UIImagePickerController 返回不正确的图像方向答案

【问题标题】：UIImagePickerController returning incorrect image orientationUIImagePickerController 返回不正确的图像方向
【发布时间】：2011-06-26 17:19:12
【问题描述】：

我正在使用 UIImagePickerController 来捕获图像然后存储它。但是，当我尝试重新调整它时，我从这张图片中得到的方向值是不正确的。当我将手机向上举起拍照时，它给了我向左的方向。有人遇到过这个问题吗？

UIImagePickerController 字典显示以下信息：

{
    UIImagePickerControllerMediaMetadata =     {
        DPIHeight = 72;
        DPIWidth = 72;
        Orientation = 3;
        "{Exif}" =         {
            ApertureValue = "2.970853654340484";
            ColorSpace = 1;
            DateTimeDigitized = "2011:02:14 10:26:17";
            DateTimeOriginal = "2011:02:14 10:26:17";
            ExposureMode = 0;
            ExposureProgram = 2;
            ExposureTime = "0.06666666666666667";
            FNumber = "2.8";
            Flash = 32;
            FocalLength = "3.85";
            ISOSpeedRatings =             (
                125
            );
            MeteringMode = 1;
            PixelXDimension = 2048;
            PixelYDimension = 1536;
            SceneType = 1;
            SensingMethod = 2;
            Sharpness = 1;
            ShutterSpeedValue = "3.910431673351467";
            SubjectArea =             (
                1023,
                767,
                614,
                614
            );
            WhiteBalance = 0;
        };
        "{TIFF}" =         {
            DateTime = "2011:02:14 10:26:17";
            Make = Apple;
            Model = "iPhone 3GS";
            Software = "4.2.1";
            XResolution = 72;
            YResolution = 72;
        };
    };
    UIImagePickerControllerMediaType = "public.image";
    UIImagePickerControllerOriginalImage = "<UIImage: 0x40efb50>";
}

但是图片返回imageOrientation == 1;

UIImage *picture = [info objectForKey:UIImagePickerControllerOriginalImage];

【问题讨论】：

标签： uiimage orientation uiimagepickercontroller scale

【解决方案1】：

我刚开始在自己的应用中解决这个问题。

我使用了 Trevor Harmon 制作的 UIImage 类别，用于调整图像大小并固定其方向，UIImage+Resize。

然后你可以在-imagePickerController:didFinishPickingMediaWithInfo:做这样的事情

UIImage *pickedImage = [info objectForKey:UIImagePickerControllerEditedImage]; UIImage *resized = [pickedImage resizedImageWithContentMode:UIViewContentModeScaleAspectFit bounds:pickedImage.size interpolationQuality:kCGInterpolationHigh];

这解决了我的问题。调整大小的图像在视觉上正确定向，并且 imageOrientation 属性报告 UIImageOrientationUp。

这个缩放/调整大小/裁剪代码有几个版本；我使用了 Trevor 的，因为它看起来很干净，并且包括一些其他的 UIImage 操纵器，我想稍后使用它们。

【讨论】：

这似乎不适用于符合 ARC 的代码。它失败并出现错误：“'UIImage' 没有可见的@interface 声明选择器'resizedImageWithContentMode:bounds:interpolationQuality:'”
您可能会在 GitHub 上查看由 Marc Charbonneau 维护的此代码的更新版本。 github.com/mbcharbonneau/UIImage-Categories>
即使使用 Marc 的叉子，这仍然不能固定方向。
它总是返回 UIImageOrientationUp。所以这仅适用于方向 UIImageOrientationUp，不适用于其他方向。

【解决方案2】：

这是我发现的解决方向问题的方法；为我工作

UIImage *initialImage = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
NSData *data = UIImagePNGRepresentation(self.initialImage);

UIImage *tempImage = [UIImage imageWithData:data];
UIImage *fixedOrientationImage = [UIImage imageWithCGImage:tempImage.CGImage
                                     scale:initialImage.scale
                               orientation:self.initialImage.imageOrientation];
initialImage = fixedOrientationImage;

【讨论】：

这会给你。收到内存警告。
谢谢，这已经帮我解决了！
不幸的是，它不起作用。新图像完全一样，方向错误

【解决方案3】：

我使用以下代码，我已将其放入一个单独的图像实用程序对象文件中，该文件具有许多其他 UIImages 编辑方法：

+ (UIImage*)imageWithImage:(UIImage*)sourceImage scaledToSizeWithSameAspectRatio:(CGSize)targetSize
{
    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;
    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;
    CGFloat scaleFactor = 0.0;
    CGFloat scaledWidth = targetWidth;
    CGFloat scaledHeight = targetHeight;
    CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

    if (CGSizeEqualToSize(imageSize, targetSize) == NO) {
        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;

        if (widthFactor > heightFactor) {
            scaleFactor = widthFactor; // scale to fit height
        }
        else {
            scaleFactor = heightFactor; // scale to fit width
        }

        scaledWidth  = width * scaleFactor;
        scaledHeight = height * scaleFactor;

