Flutter Camera Preview not rotating with phone orientation

问题

I'm new to Dart/Flutter and currently using the Flutter Camera Plugin but I am running into a problem with the CameraPreview for when the phone turns to landscape mode. The images stay vertical and don't rotate the 90degrees with the phone.

I have tried countless things including Transform.rotate(), but I can't seem to get the image to both, fill the screen and rotate 90degrees.

The pictures that were taken while the phone was sideways still saved in the correct orientation when I view them, but using the _cameraPreviewWidget.

Normal

Landscape

回答1:

Adding SystemChrome.setPreferredOrientations() to my initState() & dispose() functions solved this problem for me.

  import 'package:flutter/services.dart';

  ...

  @override
  void initState() {
    super.initState();

    SystemChrome.setPreferredOrientations([
          DeviceOrientation.portraitUp,
          DeviceOrientation.portraitDown,
      ]);    
  }

  @override
  void dispose() {
    SystemChrome.setPreferredOrientations([
      DeviceOrientation.landscapeRight,
      DeviceOrientation.landscapeLeft,
      DeviceOrientation.portraitUp,
      DeviceOrientation.portraitDown,
    ]);
  }

回答2:

A package call camera_camera https://pub.dev/packages/camera_camera
has do great work and provide great feature you can reference his source code or fork directly.

about rotate issue, please use this package https://pub.dev/packages/native_device_orientation
and wrap body like this

return Scaffold(
      body: NativeDeviceOrientationReader(builder: (context) {
        NativeDeviceOrientation orientation =
            NativeDeviceOrientationReader.orientation(context);

you can reference full code at https://github.com/marslord/camera/blob/master/lib/cam.dart ,this is not camera_camera package and author use RotateBox

return RotatedBox(
          quarterTurns: turns,
          child: Transform.scale(
            scale: 1 / controller.value.aspectRatio,
            child: Center(
              child: AspectRatio(
                aspectRatio: controller.value.aspectRatio,
                child: CameraPreview(controller),
              ),
            ),
          ),
        );

camera_camera package use this at line 76

return NativeDeviceOrientationReader(
  useSensor: true,
  builder: (context) {
    NativeDeviceOrientation orientation =
        NativeDeviceOrientationReader.orientation(context);

about fit screen issue
camera_camera package do this with below code full code is here https://github.com/gabuldev/camera_camera/blob/master/lib/page/camera.dart

    return widget.mode ==
              CameraMode.fullscreen
          ? OverflowBox(
              maxHeight: size.height,
              maxWidth: size.height *
                  previewRatio,
              child: CameraPreview(
                  bloc.controllCamera),
            )
          : AspectRatio(
              aspectRatio: bloc
                  .controllCamera
                  .value
                  .aspectRatio,
              child: CameraPreview(
                  bloc.controllCamera),
            );

execute result of camera_camera package can found on his github

execute result of https://github.com/marslord/camera

both check with real device and works

official camera plugin example rotate image can work with combine Native_device_orientation and RotateBox , you can reference https://github.com/marslord/camera/blob/master/lib/cam.dart
but official camera plugin example fit screen issue will need to modify layout code

I would suggest use camera_camera's method, Stack CameraPreview and Button. it looks more like Native Camera App and easy to maintain landscape mode

official camera plugin example rotate image code snippet with combine Native_device_orientation and RotateBox

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: _scaffoldKey,
      appBar: AppBar(
        title: const Text('Camera example'),
      ),
      body: NativeDeviceOrientationReader(builder: (context) {

        NativeDeviceOrientation orientation =
        NativeDeviceOrientationReader.orientation(context);

        int turns;
        switch (orientation) {
          case NativeDeviceOrientation.landscapeLeft:
            turns = -1;
            break;
          case NativeDeviceOrientation.landscapeRight:
            turns = 1;
            break;
          case NativeDeviceOrientation.portraitDown:
            turns = 2;
            break;
          default:
            turns = 0;
            break;
        }

        return Column(
          children: <Widget>[
            Expanded(
              child: RotatedBox(
                quarterTurns: turns,
                child: Transform.scale(
                  scale: 1 / controller.value.aspectRatio,
                  child: Container(
                    child: Padding(
                      padding: const EdgeInsets.all(1.0),
                      child: AspectRatio(
                        aspectRatio: controller.value.aspectRatio,
                        child: Center(
                          child: _cameraPreviewWidget(),
                        ),
                      ),
                    ),

回答3:

When you rotate your phone while using a camera the preview will stay vertical, however when you view the image it will be in landscape, try with the default camera app and it would be the same

You can obviously rotate your UI that is on top of the camera preview when the phone rotates

来源：https://stackoverflow.com/questions/50633608/flutter-camera-preview-not-rotating-with-phone-orientation