatingActionButton: FloatingActionButton(
        onPressed: () => {
          _loadConnectedDevices(),
        },
        tooltip: 'Refresh',
        child: const Icon(Icons.refresh),
      ),
    );
  }

  Widget _buildDeviceList() {
    if (devices.isEmpty) {
      return const Center(
        child: Text('No connected devices'),
      );
    }

    return ListView.builder(
      itemCount: devices.length,
      itemBuilder: (context, index) {
        HidDevice device = devices[index];
        return Card(
          margin: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
          child: ListTile(
            title: Text('Device $index'),
            subtitle: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text('Path: ${device.path}'),
                Text('Vendor ID: 0x${device.vendorId.toRadixString(16)}'),
                Text('Product ID: 0x${device.productId.toRadixString(16)}'),
                Text('Serial Number: ${device.serialNumber}'),
                Text('Release Number: ${device.releaseNumber}'),
                Text('Manufacturer: ${device.manufacturer}'),
                Text('Product Name: ${device.productName}'),
                Text('Usage Page: 0x${device.usagePage.toRadixString(16)}'),
                Text('Usage: 0x${device.usage.toRadixString(16)}'),
                Text('Interface Number: ${device.interfaceNumber}'),
                Text('Bus Type: ${device.busType}'),
              ],
            ),
            trailing: device.isOpen
                ? const Icon(Icons.usb, color: Colors.green)
                : const Icon(Icons.usb, color: Colors.grey),
            onTap: () async {
              await _handleDeviceTap(device, index);
            },
            onLongPress: () async {
              await _handleDeviceLongPress(context, device, index);
            },
          ),
        );
      },
    );
  }

  Future<void> _handleDeviceTap(HidDevice device, int index) async {
    try {
      if (!device.isOpen) {
        await device.open();
        if (mounted) setState(() {});
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(
              'Opened ${device.productName.isNotEmpty ? device.productName : 'device $index'}',
            ),
            duration: const Duration(seconds: 2),
          ),
        );
      } else {
        await device.close();
        if (mounted) setState(() {});
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(
              'Closed ${device.productName.isNotEmpty ? device.productName : 'device $index'}',
            ),
            duration: const Duration(seconds: 2),
          ),
        );
      }
    } catch (e) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text(
              '${device.isOpen ? 'Failed to close' : 'Failed to open'} device: $e'),
          duration: const Duration(seconds: 3),
        ),
      );
    }
  }

  Future<void> _handleDeviceLongPress(
      BuildContext context, HidDevice device, int index) async {
    if (!device.isOpen) {
      ScaffoldMessenger.of(context).showSnackBar(

```

--------------------------------

### Import hid4flutter in Dart

Source: https://pub.dev/packages/hid4flutter/install

Import the hid4flutter package into your Dart files to start using its functionalities. This line should be placed at the top of your Dart file.

```dart
import 'package:hid4flutter/hid4flutter.dart';
```

--------------------------------

### Get All Connected HID Devices

Source: https://pub.dev/packages/hid4flutter

Retrieve a list of all HID devices currently connected to the system. This is the first step in interacting with any HID device.

```dart
List<HidDevice> devices = await Hid.getDevices();

// Do something with the list

```

--------------------------------

### Deprecated 'elementAt' Usage

Source: https://pub.dev/packages/hid4flutter/score

This example shows the use of the deprecated `elementAt` method. It is recommended to use the `+` operator instead for better performance and to avoid deprecated features.

```dart
      final char = codeUnits.elementAt(i).value;

```

--------------------------------

### Get Specific HID Device by Vendor and Product ID

Source: https://pub.dev/packages/hid4flutter

Filter and retrieve a list of HID devices matching a specific vendor ID and product ID. Useful for targeting a particular device model.

```dart
List<HidDevice> devices = await Hid.getDevices(vendorId: 0x55, productId: 0x13);

// Since multiple devices can match the same vendorId 
// and productId, get the first device or null.
HidDevice? device = devices.firstOrNull;

// Do something with the device

```

--------------------------------

### Missing Type Annotation Example

Source: https://pub.dev/packages/hid4flutter/score

This snippet highlights a missing type annotation in the `registerWith` method. Ensure all methods have explicit type annotations for better code clarity and maintainability.

```dart
  static registerWith() {
  }

```

--------------------------------

### Send Output Report

Source: https://pub.dev/packages/hid4flutter

Opens a device, sends an output report, and then closes the device.

```APIDOC
## Send Output Report

```dart
final HidDevice device = ...

try {
  await device.open();

  // Send an Output report of 32 bytes (all zeroes).
  // The reportId is optional (default is 0x00).
  // It will be prefixed to the data as per HID rules.
  Uint8List data = Uint8List(32);
  await device.sendReport(reportId: 0x00, reportData);
} finally {
  await device.close();
}
```
```

--------------------------------

### Receive Input Report

Source: https://pub.dev/packages/hid4flutter

Opens a device, receives an input report with a specified timeout, and then closes the device.

```APIDOC
## Receive Input Report

```dart
final HidDevice device = ...

try {
  await device.open();

  // Receive a report of 32 bytes with timeout of 2 seconds.
  Uint8List data = await device.receiveReport(32, timeout: const Duration(seconds: 2));

  // First byte is always the reportId.
  int reportId = data[0];

  print('Received report with id $reportId: $data.');
} finally {
  await device.close();
}
```
```

--------------------------------

### Send Output Report to HID Device

Source: https://pub.dev/packages/hid4flutter

Opens a connection to a HID device, sends a custom output report, and then closes the connection. Ensure the device is available and the report format is correct.

