flutter 中拉伸的相机预览

Question

I have set the camera preview be full-screen to meet a particular UI, however the camera is full-screen, but it is very stretched.

Where am I going wrong?

final size = MediaQuery.of(context).size;
    final deviceRatio = size.width / size.height;
    return Stack(children: <Widget>[
      Center(
        child: Transform.scale(
          scale: controller.value.aspectRatio / deviceRatio,
          child: new AspectRatio(
            aspectRatio: controller.value.aspectRatio,
            child: new CameraPreview(controller),
          ),
        ),
      ),
    ]);
  }

I have attached a photo below. AS you can see, it is very blurred, and stretched, when compared against the button.

EDIT: Here is the error I am receiving:

NoSuchMethodError: The Method '[]' was called on Null.
Receiver: null
Tried calling: [](0)

EDIT - Here is the full camera page,

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

import 'MyApp/main.dart';

List<CameraDescription> cameras;

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();

  cameras = await availableCameras();
  runApp(MyApp());
}

class Camera extends StatefulWidget {
  Function setData;
  Camera({Key key, this.setData}) : super(key: key);

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

class _CameraScreenState extends State<Camera> {
  CameraController controller;
  List cameras;
  int selectedCameraIndex;
  String imgPath;
  var image;

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

  @override
  void dispose() {
    controller?.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    if (!controller.value.isInitialized) {
      return Container();
    }
    return MaterialApp(
      home: CameraPreview(controller),
    );
  }
}

Answer 1

Your screen resolution doesn't necessarily match you camera resolution, you should use camera's resolution and aspect ratio to get proper image.

Take a look at the aspectRatio property that you can get from CameraValue after initialization.

---

UPDATE:

Actually, you don't even need aspectRatio . You can just use the DevicePreview directly. If the parent widget is fullscreen, the preview will be fullscreen as well. Eg the official example in camera package is rendered like that:

Example code:

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

List<CameraDescription> cameras;

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();

  cameras = await availableCameras();
  runApp(CameraApp());
}

class CameraApp extends StatefulWidget {
  @override
  _CameraAppState createState() => _CameraAppState();
}

class _CameraAppState extends State<CameraApp> {
  CameraController controller;

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

  @override
  void dispose() {
    controller?.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    if (!controller.value.isInitialized) {
      return Container();
    }
    return MaterialApp(
      home: CameraPreview(controller),
    );
  }
}