OpenCvCameraManager.mm

#import "OpenCvCameraManager.h"
#import <React/RCTBridge.h>
#import <opencv2/videoio/cap_ios.h>

using namespace cv;

@implementation OpenCvCameraManager

@synthesize camera, img, cameraId;
RCT_EXPORT_VIEW_PROPERTY(onCodeDetected, RCTBubblingEventBlock);

RCT_CUSTOM_VIEW_PROPERTY(cameraId, NSInteger, RNTUIImageView)
{
  if ([RCTConvert NSInteger:json] != self.camera.defaultAVCaptureDevicePosition ) {
    [self hideCamera];
    if ([RCTConvert NSInteger:json] == AVCaptureDevicePositionBack) {
      self.cameraId = AVCaptureDevicePositionBack;
    } else {
      self.cameraId = AVCaptureDevicePositionFront;
    }
    [self displayCamera];
  }
}

RCT_EXPORT_MODULE()
- (UIView *)view
{
  NSLog(@"----------- init OpenCvCamera view ----------");
  CGRect screenRect = [[UIScreen mainScreen] bounds];

  self.img = [[RNTUIImageView alloc] initWithFrame:[UIScreen mainScreen].bounds];
  return img;
}


- (void)displayCamera {
  // set orientation portrait
  
  dispatch_async(dispatch_get_main_queue(), ^{
    [self.img setHidden: NO];
    
    NSNumber *value = [NSNumber numberWithInt:UIInterfaceOrientationPortrait];
    [[UIDevice currentDevice] setValue:value forKey:@"orientation"];

    self.camera = [[CvVideoCamera alloc] initWithParentView:self.img];
    self.camera.delegate = self;
    self.camera.defaultAVCaptureDevicePosition = AVCaptureDevicePositionBack;
    self.camera.defaultAVCaptureSessionPreset = AVCaptureSessionPresetHigh;
    self.camera.defaultAVCaptureVideoOrientation =  AVCaptureVideoOrientationPortrait;
    self.camera.defaultFPS = 30;
    self.camera.grayscaleMode = NO;

    NSLog(@"----------- camera start ----------");
    [self.camera start];
  });
}

#pragma mark CvVideoCameraDelegate

- (void)layoutPreviewLayer;
{
    NSLog(@"LayoutPreview");
    //if (self.parentView != nil)
    if (self.img != nil)
    {
        CALayer* layer = self.camera.customPreviewLayer;
        CGRect bounds = self.camera.customPreviewLayer.bounds;
        NSLog(@"[FixedCvVideoCamera]Custom Preview Layer bounds %fx%f", bounds.size.width, bounds.size.height);

        float previewAspectRatio = bounds.size.height / bounds.size.width;
        NSLog(@"[FixedCvVideoCamera]Preview aspect ratio %f", previewAspectRatio);

        //int rotation_angle = 0;

        //layer.position = CGPointMake(self.parentView.frame.size.width/2., self.parentView.frame.size.height/2.);
        layer.position = CGPointMake(self.img.frame.size.width/2., self.img.frame.size.height/2.);
        //layer.affineTransform = CGAffineTransformMakeRotation( DEGREES_RADIANS(rotation_angle) );

        // Get video feed's resolutions
        NSArray* devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
        AVCaptureDevice* device = nil;
        for (AVCaptureDevice *d in devices) {
            // Get the default camera device - should be either front of back camera device
            if ([d position] == self.defaultAVCaptureDevicePosition) {
                device = d;
            }
        }

        // Set the default device if not found
        if (!device) {
            device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
        }

        CMVideoDimensions dimensions = CMVideoFormatDescriptionGetDimensions(device.activeFormat.formatDescription);
        CGSize resolution = CGSizeMake(dimensions.width, dimensions.height);
        if (self.defaultAVCaptureVideoOrientation == AVCaptureVideoOrientationPortrait || self.defaultAVCaptureVideoOrientation == AVCaptureVideoOrientationPortraitUpsideDown) {
            resolution = CGSizeMake(resolution.height, resolution.width);
        }
        NSLog(@"[FixedCvVideoCamera]Video feed resolution is %fx%f", resolution.width, resolution.height);

        float videoFeedAspectRatio = resolution.height / resolution.width;
        NSLog(@"[FixedCvVideoCamera]Video feed's aspect ratio is %f", videoFeedAspectRatio);

        // Set layer bounds to ASPECT FILL by expanding either the width or the height
        if (previewAspectRatio > videoFeedAspectRatio) {
            NSLog(@"[FixedCvVideoCamera] Preview is more rectangular than the video feed aspect ratio. Expanding width to maintain aspect ratio.");
            float newWidth = bounds.size.height / videoFeedAspectRatio;
            layer.bounds = CGRectMake(0, 0, newWidth, bounds.size.height);
        } else {
            NSLog(@"[FixedCvVideoCamera] Preview is equally or less rectangular (wider) than the video feed's aspect ratio. Expanding height bound to maintain aspect ratio.");
            float newHeight = bounds.size.width * videoFeedAspectRatio;
            layer.bounds = CGRectMake(0, 0, bounds.size.width, newHeight);
        }
    }

}

@end