OpenCV QRCodeDetector not working for IOS objective C++ - objective-c

Question

I am trying to complete an app for a university project that will allow the user to take a photo which contains a QR code and some specific colours that could change over time. My app should be able to detect the QR code and changes in the colours. I am trying to use react native and openCV to complete this task concentrating on IOS first (I had hoped it would be easier). So far, using the openCV tutorial by brainhubeu/react-native-opencv-tutorial on GitHub, I am to take a picture, check for blur, but when it comes to detecting and decoding the QR code, its doesn't seem to be locating any QR in the image.
#import "RNOpenCVLibrary.h"
#import <React/RCTLog.h>
#implementation RNOpenCVLibrary
- (dispatch_queue_t)methodQueue
{
return dispatch_get_main_queue();
}
RCT_EXPORT_MODULE()
RCT_EXPORT_METHOD(addEvent:(NSString *)name location:(NSString *)location)
{
RCTLogInfo(#"Pretending to create an event %# at %#", name, location);
};
RCT_EXPORT_METHOD(checkForBlurryImage:(NSString *)imageAsBase64 callback:(RCTResponseSenderBlock)callback) {
RCTLog(#"%#", imageAsBase64);
UIImage* image = [self decodeBase64ToImage:imageAsBase64];
BOOL isImageBlurryResult = [self isImageBlurry:image];
id objects[] = { isImageBlurryResult ? #YES : #NO };
NSUInteger count = sizeof(objects) / sizeof(id);
NSArray *dataArray = [NSArray arrayWithObjects:objects
count:count];
callback(#[[NSNull null], dataArray]);
};
RCT_EXPORT_METHOD(checkForQRCode:(NSString *)imageAsBase64) {
RCTLog(#"%#", imageAsBase64);
UIImage* image = [self decodeBase64ToImage:imageAsBase64];
cv::QRCodeDetector qrDecoder = cv::QRCodeDetector();
BOOL isQRPresentResult = [self isQRPresent:image];
NSString *decodedQrData = [self decodeQRCode:image];
//BOOL isQRPresentResult = 1;
//std::string data = qrDecoder.detectAndDecode(matImage);
//std::string data = "testing";
//NSString* result = [NSString stringWithUTF8String:data.c_str()];
//NSString* result = #"test";
RCTLogInfo(#"Pretending to create an event %#", decodedQrData);
RCTLog(isQRPresentResult ? #"yes" : #"No");
};
-(BOOL)isQRPresent:(UIImage*)image{
cv::Mat matImage = [self convertUIImageToCVMat:image];
cv::Mat matImageGrey;
// converting image's color space (RGB) to grayscale
cv::cvtColor(matImage, matImageGrey, cv::COLOR_BGRA2GRAY);
std::vector<cv::Point> points;
cv::QRCodeDetector qrDecoder = cv::QRCodeDetector();
return qrDecoder.detect(matImageGrey, points);
};
-(NSString*)decodeQRCode:(UIImage*)image{
cv::Mat matImage = [self convertUIImageToCVMat:image];
cv::Mat matImageGrey;
// converting image's color space (RGB) to grayscale
cv::cvtColor(matImage, matImageGrey, cv::COLOR_BGRA2GRAY);
cv::QRCodeDetector qrDecoder = cv::QRCodeDetector();
std::string qrData;
qrData = qrDecoder.detectAndDecode(matImageGrey);
return [NSString stringWithUTF8String:qrData.c_str()];
};
- (cv::Mat)convertUIImageToCVMat:(UIImage *)image {
CGColorSpaceRef colorSpace = CGImageGetColorSpace(image.CGImage);
CGFloat cols = image.size.width;
CGFloat rows = image.size.height;
cv::Mat cvMat(rows, cols, CV_8UC4); // 8 bits per component, 4 channels (color channels + alpha)
CGContextRef contextRef = CGBitmapContextCreate(cvMat.data, // Pointer to data
cols, // Width of bitmap
rows, // Height of bitmap
8, // Bits per component
cvMat.step[0], // Bytes per row
colorSpace, // Colorspace
kCGImageAlphaNoneSkipLast |
kCGBitmapByteOrderDefault); // Bitmap info flags
CGContextDrawImage(contextRef, CGRectMake(0, 0, cols, rows), image.CGImage);
CGContextRelease(contextRef);
return cvMat;
};
- (UIImage *)decodeBase64ToImage:(NSString *)strEncodeData {
NSData *data = [[NSData alloc]initWithBase64EncodedString:strEncodeData options:NSDataBase64DecodingIgnoreUnknownCharacters];
return [UIImage imageWithData:data];
};
- (BOOL) isImageBlurry:(UIImage *) image {
// converting UIImage to OpenCV format - Mat
cv::Mat matImage = [self convertUIImageToCVMat:image];
cv::Mat matImageGrey;
// converting image's color space (RGB) to grayscale
cv::cvtColor(matImage, matImageGrey, cv::COLOR_BGRA2GRAY);
cv::Mat dst2 = [self convertUIImageToCVMat:image];
cv::Mat laplacianImage;
dst2.convertTo(laplacianImage, CV_8UC1);
// applying Laplacian operator to the image
cv::Laplacian(matImageGrey, laplacianImage, CV_8U);
cv::Mat laplacianImage8bit;
laplacianImage.convertTo(laplacianImage8bit, CV_8UC1);
unsigned char *pixels = laplacianImage8bit.data;
// 16777216 = 256*256*256
int maxLap = -16777216;
for (int i = 0; i < ( laplacianImage8bit.elemSize()*laplacianImage8bit.total()); i++) {
if (pixels[i] > maxLap) {
maxLap = pixels[i];
}
}
// one of the main parameters here: threshold sets the sensitivity for the blur check
// smaller number = less sensitive; default = 180
int threshold = 180;
return (maxLap <= threshold);
};
#end