feat: Add rotation to iOS (the sequel)

packages/google_mlkit_commons/ios/Classes/MLKVisionImage+FlutterPlugin.m

@@ -8,7 +8,12 @@ + (MLKVisionImage *)visionImageFromData:(NSDictionary *)imageData {
     if ([@"file" isEqualToString:imageType]) {
         return [self filePathToVisionImage:imageData[@"path"]];
     } else if ([@"bytes" isEqualToString:imageType]) {
-        return [self bytesToVisionImage:imageData];
+        int rotation = [imageData[@"metadata"][@"rotation"] intValue];
+        int cameraLensDirection = [imageData[@"metadata"][@"camera_lens_direction"] intValue];
+        UIImageOrientation imageOrientation = [self imageOrientationFromRotation:rotation cameraLensDirection:cameraLensDirection];
+        MLKVisionImage *image = [self bytesToVisionImage:imageData];
+        image.orientation = imageOrientation;
+        return image;
     } else {
         NSString *errorReason = [NSString stringWithFormat:@"No image type for: %@", imageType];
         @throw [NSException exceptionWithName:NSInvalidArgumentException
@@ -17,6 +22,23 @@ + (MLKVisionImage *)visionImageFromData:(NSDictionary *)imageData {
     }
 }
 
++ (UIImageOrientation)imageOrientationFromRotation:(int)rotation cameraLensDirection:(int)cameraLensDirection {
+    switch (rotation) {
+        case 90:
+            return cameraLensDirection == 0 ? UIImageOrientationRight  // Rotates the image 270 degrees to the left 
+                                            : UIImageOrientationRightMirrored;  // Rotates the image 270 degrees to the left (image is mirrored) 
+        case 180:
+            return cameraLensDirection == 0 ? UIImageOrientationDown  // Rotates the image 180 degrees to the left 
+                                            : UIImageOrientationDownMirrored;  // Rotates the image 180 degrees to the left (image is mirrored)
+        case 270:
+            return cameraLensDirection == 0 ? UIImageOrientationLeft  // Rotates the image 90 degrees to the left
+                                            : UIImageOrientationLeftMirrored;  // Rotates the image 90 degrees to the left (image is mirrored)
+        default:
+            return cameraLensDirection == 0 ? UIImageOrientationUp // Rotates 0 degreees
+                                            : UIImageOrientationUpMirrored;  // Rotates the image 0 degrees (image is mirrored)
+    }
+}
+
 + (MLKVisionImage *)filePathToVisionImage:(NSString *)filePath {
     UIImage *image = [UIImage imageWithContentsOfFile:filePath];
     MLKVisionImage *visionImage = [[MLKVisionImage alloc] initWithImage:image];

packages/google_mlkit_commons/lib/src/input_image.dart

@@ -70,12 +70,18 @@ class InputImageMetadata {
   /// Not used on Android.
   final int bytesPerRow;
 
+  // Camera lens direction.
+  ///
+  /// Not used on Android.
+  final InputImageCameraLensDirection cameraLensDirection;
+
   /// Constructor to create an instance of [InputImageMetadata].
   InputImageMetadata({
     required this.size,
     required this.rotation,
     required this.format,
     required this.bytesPerRow,
+    required this.cameraLensDirection,
   });
 
   /// Returns a json representation of an instance of [InputImageMetadata].
@@ -85,6 +91,7 @@ class InputImageMetadata {
         'rotation': rotation.rawValue,
         'image_format': format.rawValue,
         'bytes_per_row': bytesPerRow,
+        'camera_lens_direction': cameraLensDirection.rawValue,
       };
 }
 
@@ -155,3 +162,31 @@ extension InputImageFormatValue on InputImageFormat {
     }
   }
 }
+
+/// The camera lens direction to be specified
+///
+/// Not used on Android.
+enum InputImageCameraLensDirection {
+  front,
+  back,
+}
+
+extension InputImageCameraLensDirectionValue on InputImageCameraLensDirection {
+  int get rawValue {
+    switch (this) {
+      case InputImageCameraLensDirection.back:
+        return 0;
+      case InputImageCameraLensDirection.front:
+        return 1;
+    }
+  }
+
+  static InputImageCameraLensDirection? fromRawValue(int rawValue) {
+    try {
+      return InputImageCameraLensDirection.values
+          .firstWhere((element) => element.rawValue == rawValue);
+    } catch (_) {
+      return null;
+    }
+  }
+}