Flutter 拍照

 

添加相關依賴套件 （dependencies）

在調用照相機前，我們會需要將下列三個相關依賴添加於 pubspec.yaml 當中。
camera: 提供與設備照相機相關工具
path_provider: 查詢正確路徑儲存照片
path: 建立在任何平台上都可運作的路徑

dependencies:
  flutter:
    sdk: flutter
  camera:
  path_provider:
  path:    

根據 Flutter 官方教學文件

Tip:

• For android, You must have to update minSdkVersion to 21 (or higher).
• On iOS, lines below have to be added inside ios/Runner/Info.plist in order the access the camera.

• <key>NSCameraUsageDescription</key>
  <string>Explanation on why the camera access is needed.</string>

minSdkVersion 必須在21以上

為了解決這個問題，我們必須修改 Flutter 專案中 Android 的最低 SDK 版本。

在 Flutter 專案中，我們要修改的文件路徑為 PROJECT_NAME/android/app/build.gradle

def localProperties = new Properties()
def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader('UTF-8') { reader ->
        localProperties.load(reader)
    }
}

def flutterRoot = localProperties.getProperty('flutter.sdk')
if (flutterRoot == null) {
    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
}

def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
    flutterVersionCode = '1'
}

def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
    flutterVersionName = '1.0'
}

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"

android {
    compileSdkVersion flutter.compileSdkVersion

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    kotlinOptions {
        jvmTarget = '1.8'
    }

    sourceSets {
        main.java.srcDirs += 'src/main/kotlin'
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId "com.example.untitled"
        minSdkVersion 21 //flutter.minSdkVersion
        targetSdkVersion 30 //flutter.targetSdkVersion
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }

    buildTypes {
        release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }
    }
}

flutter {
    source '../..'
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
}

將minSdkVersion 修改為 21（或任何你需要的版本號）

main.dart

import 'package:flutter/material.dart';
import 'package:untitled1/TakePictureScreen.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: _mainbody(),
      ),
    );
  }
}

class _mainbody extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: RaisedButton(
        child: Text("Camera"),
        onPressed: () {
          takePictureScreen_main();
        },
      ),
    );
  }
}

TakePictureScreen.dart

import 'dart:async';
import 'dart:io';
import 'package:camera/camera.dart';
import 'package:flutter/material.dart';

Future<void> takePictureScreen_main() async {
  // Ensure that plugin services are initialized so that `availableCameras()`
  // can be called before `runApp()`
  WidgetsFlutterBinding.ensureInitialized();

  // Obtain a list of the available cameras on the device.
  final cameras = await availableCameras();

  // Get a specific camera from the list of available cameras.
  final firstCamera = cameras.first;

  runApp(
    MaterialApp(
      theme: ThemeData.dark(),
      home: TakePictureScreen(
        // Pass the appropriate camera to the TakePictureScreen widget.
        camera: firstCamera,
      ),
    ),
  );
}

// A screen that allows users to take a picture using a given camera.
class TakePictureScreen extends StatefulWidget {
  const TakePictureScreen({
    Key? key,
    required this.camera,
  }) : super(key: key);

  final CameraDescription camera;

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

class TakePictureScreenState extends State<TakePictureScreen> {
  late CameraController _controller;
  late Future<void> _initializeControllerFuture;

  @override
  void initState() {
    super.initState();
    // To display the current output from the Camera,
    // create a CameraController.
    _controller = CameraController(
      // Get a specific camera from the list of available cameras.
      widget.camera,
      // Define the resolution to use.
      ResolutionPreset.medium,
    );

    // Next, initialize the controller. This returns a Future.
    _initializeControllerFuture = _controller.initialize();
  }

  @override
  void dispose() {
    // Dispose of the controller when the widget is disposed.
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Take a picture')),
      // You must wait until the controller is initialized before displaying the
      // camera preview. Use a FutureBuilder to display a loading spinner until the
      // controller has finished initializing.
      body: FutureBuilder<void>(
        future: _initializeControllerFuture,
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.done) {
            // If the Future is complete, display the preview.
            return CameraPreview(_controller);
          } else {
            // Otherwise, display a loading indicator.
            return const Center(child: CircularProgressIndicator());
          }
        },
      ),
      floatingActionButton: FloatingActionButton(
        // Provide an onPressed callback.
        onPressed: () async {
          // Take the Picture in a try / catch block. If anything goes wrong,
          // catch the error.
          try {
            // Ensure that the camera is initialized.
            await _initializeControllerFuture;

            // Attempt to take a picture and get the file `image`
            // where it was saved.
            final image = await _controller.takePicture();

            // If the picture was taken, display it on a new screen.
            await Navigator.of(context).push(
              MaterialPageRoute(
                builder: (context) => DisplayPictureScreen(
                  // Pass the automatically generated path to
                  // the DisplayPictureScreen widget.
                  imagePath: image.path,
                ),
              ),
            );
          } catch (e) {
            // If an error occurs, log the error to the console.
            print(e);
          }
        },
        child: const Icon(Icons.camera_alt),
      ),
    );
  }
}

// A widget that displays the picture taken by the user.
class DisplayPictureScreen extends StatelessWidget {
  final String imagePath;

  const DisplayPictureScreen({Key? key, required this.imagePath})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Display the Picture')),
      // The image is stored as a file on the device. Use the `Image.file`
      // constructor with the given path to display the image.
      body: Image.file(File(imagePath)),
    );
  }
}

參考:

• [Flutter] 如何使用照相機拍照、展示圖片

截錄 :

• [Flutter] 如何使用照相機拍照、展示圖片
• [已解決][Flutter] Manifest merger failed : uses-sdk:minSdkVersion 16 cannot be smaller than version 21 declared in library [:camera]