iOS - UIImageView - 如何处理UIImage图像方向

Question

是否可以设置UIImageView来处理图像方向？当我将UIImageView设置为方向为RIGHT的图像(它是来自相机胶卷的照片)时,图像会向右旋转,但我想以正确的方向显示它.

我知道我可以旋转图像数据,但它可以做得更优雅吗？

谢谢

Answer 1

如果我明白,你想要做的是忽视UIImage的方向？如果是这样,那么你可以这样做:

UIImage *originalImage = [... whatever ...];

UIImage *imageToDisplay =
     [UIImage imageWithCGImage:[originalImage CGImage]
              scale:[originalImage scale]
              orientation: UIImageOrientationUp];

因此,您创建的新UIImage具有与原始像素数据相同的像素数据(通过其CGImage属性引用),但您指定的方向不会旋转数据.

Answer 2

您可以完全避免手工做的转换和缩放自己,在这个答案AN0的建议在这里:

- (UIImage *)normalizedImage {
    if (self.imageOrientation == UIImageOrientationUp) return self; 

    UIGraphicsBeginImageContextWithOptions(self.size, NO, self.scale);
    [self drawInRect:(CGRect){0, 0, self.size}];
    UIImage *normalizedImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return normalizedImage;
}

UIImage方法size和drawInRect的文档明确指出它们考虑了方向.

Answer 3

我将Anomie的答案中的代码(由苏格兰的valsan复制粘贴)转换为Swift:

func fixOrientation() -> UIImage {
    if self.imageOrientation == UIImageOrientation.Up {
        return self
    }

    var transform = CGAffineTransformIdentity

    switch self.imageOrientation {
    case .Down, .DownMirrored:
        transform = CGAffineTransformTranslate(transform, self.size.width, self.size.height)
        transform = CGAffineTransformRotate(transform, CGFloat(M_PI));

    case .Left, .LeftMirrored:
        transform = CGAffineTransformTranslate(transform, self.size.width, 0);
        transform = CGAffineTransformRotate(transform, CGFloat(M_PI_2));

    case .Right, .RightMirrored:
        transform = CGAffineTransformTranslate(transform, 0, self.size.height);
        transform = CGAffineTransformRotate(transform, CGFloat(-M_PI_2));

    case .Up, .UpMirrored:
        break
    }

    switch self.imageOrientation {

    case .UpMirrored, .DownMirrored:
        transform = CGAffineTransformTranslate(transform, self.size.width, 0)
        transform = CGAffineTransformScale(transform, -1, 1)

    case .LeftMirrored, .RightMirrored:
        transform = CGAffineTransformTranslate(transform, self.size.height, 0)
        transform = CGAffineTransformScale(transform, -1, 1);

    default:
        break;
    }

    // Now we draw the underlying CGImage into a new context, applying the transform
    // calculated above.
    let ctx = CGBitmapContextCreate(
        nil,
        Int(self.size.width),
        Int(self.size.height),
        CGImageGetBitsPerComponent(self.CGImage),
        0,
        CGImageGetColorSpace(self.CGImage),
        UInt32(CGImageGetBitmapInfo(self.CGImage).rawValue)
    )

    CGContextConcatCTM(ctx, transform);

    switch self.imageOrientation {
    case .Left, .LeftMirrored, .Right, .RightMirrored:
        // Grr...
        CGContextDrawImage(ctx, CGRectMake(0, 0, self.size.height,self.size.width), self.CGImage);

    default:
        CGContextDrawImage(ctx, CGRectMake(0, 0, self.size.width,self.size.height), self.CGImage);
        break;
    }

    // And now we just create a new UIImage from the drawing context
    let cgimg = CGBitmapContextCreateImage(ctx)

    let img = UIImage(CGImage: cgimg!)

    return img;
}

(我替换了参数的所有image出现self,因为我的代码是扩展名UIImage).

编辑: Swift 3版本.

