How to fix wrong rotation of photo from camera in flutter?

问题

I'm taking a photo with the newest camera plugin version and I'm using code from flutter example. This is how I pick a camera:

final cameras = await availableCameras();
final firstCamera = cameras.first;

This is inside init:

_cameraController = CameraController(
  widget.camera,
  ResolutionPreset.medium,
  enableAudio: false,
);

This is the rest of the relevant code:

Future _takePhoto(BuildContext context) async {
  try {
    await _initializeControllerFuture;
    final path = join(
      (await getTemporaryDirectory()).path,
      '${DateTime.now()}.png',
    );

    await _cameraController.takePicture(path);

    setState(() {
      _imagePath = path;
    });
  } catch (e) {
    print(e);
  }
}

Afterwards, I show the photo to the user with Image.file(File(_imagePath)) and later I send the photo to API. The problem is that the photo is sometimes captured with a wrong orientation. (I'm sure about this because the photo is also rotated in the database.) For example, on 3 years old Xiaomi phone, it works flawlessly, but on a certain new Samsung phone, the photo is always rotated.

How to make sure that the rotation is always correct? (Even on ios devices)

回答1:

You can use package https://pub.dev/packages/flutter_exif_rotation
Support iOS and Android
In some devices the exif data shows picture in landscape mode when they're actually in portrait.
This plugin fixes the orientation for pictures taken with those devices.

For Android
Add this in your AndroidManifest.xml

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

code snippet

image = await FlutterExifRotation.rotateImage(path: image.path);

//Note : iOS not implemented
image = await FlutterExifRotation.rotateAndSaveImage(path: image.path);

回答2:

This is my solution that works cross-platform and doesn't use plugins.

import 'dart:io';
import 'package:exif/exif.dart';
import 'package:image/image.dart' as img;

Future<File> fixExifRotation(String imagePath) async {
    final originalFile = File(imagePath);
    List<int> imageBytes = await originalFile.readAsBytes();

    final originalImage = img.decodeImage(imageBytes);

    final height = originalImage.height;
    final width = originalImage.width;

    // Let's check for the image size
    // This will be true also for upside-down photos but it's ok for me
    if (height >= width) {
      // I'm interested in portrait photos so
      // I'll just return here
      return originalFile;
    }

    // We'll use the exif package to read exif data
    // This is map of several exif properties
    // Let's check 'Image Orientation'
    final exifData = await readExifFromBytes(imageBytes);

    img.Image fixedImage;

    if (height < width) {
      logger.logInfo('Rotating image necessary');
      // rotate
      if (exifData['Image Orientation'].printable.contains('Horizontal')) {
        fixedImage = img.copyRotate(originalImage, 90);
      } else if (exifData['Image Orientation'].printable.contains('180')) {
        fixedImage = img.copyRotate(originalImage, -90);
      } else if (exifData['Image Orientation'].printable.contains('CCW')) {
        fixedImage = img.copyRotate(originalImage, 180);
      } else {
        fixedImage = img.copyRotate(originalImage, 0);
      }
    }

    // Here you can select whether you'd like to save it as png
    // or jpg with some compression
    // I choose jpg with 100% quality
    final fixedFile =
        await originalFile.writeAsBytes(img.encodeJpg(fixedImage));

    return fixedFile;
  }

Source

来源：https://stackoverflow.com/questions/60176001/how-to-fix-wrong-rotation-of-photo-from-camera-in-flutter

标签

Flutter

dart

android-camera