Nécessité de modifier l'image avant d'afficher sur AVCaptureVideoPreviewLayer

Question

J'utilise AVCaptureSession à la vidéo de capture de mon iPhone 3G et je dois capturer l'image et le modifier avant d'afficher sur mon AVCaptureVideoPreviewLayer. Dans mon implémentation actuelle, je suis simplement la méthode de mise en œuvre de captureOutput: et d'afficher la UIImage dans un UIImageView, mais qui ne fonctionne pas pour une raison quelconque.

Toutes les idées? AVCaptureSession en quelque sorte sous-classe?

Merci!

Answer 1

Consultez cette https://developer.apple. com / bibliothèque / ios / # SampleCode / SquareCam / introduction / intro.html Je pense qu'il le fait. Il dessine des boîtes de visage sur le visage.

- (void)drawFaceBoxesForFeatures:(NSArray *)features forVideoBox:(CGRect)clap orientation:(UIDeviceOrientation)orientation// videoMirrored:(const BOOL)ISVIDEOMIRRORED
{
    NSArray *sublayers = [NSArray arrayWithArray:[previewLayer sublayers]];
    NSInteger sublayersCount = [sublayers count], currentSublayer = 0;
    NSInteger featuresCount = [features count], currentFeature = 0;

    [CATransaction begin];
    [CATransaction setValue:(id)kCFBooleanTrue forKey:kCATransactionDisableActions];

    // hide all the face layers
    for ( CALayer *layer in sublayers ) {
        if ( [[layer name] isEqualToString:@"FaceLayer"] )
            [layer setHidden:YES];
    }   

    if ( featuresCount == 0 || !detectFaces ) {
        [CATransaction commit];
        return; // early bail.
    }

    CGSize parentFrameSize = [previewView frame].size;
    NSString *gravity = [previewLayer videoGravity];
    //BOOL isMirrored = isVideoMirrored;
#warning Deprecated
    const BOOL isMirrored = [previewLayer isMirrored]; // deprecated
    CGRect previewBox = [SquareCamViewController videoPreviewBoxForGravity:gravity 
                                                               frameSize:parentFrameSize 
                                                            apertureSize:clap.size];

    for ( CIFaceFeature *ff in features ) {
        // find the correct position for the square layer within the previewLayer
        // the feature box originates in the bottom left of the video frame.
        // (Bottom right if mirroring is turned on)
        CGRect faceRect = [ff bounds];

        // flip preview width and height
        CGFloat temp = faceRect.size.width;
        faceRect.size.width = faceRect.size.height;
        faceRect.size.height = temp;
        temp = faceRect.origin.x;
        faceRect.origin.x = faceRect.origin.y;
        faceRect.origin.y = temp;
        // scale coordinates so they fit in the preview box, which may be scaled
        CGFloat widthScaleBy = previewBox.size.width / clap.size.height;
        CGFloat heightScaleBy = previewBox.size.height / clap.size.width;
        faceRect.size.width *= widthScaleBy;
        faceRect.size.height *= heightScaleBy;
        faceRect.origin.x *= widthScaleBy;
        faceRect.origin.y *= heightScaleBy;

        if ( isMirrored )
            faceRect = CGRectOffset(faceRect, previewBox.origin.x + previewBox.size.width - faceRect.size.width - (faceRect.origin.x * 2), previewBox.origin.y);
        else
            faceRect = CGRectOffset(faceRect, previewBox.origin.x, previewBox.origin.y);

        CALayer *featureLayer = nil;

        // re-use an existing layer if possible
        while ( !featureLayer && (currentSublayer < sublayersCount) ) {
            CALayer *currentLayer = [sublayers objectAtIndex:currentSublayer++];
            if ( [[currentLayer name] isEqualToString:@"FaceLayer"] ) {
                featureLayer = currentLayer;
                [currentLayer setHidden:NO];
            }
        }

        // create a new one if necessary
        if ( !featureLayer ) {
            featureLayer = [CALayer new];
            [featureLayer setContents:(id)[square CGImage]];
            [featureLayer setName:@"FaceLayer"];
            [previewLayer addSublayer:featureLayer];
            [featureLayer release];
        }
        [featureLayer setFrame:faceRect];

        switch (orientation) {
            case UIDeviceOrientationPortrait:
                [featureLayer setAffineTransform:CGAffineTransformMakeRotation(DegreesToRadians(0.))];
                break;
            case UIDeviceOrientationPortraitUpsideDown:
                [featureLayer setAffineTransform:CGAffineTransformMakeRotation(DegreesToRadians(180.))];
                break;
            case UIDeviceOrientationLandscapeLeft:
                [featureLayer setAffineTransform:CGAffineTransformMakeRotation(DegreesToRadians(90.))];
                break;
            case UIDeviceOrientationLandscapeRight:
                [featureLayer setAffineTransform:CGAffineTransformMakeRotation(DegreesToRadians(-90.))];
                break;
            case UIDeviceOrientationFaceUp:
            case UIDeviceOrientationFaceDown:
            default:
                break; // leave the layer in its last known orientation
        }
        currentFeature++;
    }

    [CATransaction commit];
}