该方法返回一个可选项,因为许多中间调用可能会失败,我不喜欢使用!.

func fixOrientation() -> UIImage? {

    guard let cgImage = self.cgImage else {
        return nil
    }

    if self.imageOrientation == UIImageOrientation.up {
        return self
    }

    let width  = self.size.width
    let height = self.size.height

    var transform = CGAffineTransform.identity

    switch self.imageOrientation {
    case .down, .downMirrored:
        transform = transform.translatedBy(x: width, y: height)
        transform = transform.rotated(by: CGFloat.pi)

    case .left, .leftMirrored:
        transform = transform.translatedBy(x: width, y: 0)
        transform = transform.rotated(by: 0.5*CGFloat.pi)

    case .right, .rightMirrored:
        transform = transform.translatedBy(x: 0, y: height)
        transform = transform.rotated(by: -0.5*CGFloat.pi)

    case .up, .upMirrored:
        break
    }

    switch self.imageOrientation {
    case .upMirrored, .downMirrored:
        transform = transform.translatedBy(x: width, y: 0)
        transform = transform.scaledBy(x: -1, y: 1)

    case .leftMirrored, .rightMirrored:
        transform = transform.translatedBy(x: height, y: 0)
        transform = transform.scaledBy(x: -1, y: 1)

    default:
        break;
    }

    // Now we draw the underlying CGImage into a new context, applying the transform
    // calculated above.
    guard let colorSpace = cgImage.colorSpace else {
        return nil
    }

    guard let context = CGContext(
        data: nil,
        width: Int(width),
        height: Int(height),
        bitsPerComponent: cgImage.bitsPerComponent,
        bytesPerRow: 0,
        space: colorSpace,
        bitmapInfo: UInt32(cgImage.bitmapInfo.rawValue)
        ) else {
            return nil
    }

    context.concatenate(transform);

    switch self.imageOrientation {

    case .left, .leftMirrored, .right, .rightMirrored:
        // Grr...
        context.draw(cgImage, in: CGRect(x: 0, y: 0, width: height, height: width))

    default:
        context.draw(cgImage, in: CGRect(x: 0, y: 0, width: width, height: height))
    }

    // And now we just create a new UIImage from the drawing context
    guard let newCGImg = context.makeImage() else {
        return nil
    }

    let img = UIImage(cgImage: newCGImg)

    return img;
}

(注意:Swift 3版本颂歌在Xcode 8.1下编译,但尚未测试它实际上有效.可能在某处有拼写错误,混合宽度/高度等.随意指出/修复任何错误).

Answer 4

此方法首先检查UIImage的当前方向,然后以顺时针方式更改方向并返回UIImage.您可以将此图像显示为

self.imageView.image = rotateImage(currentUIImage)

   func rotateImage(image:UIImage)->UIImage
    {
        var rotatedImage = UIImage();
        switch image.imageOrientation
        {
            case UIImageOrientation.Right:
            rotatedImage = UIImage(CGImage:image.CGImage!, scale: 1, orientation:UIImageOrientation.Down);

           case UIImageOrientation.Down:
            rotatedImage = UIImage(CGImage:image.CGImage!, scale: 1, orientation:UIImageOrientation.Left);

            case UIImageOrientation.Left:
            rotatedImage = UIImage(CGImage:image.CGImage!, scale: 1, orientation:UIImageOrientation.Up);

             default:
            rotatedImage = UIImage(CGImage:image.CGImage!, scale: 1, orientation:UIImageOrientation.Right);
        }
        return rotatedImage;
    }

Swift 4版

func rotateImage(image:UIImage) -> UIImage
    {
        var rotatedImage = UIImage()
        switch image.imageOrientation
        {
        case .right:
            rotatedImage = UIImage(cgImage: image.cgImage!, scale: 1.0, orientation: .down)

        case .down:
            rotatedImage = UIImage(cgImage: image.cgImage!, scale: 1.0, orientation: .left)

        case .left:
            rotatedImage = UIImage(cgImage: image.cgImage!, scale: 1.0, orientation: .up)

        default:
            rotatedImage = UIImage(cgImage: image.cgImage!, scale: 1.0, orientation: .right)
        }

        return rotatedImage
    }

Answer 5

Swift 3.1

func fixImageOrientation(_ image: UIImage)->UIImage {
    UIGraphicsBeginImageContext(image.size)
    image.draw(at: .zero)
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return newImage ?? image
}

