我正在iOS 3.1.3 iPhone上测试我的iPhone应用程序。我正在使用UIImagePickerController选择/捕获图像:

UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
[imagePicker setSourceType:UIImagePickerControllerSourceTypeCamera];
[imagePicker setDelegate:self];
[self.navigationController presentModalViewController:imagePicker animated:YES];
[imagePicker release];



- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    self.image = [info objectForKey:UIImagePickerControllerOriginalImage];
    imageView.image = self.image;
    [self.navigationController dismissModalViewControllerAnimated:YES];
    submitButton.enabled = YES;
}

然后在某个时候,我使用ASI类将它发送到我的web服务器:

ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:[NSURL URLWithString:@"http://example.com/myscript.php"]];
[request setDelegate:self];
[request setStringEncoding:NSUTF8StringEncoding];
[request setShouldContinueWhenAppEntersBackground:YES];
//other post keys/values
[request setFile:UIImageJPEGRepresentation(self.image, 100.0f) withFileName:[NSString stringWithFormat:@"%d.jpg", [[NSDate date] timeIntervalSinceNow]] andContentType:@"image/jpg" forKey:@"imageFile"];
[request startAsynchronous];

存在的问题: 当我拿着iPhone拍照时,照片会被上传到服务器,就像你期望的那样。手持竖屏拍照时,上传的照片是旋转90度后观看的。

我的应用程序被设置为只在纵向模式(倒置和常规)下工作。

我怎样才能使图像始终显示正确的方向后上传?

在UIImageView中显示的图像是正确的(直接在拍照后),但在服务器上查看则不然。


当前回答

我在设计我的应用程序拍照时使用了这个页面,我发现以下方法将纠正方向,并且比以前的答案使用更少的内存和处理器:

CGImageRef cgRef = image.CGImage;
image = [[UIImage alloc] initWithCGImage:cgRef scale:1.0 orientation:UIImageOrientationUp];

这基本上只是用一个新的方向重新包装实际的图像数据。我使用@an0的代码,但它使一个新的图像在内存中,这可能是一个326x2448的图像,你可能会从相机。

其他回答

以下是@an0给出的答案的Swift版本:

func normalizedImage() -> UIImage {

  if (self.imageOrientation == UIImageOrientation.Up) { 
      return self;
  }

  UIGraphicsBeginImageContextWithOptions(self.size, false, self.scale);
  let rect = CGRect(x: 0, y: 0, width: self.size.width, height: self.size.height)
  self.drawInRect(rect)

  let normalizedImage : UIImage = UIGraphicsGetImageFromCurrentImageContext()
  UIGraphicsEndImageContext();
  return normalizedImage;
}

也可以用在更一般的函数中:

func fixOrientation(img:UIImage) -> UIImage {

  if (img.imageOrientation == UIImageOrientation.Up) { 
      return img;
  }

  UIGraphicsBeginImageContextWithOptions(img.size, false, img.scale);
  let rect = CGRect(x: 0, y: 0, width: img.size.width, height: img.size.height)
  img.drawInRect(rect)

  let normalizedImage : UIImage = UIGraphicsGetImageFromCurrentImageContext()
  UIGraphicsEndImageContext();
  return normalizedImage;

}

Swift 3版本:

func fixOrientation(img: UIImage) -> UIImage {
    if (img.imageOrientation == .up) {
        return img
    }

    UIGraphicsBeginImageContextWithOptions(img.size, false, img.scale)
    let rect = CGRect(x: 0, y: 0, width: img.size.width, height: img.size.height)
    img.draw(in: rect)

    let normalizedImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()

    return normalizedImage
}

我想出了一个更简单的方法:

- (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;
}

顺便说一句:@Anomie的代码没有考虑到比例,所以不适合2倍的图像。

@an0, thanks for the answer!
The only thing is autoreleasepool: 

func fixOrientation(img: UIImage) -> UIImage? {

    let result: UIImage?
    if img.imageOrientation == .up {
        result = img
    } else {

        result = autoreleasepool { () -> UIImage? in
            UIGraphicsBeginImageContextWithOptions(img.size, false, img.scale)
            let rect = CGRect(x: 0, y: 0, width: img.size.width, height: img.size.height)
            img.draw(in: rect)

            let normalizedImage = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()

            return normalizedImage
        }
    }

    return result
}

我通过在下面写几行代码来实现这一点

extension UIImage {

    public func correctlyOrientedImage() -> UIImage {
        guard imageOrientation != .up else { return self }

        UIGraphicsBeginImageContextWithOptions(size, false, scale)
        draw(in: CGRect(origin: .zero, size: size))
        let normalizedImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()

        return normalizedImage
    }
}

这是一个不改变原始图像颜色空间的解决方案。如果你想规范化一个灰度图像的方向,你不会幸运地使用所有基于UIGraphicsBeginImageContextWithOptions的解决方案,因为它在RGB颜色空间中创建了一个上下文。相反,你必须创建一个具有与原始图像相同属性的上下文并绘制:

extension UIImage {
    static let rotatedOrentations: [UIImage.Orientation] = [.left, .leftMirrored, .right, .rightMirrored]

    func normalizedImage() -> UIImage {
        if imageOrientation == .up {
            return self
        }

        let image = self.cgImage!
        let swapOrientation = UIImage.rotatedOrentations.contains(imageOrientation)
        let width = swapOrientation ? image.height : image.width
        let height = swapOrientation ? image.width : image.height
        let context = CGContext(data: nil, width: width, height: height, bitsPerComponent: image.bitsPerComponent, bytesPerRow: image.bytesPerRow, space: image.colorSpace!, bitmapInfo: image.bitmapInfo.rawValue)!
        let flipVertical = CGAffineTransform(a: 1, b: 0, c: 0, d: -1, tx: 0, ty: CGFloat(height));
        context.concatenate(flipVertical)
        UIGraphicsPushContext(context)
        self.draw(at: .zero)
        UIGraphicsPopContext()

        return UIImage(cgImage: context.makeImage()!)
    }
}