在 Swift 中旋转 UIImage

Posted 2023-02-23

【中文标题】在 Swift 中旋转 UIImage

【英文标题】：Rotating UIImage in Swift

【发布时间】：2014-11-23 18:02:13

【问题描述】：

我将 Xcode 6.0.1 与 Swift 一起使用。我有一个 UIImage，我想使用旧图像作为源制作另一个图像，新图像以某种方式旋转......比如说垂直翻转。

这个问题已经回答了a few months ago。但是，即使情况相同，该解决方案也不适合我。

当我有

var image = UIImage(CGImage: otherImage.CGImage, scale: 1.0, orientation: .DownMirrored)

Xcode 抱怨说有一个“调用中的额外参数 'scale'”。在检查了 Apple 文档之后，这没有任何意义，因为该版本的初始化程序确实采用了这三个参数。省略比例和方向参数确实可以解决问题，但会阻止我进行旋转。

我能找到的唯一其他参考是this guy，他遇到了同样的问题。

你怎么看？

我确实需要在这个版本的 Xcode 上运行它，所以如果有另一种方法来执行旋转（我还没有找到），那将会很有用。

【问题讨论】：

Xcode 6.0.1 已经过时（不知道是不是这个问题）。您的代码在我的 Xcode 6.1 中编译时没有错误或警告。仅当您省略 .CGImage（如引用的 github 页面中所示）时，您才会收到编译器错误。

如果您喜欢这个 Q/A ***.com/questions/40882487/…

，您可以轻松旋转图像视图来绘制图像

【参考方案1】：

Swift 5 解决方案

我写了Pixel SDK，它为这个问题提供了更强大的解决方案，否则这里是最简单的解决方案：

extension UIImage 
    func rotate(radians: Float) -> UIImage? 
        var newSize = CGRect(origin: CGPoint.zero, size: self.size).applying(CGAffineTransform(rotationAngle: CGFloat(radians))).size
        // Trim off the extremely small float value to prevent core graphics from rounding it up
        newSize.width = floor(newSize.width)
        newSize.height = floor(newSize.height)

        UIGraphicsBeginImageContextWithOptions(newSize, false, self.scale)
        let context = UIGraphicsGetCurrentContext()!

        // Move origin to middle
        context.translateBy(x: newSize.width/2, y: newSize.height/2)
        // Rotate around middle
        context.rotate(by: CGFloat(radians))
        // Draw the image at its center
        self.draw(in: CGRect(x: -self.size.width/2, y: -self.size.height/2, width: self.size.width, height: self.size.height))

        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return newImage
    

要使用此解决方案，您可以执行以下操作

let image = UIImage(named: "image.png")!
let newImage = image.rotate(radians: .pi/2) // Rotate 90 degrees

【讨论】：

这是一个很好的解决方案。我使用了另一个在旋转后剪切了我的图像，但是这个效果很好。

在处理具有不同方向的 UIImage 时要小心。 self.draw() 将自动以 .up 方向绘制图像。

我正在使用这个尝试在自定义 annotationView 中旋转 uiimage。该图像是摩托车的 .png。它没有旋转图像......它只是返回一个黑色方块？

.pi 是 180 度，.pi/2 是 90 度，.pi/4 是 45 度，...，.pi/180 是 1 度。

好答案。你救了我的一天！

【参考方案2】：

这是 UIImage 的一个简单扩展：

//ImageRotation.swift

import UIKit

extension UIImage   
    public func imageRotatedByDegrees(degrees: CGFloat, flip: Bool) -> UIImage 
        let radiansToDegrees: (CGFloat) -> CGFloat = 
            return $0 * (180.0 / CGFloat(M_PI))
        
        let degreesToRadians: (CGFloat) -> CGFloat = 
            return $0 / 180.0 * CGFloat(M_PI)
        

        // calculate the size of the rotated view's containing box for our drawing space
        let rotatedViewBox = UIView(frame: CGRect(origin: CGPointZero, size: size))
        let t = CGAffineTransformMakeRotation(degreesToRadians(degrees));
        rotatedViewBox.transform = t
        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.
        CGContextTranslateCTM(bitmap, rotatedSize.width / 2.0, rotatedSize.height / 2.0);

        //   // Rotate the image context
        CGContextRotateCTM(bitmap, degreesToRadians(degrees));

