UIImagePickerController 相机预览是横向应用程序中的纵向

Question

在我的纯横向 iPhone 应用程序中，我启动了一个 UIImagePickerController 来拍照，但从相机显示的实时图像是纵向的，周围有空白区域。图像已旋转。

一旦按下相机按钮，预览就会非常混乱，大部分预览都在屏幕之外，并且视图没有正确对齐。

Apple 已经承认这是一个缺陷，并且正在努力解决。

我的问题是，有没有人有解决方法（合法或非法）可以让我现在开始工作。我不会通过非法修复将其发布到 App Store，但我会为用户测试提供更好的应用程序 - 目前相机在横向上几乎无法使用。

如果可以的话，我会附上一个简单的测试项目和图片。

编辑 - 澄清一下，我得到的图像是正确的风景。我希望相机和预览 UI 看起来正确！

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Answer 1

答案比你想象的更荒谬。我遇到了同样的问题，并在某处的论坛中找到了解决方案。将您拍摄的图像传递给这样的方法：

// Code from: http://discussions.apple.com/thread.jspa?messageID=7949889
- (UIImage *)scaleAndRotateImage:(UIImage *)image {
  int kMaxResolution = 640; // Or whatever

    CGImageRef imgRef = image.CGImage;

    CGFloat width = CGImageGetWidth(imgRef);
    CGFloat height = CGImageGetHeight(imgRef);


    CGAffineTransform transform = CGAffineTransformIdentity;
    CGRect bounds = CGRectMake(0, 0, width, height);
    if (width > kMaxResolution || height > kMaxResolution) {
        CGFloat ratio = width/height;
        if (ratio > 1) {
            bounds.size.width = kMaxResolution;
            bounds.size.height = roundf(bounds.size.width / ratio);
        }
        else {
            bounds.size.height = kMaxResolution;
            bounds.size.width = roundf(bounds.size.height * ratio);
        }
    }

    CGFloat scaleRatio = bounds.size.width / width;
    CGSize imageSize = CGSizeMake(CGImageGetWidth(imgRef), CGImageGetHeight(imgRef));
    CGFloat boundHeight;
    UIImageOrientation orient = image.imageOrientation;
    switch(orient) {

        case UIImageOrientationUp: //EXIF = 1
            transform = CGAffineTransformIdentity;
            break;

        case UIImageOrientationUpMirrored: //EXIF = 2
            transform = CGAffineTransformMakeTranslation(imageSize.width, 0.0);
            transform = CGAffineTransformScale(transform, -1.0, 1.0);
            break;

        case UIImageOrientationDown: //EXIF = 3
            transform = CGAffineTransformMakeTranslation(imageSize.width, imageSize.height);
            transform = CGAffineTransformRotate(transform, M_PI);
            break;

        case UIImageOrientationDownMirrored: //EXIF = 4
            transform = CGAffineTransformMakeTranslation(0.0, imageSize.height);
            transform = CGAffineTransformScale(transform, 1.0, -1.0);
            break;

        case UIImageOrientationLeftMirrored: //EXIF = 5
            boundHeight = bounds.size.height;
            bounds.size.height = bounds.size.width;
            bounds.size.width = boundHeight;
            transform = CGAffineTransformMakeTranslation(imageSize.height, imageSize.width);
            transform = CGAffineTransformScale(transform, -1.0, 1.0);
            transform = CGAffineTransformRotate(transform, 3.0 * M_PI / 2.0);
            break;

        case UIImageOrientationLeft: //EXIF = 6
            boundHeight = bounds.size.height;
            bounds.size.height = bounds.size.width;
            bounds.size.width = boundHeight;
            transform = CGAffineTransformMakeTranslation(0.0, imageSize.width);
            transform = CGAffineTransformRotate(transform, 3.0 * M_PI / 2.0);
            break;

        case UIImageOrientationRightMirrored: //EXIF = 7
            boundHeight = bounds.size.height;
            bounds.size.height = bounds.size.width;
            bounds.size.width = boundHeight;
            transform = CGAffineTransformMakeScale(-1.0, 1.0);
            transform = CGAffineTransformRotate(transform, M_PI / 2.0);
            break;

        case UIImageOrientationRight: //EXIF = 8
            boundHeight = bounds.size.height;
            bounds.size.height = bounds.size.width;
            bounds.size.width = boundHeight;
            transform = CGAffineTransformMakeTranslation(imageSize.height, 0.0);
            transform = CGAffineTransformRotate(transform, M_PI / 2.0);
            break;

        default:
            [NSException raise:NSInternalInconsistencyException format:@"Invalid image orientation"];

