Question

这个问题的标题应该很清楚。下面的代码执行裁剪操作，然后在图像视图中显示新裁剪的照片。问题是图像一旦被裁剪，就会以与原始源图像不同的方向显示。这是为什么？我该怎么办呢？

-(void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingMediaWithInfo:(NSDictionary *)info
{
[self.popoverController dismissPopoverAnimated:true];

NSString *mediaType = [info
                       objectForKey:UIImagePickerControllerMediaType];
[self dismissModalViewControllerAnimated:YES];
if ([mediaType isEqualToString:(NSString *)kUTTypeImage]) {
    UIImage *image = [info
                      objectForKey:UIImagePickerControllerOriginalImage];


    CGRect rect = CGRectMake(0, ((image.size.height - image.size.width) / 2), image.size.width, image.size.width);


    CGImageRef subImageRef = CGImageCreateWithImageInRect(image.CGImage, rect);
    CGRect smallBounds = CGRectMake(rect.origin.x, rect.origin.y, CGImageGetWidth(subImageRef), CGImageGetHeight(subImageRef));

    UIGraphicsBeginImageContext(smallBounds.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextDrawImage(context, smallBounds, subImageRef);
    croppedImage = [UIImage imageWithCGImage:subImageRef];
    UIGraphicsEndImageContext();

    imageView.image = croppedImage;

*修改

根据评论提示问题的根本原因是删除EXIF标记我尝试使用以下代码更正方向。这仍然无法解决问题，但我认为这是朝着正确方向迈出的一步。也许它会帮助某人提出问题的新答案。

if (image.imageOrientation == UIImageOrientationLeft) {
        NSLog(@"left");
        CGContextRotateCTM (context, radians(90));

    } else if (image.imageOrientation == UIImageOrientationRight) {
        NSLog(@"right");
        CGContextRotateCTM (context, radians(-90));

    } else if (image.imageOrientation == UIImageOrientationUp) {
        NSLog(@"up");
        // NOTHING
    } else if (image.imageOrientation == UIImageOrientationDown) {
        NSLog(@"down");
        CGContextRotateCTM (context, radians(-180.));
    }

请参阅https://stackoverflow.com/a/5184134/549273

Answer 1

我认为您最好的选择是从输入的图像中获取方向，然后使用适当的旋转创建新图像。

从传入的信息词典中抓取元数据：

NSDictionary *metadata = [info objectForKey:UIImagePickerControllerMediaMetadata];
NSNumber *orientation = [metadata objectForKey:@"Orientation"];

然后当您创建UIImage：

时

croppedImage = [UIImage imageWithCGImage:subImageRef 
                                   scale:1.0 
                             orientation:[orientation intValue]];

希望这至少是你的起点。

Answer 2

你应该做的是在处理之前修复图像方向，我有同样的问题，我使用swift所以我不得不改变这个答案：

iOS UIImagePickerController result image orientation after upload

但代码工作得很好。只要记住，它会返回一个图像而不是编辑图像，我只是因为这个简单的错误而努力做到正确。顺便说一下，你不应该使用UIImageOrientation，而应该使用UIImageOrientation.rawValue，至少在swift中。

我将swift的代码留在这里，希望帮助：

extension UIImage {
public func fixOrientation() -> UIImage?{

    if self.imageOrientation.rawValue == UIImageOrientation.Up.rawValue {
        return self
    }

    var transform : CGAffineTransform = CGAffineTransformIdentity

    switch self.imageOrientation.rawValue {

    case UIImageOrientation.Down.rawValue:
            transform = CGAffineTransformTranslate(transform, self.size.width, self.size.height)
            transform = CGAffineTransformRotate(transform, CGFloat(M_PI))
    case UIImageOrientation.DownMirrored.rawValue:
            transform = CGAffineTransformTranslate(transform, self.size.width, self.size.height)
            transform = CGAffineTransformRotate(transform, CGFloat(M_PI))

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

    case UIImageOrientation.Right.rawValue:
            print("working on right orientation")
            transform = CGAffineTransformTranslate(transform, 0, self.size.height)
            transform = CGAffineTransformRotate(transform, CGFloat(-M_PI_2))
    case UIImageOrientation.RightMirrored.rawValue:
            transform = CGAffineTransformTranslate(transform, 0, self.size.height)
            transform = CGAffineTransformRotate(transform, CGFloat(-M_PI_2))

    case UIImageOrientation.Up.rawValue: break
    case UIImageOrientation.UpMirrored.rawValue: break

    default: break
    }

    switch self.imageOrientation.rawValue {

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

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

    case UIImageOrientation.Up.rawValue: break
    case UIImageOrientation.Down.rawValue: break
    case UIImageOrientation.Left.rawValue: break
    case UIImageOrientation.Right.rawValue: break

    default: break
    }

    let bitmapInfo = CGImageGetBitmapInfo(self.CGImage)

    let ctx = CGBitmapContextCreate(nil, Int(self.size.width), Int(self.size.height), CGImageGetBitsPerComponent(self.CGImage), 0, CGImageGetColorSpace(self.CGImage),
        bitmapInfo.rawValue)

    CGContextConcatCTM(ctx, transform)

    switch self.imageOrientation {

    case UIImageOrientation.Left:
            CGContextDrawImage(ctx, CGRectMake(0, 0, self.size.height, self.size.width), self.CGImage)
    case UIImageOrientation.LeftMirrored:
            CGContextDrawImage(ctx, CGRectMake(0, 0, self.size.height, self.size.width), self.CGImage)
    case UIImageOrientation.Right:
            CGContextDrawImage(ctx, CGRectMake(0, 0, self.size.height, self.size.width), self.CGImage)
    case UIImageOrientation.RightMirrored:
            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)

    }

    let cgimg = CGBitmapContextCreateImage(ctx)
    let image = UIImage(CGImage: cgimg!)

    return image

    }
}

为什么此裁剪代码会导致旋转图像？

2 个答案: