jiahong
492 lines
13 KiB
Dart
492 lines
13 KiB
Dart
// 自然写互动课堂平板端应用软件 V1.0
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// service/ble_service.dart - BLE蓝牙点阵笔连接服务
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import 'dart:async';
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import 'dart:typed_data';
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/// BLE服务UUID常量定义
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/// 基于自然写点阵笔自定义GATT Service规范
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class PadBleConstants {
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/// 点阵笔主服务UUID
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static const String penServiceUuid = '0000ffe0-0000-1000-8000-00805f9b34fb';
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/// 笔迹坐标数据特征值UUID（Notify）
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static const String strokeCharUuid = '0000ffe1-0000-1000-8000-00805f9b34fb';
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/// 笔控制指令特征值UUID（Write）
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static const String controlCharUuid = '0000ffe2-0000-1000-8000-00805f9b34fb';
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/// 电量信息特征值UUID（Read/Notify）
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static const String batteryCharUuid = '0000ffe3-0000-1000-8000-00805f9b34fb';
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/// 设备信息服务UUID
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static const String deviceInfoUuid = '0000180a-0000-1000-8000-00805f9b34fb';
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/// 扫描超时时间（秒）
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static const int scanTimeoutSeconds = 15;
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/// 自动重连延迟（秒）
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static const int reconnectDelaySeconds = 3;
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/// 最大重连次数
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static const int maxReconnectAttempts = 10;
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/// MTU协商大小
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static const int requestedMtu = 247;
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/// 笔迹数据缓冲批量回调阈值
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static const int strokeBatchSize = 8;
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/// 电量读取间隔（秒）
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static const int batteryReadInterval = 60;
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}
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/// 单个笔迹坐标点数据
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class PadPenPoint {
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/// X坐标（0.01mm精度，16位无符号）
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final double x;
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/// Y坐标（0.01mm精度，16位无符号）
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final double y;
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/// 压力值（0-255，8位无符号）
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final int pressure;
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/// 时间戳（相对值，16位无符号，单位ms）
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final int timestamp;
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/// 是否为落笔点
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final bool isPenDown;
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PadPenPoint({
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required this.x,
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required this.y,
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required this.pressure,
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required this.timestamp,
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this.isPenDown = false,
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});
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@override
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String toString() =>
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'PadPenPoint(x: ${x.toStringAsFixed(2)}, y: ${y.toStringAsFixed(2)}, '
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'p: $pressure, t: $timestamp)';
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}
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/// 点阵笔设备信息
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class PadPenDevice {
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/// 设备蓝牙MAC地址
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final String macAddress;
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/// 设备名称
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final String name;
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/// 信号强度（RSSI）
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int rssi;
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/// 当前连接状态
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PenConnectionState connectionState;
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/// 电量百分比（0-100）
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int batteryLevel;
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/// 固件版本号
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String? firmwareVersion;
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/// 当前所在点阵码页面ID
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String? currentPageId;
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PadPenDevice({
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required this.macAddress,
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required this.name,
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this.rssi = -100,
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this.connectionState = PenConnectionState.disconnected,
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this.batteryLevel = -1,
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this.firmwareVersion,
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this.currentPageId,
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});
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}
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/// 笔连接状态枚举
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enum PenConnectionState {
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/// 未连接
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disconnected,
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/// 正在扫描
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scanning,
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/// 正在连接
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connecting,
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/// 已连接
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connected,
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/// 正在断开
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disconnecting,
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/// 自动重连中
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reconnecting,
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}
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/// 笔迹数据事件（批量坐标点回调）
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class PenStrokeEvent {
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/// 来源笔的MAC地址
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final String penMac;
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/// 坐标点列表
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final List<PadPenPoint> points;
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/// 所在页面ID（点阵码识别）
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final String? pageId;
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PenStrokeEvent({
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required this.penMac,
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required this.points,
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this.pageId,
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});
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}
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/// BLE蓝牙点阵笔连接服务
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/// 负责扫描、连接、数据接收、电量监控、自动重连等功能
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/// 平板端支持同时连接1支笔（学生个人使用场景）
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class PadBleService {
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/// 已发现的设备列表
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final List<PadPenDevice> _discoveredDevices = [];
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/// 当前已连接的笔
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PadPenDevice? _connectedPen;
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/// 笔迹数据缓冲区（累积到阈值后批量回调）
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final List<PadPenPoint> _strokeBuffer = [];
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/// 扫描结果流
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final StreamController<List<PadPenDevice>> _scanController =
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StreamController<List<PadPenDevice>>.broadcast();
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/// 笔迹数据事件流
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final StreamController<PenStrokeEvent> _strokeController =
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StreamController<PenStrokeEvent>.broadcast();
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/// 连接状态变化流
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final StreamController<PenConnectionState> _connectionController =
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StreamController<PenConnectionState>.broadcast();
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/// 电量变化流
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final StreamController<int> _batteryController =
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StreamController<int>.broadcast();
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/// 自动重连计数器
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int _reconnectAttempts = 0;
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/// 重连定时器
