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。

我抓取提要，将其转换为 CIImage，然后使用 CIFilter 旋转它。我在设置必须围绕其旋转的点时遇到问题。现在它围绕左下角旋转。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

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)

Answer 2

Swift 5:

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

Docs

使用 CIFilter 围绕中心旋转 CIImage

rotate CIImage around center with CIFilter

core-graphics

ios

cifilter

ciimage

swift