react-native-camera/ios/FaceDetector/RNFaceDetectorManager.m

//
//  RNFaceDetectorManager.m
//  RCTCamera
//
//  Created by Joao Guilherme Daros Fidelis on 21/01/18.
//

#import <React/RCTConvert.h>
#import "RNCamera.h"
#import "RNFaceEncoder.h"
#import "RNFaceDetectorUtils.h"
#import "RNFaceDetectorModule.h"
#import "RNFaceDetectorManager.h"

@interface RNFaceDetectorManager() <GMVDataOutputDelegate>

@property (assign, nonatomic) long previousFacesCount;
@property (nonatomic, strong) GMVDataOutput *dataOutput;
@property (nonatomic, weak) AVCaptureSession *session;
@property (nonatomic, weak) dispatch_queue_t sessionQueue;
@property (nonatomic, assign, getter=isConnected) BOOL connected;
@property (nonatomic, weak) id <RNFaceDetectorDelegate> delegate;
@property (nonatomic, weak) AVCaptureVideoPreviewLayer *previewLayer;
@property (nonatomic, assign, getter=isDetectingFaces) BOOL faceDetecting;
@property (nonatomic, strong) NSMutableDictionary<NSString *, id> *faceDetectorOptions;

@end

@implementation RNFaceDetectorManager

static NSDictionary *defaultFaceDetectorOptions = nil;

- (NSDictionary *)constantsToExport
{
    return [[self class] constants];
}

+ (NSDictionary *)constants
{
    return [RNFaceDetectorUtils constantsToExport];
}

- (instancetype)initWithSessionQueue:(dispatch_queue_t)sessionQueue delegate:(id <RNFaceDetectorDelegate>)delegate
{
    if (self = [super init]) {
        _delegate = delegate;
        _previousFacesCount = -1;
        _sessionQueue = sessionQueue;
        _faceDetectorOptions = [[NSMutableDictionary alloc] initWithDictionary:[[self class] _getDefaultFaceDetectorOptions]];
    }
    return self;
}

# pragma mark Properties setters

- (void)setSession:(AVCaptureSession *)session
{
    _session = session;
}

# pragma mark - JS properties setters

- (void)setIsEnabled:(id)json
{
    BOOL newFaceDetecting = [RCTConvert BOOL:json];
    
    if ([self isDetectingFaces] != newFaceDetecting) {
        _faceDetecting = newFaceDetecting;
        [self _runBlockIfQueueIsPresent:^{
            if ([self isDetectingFaces]) {
                if (_dataOutput) {
                    [self _setConnectionsEnabled:true];
                } else {
                    [self tryEnablingFaceDetection];
                }
            } else {
                [self _setConnectionsEnabled:false];
            }
        }];
    }
}

- (void)setLandmarksDetected:(id)json
{
    [self _updateOptionSettingForKey:GMVDetectorFaceLandmarkType withJSONValue:json];
}

- (void)setClassificationsDetected:(id)json
{
    [self _updateOptionSettingForKey:GMVDetectorFaceClassificationType withJSONValue:json];
}

- (void)setMode:(id)json
{
    [self _updateOptionSettingForKey:GMVDetectorFaceMode withJSONValue:json];
}

# pragma mark - Public API

- (void)maybeStartFaceDetectionOnSession:(AVCaptureSession *)session withPreviewLayer:(AVCaptureVideoPreviewLayer *)previewLayer
{
    _session = session;
    _previewLayer = previewLayer;
    [self tryEnablingFaceDetection];
}

- (void)tryEnablingFaceDetection
{
    if (!_session) {
        return;
    }
    
    [_session beginConfiguration];
    
    if ([self isDetectingFaces]) {
        @try {
            GMVDetector *faceDetector = [GMVDetector detectorOfType:GMVDetectorTypeFace options:_faceDetectorOptions];
            GMVDataOutput *dataOutput = [[GMVMultiDataOutput alloc] initWithDetector:faceDetector];
            [dataOutput setDataDelegate:self];
            
            if ([_session canAddOutput:dataOutput]) {
                [_session addOutput:dataOutput];
                _dataOutput = dataOutput;
                _connected = true;
            }
            
            _previousFacesCount = -1;
            [self _notifyOfFaces:nil];
        } @catch (NSException *exception) {
            RCTLogWarn(@"%@", [exception description]);
        }
    }
    
    [_session commitConfiguration];
}

- (void)stopFaceDetection
{
    if (!_session) {
        return;
    }
    
    [_session beginConfiguration];
    
    if ([_session.outputs containsObject:_dataOutput]) {
        [_session removeOutput:_dataOutput];
        [_dataOutput cleanup];
        _dataOutput = nil;
        _connected = false;
    }
    