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Timer? _reconnectTimer;
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/// 电量读取定时器
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Timer? _batteryTimer;
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/// 是否正在扫描
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bool _isScanning = false;
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/// 公开的流
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Stream<List<PadPenDevice>> get scanStream => _scanController.stream;
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Stream<PenStrokeEvent> get strokeStream => _strokeController.stream;
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Stream<PenConnectionState> get connectionStream =>
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_connectionController.stream;
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Stream<int> get batteryStream => _batteryController.stream;
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/// 获取当前连接的笔
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PadPenDevice? get connectedPen => _connectedPen;
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/// 开始扫描附近的点阵笔设备
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/// 按服务UUID过滤，仅发现自然写点阵笔
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Future<void> startScan() async {
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if (_isScanning) return;
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_isScanning = true;
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_discoveredDevices.clear();
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// 通知扫描状态
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_connectionController.add(PenConnectionState.scanning);
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// 模拟BLE扫描（实际使用flutter_blue_plus库）
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// 过滤条件：仅发现包含pen_service_uuid的设备
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// scanFilters: [ScanFilter(serviceUuid: PadBleConstants.penServiceUuid)]
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// 设置扫描超时
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Timer(Duration(seconds: PadBleConstants.scanTimeoutSeconds), () {
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stopScan();
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});
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}
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/// 停止扫描
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Future<void> stopScan() async {
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_isScanning = false;
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// 实际调用: FlutterBluePlus.stopScan()
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}
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/// 处理扫描结果回调
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void _onScanResult(String mac, String name, int rssi) {
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// 检查是否已发现过
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final existingIndex = _discoveredDevices.indexWhere(
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(d) => d.macAddress == mac,
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);
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if (existingIndex >= 0) {
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// 更新已有设备的RSSI
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_discoveredDevices[existingIndex].rssi = rssi;
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} else {
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// 添加新发现的设备
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_discoveredDevices.add(PadPenDevice(
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macAddress: mac,
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name: name,
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rssi: rssi,
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));
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}
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// 按信号强度降序排列
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_discoveredDevices.sort((a, b) => b.rssi.compareTo(a.rssi));
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_scanController.add(List.from(_discoveredDevices));
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}
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/// 连接指定的点阵笔
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/// [device] 要连接的笔设备信息
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Future<bool> connectPen(PadPenDevice device) async {
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// 先断开已有连接
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if (_connectedPen != null) {
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await disconnectPen();
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}
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device.connectionState = PenConnectionState.connecting;
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_connectionController.add(PenConnectionState.connecting);
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try {
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// 停止扫描
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await stopScan();
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// 执行BLE连接
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// 实际调用: device.connect(timeout: Duration(seconds: 10))
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// 协商MTU
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// await device.requestMtu(PadBleConstants.requestedMtu);
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// 发现服务和特征值
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// final services = await device.discoverServices();
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// 查找笔迹数据特征值并订阅Notify
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// 设置连接成功状态
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device.connectionState = PenConnectionState.connected;
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_connectedPen = device;
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_reconnectAttempts = 0;
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_connectionController.add(PenConnectionState.connected);
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// 启动电量定时读取
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_startBatteryMonitor();
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// 订阅笔迹数据特征值
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_subscribeStrokeData();
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return true;
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} catch (e) {
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device.connectionState = PenConnectionState.disconnected;
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_connectionController.add(PenConnectionState.disconnected);
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return false;
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}
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}
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/// 订阅笔迹坐标数据Notify特征值
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void _subscribeStrokeData() {
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// 实际调用:
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// characteristic.setNotifyValue(true);
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// characteristic.onValueReceived.listen(_onStrokeDataReceived);
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}
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/// 处理接收到的笔迹原始数据（7字节紧凑编码）
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/// 数据格式：[X_H, X_L, Y_H, Y_L, Pressure, TS_H, TS_L]
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/// X: 16位无符号（0.01mm精度）
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/// Y: 16位无符号（0.01mm精度）
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/// Pressure: 8位无符号（0-255）
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/// Timestamp: 16位无符号（相对毫秒）
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void _onStrokeDataReceived(Uint8List rawData) {
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if (rawData.length < 7) return;
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// 可能包含多个坐标点（每7字节一个）
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int offset = 0;
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while (offset + 7 <= rawData.length) {
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// 解码X坐标（大端序16位）
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final int rawX = (rawData[offset] << 8) | rawData[offset + 1];
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final double x = rawX * 0.01; // 转换为毫米
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// 解码Y坐标
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final int rawY = (rawData[offset + 2] << 8) | rawData[offset + 3];
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final double y = rawY * 0.01;
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// 解码压力值
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final int pressure = rawData[offset + 4];
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// 解码时间戳
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final int timestamp =
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(rawData[offset + 5] << 8) | rawData[offset + 6];
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// 判断落笔/抬笔（压力值>0为落笔）
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final bool isPenDown = pressure > 0;
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final point = PadPenPoint(
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x: x,
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y: y,
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pressure: pressure,
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timestamp: timestamp,
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isPenDown: isPenDown,
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);
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_strokeBuffer.add(point);
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offset += 7;
