Flutter功能扩展插件zebrautil的使用

Flutter 功能扩展插件 zebrautil 的使用

Zebra utility 是一个在 Flutter 项目中轻松操作斑马打印机的插件。

功能介绍

• 在 Android 和 iOS 中发现蓝牙和 Wi-Fi 打印机。
• 连接和断开打印机连接。
• 设置介质类型、对比度、校准命令（无需编写任何 ZPL 代码）。
• 旋转 ZPL 而不改变 ZPL 代码。

安装

Android

在 build.gradle 文件的 Android 块中添加以下代码：

android {
    packagingOptions {
        exclude 'META-INF/LICENSE.txt'
        exclude 'META-INF/NOTICE.txt'
        exclude 'META-INF/NOTICE'
        exclude 'META-INF/LICENSE'
        exclude 'META-INF/DEPENDENCIES'
    }
}

在 AndroidManifest.xml 中添加必要的权限：

<uses-permission android:name="android.permission.BLUETOOTH_SCAN" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

iOS

在 Info.plist 文件中添加 Supported external accessory protocols 并添加 com.zebra.rawport。同时添加 Privacy - Local Network Usage Description：

<key>UISupportedExternalAccessoryProtocols</key>
<array>
    <string>com.zebra.rawport</string>
</array>

<key>NSLocalNetworkUsageDescription</key>
<string>Your description here</string>

示例

入门指南

首先，创建一个 FutureBuilder 来获取打印机实例：

FutureBuilder(
  future: ZebraUtil.getPrinterInstance(), // 异步获取打印机实例
  builder: (context, snapshot) {
    if (!snapshot.hasData) {
      return const Center(
        child: CircularProgressIndicator(),
      );
    }
    final zebraPrinter = snapshot.data as ZebraPrinter;
    return PrinterTemplate(zebraPrinter);
  },
),

你可以为 onDiscoveryError 或 onPermissionDenied 添加回调函数：

zebraPrinter.onDiscoveryError =  (errorCode, errorText) {
  print("Error: $errorCode, $errorText");
};
zebraPrinter.onPermissionDenied = () {
  print("Permission denied");
};

方法

配置完实例后，可以使用以下方法开始搜索可用设备：

zebraPrinter.startScanning();

如果要停止扫描，调用：

zebraPrinter.stopScanning();

使用 ZebraController 监听并显示任何设备：

ListenableBuilder(
  listenable: zebraPrinter.controller,
  builder: (context, child) {
    final printers = zebraPrinter.controller.printers;
    if (printers.isEmpty) {
      return _getNotAvailablePage();
    }
    return _getListDevices(printers);
  },
)

连接到打印机时，传递 IP 地址（Wi-Fi 打印机）或 MAC 地址（蓝牙打印机）给 connectToPrinter 方法：

zebraPrinter.connectToPrinter("192.168.47.50");

设置介质类型：

zebraPrinter.setMediaType(EnumMediaType.BlackMark);

校准打印机：

zebraPrinter.calibratePrinter();

设置对比度：

zebraPrinter.setDarkness(25);

打印 ZPL 代码：

zebraPrinter.print("Your ZPL");

旋转 ZPL：

zebraPrinter.rotate();

断开与打印机的连接：

zebraPrinter.disconnect();

注意事项

一旦连接到打印机，可能无法通过扫描找到它。建议在成功连接打印机后停止扫描，直到问题解决。

示例代码

import 'package:flutter/material.dart';
import 'package:zebrautil/zebra_device.dart';
import 'package:zebrautil/zebra_printer.dart';
import 'package:zebrautil/zebra_util.dart';

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

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

  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: FutureBuilder(
        future: ZebraUtil.getPrinterInstance(),
        builder: (context, snapshot) {
          if (!snapshot.hasData) {
            return const Center(
              child: CircularProgressIndicator(),
            );
          }
          final printer = snapshot.data as ZebraPrinter;
          return PrinterTemplate(printer);
        },
      ),
    );
  }
}

class PrinterTemplate extends StatefulWidget {
  const PrinterTemplate(this.printer, {super.key});
  final ZebraPrinter printer;

  [@override](/user/override)
  State<PrinterTemplate> createState() => _PrinterTemplateState();
}

class _PrinterTemplateState extends State<PrinterTemplate> {
  late ZebraPrinter zebraPrinter;
  late ZebraController controller;
  final String dataToPrint = """^XA
        ^FX Top section with logo, name and address.
        ^CF0,60
        ^FO50,50^GB100,100,100^FS
        ^FO75,75^FR^GB100,100,100^FS
        ^FO93,93^GB40,40,40^FS
        ^FO220,50^FDIntershipping, Inc.^FS
        ^CF0,30
        ^FO220,115^FD1000 Shipping Lane^FS
        ^FO220,155^FDShelbyville TN 38102^FS
        ^FO220,195^FDUnited States (USA)^FS
        ^FO50,250^GB700,3,3^FS
        ^XZ""";

  [@override](/user/override)
  void initState() {
    zebraPrinter = widget.printer;
    controller = zebraPrinter.controller;
    zebraPrinter.startScanning();
    super.initState();
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Column(
            children: [
              const Text("My Printers"),
              if (zebraPrinter.isScanning)
                const Text(
                  "Seaching for printers...",
                  style: TextStyle(color: Colors.grey, fontSize: 12),
                ),
            ],
          ),
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () {
            if (zebraPrinter.isScanning) {
              zebraPrinter.stopScanning();
            } else {
              zebraPrinter.startScanning();
            }
            setState(() {});
          },
          child: Icon(
              zebraPrinter.isScanning ? Icons.stop_circle : Icons.play_circle),
        ),
        body: ListenableBuilder(
          listenable: controller,
          builder: (context, child) {
            final printers = controller.printers;
            if (printers.isEmpty) {
              return _getNotAvailablePage();
            }
            return _getListDevices(printers);
          },
        ));
  }

  Widget _getListDevices(List<ZebraDevice> printers) {
    return ListView.builder(
        itemBuilder: (BuildContext context, int index) {
          return ListTile(
            title: Text(printers[index].name),
            subtitle: Text(printers[index].status,
                style: TextStyle(color: printers[index].color)),
            leading: IconButton(
              icon: Icon(Icons.print, color: printers[index].color),
              onPressed: () {
                zebraPrinter.print(data: dataToPrint);
              },
            ),
            trailing: IconButton(
              icon: Icon(Icons.bluetooth_connected_rounded,
                  color: printers[index].color),
              onPressed: () {
                zebraPrinter.connectToPrinter(printers[index].address);
              },
            ),
          );
        },
        itemCount: printers.length);
  }

  SizedBox _getNotAvailablePage() {
    return const SizedBox(
      width: double.infinity,
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.center,
        mainAxisSize: MainAxisSize.max,
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Text("Printers not found"),
        ],
      ),
    );
  }
}