AVFoundation图像方向在预览中偏离90度，但在相机胶卷中很好 [英] AVFoundation Image orientation off by 90 degrees in the preview but fine in Camera roll

问题描述

发生了一些非常奇怪的事情，我正在尝试使用AVFoundation拍摄图像，相机胶卷图像看起来很好，但图像预览将图像旋转了90度。

Something really strange is happening, I am trying to capture an image using AVFoundation, the Camera roll image seems just fine, but the image preview has the image rotated by 90 degrees.

这是我用来捕捉图像的代码

This is the code I am using to capture an image

AVCaptureConnection *videoConnection = nil;
for (AVCaptureConnection *connection in stillImageOutput.connections)
{
    for (AVCaptureInputPort *port in [connection inputPorts])
    {
        if ([[port mediaType] isEqual:AVMediaTypeVideo] )
        {
            videoConnection = connection;
            break;
        }
    }
    if (videoConnection)
    {
        break;
    }
}

//NSLog(@"about to request a capture from: %@", stillImageOutput);
[stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error)
 {
     CFDictionaryRef exifAttachments = CMGetAttachment( imageSampleBuffer, kCGImagePropertyExifDictionary, NULL);
     if (exifAttachments)
     {
         // Do something with the attachments.
         //NSLog(@"attachements: %@", exifAttachments);
     } else {
         NSLog(@"no attachments");
     }

     NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];

     UIImage *image = [[UIImage alloc] initWithData:imageData];

     self.vImage.image = image;

     UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
 }];

推荐答案

是的，当您以纵向方向捕获图像时会发生这种情况您的设备并在应用程序中使用该图像，因为图像的默认方向是任何IOS设备中的横向，因此您需要在从图库中选择后更改图像的方向以在您的应用中使用。

yes ,it happens when you capture image in Portrait orientation of your device and use that image in your application, because the default orientation of image is Landscape in any IOS Device, so you need to change the orientation of image after picking from Gallery to use in your app.

我已经付了代码来实现这个目标

I have put code to achieve this

Objective-C代码

- (UIImage *)fixOrientationOfImage:(UIImage *)image {

    // No-op if the orientation is already correct
    if (image.imageOrientation == UIImageOrientationUp) return image;

    // We need to calculate the proper transformation to make the image upright.
    // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
    CGAffineTransform transform = CGAffineTransformIdentity;

    switch (image.imageOrientation) {
        case UIImageOrientationDown:
        case UIImageOrientationDownMirrored:
            transform = CGAffineTransformTranslate(transform, image.size.width, image.size.height);
            transform = CGAffineTransformRotate(transform, M_PI);
            break;

        case UIImageOrientationLeft:
        case UIImageOrientationLeftMirrored:
            transform = CGAffineTransformTranslate(transform, image.size.width, 0);
            transform = CGAffineTransformRotate(transform, M_PI_2);
            break;

        case UIImageOrientationRight:
        case UIImageOrientationRightMirrored:
            transform = CGAffineTransformTranslate(transform, 0, image.size.height);
            transform = CGAffineTransformRotate(transform, -M_PI_2);
            break;
        case UIImageOrientationUp:
        case UIImageOrientationUpMirrored:
            break;
    }

    switch (image.imageOrientation) {
        case UIImageOrientationUpMirrored:
        case UIImageOrientationDownMirrored:
            transform = CGAffineTransformTranslate(transform, image.size.width, 0);
            transform = CGAffineTransformScale(transform, -1, 1);
            break;

        case UIImageOrientationLeftMirrored:
        case UIImageOrientationRightMirrored:
            transform = CGAffineTransformTranslate(transform, image.size.height, 0);
            transform = CGAffineTransformScale(transform, -1, 1);
            break;
        case UIImageOrientationUp:
        case UIImageOrientationDown:
        case UIImageOrientationLeft:
        case UIImageOrientationRight:
            break;
    }