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

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

        CGContextScaleCTM(bitmap, yFlip, -1.0)
        CGContextDrawImage(bitmap, CGRectMake(-size.width / 2, -size.height / 2, size.width, size.height), CGImage)

        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return newImage
    

(Source)

使用它：

rotatedPhoto = rotatedPhoto?.imageRotatedByDegrees(90, flip: false) 

如果flip设置为true，前者将旋转图像并翻转它。

【讨论】：

配置文件，翻转效果很棒。旋转的问题是确实旋转了图像，但是 - 它改变了纵横比并“破坏它”，你能检查它并修改代码吗？那会很好。谢谢！

还发现它可以修改比率 - 非常接近！

UIGraphicsBeginImageContext(rotatedSize) 应该是 UIGraphicsBeginImageContextWithOptions(rotatedSize, false, self.scale) 以保持比例

Xcode 建议将此代码转换为 Swift 3，但 CGContextDrawImage(bitmap, CGRectMake(-size.width / 2, -size.height / 2, size.width, size.height), CGImage) 这一行除外。将其更改为bitmap?.draw( cgImage!, in: CGRect(x: -size.width / 2, y: -size.height / 2,width: size.width,height: size.height))

这种方式不会释放内存。每次我旋转使用 iPhone 6 拍摄的新照片时，它都会保留大约 30MB 内存。

【参考方案3】：

extension UIImage 
    struct RotationOptions: OptionSet 
        let rawValue: Int

        static let flipOnVerticalAxis = RotationOptions(rawValue: 1)
        static let flipOnHorizontalAxis = RotationOptions(rawValue: 2)
    

    func rotated(by rotationAngle: Measurement<UnitAngle>, options: RotationOptions = []) -> UIImage? 
        guard let cgImage = self.cgImage else  return nil 

        let rotationInRadians = CGFloat(rotationAngle.converted(to: .radians).value)
        let transform = CGAffineTransform(rotationAngle: rotationInRadians)
        var rect = CGRect(origin: .zero, size: self.size).applying(transform)
        rect.origin = .zero

        let renderer = UIGraphicsImageRenderer(size: rect.size)
        return renderer.image  renderContext in
            renderContext.cgContext.translateBy(x: rect.midX, y: rect.midY)
            renderContext.cgContext.rotate(by: rotationInRadians)

            let x = options.contains(.flipOnVerticalAxis) ? -1.0 : 1.0
            let y = options.contains(.flipOnHorizontalAxis) ? 1.0 : -1.0
            renderContext.cgContext.scaleBy(x: CGFloat(x), y: CGFloat(y))

            let drawRect = CGRect(origin: CGPoint(x: -self.size.width/2, y: -self.size.height/2), size: self.size)
            renderContext.cgContext.draw(cgImage, in: drawRect)
        
    

你可以这样使用它：

let rotatedImage = UIImage(named: "my_amazing_image")?.rotated(by: Measurement(value: 48.0, unit: .degrees))

指定翻转标志：

let flippedImage = UIImage(named: "my_amazing_image")?.rotated(by: Measurement(value: 48.0, unit: .degrees), options: [.flipOnVerticalAxis])

【讨论】：

谢谢，很好的解决方案。您能否提供翻转图像的解决方案？

@ixany 我已经更新了在垂直轴上翻转的答案。你是这个意思吗？

这正是我想要的。再次感谢你！ :)

我的研究到此结束，谢谢！！

此功能存在严重问题。当 imageOrientation != UIImage.Orientation.up 时，函数给出完全错误的图像。

【参考方案4】：

斯威夫特 3：

向右旋转：

let image = UIImage(cgImage: otherImage.cgImage!, scale: CGFloat(1.0), orientation: .right)

在游乐场测试：

// MyPlayground.playground

import UIKit
import PlaygroundSupport

let view = UIView(frame: CGRect(x: 0, y: 0, width: 500, height: 500))
view.backgroundColor = UIColor.white
PlaygroundPage.current.liveView = view

let otherImage = UIImage(named: "burger.png", in: Bundle.main,
                         compatibleWith: nil)
let imageViewLeft = UIImageView(image: UIImage(cgImage: (otherImage?.cgImage!)!, scale: CGFloat(1.0), orientation: .left)) 
let imageViewRight = UIImageView(image: UIImage(cgImage: (otherImage?.cgImage!)!, scale: CGFloat(1.0), orientation: .right))

view.addSubview(imageViewLeft)
view.addSubview(imageViewRight)
view.layoutIfNeeded()

