Flutter |如何从相机单击正方形图像并显示正方形图像

Question

[这里，我正在处理一个项目，在该项目中，我需要单击相机中的图像并在另一个屏幕中预览。所以我做到了。但是这里有些问题，我需要单击正方形图像并显示正方形图像，我已经尝试了很多解决方案，但是它不起作用。希望你理解这个问题。请帮我。您的小小的帮助可以使我过得愉快。

这是我的代码。

availableCameras().then((availableCameras) {
  cameras = availableCameras;

  if (cameras.length > 0) {
    setState(() {
      selectedCameraIdx = 0;
    });

    _initCameraController(cameras[selectedCameraIdx]).then((void v) {});
  } else {
    print("No camera available");
  }
}).catchError((err) {
  print('Error: $err.code\nError Message: $err.message');
});
//---------------------------------------------------------------------
    AspectRatio(
          aspectRatio: 1,
          child: ClipRect(
            child: Transform.scale(
              scale: 1 / controller.value.aspectRatio,
              child: Center(
                child: AspectRatio(
                  aspectRatio: controller.value.aspectRatio,
                  child: CameraPreview(controller),
                ),
              ),
            ),
          ),
        )

这是用于显示图像

Image.file(
   File(widget.imagePath),
 )

Answer 1

我希望，这是您想要的合适答案。

运行此代码：

import 'dart:async';
import 'dart:io';
import 'package:camera/camera.dart';
import 'package:flutter/material.dart';
import 'package:path/path.dart' show join;
import 'package:path_provider/path_provider.dart';

Future<void> 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(
    MyApp(firstCamera: firstCamera,)
  );
}



class MyApp extends StatelessWidget {
  final firstCamera;
  // This widget is the root of your application.
  MyApp({this.firstCamera});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      // routes: routes,
       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 {
  final CameraDescription camera;

  const TakePictureScreen({
    Key key,
    @required this.camera,
  }) : super(key: key);

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

class TakePictureScreenState extends State<TakePictureScreen> {
  CameraController _controller;
  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: Text('Take a picture')),
      // 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.

      //Camera View in square shape 
      body: Center(
        child: Container(
          height: 400,
          child: 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 Center(child: CircularProgressIndicator());
              }
            },
          ),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.camera_alt),
        // 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;

            // Construct the path where the image should be saved using the
            // pattern package.
            final path = join(
              // Store the picture in the temp directory.
              // Find the temp directory using the `path_provider` plugin.
              (await getTemporaryDirectory()).path,
              '${DateTime.now()}.png',
            );

            // Attempt to take a picture and log where it's been saved.
            await _controller.takePicture(path);

            // If the picture was taken, display it on a new screen.
            Navigator.push(
              context,
              MaterialPageRoute(
                builder: (context) => DisplayPictureScreen(imagePath: path),
              ),
            );
          } catch (e) {
            // If an error occurs, log the error to the console.
            print(e);
          }
        },
      ),
    );
  }
}

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

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: 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.

       //Captured in square shape 
      body: Center(
        child: Container(
          height: MediaQuery.of(context).size.height/2, //400
          //  width: MediaQuery.of(context).size.width/1.2,//400
           decoration: BoxDecoration(
             border: Border.all(color: Colors.red),
             image: DecorationImage(
               image: FileImage(File(imagePath)),
               fit: BoxFit.cover
              )
           ),
        ),
      )
    );
  }
}

方形摄像机视图：

以正方形视图捕获的图像：

Answer 2

您应为此功能使用图像裁剪器。当您从相机或图库中拍摄图像时，只需通过以下图像进行裁切：https://pub.dev/packages/image_cropper