fix: correct android preview orientation

android/build.gradle

@@ -2,7 +2,7 @@ group 'dev.steenbakker.mobile_scanner'
 version '1.0-SNAPSHOT'
 
 buildscript {
-    ext.kotlin_version = '1.7.22'
+    ext.kotlin_version = '1.8.0'
     repositories {
         google()
         mavenCentral()
@@ -29,7 +29,7 @@ android {
         namespace 'dev.steenbakker.mobile_scanner'
     }
 
-    compileSdk 34
+    compileSdk 35
 
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_1_8

android/src/main/kotlin/dev/steenbakker/mobile_scanner/MobileScanner.kt

@@ -638,7 +638,7 @@ class MobileScanner(
         }
         val paint = Paint().apply { colorFilter = ColorMatrixColorFilter(colorMatrix) }
 
-        val invertedBitmap = Bitmap.createBitmap(bitmap.width, bitmap.height, bitmap.config)
+        val invertedBitmap = Bitmap.createBitmap(bitmap.width, bitmap.height, bitmap.config!!)
         val canvas = Canvas(invertedBitmap)
         canvas.drawBitmap(bitmap, 0f, 0f, paint)
 

android/src/main/kotlin/dev/steenbakker/mobile_scanner/MobileScannerHandler.kt

@@ -191,7 +191,7 @@ class MobileScannerHandler(
                         "textureId" to it.id,
                         "size" to mapOf("width" to it.width, "height" to it.height),
                         "naturalDeviceOrientation" to it.naturalDeviceOrientation,
-                        "isPreviewPreTransformed" to it.isPreviewPreTransformed,
+                        "handlesCropAndRotation" to it.handlesCropAndRotation,
                         "sensorOrientation" to it.sensorOrientation,
                         "currentTorchState" to it.currentTorchState,
                         "numberOfCameras" to it.numberOfCameras,

android/src/main/kotlin/dev/steenbakker/mobile_scanner/objects/MobileScannerStartParameters.kt

@@ -5,7 +5,7 @@ class MobileScannerStartParameters(
     val height: Double,
     val naturalDeviceOrientation: String,
     val sensorOrientation: Int,
-    val isPreviewPreTransformed: Boolean,
+    val handlesCropAndRotation: Boolean,
     val currentTorchState: Int,
     val id: Long,
     val numberOfCameras: Int,

example/android/.gitignore

@@ -11,3 +11,5 @@ GeneratedPluginRegistrant.java
 key.properties
 **/*.keystore
 **/*.jks
+
+**/.cxx

example/android/app/build.gradle

@@ -24,7 +24,7 @@ if (flutterVersionName == null) {
 
 android {
     namespace "dev.steenbakker.mobile_scanner_example"
-    compileSdk 34
+    compileSdk 35
 
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_17
@@ -43,7 +43,8 @@ android {
         // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
         applicationId "dev.steenbakker.mobile_scanner_example"
         minSdkVersion 24
-        targetSdkVersion 34
+        targetSdkVersion 35
+        ndkVersion flutter.ndkVersion
         versionCode flutterVersionCode.toInteger()
         versionName flutterVersionName
     }

example/pubspec.yaml

@@ -19,7 +19,7 @@ dependencies:
   flutter:
     sdk: flutter
 
-  image_picker: ^1.0.4
+  image_picker: ^1.1.2
   mobile_scanner:
     # When depending on this package from a real application you should use:
     #   mobile_scanner: ^x.y.z

lib/src/method_channel/android_surface_producer_delegate.dart

@@ -1,7 +1,4 @@
-import 'dart:async';
-
 import 'package:flutter/services.dart';
-import 'package:flutter/widgets.dart';
 import 'package:mobile_scanner/src/enums/camera_facing.dart';
 import 'package:mobile_scanner/src/enums/mobile_scanner_error_code.dart';
 import 'package:mobile_scanner/src/mobile_scanner_exception.dart';
@@ -12,10 +9,10 @@ import 'package:mobile_scanner/src/utils/parse_device_orientation_extension.dart
 class AndroidSurfaceProducerDelegate {
   /// Construct a new [AndroidSurfaceProducerDelegate].
   AndroidSurfaceProducerDelegate({
-    required this.cameraIsFrontFacing,
-    required this.isPreviewPreTransformed,
-    required this.naturalOrientation,
-    required this.sensorOrientation,
+    required this.cameraFacingDirection,
+    required this.handlesCropAndRotation,
+    required this.initialDeviceOrientation,
+    required this.sensorOrientationDegrees,
   });
 
