將圖像旋轉3 * Double.pi / 2使圖像不出現（swift3）

Question

嘗試將圖像方向旋轉270度，我可以旋轉90度，並且圖像出現，但是當將圖像旋轉270度時，什么也沒有發生。 我添加了2張90度和270度命令的圖片，以使事情更加清晰。

extension CIImage {
var image: UIImage? { return UIImage(ciImage: self) }
var rotatingLeft: CIImage? {
    let transform = CGAffineTransform(translationX: extent.midX, y: extent.midY)
        .rotated(by: CGFloat.pi.divided(by: 2))
        .translatedBy(x: -extent.midX, y: -extent.midY)
    return CIFilter(name: "CIAffineTransform", withInputParameters: [kCIInputImageKey: self, kCIInputTransformKey: NSValue(cgAffineTransform: transform)])?.outputImage
}
var rotatingRight: CIImage? {
    let transform = CGAffineTransform(translationX: extent.midX, y: extent.midY)
        .rotated(by: -CGFloat.pi.divided(by: 2))
        .translatedBy(x: -extent.midX, y: -extent.midY)
    return CIFilter(name: "CIAffineTransform", withInputParameters: [kCIInputImageKey: self, kCIInputTransformKey: NSValue(cgAffineTransform: transform)])?.outputImage
}
}

extension UIImage {
var ciimage: CIImage? { return CIImage(image: self) }
}





import UIKit

class ViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate   {
@IBOutlet var displayImage: UIImageView!


var currentImageView: UIImageView?

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
    let image = info[UIImagePickerControllerOriginalImage] as! UIImage
    self.currentImageView?.image = displayImage.image

    self.currentImageView?.image = image.ciimage?.rotatingLeft?.image

    self.dismiss(animated: true)


}

    func image(_ image: UIImage, didFinishSavingWithError error: NSError?, contextInfo: UnsafeRawPointer) {
        if let error = error {
            // we got back an error!
            let ac = UIAlertController(title: "Save error", message: error.localizedDescription, preferredStyle: .alert)
            ac.addAction(UIAlertAction(title: "OK", style: .default))
            present(ac, animated: true)
        } else {

            let ac = UIAlertController(title: "Image Saved!", message: "Your image has been saved to your photos.", preferredStyle: .alert)
            ac.addAction(UIAlertAction(title: "OK", style: .default))
            present(ac, animated: true)
        }
    }

@IBAction func takePhoto(_ sender: Any) {



    self.currentImageView = self.displayImage



    let imagePicker = UIImagePickerController()
    imagePicker.delegate = self


    imagePicker.sourceType = UIImagePickerControllerSourceType.camera;
    imagePicker.allowsEditing = false
    self.present(imagePicker, animated: true, completion: nil)

}}

Answer 1

您可以擴展CIImage而不是UIImage，並使用轉換矩陣使用核心圖像過濾器CIAffineTransform。 開始將其平移到中心，將其旋轉90度（.pi / 2），然后將其移回：

extension CIImage {
    var image: UIImage? { return UIImage(ciImage: self) }
    func rotated(_ angle: CGFloat) -> CIImage? {
        let transform = CGAffineTransform(translationX: extent.midX, y: extent.midY)
            .rotated(by: angle * .pi /  180)
            .translatedBy(x: -extent.midX, y: -extent.midY)
        return CIFilter(name: "CIAffineTransform", withInputParameters: [kCIInputImageKey: self, kCIInputTransformKey: NSValue(cgAffineTransform: transform)])?.outputImage
    }
    var rotatedLeft: CIImage? { return rotated(90) }
    var rotatedRight: CIImage? { return rotated(-90) }
}

---

游樂場測試：

let image = UIImage(data: try! Data(contentsOf: URL(string:"https://i.stack.imgur.com/Xs4RX.jpg")!))!
image.ciimage?.rotated(22.5)?.image
image.ciimage?.rotatedRight?.image
image.ciimage?.rotatedLeft?.image