aman-satu-flutter/lib/views/settings/printer_bluetooth/printer_view.dart

import 'dart:async';
import 'dart:convert';
import 'dart:typed_data';

import 'package:bluetooth_print/bluetooth_print.dart';
import 'package:bluetooth_print/bluetooth_print_model.dart';
import 'package:charset_converter/charset_converter.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

import 'package:logger/logger.dart';
import 'package:satu/core/utils/logger.dart';
import 'package:satu/core/utils/pos_printer.dart';

class PrinterView extends StatefulWidget {
  const PrinterView({Key? key}) : super(key: key);

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

class _PrinterViewState extends State<PrinterView> {
  final Logger log = getLogger('_PrinterViewState');
  BluetoothPrint? bluetoothPrint;

  bool _connected = false;
  BluetoothDevice? _device;
  String tips = 'no device connect';

  @override
  void initState() {
    bluetoothPrint = BluetoothPrint.instance;
    if (WidgetsBinding.instance != null) {
      WidgetsBinding.instance!.addPostFrameCallback((_) => initBluetooth());
    }

    super.initState();
  }

  // Platform messages are asynchronous, so we initialize in an async method.
  Future<void> initBluetooth() async {
    bluetoothPrint!.startScan(timeout: Duration(seconds: 4));

    final bool isConnected = await bluetoothPrint!.isConnected ?? false;

    bluetoothPrint!.state.listen((state) {
      print('cur device status: $state');

      switch (state) {
        case BluetoothPrint.CONNECTED:
          setState(() {
            _connected = true;
            tips = 'connect success';
          });
          break;
        case BluetoothPrint.DISCONNECTED:
          setState(() {
            _connected = false;
            tips = 'disconnect success';
          });
          break;
        default:
          break;
      }
    });

    if (!mounted) return;

    if (isConnected) {
      setState(() {
        _connected = true;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('BluetoothPrint example app'),
        ),
        body: RefreshIndicator(
          onRefresh: () =>
              bluetoothPrint!.startScan(timeout: Duration(seconds: 4)),
          child: SingleChildScrollView(
            child: Column(
              children: <Widget>[
                Row(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: <Widget>[
                    Padding(
                      padding:
                          EdgeInsets.symmetric(vertical: 10, horizontal: 10),
                      child: Text(tips),
                    ),
                  ],
                ),
                const Divider(),
                StreamBuilder<List<BluetoothDevice>>(
                  stream: bluetoothPrint!.scanResults,
                  initialData: const [],
                  builder: (c, snapshot) => Column(
                    children: (snapshot.data ?? [])
                        .map((d) => ListTile(
                              title: Text(d.name ?? ''),
                              subtitle: Text(d.address ?? ''),
                              onTap: () async {
                                setState(() {
                                  _device = d;
                                });
                              },
                              trailing: _device != null &&
                                      _device!.address == d.address
                                  ? const Icon(
                                      Icons.check,
                                      color: Colors.green,
                                    )
                                  : null,
                            ))
                        .toList(),
                  ),
                ),
                const Divider(),
                Container(
                  padding: EdgeInsets.fromLTRB(20, 5, 20, 10),
                  child: Column(
                    children: <Widget>[
                      Row(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: <Widget>[
                          OutlinedButton(
                            onPressed: _connected
                                ? null
                                : () async {
                                    if (_device != null &&
                                        _device!.address != null) {
                                      await bluetoothPrint!.connect(_device!);
                                    } else {
                                      setState(() {
                                        tips = 'please select device';
                                      });
                                      print('please select device');
                                    }
                                  },
                            child: const Text('connect'),
                          ),
                          SizedBox(width: 10.0),
                          OutlinedButton(
                            onPressed: _connected
                                ? () async {
                                    await bluetoothPrint!.disconnect();
                                  }
                                : null,
                            child: const Text('disconnect'),
                          ),
                        ],
                      ),
                      OutlinedButton(
                        onPressed: _connected
                            ? () async {
                                Map<String, dynamic> config = Map();
                                await bluetoothPrint!
                                    .rawBytes(config, await getReceipt());
                              }
                            : null,
                        child: const Text('print receipt(esc) - text'),
                      ),
                      OutlinedButton(
                        onPressed: _connected
                            ? () async {
                                Map<String, dynamic> config = Map();
                                await bluetoothPrint!
                                    .rawBytes(config, await getReceiptImg());
                              }
                            : null,
                        child: const Text('print label(esc) img'),
                      ),
                    ],
                  ),
                )
              ],
            ),
          ),
        ),
        floatingActionButton: StreamBuilder<bool>(
          stream: bluetoothPrint!.isScanning,
          initialData: false,
          builder: (c, snapshot) {
            if (snapshot.data != null) {
              return FloatingActionButton(
                onPressed: () => bluetoothPrint!.stopScan(),
                backgroundColor: Colors.red,
                child: const Icon(Icons.stop),
              );
            } else {
              return FloatingActionButton(
                  child: const Icon(Icons.search),
                  onPressed: () => bluetoothPrint!
                      .startScan(timeout: const Duration(seconds: 4)));
            }
          },
        ),
      ),
    );
  }
}