Flutter打印管理插件x_printer的使用

Flutter打印管理插件x_printer的使用

介绍

x_printer 是一个用于Flutter的打印机插件，帮助开发者为iOS和Android平台构建蓝牙热敏打印机应用程序或功能。

功能

以下是 x_printer 插件的主要功能：

入门指南

要使用此插件，请按照以下步骤操作：

1. 在 pubspec.yaml 文件中添加依赖项：

   dependencies:
     flutter:
       sdk: flutter
     x_printer:
   

2. 添加蓝牙权限：

   • iOS： 在 ios/Runner/Info.plist 文件中添加以下权限：

     <dict>
       <key>NSBluetoothAlwaysUsageDescription</key>
       <string>需要蓝牙权限</string>
       <key>NSBluetoothPeripheralUsageDescription</key>
       <string>需要蓝牙权限</string>
       <key>NSLocationAlwaysAndWhenInUseUsageDescription</key>
       <string>需要位置权限</string>
       <key>NSLocationAlwaysUsageDescription</key>
       <string>需要位置权限</string>
       <key>NSLocationWhenInUseUsageDescription</key>
       <string>需要位置权限</string>
     </dict>
     

使用示例

以下是一个完整的示例代码，展示了如何使用 x_printer 插件进行蓝牙打印机的操作，包括扫描、连接、打印文本、打印图像和切纸等功能。

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:x_printer/x_printer.dart';
import 'package:image_picker/image_picker.dart';
import 'package:image/image.dart' as img;

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

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

  [@override](/user/override)
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  final _plugin = XPrinter();
  final contentController = TextEditingController();

  bool _isConnected = false;

  [@override](/user/override)
  void initState() {
    super.initState();

    WidgetsBinding.instance.addPostFrameCallback(
      (_) {
        _getCurrentState();
      },
    );

    // 监听打印机状态变化
    _plugin.statusStream.listen((event) {
      print(">>> status: ${event.status.name}");
      _getCurrentState();
    });
  }

  void _getCurrentState() {
    _plugin.isConnected.then((value) {
      print(">>> isConnected: $value");
      setState(() {
        _isConnected = value;
      });
    });
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('XPrinter Plugin Example'),
        ),
        body: Column(
          children: [
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceAround,
              children: [
                Expanded(
                  child: StreamBuilder<PrinterStatus>(
                    stream: _plugin.statusStream,
                    builder: (context, snapshot) {
                      if (snapshot.data == null) {
                        return Column(
                          children: [
                            _isConnected
                                ? const Text('已连接')
                                : const Text('未连接'),
                            if (_isConnected) _buildDisconnectButton(),
                          ],
                        );
                      }
                      return Column(
                        children: [
                          Text('${snapshot.data?.status.name}'),
                          if (snapshot.data?.status == PeripheralStatus.connected)
                            _buildDisconnectButton(),
                        ],
                      );
                    },
                  ),
                ),
                Expanded(
                  child: Builder(builder: (context) {
                    return TextButton(
                      onPressed: () {
                        Navigator.of(context).push(MaterialPageRoute(builder: (context) {
                          return SelectDevice(plugin: _plugin);
                        }));
                      },
                      child: const Text('选择设备'),
                    );
                  }),
                ),
              ],
            ),
            Padding(
              padding: const EdgeInsets.all(12.0),
              child: TextFormField(
                controller: contentController,
                decoration: const InputDecoration(
                  border: OutlineInputBorder(),
                  labelText: '内容',
                ),
                minLines: 2,
                maxLines: 5,
              ),
            ),
            Expanded(child: Container()),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceAround,
              children: [
                Expanded(
                  child: TextButton(
                    onPressed: _printText,
                    child: const Text('打印文本'),
                  ),
                ),
                Expanded(
                  child: TextButton(
                    onPressed: _selectImage,
                    child: const Text('打印图片'),
                  ),
                ),
              ],
            ),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceAround,
              children: [
                Expanded(
                  child: TextButton(
                    onPressed: _cutPaper,
                    child: const Text('切纸'),
                  ),
                ),
                Expanded(
                  child: TextButton(
                    onPressed: _printExample,
                    child: const Text('打印示例'),
                  ),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }

  TextButton _buildDisconnectButton() {
    return TextButton(
      onPressed: () {
        _plugin.disconnect();
      },
      child: const Text('断开连接'),
    );
  }

  void _printText() {
    _plugin.printText(contentController.text);
  }

  void _cutPaper() {
    _plugin.cutPaper();
  }

  void _printExample() {
    _plugin.printText('=======================================');
    _plugin.printText("左对齐");
    _plugin.printText(
      "居中",
      align: PTextAlign.center,
    );
    _plugin.printText(
      "右对齐",
      align: PTextAlign.right,
    );

    _plugin.printText('=======================================');
    _plugin.printText("字体B", attribute: PTextAttribute.fontB);
    _plugin.printText("加粗", attribute: PTextAttribute.bold);
    _plugin.printText(
      "下划线",
      attribute: PTextAttribute.underline,
    );
    _plugin.printText(
      "双下划线",
      attribute: PTextAttribute.underline2,
    );
    _plugin.printText('=======================================');
    _plugin.printText(
      "W1",
      width: PTextW.w2,
      height: PTextH.h2,
    );
    _plugin.printText(
      "W2",
      width: PTextW.w2,
      height: PTextH.h2,
    );
    _plugin.printText(
      "W3",
      width: PTextW.w3,
      height: PTextH.h3,
    );
    _plugin.printText(
      "W4",
      width: PTextW.w4,
      height: PTextH.h4,
    );

    _plugin.cutPaper();
  }

  void _selectImage() async {
    final ImagePicker picker = ImagePicker();

    final XFile? image = await picker.pickImage(source: ImageSource.gallery);
    if (image != null) {
      _printImage(image);
    }
  }

  void _printImage(XFile file) async {
    final img.Image? image = img.decodeImage(await file.readAsBytes());

    if (image != null) {
      // 调整图像大小以适应打印机
      final img.Image resizedImage = img.copyResize(image, width: 460);

      final List<int> compressedImage = img.encodePng(resizedImage);

      final String base64Image = base64Encode(compressedImage);

      _plugin.printImage(base64Image, width: 460);
      _plugin.cutPaper();
    } else {
      print('Failed to decode image');
    }
  }
}