Answer 6

这是一个可行的样本鳕鱼,考虑到图像方向:

#define rad(angle) ((angle) / 180.0 * M_PI)
- (CGAffineTransform)orientationTransformedRectOfImage:(UIImage *)img
{
    CGAffineTransform rectTransform;
    switch (img.imageOrientation)
    {
        case UIImageOrientationLeft:
            rectTransform = CGAffineTransformTranslate(CGAffineTransformMakeRotation(rad(90)), 0, -img.size.height);
            break;
        case UIImageOrientationRight:
            rectTransform = CGAffineTransformTranslate(CGAffineTransformMakeRotation(rad(-90)), -img.size.width, 0);
            break;
        case UIImageOrientationDown:
            rectTransform = CGAffineTransformTranslate(CGAffineTransformMakeRotation(rad(-180)), -img.size.width, -img.size.height);
            break;
        default:
            rectTransform = CGAffineTransformIdentity;
    };

    return CGAffineTransformScale(rectTransform, img.scale, img.scale);
}


- (UIImage *)croppedImage:(UIImage*)orignialImage InRect:(CGRect)visibleRect{
    //transform visible rect to image orientation
    CGAffineTransform rectTransform = [self orientationTransformedRectOfImage:orignialImage];
    visibleRect = CGRectApplyAffineTransform(visibleRect, rectTransform);

    //crop image
    CGImageRef imageRef = CGImageCreateWithImageInRect([orignialImage CGImage], visibleRect);
    UIImage *result = [UIImage imageWithCGImage:imageRef scale:orignialImage.scale orientation:orignialImage.imageOrientation];
    CGImageRelease(imageRef);
    return result;
}

Answer 7

Swift中的UIImage扩展.你根本不需要做任何翻转,真的.Objective-C 原创在这里,但我添加了一个尊重原始图像的alpha的位(粗略地说,但它可以区分不透明图像和透明图像).

// from https://github.com/mbcharbonneau/UIImage-Categories/blob/master/UIImage%2BAlpha.m
// Returns true if the image has an alpha layer
    private func hasAlpha() -> Bool {
        guard let cg = self.cgImage else { return false }
        let alpha = cg.alphaInfo
        let retVal = (alpha == .first || alpha == .last || alpha == .premultipliedFirst || alpha == .premultipliedLast)
        return retVal
    }

    func normalizedImage() -> UIImage? {
        if self.imageOrientation == .up {
            return self
        }
        UIGraphicsBeginImageContextWithOptions(self.size, !self.hasAlpha(), self.scale)
        var rect = CGRect.zero
        rect.size = self.size
        self.draw(in: rect)
        let retVal = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return retVal
    }

Answer 8

我将代码从@Nicolas Miari的答案转换为Swift 3,万一有人需要它

func fixOrientation() -> UIImage
{

    if self.imageOrientation == UIImageOrientation.up {
        return self
    }

    var transform = CGAffineTransform.identity

    switch self.imageOrientation {
    case .down, .downMirrored:
        transform = transform.translatedBy(x: self.size.width, y: self.size.height)
        transform = transform.rotated(by: CGFloat(M_PI));

    case .left, .leftMirrored:
        transform = transform.translatedBy(x: self.size.width, y: 0);
        transform = transform.rotated(by: CGFloat(M_PI_2));

    case .right, .rightMirrored:
        transform = transform.translatedBy(x: 0, y: self.size.height);
        transform = transform.rotated(by: CGFloat(-M_PI_2));

    case .up, .upMirrored:
        break
    }


    switch self.imageOrientation {

    case .upMirrored, .downMirrored:
        transform = transform.translatedBy(x: self.size.width, y: 0)
        transform = transform.scaledBy(x: -1, y: 1)

    case .leftMirrored, .rightMirrored:
        transform = transform.translatedBy(x: self.size.height, y: 0)
        transform = transform.scaledBy(x: -1, y: 1);