        // center the image
        if (widthFactor > heightFactor) {
            thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
        }
        else if (widthFactor < heightFactor) {
            thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
        }
    }

    CGImageRef imageRef = [sourceImage CGImage];
    CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
    CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);

    if (bitmapInfo == kCGImageAlphaNone) {
        bitmapInfo = kCGImageAlphaNoneSkipLast;
    }

    CGContextRef bitmap;

    if (sourceImage.imageOrientation == UIImageOrientationUp || sourceImage.imageOrientation == UIImageOrientationDown) {
        bitmap = CGBitmapContextCreate(NULL, targetWidth, targetHeight, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

    } else {
        bitmap = CGBitmapContextCreate(NULL, targetHeight, targetWidth, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

    }

    // In the right or left cases, we need to switch scaledWidth and scaledHeight,
    // and also the thumbnail point
    if (sourceImage.imageOrientation == UIImageOrientationLeft) {
        thumbnailPoint = CGPointMake(thumbnailPoint.y, thumbnailPoint.x);
        CGFloat oldScaledWidth = scaledWidth;
        scaledWidth = scaledHeight;
        scaledHeight = oldScaledWidth;

        CGContextRotateCTM (bitmap, M_PI_2); // + 90 degrees
        CGContextTranslateCTM (bitmap, 0, -targetHeight);

    } else if (sourceImage.imageOrientation == UIImageOrientationRight) {
        thumbnailPoint = CGPointMake(thumbnailPoint.y, thumbnailPoint.x);
        CGFloat oldScaledWidth = scaledWidth;
        scaledWidth = scaledHeight;
        scaledHeight = oldScaledWidth;

        CGContextRotateCTM (bitmap, -M_PI_2); // - 90 degrees
        CGContextTranslateCTM (bitmap, -targetWidth, 0);

    } else if (sourceImage.imageOrientation == UIImageOrientationUp) {
        // NOTHING
    } else if (sourceImage.imageOrientation == UIImageOrientationDown) {
        CGContextTranslateCTM (bitmap, targetWidth, targetHeight);
        CGContextRotateCTM (bitmap, -M_PI); // - 180 degrees
    }

    CGContextDrawImage(bitmap, CGRectMake(thumbnailPoint.x, thumbnailPoint.y, scaledWidth, scaledHeight), imageRef);
    CGImageRef ref = CGBitmapContextCreateImage(bitmap);
    UIImage* newImage = [UIImage imageWithCGImage:ref];

    CGContextRelease(bitmap);
    CGImageRelease(ref);

    return newImage; 
}

然后我打电话给

UIImage *pickedImage = [info objectForKey:UIImagePickerControllerOriginalImage];
        UIImage *fixedOriginal = [ImageUtil imageWithImage:[mediaInfoDict objectForKey:UIImagePickerControllerOriginalImage] scaledToSizeWithSameAspectRatio:pickedImage.size];

【讨论】：

【解决方案4】：

这是一个可以有效解决问题的 Swift sn-p：

let orientedImage = UIImage(CGImage: initialImage.CGImage, scale: 1, orientation: initialImage.imageOrientation)!

【讨论】：

【解决方案5】：

在 iOS 7 中，我需要依赖于 UIImage.imageOrientation 的代码来纠正不同的方向。现在，在 iOS 8.2 中，当我通过 UIImagePickerController 从相册中挑选旧的测试图像时，所有图像的方向都是 UIImageOrientationUp。当我拍摄照片 (UIImagePickerControllerSourceTypeCamera) 时，无论设备方向如何，这些图像也将始终向上。因此，在这些 iOS 版本之间，显然已经修复了 UIImagePickerController 已经在必要时旋转图像的问题。您甚至可以注意到，在显示专辑图像时：在瞬间，它们将以原始方向显示，然后以新的向上方向显示。

【讨论】：

【解决方案6】：

唯一对我有用的是重新渲染图像以强制正确的方向。

if (photo.imageOrientation != .up) {
   UIGraphicsBeginImageContextWithOptions(photo.size, false, 1.0);
   let rect = CGRect(x: 0, y: 0, width: photo.size.width, height: photo.size.height);
   photo.draw(in: rect)
   let newImage = UIGraphicsGetImageFromCurrentImageContext()
   UIGraphicsEndImageContext()
   photo = newImage;
}

【讨论】：