    [_session commitConfiguration];
    
    if ([self isDetectingFaces]) {
        _previousFacesCount = -1;
        [self _notifyOfFaces:nil];
    }
}

# pragma mark Private API

- (void)_setConnectionsEnabled:(BOOL)enabled
{
    if (!_dataOutput) {
        return;
    }
    for (AVCaptureConnection *connection in _dataOutput.connections) {
        connection.enabled = enabled;
    }
}

- (void)_resetFaceDetector
{
    [self stopFaceDetection];
    [self tryEnablingFaceDetection];
}

- (void)_notifyOfFaces:(NSArray<NSDictionary *> *)faces
{
    NSArray<NSDictionary *> *reportableFaces = faces == nil ? @[] : faces;
    // Send event when there are faces that have been detected ([faces count] > 0)
    // or if the listener may think that there are still faces in the video (_prevCount > 0)
    // or if we really want the event to be sent, eg. to reset listener info (_prevCount == -1).
    if ([reportableFaces count] > 0 || _previousFacesCount != 0) {
        if (_delegate) {
            [_delegate onFacesDetected:reportableFaces];
        }
        // Maybe if the delegate is not present anymore we should disable encoding,
        // however this should never happen.
        
        _previousFacesCount = [reportableFaces count];
    }
}

# pragma mark - Utilities

- (long)_getLongOptionValueForKey:(NSString *)key
{
    return [(NSNumber *)[_faceDetectorOptions valueForKey:key] longValue];
}

- (void)_updateOptionSettingForKey:(NSString *)key withJSONValue:(id)json
{
    long requestedValue = [RCTConvert NSInteger:json];
    long currentValue = [self _getLongOptionValueForKey:key];
    
    if (requestedValue != currentValue) {
        [_faceDetectorOptions setValue:@(requestedValue) forKey:key];
        [self _runBlockIfQueueIsPresent:^{
            [self _resetFaceDetector];
        }];
    }
}

- (void)_runBlockIfQueueIsPresent:(void (^)(void))block
{
    if (_sessionQueue) {
        dispatch_async(_sessionQueue, block);
    }
}

#pragma mark - GMVDataOutputDelegate

- (void)dataOutput:(GMVDataOutput *)dataOutput didFinishedDetection:(NSArray<__kindof GMVFeature *> *)results
{
    // Calling dataOutput:didFinishedDetection with dataOutput that in videoSettings has no information about
    // width or height started happen after refactor: moving face detection logic from EXCameraManager to EXFaceDetectorManager.
    // I suppose no information is provided because data output is already disconnected from the input and it has no
    // information about the source. Let's reset the information then.
    if (!_connected) {
        [self _notifyOfFaces:nil];
        return;
    }
    
    AVCaptureVideoOrientation interfaceVideoOrientation = _previewLayer.connection.videoOrientation;
    CGAffineTransform transform = [RNFaceDetectorUtils transformFromDeviceOutput:dataOutput toInterfaceVideoOrientation:interfaceVideoOrientation];
    
    RNFaceEncoder *faceEncoder = [[RNFaceEncoder alloc] initWithTransform:transform];
    
    NSMutableArray<NSDictionary *> *encodedFaces = [NSMutableArray arrayWithCapacity:[results count]];
    
    [results enumerateObjectsUsingBlock:^(GMVFeature * _Nonnull feature, NSUInteger _idx, BOOL * _Nonnull _stop) {
        if([feature isKindOfClass:[GMVFaceFeature class]]) {
            GMVFaceFeature *face = (GMVFaceFeature *)feature;
            [encodedFaces addObject:[faceEncoder encode:face]];
        }
    }];
    
    [self _notifyOfFaces:encodedFaces];
}

# pragma mark - Default options

+ (NSDictionary *)_getDefaultFaceDetectorOptions
{
    if (defaultFaceDetectorOptions == nil) {
        [self _initDefaultFaceDetectorOptions];
    }
    
    return defaultFaceDetectorOptions;
}

+ (void)_initDefaultFaceDetectorOptions
{
    defaultFaceDetectorOptions = @{
                                   GMVDetectorFaceTrackingEnabled : @(YES),
                                   GMVDetectorFaceMode : @(GMVDetectorFaceFastMode),
                                   GMVDetectorFaceLandmarkType : @(GMVDetectorFaceLandmarkNone),
                                   GMVDetectorFaceClassificationType : @(GMVDetectorFaceClassificationNone),
                                   GMVDetectorFaceMinSize : @(0.15)
                                   };
}

@end