如何水平翻转UIImage？

Question

如何水平翻转UIImage，我发现UIImageOrientationUpMirrored的枚举值在UIImage类的引用中，如何利用这个属性来翻转UIImage。

Answer 1

UIImage* sourceImage = [UIImage imageNamed:@"whatever.png"]; 

UIImage* flippedImage = [UIImage imageWithCGImage:sourceImage.CGImage 
              scale:sourceImage.scale 
             orientation:UIImageOrientationUpMirrored]; 

Answer 2

因为它形象定位定义：

typedef NS_ENUM(NSInteger, UIImageOrientation) { 
UIImageOrientationUp,   // default orientation 
UIImageOrientationDown,   // 180 deg rotation 
UIImageOrientationLeft,   // 90 deg CCW 
UIImageOrientationRight,   // 90 deg CW 
UIImageOrientationUpMirrored, // as above but image mirrored along other axis. horizontal flip 
UIImageOrientationDownMirrored, // horizontal flip 
UIImageOrientationLeftMirrored, // vertical flip 
UIImageOrientationRightMirrored, // vertical flip 
}; 

我做了一些改进，更多的情况下，像AVCaptureSession处理的UIImage。

UIImage* sourceImage = [UIImage imageNamed:@"whatever.png"]; 
UIImageOrientation flipingOrientation; 
if(sourceImage.imageOrientation>=4){ 
    flippedOrientation = sourceImage.imageOrientation - 4; 
}else{ 
    flippedOrientation = sourceImage.imageOrientation + 4; 
} 
UIImage* flippedImage = [UIImage imageWithCGImage:sourceImage.CGImage 
        scale: sourceImage.scale orientation: flipingOrientation]; 

Answer 3

可能这将是使用了一段：

UIImageOrientation imageOrientation; 

    switch (sourceImage.imageOrientation) { 
     case UIImageOrientationDown: 
      imageOrientation = UIImageOrientationDownMirrored; 
      break; 

     case UIImageOrientationDownMirrored: 
      imageOrientation = UIImageOrientationDown; 
      break; 

     case UIImageOrientationLeft: 
      imageOrientation = UIImageOrientationLeftMirrored; 
      break; 

     case UIImageOrientationLeftMirrored: 
      imageOrientation = UIImageOrientationLeft; 

      break; 

     case UIImageOrientationRight: 
      imageOrientation = UIImageOrientationRightMirrored; 

      break; 

     case UIImageOrientationRightMirrored: 
      imageOrientation = UIImageOrientationRight; 

      break; 

     case UIImageOrientationUp: 
      imageOrientation = UIImageOrientationUpMirrored; 
      break; 

     case UIImageOrientationUpMirrored: 
      imageOrientation = UIImageOrientationUp; 
      break; 
     default: 
      break; 
    } 

    resultImage = [UIImage imageWithCGImage:sourceImage.CGImage scale:sourceImage.scale orientation:imageOrientation]; 

Answer 4

垂直翻转，往往需要使用glTexImage2d(...)初始化的OpenGL纹理。上面提出的技巧并没有实际修改图像数据，在这种情况下不起作用。下面是一个代码由https://stackoverflow.com/a/17909372

- (UIImage *)flipImage:(UIImage *)image 
{ 
    UIGraphicsBeginImageContext(image.size); 
    CGContextDrawImage(UIGraphicsGetCurrentContext(),CGRectMake(0.,0., image.size.width, image.size.height),image.CGImage); 
    UIImage *i = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 
    return i; 
} 

Answer 5

这里做灵感的实际数据翻转的SWIFT版本：（我看到在评论这个问题）

let srcImage = UIImage(named: "imageName") 
let flippedImage = UIImage(CGImage: srcImage.CGImage, scale: srcImage.scale, orientation: UIImageOrientation.UpMirrored) 

Answer 6

一个你可以做到这一点很简单的方法是通过创建一个UIImageView而不是一个UIImage，并对UIImageView进行转换。

yourImageView.image =[UIImage imageNamed:@"whatever.png"]; 
yourImageView.transform = CGAffineTransformMakeScale(-1, 1); //Flipped 

希望这会有所帮助。

Answer 7

我试图与imageFlippedForRightToLeftLayoutDirection，并创建具有diferent方向新的UIImage，但至少这是我发现我的翻转图像

let ciimage: CIImage = CIImage(CGImage: imagenInicial.CGImage!) 
let rotada3 = ciimage.imageByApplyingTransform(CGAffineTransformMakeScale(-1, 1)) 