    }

    UIGraphicsBeginImageContext(bounds.size);

    CGContextRef context = UIGraphicsGetCurrentContext();

    if (orient == UIImageOrientationRight || orient == UIImageOrientationLeft) {
        CGContextScaleCTM(context, -scaleRatio, scaleRatio);
        CGContextTranslateCTM(context, -height, 0);
    }
    else {
        CGContextScaleCTM(context, scaleRatio, -scaleRatio);
        CGContextTranslateCTM(context, 0, -height);
    }

    CGContextConcatCTM(context, transform);

    CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, width, height), imgRef);
    UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return imageCopy;
}

:(

Answer 2

我认为您根本不需要额外的工作来处理 imageRotation 或 EXIF 数据。 Image drawInRect 会自动处理。

所以，你只需要得到这个尺寸或者图像，然后重新绘制成一个新的图像，就足够了。

Answer 3

我不想在捕获后旋转图像；我想在横向模式下正确显示预览。所以在 iOS 6 中，我在应用层允许纵向模式，但是将应用的根视图控制器设置为 MyNonrotatingNavigationController 类，定义如下：

@implementation MyNonrotatingNavigationController

-(NSUInteger) supportedInterfaceOrientations
{
    return UIInterfaceOrientationMaskLandscape;
}

@end

因此，在此导航控制器中显示的所有内容都将是横向的（您可以使用任何视图控制器执行此操作）。现在，当我需要显示图像选择器时，我将应用程序窗口的根视图控制器替换为支持纵向模式的通用控制器。为了防止旧的根视图控制器及其视图被解除分配，我维护指向它们的指针，直到我准备好将它们放回应用程序窗口中。

#define APP_DELEGATE ((MyAppDelegate*)[[UIApplication sharedApplication] delegate])
static UIViewController *pickerContainer = nil;
static UIViewController *oldRoot = nil;
static UIView *holdView = nil;

-(void) showPicker
{
    ...create UIImagePickerController...

    oldRoot = APP_DELEGATE.window.rootViewController;
    holdView = [[UIView alloc] initWithFrame:APP_DELEGATE.window.bounds];
    [holdView addSubview:oldRoot.view];

    pickerContainer = [UIViewController new];
    pickerContainer.view = [[UIView alloc] initWithFrame:APP_DELEGATE.window.bounds];
    APP_DELEGATE.window.rootViewController = pickerContainer;
    [pickerContainer presentViewController:picker animated:YES completion:NULL];
}

-(void) imagePickerController:(UIImagePickerController*)picker didFinishPickingMediaWithInfo:(NSDictionary*)info
{
    [pickerContainer dismissViewControllerAnimated:YES completion:^{
        dispatch_async( dispatch_get_main_queue(), ^{
            APP_DELEGATE.window.rootViewController = oldRoot;
            [APP_DELEGATE.window addSubview:oldRoot.view];
            pickerContainer = nil;
            oldRoot = nil;
            holdView = nil;
        });
    }];
}

有点痛苦，但它似乎对照片和视频都有效。图像选择器的控件以纵向模式显示，但应用的其余部分仅以横向模式显示。

Answer 4

我通过让UIImagePickerController 以全屏模式显示解决了这个问题，这也是 Apple 推荐的 iPad 的做法。

来自UIImagePickerController documentation：

在 iPad 上，如果您指定 UIImagePickerControllerSourceTypeCamera 的源类型，您可以模态（全屏）或使用弹出框呈现图像选择器。但是，Apple 建议您仅全屏显示相机界面。

