iOS：保存为PNG表示数据后，图像旋转90度 [英] iOS: Image get rotated 90 degree after saved as PNG representation data

问题描述

我已经研究了足够的工作，但无法修复它。只要我将图像存储为UIImage，从相机拍照后，它就可以了，但只要我将此图像存储为PNG表示，它就会旋转90度。

以下是我的代码和我尝试过的所有内容：

   - （void）imagePickerController：（UIImagePickerController *）picker didFinishPickingMediaWithInfo：（NSDictionary * ）info 
 {
 NSString * mediaType = [info valueForKey：UIImagePickerControllerMediaType]; 
 
 if（[mediaType isEqualToString：（NSString *）kUTTypeImage]）
 {
 AppDelegate * delegate =（AppDelegate *）[[UIApplication sharedApplication] delegate]; 
 delegate.originalPhoto = [info objectForKey：@UIImagePickerControllerOriginalImage]; 
 NSLog（@保存照片）; 
 [self saveImage]; 
 NSLog（@修复方向）; 
 delegate.fixOrientationPhoto = [self fixOrientation：[UIImage imageWithContentsOfFile：[delegate filePath：imageName]]]; 
 NSLog（@缩放照片）; 
 delegate.scaledAndRotatedPhoto = [self scaleAndRotateImage：[UIImage imageWithContentsOfFile：[delegate filePath：imageName]]]; 
} 
 [picker dismissModalViewControllerAnimated：YES]; 
 [选择器发布]; 
} 
 
 
  - （void）saveImage 
 {
 AppDelegate * delegate =（AppDelegate *）[[UIApplication sharedApplication] delegate]; 
 NSData * imageData = UIImagePNGRepresentation（delegate.originalPhoto）; 
 [imageData writeToFile：[delegate filePath：imageName] atomically：YES]; 
} 
  

这里的fixOrientation和scaleAndRotateImage函数取自。

I have researched enough to get this working but not able to fix it. After taking picture from camera as long as I have image stored as UIImage, it's fine but as soon as I stored this image as PNG representation, its get rotated 90 degree.

Following is my code and all things I tried:

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info 
{
    NSString *mediaType = [info valueForKey:UIImagePickerControllerMediaType];

    if([mediaType isEqualToString:(NSString*)kUTTypeImage]) 
    {
        AppDelegate *delegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
        delegate.originalPhoto  = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
        NSLog(@"Saving photo");
        [self saveImage];
        NSLog(@"Fixing orientation");
        delegate.fixOrientationPhoto  = [self fixOrientation:[UIImage imageWithContentsOfFile:[delegate filePath:imageName]]];      
        NSLog(@"Scaling photo");
        delegate.scaledAndRotatedPhoto  =  [self scaleAndRotateImage:[UIImage imageWithContentsOfFile:[delegate filePath:imageName]]];
    }
    [picker dismissModalViewControllerAnimated:YES];
    [picker release];
}


- (void)saveImage
{
    AppDelegate *delegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
    NSData *imageData = UIImagePNGRepresentation(delegate.originalPhoto);
    [imageData writeToFile:[delegate filePath:imageName] atomically:YES];
}

Here fixOrientation and scaleAndRotateImage functions taken from here and here respectively. They works fine and rotate image when I apply them on UIImage but doesn't work if I save image as PNG representation and apply them.

Please refere the following picture after executing above functions:

解决方案

Starting with iOS 4.0 when the camera takes a photo it does not rotate it before saving, it

simply sets a rotation flag in the EXIF data of the JPEG.If you save a UIImage as a JPEG, it

will set the rotation flag.PNGs do not support a rotation flag, so if you save a UIImage as a

PNG, it will be rotated incorrectly and not have a flag set to fix it. So if you want PNG

images you must rotate them yourself, for that check this link.

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