将图像旋转 3*Double.pi/2 使图像不出现(swift3) [英] Rotating image by 3*Double.pi/2 makes image not appear (swift3)

问题描述

尝试将我的图像方向旋转 270 度我可以旋转 90 度并且图像出现但是当将图像旋转 270 时没有任何反应.我添加了 2 张 90 度和 270 度命令的图片，以使事情更清楚.

Trying to rotate my image orientation by 270 degrees I can rotate by 90 degrees and the image appears however when rotating the image by 270 nothing happens. I have added 2 pictures of the 90 and 270 degrees commands to make things more clear.

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)

}}

推荐答案

您可以扩展 CIImage 而不是 UIImage，并使用转换矩阵使用核心图像过滤器 CIAffineTransform.开始将其平移到中心，将其旋转 90 度 (.pi/2) 并将其移回:

You can extend CIImage instead of UIImage and use core image filter CIAffineTransform using the transformation matrix. Start translating it to the center, rotate it 90 degrees (.pi/2) and move it back:

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) }
}

<小时>

游乐场测试:

---

Playground testing:

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

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