```dart
final HidDevice device = ...

try {
  await device.open();

  // Send an Output report of 32 bytes (all zeroes).
  // The reportId is optional (default is 0x00).
  // It will be prefixed to the data as per HID rules.
  Uint8List data = Uint8List(32);
  await device.sendReport(reportId: 0x00, reportData);
} finally {
  await device.close();
}

```

--------------------------------

### Add hid4flutter Dependency

Source: https://pub.dev/packages/hid4flutter/install

Run this command in your project's root directory to add the hid4flutter package as a dependency. This command automatically updates your pubspec.yaml file.

```bash
$ flutter pub add hid4flutter
```

--------------------------------

### Receive Input Report from HID Device

Source: https://pub.dev/packages/hid4flutter

Opens a connection to a HID device, attempts to receive an input report within a specified timeout, and then closes the connection. The first byte of the received data is the report ID.

```dart
final HidDevice device = ...

try {
  await device.open();

  // Receive a report of 32 bytes with timeout of 2 seconds.
  Uint8List data = await device.receiveReport(32, timeout: const Duration(seconds: 2));

  // First byte is always the reportId.
  int reportId = data[0];

  print('Received report with id $reportId: $data.');
} finally {
  await device.close();
}

```

--------------------------------

### Update pubspec.yaml

Source: https://pub.dev/packages/hid4flutter/install

After running `flutter pub add`, your pubspec.yaml file will include the hid4flutter dependency. Ensure this line is present.

```yaml
dependencies:
  hid4flutter: ^0.2.0
```

--------------------------------

### Add hid4flutter Dependency

Source: https://pub.dev/packages/hid4flutter

Add the hid4flutter package to your pubspec.yaml file to include it in your Flutter project.

```yaml
dependencies:
  hid4flutter: ^0.2.0

```

--------------------------------

### Convert Hex String to Bytes

Source: https://pub.dev/packages/hid4flutter/example

A utility function to convert a hexadecimal string representation of bytes into a Uint8List. It handles optional '0x' prefixes, spaces, and ensures the input string has an even number of characters for proper parsing.

```dart
Uint8List _hexToBytes(String hexInput) {
  String s = hexInput
      .trim()
      .replaceAll(RegExp(r'0x', caseSensitive: false), '')
      .replaceAll(RegExp(r'[^0-9a-fA-F]'), '');
  if (s.length % 2 != 0) s = '0$s';
  final out = Uint8List(s.length ~/ 2);
  for (int i = 0, j = 0; i < s.length; i += 2, j++) {
    out[j] = int.parse(s.substring(i, i + 2), radix: 16);
  }
  return out;
}
```

--------------------------------

### Prompt User for Report Payload

Source: https://pub.dev/packages/hid4flutter/example

This function displays a dialog to collect the report ID and data bytes (in hexadecimal format) from the user. It validates the input and returns a _ReportPayload object or null if the user cancels or provides invalid input.

```dart
Future<_ReportPayload?> _promptReportPayload(BuildContext context) async {
    final hexController = TextEditingController();
    final reportIdController = TextEditingController(text: '00');

    final confirmed = await showDialog<bool>(
      context: context,
      builder: (ctx) {
        return AlertDialog(
          title: const Text('Send custom HEX bytes'),
          content: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              TextField(
                controller: reportIdController,
                decoration: const InputDecoration(
                  labelText: 'Report ID (hex, e.g. 00)',
                ),
              ),
              const SizedBox(height: 8),
              TextField(
                controller: hexController,
                decoration: const InputDecoration(
                  labelText: 'Data bytes (hex, e.g. 01 02 0A FF)',
                ),
              ),
            ],
          ),
          actions: [
            TextButton(
              onPressed: () => Navigator.of(ctx).pop(false),
              child: const Text('Cancel'),
            ),
            ElevatedButton(
              onPressed: () => Navigator.of(ctx).pop(true),
              child: const Text('Send'),
            ),
          ],
        );
      },
    );

    if (confirmed != true) return null;

    try {
      final reportId = int.parse(
          reportIdController.text.replaceAll('0x', '').replaceAll(' ', ''),
          radix: 16);
      final bytes = _hexToBytes(hexController.text);
      return _ReportPayload(reportId, bytes);
    } catch (e) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('Invalid input: $e')),
      );
      return null;
    }
  }
```

--------------------------------

### Send Custom Data to HID Device

Source: https://pub.dev/packages/hid4flutter/example

Use this function to send custom hexadecimal byte data to a connected HID device. It prompts the user for a report ID and the data bytes, handling potential errors during parsing and sending.

```dart
Future<void> _sendReport(BuildContext context, HidDevice device) async {
    if (device.isClosed) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Open the device first to send data.')),
      );
      return;
    }

    final payload = await _promptReportPayload(context);
    if (payload == null) return;

    try {
      await device.sendReport(payload.bytes, reportId: payload.reportId);
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Data sent.')),
      );
    } catch (e) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('Failed to send: $e')),
      );
    }
  }
```
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