【讨论】：

为什么不呢？给我看看你的 Playground 文件！

这就是答案！谢谢！

这并没有回答问题，因为他们要求一种方法来制作另一个图像。此解决方案仅使用方向 EXIF 数据来显示向右转动的图像。因此，例如，您不能调用两次来将图像旋转 180 度。

@typewrite：你是对的，但它可以帮助其他人旋转 UIImages

【参考方案5】：

“调用中的额外参数”通常发生在其中一种输入类型不正确时。

你可以修复你的代码

var image = UIImage(CGImage: otherImage.CGImage, scale: CGFloat(1.0), orientation: .DownMirrored)

【参考方案6】：

@confile 答案已更新至 Swift 4

import UIKit

extension UIImage 

    public func imageRotatedByDegrees(degrees: CGFloat, flip: Bool) -> UIImage 
        let radiansToDegrees: (CGFloat) -> CGFloat = 
            return $0 * (180.0 / CGFloat.pi)
        
        let degreesToRadians: (CGFloat) -> CGFloat = 
            return $0 / 180.0 * CGFloat.pi
        

        // calculate the size of the rotated view's containing box for our drawing space
        let rotatedViewBox = UIView(frame: CGRect(origin: .zero, size: size))
        let t = CGAffineTransform(rotationAngle: degreesToRadians(degrees));
        rotatedViewBox.transform = t
        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)

        //   // Rotate the image context
        bitmap?.rotate(by: degreesToRadians(degrees))

        // 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)
        let rect = CGRect(x: -size.width / 2, y: -size.height / 2, width: size.width, height: size.height)

        bitmap?.draw(cgImage!, in: rect)

        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return newImage!
    

【参考方案7】：

试试这个代码，它对我有用：

@IBAction func btnRotateImagePressed(sender: AnyObject) 
    if let originalImage = self.imageView.image 

        let rotateSize = CGSize(width: originalImage.size.height, height: originalImage.size.width)
        UIGraphicsBeginImageContextWithOptions(rotateSize, true, 2.0)
        if let context = UIGraphicsGetCurrentContext() 
            CGContextRotateCTM(context, 90.0 * CGFloat(M_PI) / 180.0)
            CGContextTranslateCTM(context, 0, -originalImage.size.height)
            originalImage.drawInRect(CGRectMake(0, 0, originalImage.size.width, originalImage.size.height))
            self.imageView.image = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()
        
    

【讨论】：

我将它转换为 Swift4 但它会导致内存问题。

使用 UIGraphicsEndImageContext() 后内存问题解决了。

当拍摄landscapeLeft图像然后显示图像是错误的一面。

【参考方案8】：

不要使用UIGraphicsBeginImageContext，因为它会破坏你的向量的质量，使用UIGraphicsBeginImageContextWithOptions。这是我在 Swift 3/4 中的实现：

extension UIImage 

  func rotated(degrees: CGFloat) -> UIImage? 

    let degreesToRadians: (CGFloat) -> CGFloat =  (degrees: CGFloat) in
      return degrees / 180.0 * CGFloat.pi
    

    // Calculate the size of the rotated view's containing box for our drawing space
    let rotatedViewBox: UIView = UIView(frame: CGRect(origin: .zero, size: size))
    rotatedViewBox.transform = CGAffineTransform(rotationAngle: degreesToRadians(degrees))
    let rotatedSize: CGSize = rotatedViewBox.frame.size

    // Create the bitmap context
    UIGraphicsBeginImageContextWithOptions(rotatedSize, false, 0.0)

    guard let bitmap: CGContext = UIGraphicsGetCurrentContext(), let unwrappedCgImage: CGImage = cgImage else 
      return nil
    

    // 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)

    // Rotate the image context
    bitmap.rotate(by: degreesToRadians(degrees))

    bitmap.scaleBy(x: CGFloat(1.0), y: -1.0)

    let rect: CGRect = CGRect(
        x: -size.width/2,
        y: -size.height/2,
        width: size.width,
        height: size.height)

    bitmap.draw(unwrappedCgImage, in: rect)

    guard let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext() else 
      return nil
    

    UIGraphicsEndImageContext()

    return newImage
  

【讨论】：

我如何使用这个扩展。我尝试这样使用它：让 originalImage = UIImage(named: "image").rotated(degrees: 90) 并没有工作。