   /// Construct a new [AndroidSurfaceProducerDelegate]
@@ -28,18 +25,19 @@ class AndroidSurfaceProducerDelegate {
   ) {
     if (config
         case {
-          'isPreviewPreTransformed': final bool isPreviewPreTransformed,
+          'handlesCropAndRotation': final bool handlesCropAndRotation,
           'naturalDeviceOrientation': final String naturalDeviceOrientation,
-          'sensorOrientation': final int sensorOrientation
+          'sensorOrientation': final int sensorOrientation,
         }) {
       final DeviceOrientation naturalOrientation =
           naturalDeviceOrientation.parseDeviceOrientation();
 
       return AndroidSurfaceProducerDelegate(
-        cameraIsFrontFacing: cameraDirection == CameraFacing.front,
-        isPreviewPreTransformed: isPreviewPreTransformed,
-        naturalOrientation: naturalOrientation,
-        sensorOrientation: sensorOrientation,
+        cameraFacingDirection: cameraDirection,
+        handlesCropAndRotation: handlesCropAndRotation,
+        initialDeviceOrientation: naturalOrientation,
+        // FIXME: This is bad, will cause a flash/frame in the wrong rotation if started in another rotation.
+        sensorOrientationDegrees: sensorOrientation.toDouble(),
       );
     }
 
@@ -51,127 +49,17 @@ class AndroidSurfaceProducerDelegate {
     );
   }
 
-  /// The rotation degrees corresponding to each device orientation.
-  static const Map<DeviceOrientation, int> _degreesForDeviceOrientation =
-      <DeviceOrientation, int>{
-    DeviceOrientation.portraitUp: 0,
-    DeviceOrientation.landscapeRight: 90,
-    DeviceOrientation.portraitDown: 180,
-    DeviceOrientation.landscapeLeft: 270,
-  };
-
-  // TODO: remove this flag once the rotation correction functions correctly on Impeller.
-  // See https://github.com/juliansteenbakker/mobile_scanner/pull/1283#discussion_r1927798329
-  static const bool _rotationCorrectionEnabled = false;
-
-  /// The subscription that listens to device orientation changes.
-  StreamSubscription<Object?>? _deviceOrientationSubscription;
-
-  /// Whether the current camera is a front facing camera.
-  ///
-  /// This is used to determine whether the orientation correction
-  /// should apply an additional correction for front facing cameras.
-  final bool cameraIsFrontFacing;
-
-  /// The current orientation of the device.
-  ///
-  /// When the orientation changes this field is updated by notifications from
-  /// the [_deviceOrientationSubscription].
-  DeviceOrientation? currentDeviceOrientation;
-
-  /// Whether the camera preview is pre-transformed,
-  /// and thus does not need an orientation correction.
-  final bool isPreviewPreTransformed;
+  /// The facing direction of the active camera.
+  final CameraFacing cameraFacingDirection;
 
-  /// The initial orientation of the device, when the camera was started.
+  /// Whether the underlying surface producer handles crop and rotation.
   ///
-  /// The camera preview will use this orientation as the natural orientation
-  /// to correct its rotation with respect to, if necessary.
-  final DeviceOrientation naturalOrientation;
-
-  /// The sensor orientation of the current camera, in degrees.
-  final int sensorOrientation;
-
-  /// Apply a rotation correction to the given [texture] widget.
-  Widget applyRotationCorrection(Widget texture) {
-    if (!_rotationCorrectionEnabled) {
-      return texture;
-    }
-
-    int naturalDeviceOrientationDegrees =
-        _degreesForDeviceOrientation[naturalOrientation]!;
-
-    if (isPreviewPreTransformed) {
-      // If the camera preview is backed by a SurfaceTexture, the transformation
-      // needed to correctly rotate the preview has already been applied.
-      //
-      // However, the camera preview rotation may need to be corrected if the
-      // device is naturally landscape-oriented.
-      if (naturalOrientation == DeviceOrientation.landscapeLeft ||
-          naturalOrientation == DeviceOrientation.landscapeRight) {
-        final int quarterTurns = (-naturalDeviceOrientationDegrees + 360) ~/ 4;
-
-        return RotatedBox(
-          quarterTurns: quarterTurns,
-          child: texture,
-        );
-      }
-
-      return texture;
-    }
-
-    // If the camera preview is not backed by a SurfaceTexture,
-    // the camera preview rotation needs to be manually applied,
-    // while also taking into account devices that are naturally landscape-oriented.
-    final int signForCameraDirection = cameraIsFrontFacing ? 1 : -1;
-
-    // For front-facing cameras, the preview is rotated counterclockwise,
-    // so determine the rotation needed to correct the camera preview with
-    // respect to the natural orientation of the device, based on the inverse of
-    // of the natural orientation.
-    if (signForCameraDirection == 1 &&
-        (currentDeviceOrientation == DeviceOrientation.landscapeLeft ||
-            currentDeviceOrientation == DeviceOrientation.landscapeRight)) {
-      naturalDeviceOrientationDegrees += 180;
-    }
+  /// If this is false, the preview needs to be manually rotated.
+  final bool handlesCropAndRotation;
 
