Flutter 如何将摄像头图像保存到 DCIM 文件夹？

2024-03-01 02:30:19

Flutter中将摄像头图像保存到DCIM文件夹的全面指南

引言

在Flutter应用中，将摄像头拍摄的图像保存到特定的文件夹（如DCIM）中非常重要。这样可以确保图像以组织良好的方式存储，便于用户查找和管理。本文将深入探讨如何在Flutter中将摄像头图像保存到DCIM文件夹。

步骤详解

1. 请求存储权限

在访问设备存储之前，我们需要请求存储权限。我们可以使用permission_handler插件来完成此操作：

Future<void> _requestStoragePermission() async {
  final status = await Permission.storage.request();
  print('Permission status: $status');
}

2. 创建目标文件夹

接下来，我们需要使用path_provider插件获取外部存储目录，并创建目标文件夹DCIM/AppTestPhotos：

Future<void> _createDCIMFolder() async {
  final Directory? extDir = await getExternalStorageDirectory();
  if (extDir != null) {
    final String dirPath = '${extDir.path}/DCIM/AppTestPhotos';
    await Directory(dirPath).create(recursive: true);
    print('DCIM folder created at: $dirPath');
  }
}

3. 保存图像

在拍摄图像后，我们可以使用XFile.saveTo方法将图像保存到目标文件夹：

floatingActionButton: FloatingActionButton(
  child: const Icon(Icons.camera),
  onPressed: () async {
    final XFile photo = await controller.takePicture();
    final Directory? extDir = await getExternalStorageDirectory();
    if (extDir != null) {
      final String dirPath = '${extDir.path}/DCIM/AppTestPhotos';
      await Directory(dirPath).create(recursive: true);
      final String filePath = '$dirPath/${DateTime.now()}.jpg';
      await photo.saveTo(filePath);
      print('Picture saved at: $filePath');
    }
  },
),

完整代码示例

以下是如何将摄像头图像保存到DCIM/AppTestPhotos文件夹的完整代码示例：

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

List<CameraDescription> cameras = [];

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  cameras = await availableCameras();
  runApp(const CameraApp());
}

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

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

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

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

class _CameraScreenState extends State<CameraScreen> {
  late CameraController controller;
  bool showFocusCircle = false;
  double x = 0;
  double y = 0;

  @override
  void initState() {
    super.initState();
    controller = CameraController(cameras[0], ResolutionPreset.medium);
    controller.initialize().then((_) {
      if (!mounted) {
        return;
      }
      setState(() {});
    });
  }

  @override
  Widget build(BuildContext context) {
    if (!controller.value.isInitialized) {
      return Container();
    }
    return Scaffold(
      appBar: AppBar(title: const Text('Take a picture')),
      body: GestureDetector(
        onTapUp: (details) {
          _onTap(details);
        },
        child: Stack(
          children: [
            Center(child: CameraPreview(controller)),
            if (showFocusCircle)
              Positioned(
                top: y - 20,
                left: x - 20,
                child: Container(
                  height: 40,
                  width: 40,
                  decoration: BoxDecoration(
                    shape: BoxShape.circle,
                    border: Border.all(color: Colors.white, width: 1.5),
                  ),
                ),
              ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        child: const Icon(Icons.camera),
        onPressed: () async {
          final XFile photo = await controller.takePicture();
          final Directory? extDir = await getExternalStorageDirectory();
          if (extDir != null) {
            final String dirPath = '${extDir.path}/DCIM/AppTestPhotos';
            await Directory(dirPath).create(recursive: true);
            final String filePath = '$dirPath/${DateTime.now()}.jpg';
            await photo.saveTo(filePath);
            print('Picture saved at: $filePath');
          }
        },
      ),
    );
  }

  Future<void> _onTap(TapUpDetails details) async {
    if (controller.value.isInitialized) {
      showFocusCircle = true;
      x = details.localPosition.dx;
      y = details.localPosition.dy;
      double fullWidth = MediaQuery.of(context).size.width;
      double cameraHeight = fullWidth * controller.value.aspectRatio;
      double xp = x / fullWidth;
      double yp = y / cameraHeight;
      Offset point = Offset(xp, yp);
      await controller.setFocusPoint(point);
      setState(() {
        Future.delayed(const Duration(seconds: 2)).whenComplete(() {
          setState(() {
            showFocusCircle = false;
          });
        });
      });
    }
  }
}

Future<void> _requestStoragePermission() async {
  final status = await Permission.storage.request();
  print('Permission status: $status');
}