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}
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// CRC-16 CCITT校验（如果数据包尾部有2字节CRC）
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if (rawData.length > offset + 1) {
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final int receivedCrc = (rawData[offset] << 8) | rawData[offset + 1];
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final int calculatedCrc = _calculateCrc16(
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rawData.sublist(0, offset),
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);
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if (receivedCrc != calculatedCrc) {
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// CRC校验失败，丢弃本批数据
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_strokeBuffer.clear();
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return;
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}
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}
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// 达到批量阈值后回调
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if (_strokeBuffer.length >= PadBleConstants.strokeBatchSize) {
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_flushStrokeBuffer();
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}
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}
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/// 将缓冲区中的笔迹数据批量回调
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void _flushStrokeBuffer() {
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if (_strokeBuffer.isEmpty || _connectedPen == null) return;
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final event = PenStrokeEvent(
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penMac: _connectedPen!.macAddress,
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points: List.from(_strokeBuffer),
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pageId: _connectedPen!.currentPageId,
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);
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_strokeController.add(event);
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_strokeBuffer.clear();
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}
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/// CRC-16 CCITT校验算法
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/// 多项式: 0x1021, 初始值: 0xFFFF
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int _calculateCrc16(Uint8List data) {
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int crc = 0xFFFF;
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for (int i = 0; i < data.length; i++) {
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crc ^= (data[i] << 8);
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for (int j = 0; j < 8; j++) {
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if ((crc & 0x8000) != 0) {
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crc = ((crc << 1) ^ 0x1021) & 0xFFFF;
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} else {
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crc = (crc << 1) & 0xFFFF;
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}
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}
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}
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return crc;
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}
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/// 启动电量定时读取
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void _startBatteryMonitor() {
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_batteryTimer?.cancel();
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_batteryTimer = Timer.periodic(
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Duration(seconds: PadBleConstants.batteryReadInterval),
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(_) => _readBatteryLevel(),
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);
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// 立即读取一次
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_readBatteryLevel();
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}
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/// 读取笔电量
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Future<void> _readBatteryLevel() async {
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if (_connectedPen == null) return;
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try {
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// 实际调用: 读取battery特征值
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// final value = await batteryCharacteristic.read();
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// _connectedPen!.batteryLevel = value[0];
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// _batteryController.add(_connectedPen!.batteryLevel);
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} catch (e) {
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// 读取失败，忽略
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}
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}
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/// 向笔发送控制指令
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/// [command] 指令类型（如：LED闪烁、蜂鸣提示、固件信息查询）
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Future<void> sendCommand(int command, [Uint8List? payload]) async {
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if (_connectedPen == null) return;
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// 构建指令包：[CMD, LEN, PAYLOAD..., CRC_H, CRC_L]
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final List<int> packet = [command];
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if (payload != null) {
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packet.add(payload.length);
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packet.addAll(payload);
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} else {
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packet.add(0);
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}
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// 追加CRC校验
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final crc = _calculateCrc16(Uint8List.fromList(packet));
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packet.add((crc >> 8) & 0xFF);
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packet.add(crc & 0xFF);
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// 实际调用: controlCharacteristic.write(Uint8List.fromList(packet));
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}
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/// 断开当前笔连接
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Future<void> disconnectPen() async {
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_batteryTimer?.cancel();
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_reconnectTimer?.cancel();
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if (_connectedPen != null) {
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_connectedPen!.connectionState = PenConnectionState.disconnecting;
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_connectionController.add(PenConnectionState.disconnecting);
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// 实际调用: device.disconnect();
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_connectedPen!.connectionState = PenConnectionState.disconnected;
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_connectedPen = null;
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_connectionController.add(PenConnectionState.disconnected);
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}
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// 清空缓冲区
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_flushStrokeBuffer();
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}
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/// 处理连接意外断开，启动自动重连
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void _onDisconnected(PadPenDevice device) {
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if (_reconnectAttempts >= PadBleConstants.maxReconnectAttempts) {
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// 超过最大重连次数，放弃重连
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_connectionController.add(PenConnectionState.disconnected);
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return;
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}
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_connectionController.add(PenConnectionState.reconnecting);
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_reconnectAttempts++;
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// 指数退避延迟重连
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final delay = PadBleConstants.reconnectDelaySeconds * _reconnectAttempts;
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final clampedDelay = delay > 30 ? 30 : delay;
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_reconnectTimer = Timer(Duration(seconds: clampedDelay), () async {
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final success = await connectPen(device);
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if (!success) {
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_onDisconnected(device);
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}
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});
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}
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/// 释放所有资源
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void dispose() {
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_batteryTimer?.cancel();
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_reconnectTimer?.cancel();
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_scanController.close();
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_strokeController.close();
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_connectionController.close();
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_batteryController.close();
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_strokeBuffer.clear();
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}
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}
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