-    // See https://developer.android.com/media/camera/camera2/camera-preview#orientation_calculation
-    final double rotation = (sensorOrientation +
-            naturalDeviceOrientationDegrees * signForCameraDirection +
-            360) %
-        360;
+  /// The initial device orientation when this [AndroidSurfaceProducerDelegate] is created.
+  final DeviceOrientation initialDeviceOrientation;
 
-    int quarterTurnsToCorrectPreview = rotation ~/ 90;
-
-    // Correct the camera preview rotation for devices that are naturally landscape-oriented.
-    if (naturalOrientation == DeviceOrientation.landscapeLeft ||
-        naturalOrientation == DeviceOrientation.landscapeRight) {
-      quarterTurnsToCorrectPreview +=
-          (-naturalDeviceOrientationDegrees + 360) ~/ 4;
-    }
-
-    return RotatedBox(
-      quarterTurns: quarterTurnsToCorrectPreview,
-      child: texture,
-    );
-  }
-
-  /// Start listening to device orientation changes,
-  /// which are provided by the given [stream].
-  void startListeningToDeviceOrientation(Stream<DeviceOrientation> stream) {
-    if (!_rotationCorrectionEnabled) {
-      return;
-    }
-
-    _deviceOrientationSubscription ??=
-        stream.listen((DeviceOrientation newOrientation) {
-      currentDeviceOrientation = newOrientation;
-    });
-  }
-
-  /// Dispose of this delegate.
-  void dispose() {
-    _deviceOrientationSubscription?.cancel();
-    _deviceOrientationSubscription = null;
-  }
+  /// The orientation of the camera sensor on the device, in degrees.
+  final double sensorOrientationDegrees;
 }

lib/src/method_channel/mobile_scanner_method_channel.dart

@@ -9,6 +9,7 @@ import 'package:mobile_scanner/src/enums/mobile_scanner_authorization_state.dart
 import 'package:mobile_scanner/src/enums/mobile_scanner_error_code.dart';
 import 'package:mobile_scanner/src/enums/torch_state.dart';
 import 'package:mobile_scanner/src/method_channel/android_surface_producer_delegate.dart';
+import 'package:mobile_scanner/src/method_channel/rotated_preview.dart';
 import 'package:mobile_scanner/src/mobile_scanner_exception.dart';
 import 'package:mobile_scanner/src/mobile_scanner_platform_interface.dart';
 import 'package:mobile_scanner/src/mobile_scanner_view_attributes.dart';
@@ -239,9 +240,20 @@ class MethodChannelMobileScanner extends MobileScannerPlatform {
 
     final Widget texture = Texture(textureId: _textureId!);
 
+    // If the preview needs manual orientation corrections,
+    // correct the preview orientation based on the currently reported device orientation.
+    // On Android, the underlying device orientation stream will emit the current orientation
+    // when the first listener is attached.
     if (_surfaceProducerDelegate
-        case final AndroidSurfaceProducerDelegate delegate) {
-      return delegate.applyRotationCorrection(texture);
+        case final AndroidSurfaceProducerDelegate delegate
+        when !delegate.handlesCropAndRotation) {
+      return RotatedPreview.fromCameraDirection(
+        delegate.cameraFacingDirection,
+        deviceOrientationStream: deviceOrientationChangedStream,
+        initialDeviceOrientation: delegate.initialDeviceOrientation,
+        sensorOrientationDegrees: delegate.sensorOrientationDegrees,
+        child: texture,
+      );
     }
 
     return texture;
@@ -319,9 +331,6 @@ class MethodChannelMobileScanner extends MobileScannerPlatform {
         startResult,
         cameraDirection,
       );
-      _surfaceProducerDelegate?.startListeningToDeviceOrientation(
-        deviceOrientationChangedStream,
-      );
     }
 
     final int? numberOfCameras = startResult['numberOfCameras'] as int?;
@@ -356,7 +365,6 @@ class MethodChannelMobileScanner extends MobileScannerPlatform {
 
     _textureId = null;
     _pausing = false;
-    _surfaceProducerDelegate?.dispose();
     _surfaceProducerDelegate = null;
 
     await methodChannel.invokeMethod<void>('stop');