使用 CIFilter 围绕中心旋转 CIImage

Question

我正在尝试旋转CMSampleBuffer(来自相机(的像素数据并将其显示在UIImageView中。我不想旋转视图本身。它必须是实际的像素数据。

我抓住提要，将其转换为CIImage，然后使用CIFilter旋转它。我在设置它必须旋转的点时遇到问题。现在它围绕左下点旋转。我想围绕它的中心旋转它。

 func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) {
            //create pixelbuffer
            let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)!
            let context = CIContext.init(options: nil)
            // calculating the radians to rotate the ciimage by
            let radians : Float = atan2f(Float(boxView!.transform.b), Float(boxView!.transform.a));
            //create ciimage from the pixelbuffer
            let options = [kCVPixelBufferCGImageCompatibilityKey as String: true,
                kCVPixelBufferCGBitmapContextCompatibilityKey as String: true,]
            let ci = CIImage.init(cvPixelBuffer: pixelBuffer, options: options)
            //transform filter
            let filter = CIFilter.init(name: "CIAffineTransform")
            //set translation point to center
            var transform = CGAffineTransform(translationX: self.view.frame.midX, y: self.view.frame.midY)
            //rotate
            transform = CGAffineTransform(rotationAngle:CGFloat(radians))
            // set translation point back again to normal
            var transformBack = CGAffineTransform(translationX: -self.view.frame.midX, y: -self.view.frame.midY)
            //applying the transform
            transform.concatenating(transformBack)
            filter!.setValue(transform, forKey: kCIInputTransformKey)
            filter!.setValue(ci, forKey: kCIInputImageKey)
            let output = filter?.outputImage
            let img = context.createCGImage(output!, from: imageView!.frame)
            // send image to be displayed
            self.imageView!.image = UIImage(cgImage: img!)
}

Answer 1

Swift 5：

let image = CIImage(cvPixelBuffer: yourBuffer)
let rotatedImage = image.oriented(.right)

文档

Answer 2

找到了。我必须对转换变量本身应用转换。

let transform = CGAffineTransform(translationX: self.view.frame.midX, y: self.view.frame.midY).rotate(angle: CGFloat(radians)).translatedBy(x: -self.view.frame.midX, y: -self.view.frame.midY)