CODEWITHSUNDEEP
flutterdartflutter-dependencies
Mohit Jha
Mohit Jha

Reputation: 79

Unable to load cameras from android emulator in flutter

I am trying to use the camera plugin for flutter.

I call availableCameras() in the main function of the app, as I have seen in documentation like this:

List<CameraDescription> cameras;
Future<void> main() async {
  try {
    cameras = await availableCameras();
  } catch (e) {
    print("Error: $e");
  }
  runApp(MyApp());
}

The try statement fails instantly printing

Error: Null check operator used on a null value

I call Home() in MyApp(), which has a tabbed navigator, which calls FaceAScreen() like this:

return Scaffold(
  appBar: buildAppBar(),
  bottomNavigationBar: BottomNavBar(tabController: _tabController, myTabs: myTabs),
  body: TabBarView(
    controller: _tabController,
    children: <Widget>[Body(), FaceAScreen(cameras: widget.cameras)],
  ),
);

I want the Camera in the FaceAScreen() page, but it shows, expectedly, "No Camera!" text, since the List cameras is null.

The code build method for FaceAScreen() is:

@override
Widget build(BuildContext context) {
  if (!isDetecting) {
    return Center(
      child: Container(
        margin: EdgeInsets.all(10),
          child: Text("No cameras!"),
      ),
    );
  }
  // This is not what causes the no camera to show on the page
  if (!controller.value.isInitialized) {
    return Container(child: Text("No cameras"));
  }

  return AspectRatio(
    aspectRatio: controller.value.aspectRatio,
    child: CameraPreview(controller),
  );
}

I have looked at the null value error relentlessly and have upgraded my flutter package from the terminal many times, including running flutter clean. Flutter doctor shows everything is fine. I also have double checked the settings on my android emulator and have front facing set to webcam0 and back facing as "emulated". I checked opening the camera app in the emulator and that works. All the tutorials seem to write use the availableCameras() method exactly as I did (without the try catch even). Any help would be great, thanks!

Upvotes: 1

Views: 2994

Answers (1)

Ουιλιαμ Αρκευα
Ουιλιαμ Αρκευα

Reputation: 6239

Recently I finished a tutorial, which uses camera and works fine. The code below can be of help to you:

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


class CameraPage extends StatefulWidget {
  CameraPage({Key key}) : super(key: key);

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

/* ============================================================================================= */

class _CameraPageState extends State<CameraPage> {
  List<CameraDescription> _cameras;
  CameraController _controller;
  var _isReady = false;
  /* ---------------------------------------------------------------------------- */
  @override
  void initState() {
    super.initState();
    _setUpCamera();
  }
  /* ---------------------------------------------------------------------------- */
  void _setUpCamera() async {
    try {
      // initialize cameras
      _cameras = await availableCameras();
      // initialize camera controllers
      // Current bug for high/medium with Samsung devices
      _controller = CameraController(_cameras[0], ResolutionPreset.medium);
      await _controller.initialize();
    } on CameraException catch (_) {
      // do something on error
    }

    if (mounted) setState(() => _isReady = true);
  }
  /* ---------------------------------------------------------------------------- */
  Widget cameraPreview() {
    return AspectRatio(
      aspectRatio: _controller.value.aspectRatio,
      child: CameraPreview(_controller),
    );
  }
  /* ---------------------------------------------------------------------------- */
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.black,
      floatingActionButton: getFooter(),
      body: getBody(),
    );
  }
  /* ---------------------------------------------------------------------------- */
  Widget getBody() {
    final size = MediaQuery.of(context).size;
    var flag = !_isReady || _controller == null || !_controller.value.isInitialized;

    return Container(
      decoration: flag ? BoxDecoration(color: Colors.white) : null,
      width: size.width,
      height: size.height,
      child: flag 
        ? Center(
          child: SizedBox(
            width: 25,
            height: 25,
            child: CircularProgressIndicator(strokeWidth: 3),
          ),
        )
        : ClipRRect(
          borderRadius: BorderRadius.only(
            bottomLeft: Radius.circular(10),
            bottomRight: Radius.circular(10),
          ),
          child: cameraPreview(),
        ),
    );
  }
.....
}

Obviously your Android device emulator must have enabled cameras and SD Card.

Upvotes: 1

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