ios 如何在 Swift 中旋转图像？

How to rotate image in Swift?

提问by TechChain

I am unable to rotate the image by 90 degrees in swift. I have written below code but there is an error and doesn't compile

我无法快速将图像旋转 90 度。我写了下面的代码但是有一个错误并且不能编译

  func imageRotatedByDegrees(oldImage: UIImage, deg degrees: CGFloat) -> UIImage {

    //Calculate the size of the rotated view's containing box for our drawing space
    let rotatedViewBox: UIView = UIView(frame: CGRect(x: 0, y: 0, width: oldImage.size.width, height: oldImage.size.height))
    let t: CGAffineTransform = CGAffineTransform(rotationAngle: degrees * CGFloat(M_PI / 180))
    rotatedViewBox.transform = t
    let rotatedSize: CGSize = rotatedViewBox.frame.size

    //Create the bitmap context
    UIGraphicsBeginImageContext(rotatedSize)
    let bitmap: CGContext = UIGraphicsGetCurrentContext()!

    //Move the origin to the middle of the image so we will rotate and scale around the center.
    bitmap.translateBy(x: rotatedSize.width / 2, y: rotatedSize.height / 2)

    //Rotate the image context
    bitmap.rotate(by: (degrees * CGFloat(M_PI / 180)))

    //Now, draw the rotated/scaled image into the context
    bitmap.scaleBy(x: 1.0, y: -1.0)
    bitmap.draw(oldImage, in:  CGRect(origin: (x: -oldImage.size.width / 2,  y: -oldImage.size.height / 2, width:  oldImage.size.width, height: oldImage.size.height), size: oldImage.cgImage))

    let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()

    return newImage

  }

below is the code i am not sure about

下面是我不确定的代码

bitmap.draw(oldImage, in:  CGRect(origin: (x: -oldImage.size.width / 2,  y: -oldImage.size.height / 2, width:  oldImage.size.width, height: oldImage.size.height), size: oldImage.cgImage))

采纳答案by CodeBender

This is an extension of UIImagethat targets Swift 4.0and can rotate just the image without the need for a UIImageView. Tested successfully that the image was rotated, and not just had its exif data changed.

这是UIImage针对Swift 4.0的扩展，可以仅旋转图像而无需UIImageView. 成功测试图像已旋转，而不仅仅是更改了 exif 数据。

import UIKit

extension UIImage {
    func rotate(radians: CGFloat) -> UIImage {
        let rotatedSize = CGRect(origin: .zero, size: size)
            .applying(CGAffineTransform(rotationAngle: CGFloat(radians)))
            .integral.size
        UIGraphicsBeginImageContext(rotatedSize)
        if let context = UIGraphicsGetCurrentContext() {
            let origin = CGPoint(x: rotatedSize.width / 2.0,
                                 y: rotatedSize.height / 2.0)
            context.translateBy(x: origin.x, y: origin.y)
            context.rotate(by: radians)
            draw(in: CGRect(x: -origin.y, y: -origin.x,
                            width: size.width, height: size.height))
            let rotatedImage = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()

            return rotatedImage ?? self
        }

        return self
    }
}

To perform a 180 degree rotation, you can call it like this:

要执行 180 度旋转，您可以这样调用：

let rotatedImage = image.rotate(radians: .pi)

If for whatever reason it fails to rotate, the original image will then be returned.

如果由于某种原因无法旋转，则将返回原始图像。

回答by Jayesh Miruliya

set ImageView image

设置 ImageView 图像

ImageView.transform = ImageView.transform.rotated(by: CGFloat(M_PI_2))

Swift 5

斯威夫特 5

ImageView.transform = ImageView.transform.rotated(by: .pi)        // 180?

ImageView.transform = ImageView.transform.rotated(by: .pi / 2)    // 90?

ImageView.transform = ImageView.transform.rotated(by: .pi * 1.5)  // 270?

回答by Aaron Halvorsen

In one line:

在一行中：

rotatedViewBox.transform = CGAffineTransform(rotationAngle: CGFloat.pi/2)

回答by Chirag kukreja

 let angle =  CGFloat(M_PI_2)
  let tr = CGAffineTransform.identity.rotated(by: angle)
  ImageView.transform = tr

回答by iOS

In Swift 4.2 and Xcode 10.0

在 Swift 4.2 和 Xcode 10.0 中

dropDownImageView.transform = dropDownImageView.transform.rotated(by: CGFloat(Double.pi / 2))

If you want to add animation...

如果要添加动画...

UIView.animate(withDuration: 2.0, animations: {
   self.dropDownImageView.transform = self.dropDownImageView.transform.rotated(by: CGFloat(Double.pi / 2))
})

回答by Smit Yash

You can use the code below for Swift 3:

您可以将以下代码用于 Swift 3：

extension UIImage {

func fixImageOrientation() -> UIImage? {
    var flip:Bool = false //used to see if the image is mirrored
    var isRotatedBy90:Bool = false // used to check whether aspect ratio is to be changed or not

    var transform = CGAffineTransform.identity

    //check current orientation of original image
    switch self.imageOrientation {
    case .down, .downMirrored:
        transform = transform.rotated(by: CGFloat(M_PI));

    case .left, .leftMirrored:
        transform = transform.rotated(by: CGFloat(M_PI_2));
        isRotatedBy90 = true
    case .right, .rightMirrored:
        transform = transform.rotated(by: CGFloat(-M_PI_2));
        isRotatedBy90 = true
    case .up, .upMirrored:
        break
    }

    switch self.imageOrientation {

    case .upMirrored, .downMirrored:
        transform = transform.translatedBy(x: self.size.width, y: 0)
        flip = true

    case .leftMirrored, .rightMirrored:
        transform = transform.translatedBy(x: self.size.height, y: 0)
        flip = true
    default:
        break;
    }

