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ライブ カメラ フィードで四角形を検出し、検出された四角形を強調表示するアプリケーションを開発しています。AVFoundation検出された長方形を検出して強調表示するために、以下の方法を使用してカメラを使用しました。

var detector: CIDetector?;

override func viewDidLoad() {
    super.viewDidLoad();

    detector = self.prepareRectangleDetector();
}

func captureOutput(captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, fromConnection connection: AVCaptureConnection!) { // re check this method

    // Need to shimmy this through type-hell
    let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)

    // Force the type change - pass through opaque buffer
    let opaqueBuffer = Unmanaged<CVImageBuffer>.passUnretained(imageBuffer!).toOpaque()
    let pixelBuffer = Unmanaged<CVPixelBuffer>.fromOpaque(opaqueBuffer).takeUnretainedValue()

    let sourceImage = CIImage(CVPixelBuffer: pixelBuffer, options: nil)

    // Do some detection on the image
    self.performRectangleDetection(sourceImage);

    var outputImage = sourceImage

    // Do some clipping
    var drawFrame = outputImage.extent
    let imageAR = drawFrame.width / drawFrame.height
    let viewAR = videoDisplayViewBounds.width / videoDisplayViewBounds.height

    if imageAR > viewAR {
        drawFrame.origin.x += (drawFrame.width - drawFrame.height * viewAR) / 2.0
        drawFrame.size.width = drawFrame.height / viewAR
    } else {
        drawFrame.origin.y += (drawFrame.height - drawFrame.width / viewAR) / 2.0
        drawFrame.size.height = drawFrame.width / viewAR
    }

    //videoDisplayView is a GLKView which is used to display camera feed
    videoDisplayView.bindDrawable()
    if videoDisplayView.context != EAGLContext.currentContext() {
        EAGLContext.setCurrentContext(videoDisplayView.context)
    }

    // clear eagl view to grey
    glClearColor(0.5, 0.5, 0.5, 1.0);
    glClear(0x00004000)

    // set the blend mode to "source over" so that CI will use that
    glEnable(0x0BE2);
    glBlendFunc(1, 0x0303);

    renderContext.drawImage(outputImage, inRect: videoDisplayViewBounds, fromRect: drawFrame);

    videoDisplayView.display();

}

func prepareRectangleDetector() -> CIDetector {

    let options: [String: AnyObject] = [CIDetectorAccuracy: CIDetectorAccuracyHigh];
    return CIDetector(ofType: CIDetectorTypeRectangle, context: nil, options: options);
}

func performRectangleDetection(image: CIImage){

    let resultImage: CIImage? = nil;

    if let detector = detector {

        // Get the detections
        let features = detector.featuresInImage(image, options: [CIDetectorAspectRatio:NSNumber(float:1.43)]);


        if features.count != 0{ // feature found

            for feature in features as! [CIRectangleFeature] {

                self.previewImageView.layer.sublayers = nil;

                let line: CAShapeLayer = CAShapeLayer();
                line.frame = self.videoDisplayView.bounds;
                let linePath: UIBezierPath = UIBezierPath();

                linePath.moveToPoint(feature.topLeft);
                linePath.addLineToPoint(feature.topRight);
                linePath.addLineToPoint(feature.bottomRight);
                linePath.addLineToPoint(feature.bottomLeft);
                linePath.addLineToPoint(feature.topLeft);
                linePath.closePath();

                line.lineWidth = 5.0;
                line.path = linePath.CGPath;
                line.fillColor = UIColor.clearColor().CGColor;
                line.strokeColor = UIColor(netHex: 0x3399CC, alpha: 1.0).CGColor;

                // videoDisplayParentView is the parent of videoDisplayView and they both have same bounds
                self.videoDisplayParentView.layer.addSublayer(line);
             }    
         }                    
     }
}

と を使っCAShapeLayerてUIBezierPath四角形を描きました。これは非常に遅いです。パスは数分後に表示されます。

誰かが遅い理由を理解するのを手伝ってくれますか、ここで何か間違っているかどうか教えてください。どんな助けでも大歓迎です。

または、これよりも簡単な方法があれば、それも知りたいです。

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