Flutter蓝牙打印机插件fp_bt_printer的使用

fp_bt_printer 是一个用于在Android设备上通过蓝牙连接热敏打印机进行打印的Flutter插件。该插件支持58mm和80mm宽度的打印机，并允许打印QR码、条形码、图像等。

主要功能

• 列出已配对的蓝牙设备。
• 检查设备是否已连接。
• 打印数据，包括文本、图像、二维码等。

示例代码

以下是一个完整的示例应用，展示了如何使用 fp_bt_printer 插件来扫描并连接到蓝牙打印机，然后打印一张带有样式和图像的收据。

1. 添加依赖

首先，在你的 pubspec.yaml 文件中添加以下依赖：

dependencies:
  flutter:
    sdk: flutter
  fp_bt_printer: ^x.x.x # 替换为最新版本号
  esc_pos_utils: ^x.x.x # 替换为最新版本号
  image: ^x.x.x # 替换为最新版本号

运行 flutter pub get 来安装这些依赖。

2. 创建主应用

创建一个简单的Flutter应用程序，包含以下内容：

import 'dart:typed_data';
import 'package:esc_pos_utils/esc_pos_utils.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:image/image.dart' as img;
import 'package:fp_bt_printer/fp_bt_printer.dart';

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

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  List<PrinterDevice> devices = [];
  PrinterDevice? device;
  bool connected = false;

  FpBtPrinter printer = FpBtPrinter();

  Future<void> getDevices() async {
    final response = await printer.scanBondedDevices();
    setState(() {
      devices = response;
    });
  }

  Future<void> setConnet(PrinterDevice d) async {
    final response = await printer.checkConnection(d.address);
    print(response.message);
    setState(() {
      if (response.success) {
        device = d;
        connected = true;
      } else {
        connected = false;
        device = null;
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: HomeScreen(),
    );
  }
}

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

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('List of devices - Printers'),
      ),
      body: Column(
        children: [
          Container(
            child: Column(
              children: [
                TextButton(
                  child: Center(child: Text("Open Settings")),
                  onPressed: () => printer.openSettings(),
                )
              ],
            ),
          ),
          Divider(),
          Text("Search Paired Bluetooth"),
          TextButton(
            onPressed: () {
              this.getDevices();
            },
            child: Text("Search"),
          ),
          Padding(
            padding: const EdgeInsets.symmetric(horizontal: 10.0),
            child: Card(
              child: Container(
                padding: const EdgeInsets.all(5),
                height: 200,
                child: ListView.separated(
                  separatorBuilder: (context, index) => Divider(),
                  itemCount: devices.length > 0 ? devices.length : 0,
                  itemBuilder: (context, index) {
                    return ListTile(
                      leading: Icon(Icons.print_rounded),
                      onTap: () => setConnet(devices[index]),
                      title: Text(
                          '${devices[index].name} - ${devices[index].address}'),
                      subtitle: Text("Click to connect"),
                    );
                  },
                ),
              ),
            ),
          ),
          SizedBox(
            height: 30,
          ),
          Padding(
            padding: const EdgeInsets.all(15.0),
            child: Container(
              color: Colors.grey.shade300,
              child: Column(
                children: [
                  Center(
                    child: Padding(
                      padding: const EdgeInsets.all(8.0),
                      child: Icon(
                        Icons.print_rounded,
                        color: connected ? Colors.green : Colors.red,
                      ),
                    ),
                  ),
                  ListTile(
                    minVerticalPadding: 5,
                    dense: true,
                    title: connected
                        ? Center(child: Text(device!.name!))
                        : Center(child: Text("No device")),
                    subtitle: connected
                        ? Center(child: Text(device!.address))
                        : Center(child: Text("Select a device of the list")),
                  ),
                  TextButton(
                    onPressed: connected
                        ? () => this.printTicket(device!.address)
                        : null,
                    child: Text("PRINT DATA"),
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }

  Future<void> printTicket(String address) async {
    final profile = await CapabilityProfile.load();
    final generator = Generator(PaperSize.mm80, profile);
    List<int> bytes = [];

    // Print image:
    final ByteData data = await rootBundle.load('assets/wz.png');
    final Uint8List bytesImg = data.buffer.asUint8List();
    var image = img.decodePng(bytesImg);

    // Resize
    var thumbnail =
        img.copyResize(image!, interpolation: img.Interpolation.nearest, height: 200);

    bytes += generator.text("fp_bt_printer",
        styles: PosStyles(align: PosAlign.center, bold: true));

    bytes += generator.imageRaster(thumbnail, align: PosAlign.center);

    bytes += generator.reset();
    bytes += generator.setGlobalCodeTable('CP1252');
    bytes += generator.feed(1);
    bytes += generator.text("HELLO PRINTER by FPV",
        styles: PosStyles(align: PosAlign.center, bold: true));
    bytes += generator.qrcode("https://github.com/FranciscoPV94",
        size: QRSize.Size6);
    bytes += generator.feed(1);
    bytes += generator.feed(1);

    final resp = await printer.printData(bytes, address: address);

    print(resp.message);
    print("$address");
  }
}

注意事项

• 确保你的Android设备已经开启了蓝牙，并且已经与目标打印机进行了配对。
• 你可以在 assets 目录下放置一个名为 wz.png 的图片文件，并在 pubspec.yaml 中声明这个资源。
• 这个插件目前仅支持Android平台。

希望这个示例能帮助你快速上手使用 fp_bt_printer 插件来实现蓝牙打印功能！