Answer 5

如果不鼓励重新发布上述最佳答案，请告诉我，我为 Alex Wayne 的答案提供了 2019 年 swift 版本。

/**
 Scale and rotate a UIImage so that it is correctly oriented

 :param: image: The image to be rotated

 :returns: UIImage
 */
func scaleAndRotateImage(_ image: UIImage) -> UIImage {
    let kMaxResolution: CGFloat = 640
    let imgRef: CGImage = image.cgImage!
    let width: CGFloat = CGFloat(imgRef.width)
    let height: CGFloat = CGFloat(imgRef.height)
    var transform: CGAffineTransform = CGAffineTransform.identity
    var bounds: CGRect = CGRect(x: 0, y: 0, width: width, height: height)
    if width > kMaxResolution || height > kMaxResolution {
        let ratio: CGFloat = width / height
        if ratio > 1 {
            bounds.size.width = kMaxResolution
            bounds.size.height = (bounds.size.width / ratio)
        }
        else {
            bounds.size.height = kMaxResolution
            bounds.size.width = (bounds.size.height * ratio)
        }
    }
    let scaleRatio: CGFloat = bounds.size.width / width
    let imageSize: CGSize = CGSize(width: CGFloat(imgRef.width), height: CGFloat(imgRef.height))
    var boundHeight: CGFloat
    let orient: UIImage.Orientation = image.imageOrientation
    switch orient {
    case UIImageOrientation.up:
        transform = CGAffineTransform.identity
    case UIImageOrientation.upMirrored:
        transform = CGAffineTransform(translationX: imageSize.width, y: 0.0)
        transform = transform.scaledBy(x: -1.0, y: 1.0)
    case UIImageOrientation.down:
        transform = CGAffineTransform(translationX: imageSize.width, y: imageSize.height)
        transform = transform.rotated(by: CGFloat(Double.pi))
    case UIImageOrientation.downMirrored:
        transform = CGAffineTransform(translationX: 0.0, y: imageSize.height)
        transform = transform.scaledBy(x: 1.0, y: -1.0)
    case UIImageOrientation.leftMirrored:
        boundHeight = bounds.size.height
        bounds.size.height = bounds.size.width
        bounds.size.width = boundHeight
        transform = CGAffineTransform(translationX: imageSize.height, y: imageSize.width)
        transform = transform.scaledBy(x: -1.0, y: 1.0)
        transform = transform.rotated(by: CGFloat(3.0 * .pi / 2.0))
    case UIImageOrientation.left:
        boundHeight = bounds.size.height
        bounds.size.height = bounds.size.width
        bounds.size.width = boundHeight
        transform = CGAffineTransform(translationX: 0.0, y: imageSize.width)
        transform = transform.rotated(by: CGFloat(3.0 * .pi / 2.0))
    case UIImageOrientation.rightMirrored:
        boundHeight = bounds.size.height
        bounds.size.height = bounds.size.width
        bounds.size.width = boundHeight
        transform = CGAffineTransform(scaleX: -1.0, y: 1.0)
        transform = transform.rotated(by: CGFloat(.pi / 2.0))
    case UIImageOrientation.right:
        boundHeight = bounds.size.height
        bounds.size.height = bounds.size.width
        bounds.size.width = boundHeight
        transform = CGAffineTransform(translationX: imageSize.height, y: 0.0)
        transform = transform.rotated(by: CGFloat(.pi / 2.0))
    }
    UIGraphicsBeginImageContext(bounds.size)
    let context: CGContext = UIGraphicsGetCurrentContext()!
    if orient == UIImage.Orientation.right || orient == UIImage.Orientation.left {
        context.scaleBy(x: -scaleRatio, y: scaleRatio)
        context.translateBy(x: -height, y: 0)
    }
    else {
        context.scaleBy(x: scaleRatio, y: -scaleRatio)
        context.translateBy(x: 0, y: -height)
    }
    context.concatenate(transform)
    UIGraphicsGetCurrentContext()?.draw(imgRef, in: CGRect(x: 0, y: 0, width: width, height: height))
    let imageCopy: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return imageCopy
}

Answer 6

您需要将自定义视图（带有工具栏和标题）设置为cameraOverlayView，还需要将allowsEditing 和showsCameraControls 设置为NO，因为这将隐藏标准控件和预览。 这就是我在我正在制作的应用程序中发现的必要内容（我认为我需要选择器是纵向的，但如果用户将他的设备旋转到横向，我需要它来应用一些 UI 更改）。
如果需要，可以提供代码。

附：我的代码中仍有一些错误，但我正在努力解决它:)

Answer 7

可以通过将modalPresentationStyle 设置为overCurrentContext 来解决此问题，如下所示，

 picker.modalPresentationStyle = .overCurrentContext

并在Main Thread 上展示您的图像选择器，

DispatchQueue.main.async {

   self.present(picker, animated: true) {

   }
}

为什么会这样？

因为ImagePickerController 仅适用于纵向模式，当您尝试从横向视图控制器中显示选择器时，它会尝试将您的状态栏设置为纵向模式。因此，如果您将modalPresentationStyle 设置为overCurrentContext，则它不会尝试设置方向。它将考虑当前方向。

请参阅 Apple guide line 以获取 ImagePickerController。它指出，

UIImagePickerController 类仅支持纵向模式。此类旨在按原样使用，不支持子类化。此类的视图层次结构是私有的，不得修改，但有一个例外。您可以将自定义视图分配给 cameraOverlayView 属性，并使用该视图来显示附加信息或管理相机界面和代码之间的交互。