    default:
        break;
    }

    // Now we draw the underlying CGImage into a new context, applying the transform
    // calculated above.
    let ctx = CGContext(
        data: nil,
        width: Int(self.size.width),
        height: Int(self.size.height),
        bitsPerComponent: self.cgImage!.bitsPerComponent,
        bytesPerRow: 0,
        space: self.cgImage!.colorSpace!,
        bitmapInfo: UInt32(self.cgImage!.bitmapInfo.rawValue)
    )



    ctx!.concatenate(transform);

    switch self.imageOrientation {

    case .left, .leftMirrored, .right, .rightMirrored:
        // Grr...
        ctx?.draw(self.cgImage!, in: CGRect(x:0 ,y: 0 ,width: self.size.height ,height:self.size.width))

    default:
        ctx?.draw(self.cgImage!, in: CGRect(x:0 ,y: 0 ,width: self.size.width ,height:self.size.height))
        break;
    }

    // And now we just create a new UIImage from the drawing context
    let cgimg = ctx!.makeImage()

    let img = UIImage(cgImage: cgimg!)

    return img;

}

Answer 9

如果您需要旋转并固定图像方向，下面的扩展将很有用。

extension UIImage {

    public func imageRotatedByDegrees(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: self.size.width, height: self.size.height))
        let t: CGAffineTransform = CGAffineTransform(rotationAngle: degrees * CGFloat.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.pi / 180))
        //Now, draw the rotated/scaled image into the context
        bitmap.scaleBy(x: 1.0, y: -1.0)
        bitmap.draw(self.cgImage!, in: CGRect(x: -self.size.width / 2, y: -self.size.height / 2, width: self.size.width, height: self.size.height))
        let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()
        return newImage
    }


    public func fixedOrientation() -> UIImage {
        if imageOrientation == UIImageOrientation.up {
            return self
        }

        var transform: CGAffineTransform = CGAffineTransform.identity

        switch imageOrientation {
        case UIImageOrientation.down, UIImageOrientation.downMirrored:
            transform = transform.translatedBy(x: size.width, y: size.height)
            transform = transform.rotated(by: CGFloat.pi)
            break
        case UIImageOrientation.left, UIImageOrientation.leftMirrored:
            transform = transform.translatedBy(x: size.width, y: 0)
            transform = transform.rotated(by: CGFloat.pi/2)
            break
        case UIImageOrientation.right, UIImageOrientation.rightMirrored:
            transform = transform.translatedBy(x: 0, y: size.height)
            transform = transform.rotated(by: -CGFloat.pi/2)
            break
        case UIImageOrientation.up, UIImageOrientation.upMirrored:
            break
        }

        switch imageOrientation {
        case UIImageOrientation.upMirrored, UIImageOrientation.downMirrored:
            transform.translatedBy(x: size.width, y: 0)
            transform.scaledBy(x: -1, y: 1)
            break
        case UIImageOrientation.leftMirrored, UIImageOrientation.rightMirrored:
            transform.translatedBy(x: size.height, y: 0)
            transform.scaledBy(x: -1, y: 1)
        case UIImageOrientation.up, UIImageOrientation.down, UIImageOrientation.left, UIImageOrientation.right:
            break
        }

        let ctx: CGContext = CGContext(data: nil,
                                       width: Int(size.width),
                                       height: Int(size.height),
                                       bitsPerComponent: self.cgImage!.bitsPerComponent,
                                       bytesPerRow: 0,
                                       space: self.cgImage!.colorSpace!,
                                       bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue)!

        ctx.concatenate(transform)

        switch imageOrientation {
        case UIImageOrientation.left, UIImageOrientation.leftMirrored, UIImageOrientation.right, UIImageOrientation.rightMirrored:
            ctx.draw(self.cgImage!, in: CGRect(x: 0, y: 0, width: size.height, height: size.width))
        default:
            ctx.draw(self.cgImage!, in: CGRect(x: 0, y: 0, width: size.width, height: size.height))
            break
        }

        let cgImage: CGImage = ctx.makeImage()!

        return UIImage(cgImage: cgImage)
    }
}