正如你可以在我的游乐场，它的工作看到的唯一的解决方案！ :)

而且，当然，让finalImage = UIImage的（CIImage：rotada3）

Answer 8

这是一个工作iOS8上/ 9兼容版本：

UIImage *image = [UIImage imageNamed:name]; 

if ([[UIApplication sharedApplication] userInterfaceLayoutDirection] == UIUserInterfaceLayoutDirectionRightToLeft) { 

    if ([image respondsToSelector:@selector(imageFlippedForRightToLeftLayoutDirection)]) { 
     //iOS9 
     image = image.imageFlippedForRightToLeftLayoutDirection; 
    } 
    else { 
     //iOS8 
     CIImage *coreImage = [CIImage imageWithCGImage:image.CGImage]; 
     coreImage = [coreImage imageByApplyingTransform:CGAffineTransformMakeScale(-1, 1)]; 
     image = [UIImage imageWithCIImage:coreImage scale:image.scale orientation:UIImageOrientationUp]; 
    } 
} 

return image; 

Answer 9

的SWIFT 3：

imageView.transform = CGAffineTransform(scaleX: -1, y: 1) 

Answer 10

这是一个可靠的实现，用于水平镜像/翻转UIImage，并且可以将图像应用到背面前进。由于它改变了底层图像数据，所以绘图（如截图）也会改变。测试工作，没有质量损失。

func flipImage() -> UIImage? { 
     UIGraphicsBeginImageContextWithOptions(self.size, false, self.scale) 
     let bitmap = UIGraphicsGetCurrentContext()! 

     bitmap.translateBy(x: size.width/2, y: size.height/2) 
     bitmap.scaleBy(x: -1.0, y: -1.0) 

     bitmap.translateBy(x: -size.width/2, y: -size.height/2) 
     bitmap.draw(self.cgImage!, in: CGRect(x: 0, y: 0, width: size.width, height: size.height)) 

     let image = UIGraphicsGetImageFromCurrentImageContext() 
     UIGraphicsEndImageContext() 

     return image? 
} 

Answer 11

这里的上述修改和斯威夫特3的答案，我发现是特别有用的，当你有一个按钮，需要保持翻转图像来回之一。

func flipImage(sourceImage: UIImage,orientation: UIImageOrientation) -> UIImage { 


     var imageOrientation = orientation 

     switch sourceImage.imageOrientation { 

     case UIImageOrientation.down: 
      imageOrientation = UIImageOrientation.downMirrored; 
      break; 

     case UIImageOrientation.downMirrored: 
      imageOrientation = UIImageOrientation.down; 
      break; 

     case UIImageOrientation.left: 
      imageOrientation = UIImageOrientation.leftMirrored; 
      break; 

     case UIImageOrientation.leftMirrored: 
      imageOrientation = UIImageOrientation.left; 

      break; 

     case UIImageOrientation.right: 
      imageOrientation = UIImageOrientation.rightMirrored; 

      break; 

     case UIImageOrientation.rightMirrored: 
      imageOrientation = UIImageOrientation.right; 

      break; 

     case UIImageOrientation.up: 
      imageOrientation = UIImageOrientation.upMirrored; 
      break; 

     case UIImageOrientation.upMirrored: 
      imageOrientation = UIImageOrientation.up; 
      break; 


     } 


     return UIImage(cgImage: sourceImage.cgImage!, scale: sourceImage.scale, orientation: imageOrientation) 

    } 

用途：

imageToFlip: UIImage = flipImage(sourceImage: imageToFlip, orientation: imageToFlip.imageOrientation) 

Answer 12

的简单延伸。

extension UIImage { 

    var flipped: UIImage { 
     guard let cgImage = cgImage else { 
      return self 
     } 

     return UIImage(cgImage: cgImage, scale: scale, orientation: .upMirrored) 
    } 
} 

用法：

let image = #imageLiteral(resourceName: "imageName") 
let imageView = UIImageView(image: image.flipped) 

Answer 13

aroth的答案SWIFT 3：

let sourceImage = UIImage(named: "whatever.png")! 
let flippedImage = UIImage(cgImage: sourceImage.cgImage!, scale: sourceImage.scale, orientation: .upMirrored) 

Answer 14

的iOS 10+

[myImage imageWithHorizontallyFlippedOrientation]; 

Answer 15

SWIFT 4

yourImage.transform = CGAffineTransform(scaleX: -1, y: 1);