    // calculate the size of the rotated view's containing box for our drawing space
    let rotatedViewBox = UIView(frame: CGRect(origin: CGPoint(x:0, y:0), size: size))
    rotatedViewBox.transform = transform
    let rotatedSize = rotatedViewBox.frame.size

    // Create the bitmap context
    UIGraphicsBeginImageContext(rotatedSize)
    let bitmap = UIGraphicsGetCurrentContext()

    // Move the origin to the middle of the image so we will rotate and scale around the center.
    bitmap!.translateBy(x: rotatedSize.width / 2.0, y: rotatedSize.height / 2.0);

    // Now, draw the rotated/scaled image into the context
    var yFlip: CGFloat

    if(flip){
        yFlip = CGFloat(-1.0)
    } else {
        yFlip = CGFloat(1.0)
    }

    bitmap!.scaleBy(x: yFlip, y: -1.0)

    //check if we have to fix the aspect ratio
    if isRotatedBy90 {
        bitmap?.draw(self.cgImage!, in: CGRect(x: -size.width / 2, y: -size.height / 2, width: size.height,height: size.width))
    } else {
        bitmap?.draw(self.cgImage!, in: CGRect(x: -size.width / 2, y: -size.height / 2, width: size.width,height: size.height))
    }

    let fixedImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return fixedImage
}

回答by Sarath Raveendran

Rotate image via UIGraphics Context is comparatively heavy operation. The problems you may seen loosing quality and memory increase.

通过 UIGraphics Context 旋转图像是比较繁重的操作。您可能会遇到质量下降和内存下降的问题。

I suggest you should try to rotate the layer or view itself.

我建议您应该尝试旋转图层或查看本身。

extension UIView {


    func rotate(degrees: CGFloat) {

        let degreesToRadians: (CGFloat) -> CGFloat = { (degrees: CGFloat) in
            return degrees / 180.0 * CGFloat.pi
        }
        self.transform =  CGAffineTransform(rotationAngle: degreesToRadians(degrees))

        // If you like to use layer you can uncomment the following line 
        //layer.transform = CATransform3DMakeRotation(degreesToRadians(degrees), 0.0, 0.0, 1.0)
    }
}

How to use

如何使用

yourImageView.rotate(degrees: 40)

回答by par

Your code is not that far off from functional. You can apply the transform as you are doing directly to the bitmap, you don't need an intermediate view:

你的代码离功能不远了。您可以直接对位图应用转换，不需要中间视图：

func imageRotatedByDegrees(oldImage: UIImage, deg degrees: CGFloat) -> UIImage {
    let size = oldImage.size

    UIGraphicsBeginImageContext(size)

    let bitmap: CGContext = UIGraphicsGetCurrentContext()!
    //Move the origin to the middle of the image so we will rotate and scale around the center.
    bitmap.translateBy(x: size.width / 2, y: size.height / 2)
    //Rotate the image context
    bitmap.rotate(by: (degrees * CGFloat(M_PI / 180)))
    //Now, draw the rotated/scaled image into the context
    bitmap.scaleBy(x: 1.0, y: -1.0)

    let origin = CGPoint(x: -size.width / 2, y: -size.width / 2)

    bitmap.draw(oldImage.cgImage!, in: CGRect(origin: origin, size: size))

    let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return newImage
}

Also, if you're going to create a function that rotates an image, it is typically good form to include a clockwise: Boolparameter that will interpret the degreesargument as rotating clockwise or not. The implementation and appropriate conversion to radians I leave to you.

此外，如果您要创建一个旋转图像的函数，通常最好包含一个clockwise: Bool参数，该参数会将参数解释degrees为是否顺时针旋转。弧度的实现和适当的转换我留给你。

Also note that it's a bit hand-wavy on my part to assume that oldImage.sizeis non-zero. If it is, force-unwrapping UIGraphicsGetCurrentContext()!will probably crash. You should validate the oldImage's size and if it's invalid just return oldImage.

另请注意，假设它oldImage.size不为零对我来说有点摇摆不定。如果是，强制展开UIGraphicsGetCurrentContext()!可能会崩溃。您应该验证oldImage的大小，如果无效则返回oldImage。

回答by Okan

You can first set your image in imageView and rotate get your image in imageView

您可以先在 imageView 中设置图像并旋转在 imageView 中获取图像

Here:

这里：

let customImageView = UIImageView()
customImageView.frame = CGRect.init(x: 0, y: 0, w: 250, h: 250)
customImageView.image = UIImage(named: "yourImage")

customImageView .transform = customImageView .transform.rotated(by: CGFloat.init(M_PI_2))
var rotatedImage = UIImage()
rotatedImage = customImageView.image!

回答by user1039695

If you just don't want specific rotation and like to use all orientations one by one.

如果您只是不想要特定的旋转并且喜欢一个一个地使用所有方向。

func rotateImage() -> UIImage {
    let newOrientation = Orientation(rawValue: self.imageOrientation.rawValue + 1) ?? UIImage.Orientation(rawValue: 0)
    return UIImage(cgImage: self.cgImage!, scale: self.scale, orientation: newOrientation!)
}