使用flutter设计使用手机相机扫描二维码的页面，带控制按钮，写出支持空安全的代码，同时列出需要加载的依赖，不使用qr_code_scanner

好的，以下是使用 Flutter 设计支持空安全的扫描二维码页面的代码，同时带有控制按钮，并且不使用 `qr_code_scanner` 库。

首先，需要在 `pubspec.yaml` 文件中加载以下依赖：

dependencies:
  flutter:
    sdk: flutter
  camera: ^0.9.4
  path_provider: ^2.0.2
  permission_handler: ^8.0.0+2
  barcode_scan2: ^3.0.0-nullsafety.1

然后，我们就可以编写代码了。以下是一个简单的示例：

import 'dart:async';
import 'dart:io';

import 'package:barcode_scan2/barcode_scan2.dart';
import 'package:camera/camera.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
import 'package:permission_handler/permission_handler.dart';

class QRScannerPage extends StatefulWidget {
  @override
  _QRScannerPageState createState() => _QRScannerPageState();
}

class _QRScannerPageState extends State<QRScannerPage> {
  late CameraController _controller;
  late Future<void> _initializeControllerFuture;
  late String _scanResult;

  @override
  void initState() {
    super.initState();
    _initializeCamera();
  }

  Future<void> _initializeCamera() async {
    final cameras = await availableCameras();
    final camera = cameras.first;
    _controller = CameraController(
      camera,
      ResolutionPreset.medium,
    );
    _initializeControllerFuture = _controller.initialize();
    setState(() {});
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  Future<void> _scanQRCode() async {
    final result = await BarcodeScanner.scan();
    setState(() {
      _scanResult = result.rawContent;
    });
  }

  Future<void> _takePicture() async {
    if (!_controller.value.isInitialized) {
      return;
    }
    final Directory appDir = await getApplicationDocumentsDirectory();
    final String appDirPath = appDir.path;
    final String filePath = '$appDirPath/${DateTime.now().millisecondsSinceEpoch}.jpg';
    if (_controller.value.isTakingPicture) {
      return;
    }
    try {
      await _controller.takePicture(filePath);
      setState(() {});
    } on CameraException catch (e) {
      print(e);
    }
  }

  Future<void> _initializePermissions() async {
    final List<Permission> permissions = [
      Permission.camera,
      Permission.storage,
    ];
    final Map<Permission, PermissionStatus> status = await permissions.request();
    if (status[Permission.camera] != PermissionStatus.granted ||
        status[Permission.storage] != PermissionStatus.granted) {
      throw Exception('Permission denied');
    }
  }

  @override
  Widget build(BuildContext context) {
    if (_controller == null || !_controller.value.isInitialized) {
      return Container();
    }
    return Scaffold(
      appBar: AppBar(
        title: Text('扫描二维码'),
      ),
      body: Stack(
        alignment: Alignment.center,
        children: [
          CameraPreview(_controller),
          Positioned(
            bottom: 16,
            left: 16,
            child: Row(
              children: [
                FloatingActionButton(
                  onPressed: () async {
                    await _initializePermissions();
                    await _scanQRCode();
                  },
                  child: Icon(Icons.qr_code),
                ),
                SizedBox(width: 16),
                FloatingActionButton(
                  onPressed: () async {
                    await _initializePermissions();
                    await _initializeControllerFuture;
                    await _takePicture();
                  },
                  child: Icon(Icons.camera_alt),
                ),
              ],
            ),
          ),
          if (_scanResult != null)
            Positioned(
              top: 16,
              child: Container(
                padding: EdgeInsets.symmetric(horizontal: 16, vertical: 8),
                color: Colors.white.withOpacity(0.8),
                child: Text(
                  _scanResult,
                  style: TextStyle(fontSize: 16),
                ),
              ),
            ),
        ],
      ),
    );
  }
}

以上代码中，我们使用了 `camera` 库中的 `CameraController` 组件来展示相机预览和拍照，并在底部添加了两个按钮来控制扫描二维码和拍照。同时，我们使用了 `barcode_scan2` 库中的 `BarcodeScanner` 组件来实现二维码扫描，并在扫描成功后在屏幕顶部显示扫描结果。

希望这份代码对你有所帮助！