【参考方案9】：

对于 Swift 4.2

extension UIImage 


func rotate(_ radians: CGFloat) -> UIImage 
    let cgImage = self.cgImage!
    let LARGEST_SIZE = CGFloat(max(self.size.width, self.size.height))
    let context = CGContext.init(data: nil, width:Int(LARGEST_SIZE), height:Int(LARGEST_SIZE), bitsPerComponent: cgImage.bitsPerComponent, bytesPerRow: 0, space: cgImage.colorSpace!, bitmapInfo: cgImage.bitmapInfo.rawValue)!

    var drawRect = CGRect.zero
    drawRect.size = self.size
    let drawOrigin = CGPoint(x: (LARGEST_SIZE - self.size.width) * 0.5,y: (LARGEST_SIZE - self.size.height) * 0.5)
    drawRect.origin = drawOrigin
    var tf = CGAffineTransform.identity
    tf = tf.translatedBy(x: LARGEST_SIZE * 0.5, y: LARGEST_SIZE * 0.5)
    tf = tf.rotated(by: CGFloat(radians))
    tf = tf.translatedBy(x: LARGEST_SIZE * -0.5, y: LARGEST_SIZE * -0.5)
    context.concatenate(tf)
    context.draw(cgImage, in: drawRect)
    var rotatedImage = context.makeImage()!

    drawRect = drawRect.applying(tf)

    rotatedImage = rotatedImage.cropping(to: drawRect)!
    let resultImage = UIImage(cgImage: rotatedImage)
    return resultImage

【参考方案10】：

这适用于 ios 8+ 并保持图像质量。这是 UIImage 的两个扩展。

  extension UIImage 
    func withSize(_ width: CGFloat, _ height: CGFloat) -> UIImage 

      let target = CGSize(width, height)

      var scaledImageRect = CGRect.zero

      let aspectWidth:CGFloat = target.width / self.size.width
      let aspectHeight:CGFloat = target.height / self.size.height
      let aspectRatio:CGFloat = min(aspectWidth, aspectHeight)

      scaledImageRect.size.width = self.size.width * aspectRatio
      scaledImageRect.size.height = self.size.height * aspectRatio
      scaledImageRect.origin.x = (target.width - scaledImageRect.size.width) / 2.0
      scaledImageRect.origin.y = (target.height - scaledImageRect.size.height) / 2.0

      UIGraphicsBeginImageContextWithOptions(target, false, 0)

      self.draw(in: scaledImageRect)

      let scaledImage = UIGraphicsGetImageFromCurrentImageContext()
      UIGraphicsEndImageContext()

      return scaledImage!
    

    func rotated(degrees: Double) -> UIImage 

      let radians = CGFloat(Double.pi * degrees / 180)

      var rotatedViewBox: UIView? = UIView(frame: CGRect(x: 0, y: 0, width: size.width * scale, height: size.height * scale))
      let t = CGAffineTransform(rotationAngle: radians)
      rotatedViewBox!.transform = t
      let rotatedSize = rotatedViewBox!.frame.size
      rotatedViewBox = nil

      // 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, y: rotatedSize.height/2)

      //   // Rotate the image context
      bitmap.rotate(by: radians)

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

      let newImage = UIGraphicsGetImageFromCurrentImageContext()!
      UIGraphicsEndImageContext()

      return newImage.withSize(newImage.size.width/scale, newImage.size.height/scale)
    
  

【参考方案11】：

如果您需要水平翻转图像或者如果您需要原始图像的镜像，有一个简单的方法：

此代码适用于我翻转图像：

let originalImage = UIImage(named: "image")
let flippedImage = originalImage?.withHorizontallyFlippedOrientation()

Documentation

【参考方案12】：

检查一下：

func rotatedImage(with angle: CGFloat) -> UIImage 

    let updatedSize = CGRect(origin: .zero, size: size)
        .applying(CGAffineTransform(rotationAngle: angle))
        .size

    return UIGraphicsImageRenderer(size: updatedSize)
        .image  _ in

            let context = UIGraphicsGetCurrentContext()

            context?.translateBy(x: updatedSize.width / 2.0, y: updatedSize.height / 2.0)
            context?.rotate(by: angle)

            draw(in: CGRect(x: -size.width / 2.0, y: -size.height / 2.0, width: size.width, height: size.height))
        
        .withRenderingMode(renderingMode)

【参考方案13】：

使用 Swift 5 Xcode 13 测试

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))
    

以度为单位传递角度

myView.rotate(degrees : 90)