    // Now we draw the underlying CGImage into a new context, applying the transform
    // calculated above.
    CGContextRef ctx = CGBitmapContextCreate(NULL, image.size.width, image.size.height,
                                             CGImageGetBitsPerComponent(image.CGImage), 0,
                                             CGImageGetColorSpace(image.CGImage),
                                             CGImageGetBitmapInfo(image.CGImage));
    CGContextConcatCTM(ctx, transform);
    switch (image.imageOrientation) {
        case UIImageOrientationLeft:
        case UIImageOrientationLeftMirrored:
        case UIImageOrientationRight:
        case UIImageOrientationRightMirrored:
            // Grr...
            CGContextDrawImage(ctx, CGRectMake(0,0,image.size.height,image.size.width), image.CGImage);
            break;

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

    // And now we just create a new UIImage from the drawing context
    CGImageRef cgimg = CGBitmapContextCreateImage(ctx);
    UIImage *img = [UIImage imageWithCGImage:cgimg];
    CGContextRelease(ctx);
    CGImageRelease(cgimg);
    return img;
}

Swift代码

func fixOrientationOfImage(image: UIImage) -> UIImage? {
   if image.imageOrientation == .Up {
      return image
   }

   // We need to calculate the proper transformation to make the image upright.
   // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
   var transform = CGAffineTransformIdentity

   switch image.imageOrientation {
   case .Down, .DownMirrored:
      transform = CGAffineTransformTranslate(transform, image.size.width, image.size.height)
      transform = CGAffineTransformRotate(transform, CGFloat(M_PI))
   case .Left, .LeftMirrored:
      transform = CGAffineTransformTranslate(transform, image.size.width, 0)
      transform = CGAffineTransformRotate(transform, CGFloat(M_PI_2))
   case .Right, .RightMirrored:
      transform = CGAffineTransformTranslate(transform, 0, image.size.height)
      transform = CGAffineTransformRotate(transform, -CGFloat(M_PI_2))
   default:
      break
   }

   switch image.imageOrientation {
   case .UpMirrored, .DownMirrored:
      transform = CGAffineTransformTranslate(transform, image.size.width, 0)
      transform = CGAffineTransformScale(transform, -1, 1)
   case .LeftMirrored, .RightMirrored:
      transform = CGAffineTransformTranslate(transform, image.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.
   guard let context = CGBitmapContextCreate(nil, Int(image.size.width), Int(image.size.height), CGImageGetBitsPerComponent(image.CGImage), 0, CGImageGetColorSpace(image.CGImage), CGImageGetBitmapInfo(image.CGImage).rawValue) else {
      return nil
   }

   CGContextConcatCTM(context, transform)

   switch image.imageOrientation {
   case .Left, .LeftMirrored, .Right, .RightMirrored:
      CGContextDrawImage(context, CGRect(x: 0, y: 0, width: image.size.height, height: image.size.width), image.CGImage)
   default:
      CGContextDrawImage(context, CGRect(origin: .zero, size: image.size), image.CGImage)
   }

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

   return UIImage(CGImage: CGImage)
}

Swift 3.0

func fixOrientationOfImage(image: UIImage) -> UIImage? {
    if image.imageOrientation == .up {
        return image
    }

    // We need to calculate the proper transformation to make the image upright.
    // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
    var transform = CGAffineTransform.identity

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

    switch image.imageOrientation {
    case .upMirrored, .downMirrored:
        transform = transform.translatedBy(x: image.size.width, y: 0)
        transform = transform.scaledBy(x: -1, y: 1)
    case .leftMirrored, .rightMirrored:
        transform = transform.translatedBy(x: image.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.
    guard let context = CGContext(data: nil, width: Int(image.size.width), height: Int(image.size.height), bitsPerComponent: image.cgImage!.bitsPerComponent, bytesPerRow: 0, space: image.cgImage!.colorSpace!, bitmapInfo: image.cgImage!.bitmapInfo.rawValue) else {
        return nil
    }

    context.concatenate(transform)

    switch image.imageOrientation {
      case .left, .leftMirrored, .right, .rightMirrored:
        context.draw(image.cgImage!, in: CGRect(x: 0, y: 0, width: image.size.height, height: image.size.width))
       default:
          context.draw(image.cgImage!, in: CGRect(origin: .zero, size: image.size))
    }

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

    return UIImage(cgImage: CGImage)
}

这篇关于AVFoundation图像方向在预览中偏离90度，但在相机胶卷中很好的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！