wacom_stu_plugin #

A Flutter Windows plugin for Wacom STU signature tablet communication.

Provides MethodChannel and EventChannel interfaces to connect, disconnect, control the display, and stream real-time pen input from Wacom STU USB devices.

Platform: Windows only. Requires the Wacom STU SDK installed at C:/Program Files (x86)/Wacom STU SDK/cpp.

Used by #

flutter_wacom_signature_pad — a higher-level package providing ready-made PDF signing widgets built on top of this plugin. Use that package if you want drag-to-place signature boxes, PDF embedding, and upload support without writing low-level channel code.

Platform support #

Installation #

dependencies:
  wacom_stu_plugin: ^1.0.1

flutter pub get

Channels #

MethodChannel — wacom_stu_channel #

EventChannel — wacom_stu_events #

Streams real-time pen input events as Map<String, int>:

Usage #

Connect and disconnect #

import 'package:flutter/services.dart';

const _channel = MethodChannel('wacom_stu_channel');

// Connect — returns tablet capabilities
final Map result = await _channel.invokeMethod('connect');
final double maxX         = (result['maxX'] as int).toDouble();
final double maxY         = (result['maxY'] as int).toDouble();
final double screenWidth  = (result['screenWidth'] as int).toDouble();
final double screenHeight = (result['screenHeight'] as int).toDouble();

// Disconnect
await _channel.invokeMethod('disconnect');

Stream pen events #

import 'package:flutter/services.dart';

const _events = EventChannel('wacom_stu_events');

final subscription = _events.receiveBroadcastStream().listen((event) {
  final int x        = event['x'];
  final int y        = event['y'];
  final int pressure = event['pressure'];
  final int sw       = event['sw']; // 1 = pen button pressed

  // Convert raw tablet coords to canvas coords:
  // canvasX = (x / maxX) * canvasWidth
  // canvasY = (y / maxY) * canvasHeight
});

// Cancel when done
await subscription.cancel();

Display an image on the tablet screen #

import 'dart:typed_data';
import 'package:flutter/services.dart';

const _channel = MethodChannel('wacom_stu_channel');

// rgbBytes — raw RGB bytes (width × height × 3)
// mode     — display mode integer (device-specific)
await _channel.invokeMethod('setSignatureScreen', {
  'data': rgbBytes,
  'mode': mode,
});

Clear the tablet screen #

await _channel.invokeMethod('clearScreen');

Full example — capture a signature #

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

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

  @override
  State<WacomSignatureCapture> createState() => _WacomSignatureCaptureState();
}

class _WacomSignatureCaptureState extends State<WacomSignatureCapture> {
  static const _channel = MethodChannel('wacom_stu_channel');
  static const _events  = EventChannel('wacom_stu_events');

  StreamSubscription? _sub;
  final List<Offset> _points = [];
  double _maxX = 1.0, _maxY = 1.0;
  bool _connected = false;

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

  Future<void> _connect() async {
    final result = await _channel.invokeMethod('connect');
    setState(() {
      _maxX = (result['maxX'] as int).toDouble();
      _maxY = (result['maxY'] as int).toDouble();
      _connected = true;
    });

    _sub = _events.receiveBroadcastStream().listen((event) {
      final double px = (event['x'] as int) / _maxX;
      final double py = (event['y'] as int) / _maxY;
      setState(() => _points.add(Offset(px, py)));
    });
  }

  @override
  void dispose() {
    _sub?.cancel();
    _channel.invokeMethod('disconnect');
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(_connected ? 'Tablet connected' : 'Connecting...'),
        actions: [
          IconButton(
            icon: const Icon(Icons.clear),
            onPressed: () => setState(() => _points.clear()),
          ),
        ],
      ),
      body: CustomPaint(
        painter: _SignaturePainter(_points),
        child: const SizedBox.expand(),
      ),
    );
  }
}

class _SignaturePainter extends CustomPainter {
  final List<Offset> points;
  _SignaturePainter(this.points);

  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint()
      ..color = Colors.black
      ..strokeWidth = 2.0
      ..strokeCap = StrokeCap.round;

    for (int i = 0; i < points.length - 1; i++) {
      canvas.drawLine(
        Offset(points[i].dx * size.width, points[i].dy * size.height),
        Offset(points[i + 1].dx * size.width, points[i + 1].dy * size.height),
        paint,
      );
    }
  }

  @override
  bool shouldRepaint(_SignaturePainter old) => old.points != points;
}

Requirements #

• Wacom STU SDK installed at C:/Program Files (x86)/Wacom STU SDK/cpp
• Windows 10 or later
• Wacom STU device connected via USB

Changelog #

See CHANGELOG.md.

License #

MIT — see LICENSE.