Uploading image on server, receiving rotated image

问题

In my application I want to upload the image to the server and retrieve the url of uploaded image to display it in the application. I send the NSData of image. Here is my code :

AsynchronousImageView *imgVw_User = (AsynchronousImageView*)[self.view viewWithTag:K_TagImageViewUser];
UIImage *UserImgForBioData = imgVw_User.image;
UserImgForBioData = [UIImage imageWithCGImage:UserImgForBioData.CGImage scale:1.0f orientation:UserImgForBioData.imageOrientation];
NSData *imageData = [NSData dataWithData:UIImageJPEGRepresentation(UserImgForBioData,0.5)];

 Base64Transcoder *temp_transcoder=[[Base64Transcoder alloc]init];
NSString * temp_base64EncodedImage= @"";
if (imageData!=nil)
    {
        temp_base64EncodedImage = [NSString stringWithFormat:@"%@",[temp_transcoder base64EncodedStringfromData:imageData]];
       temp_base64EncodedImage = [[temp_base64EncodedImage stringByReplacingOccurrencesOfString:@"\n"
                                           withString:@""]
                                         mutableCopy];
      }

Sometime when I display the image, by fetching the url of the image, the image gets rotated. Am I doing something wrong?

回答1:

If you r capturing Image from Camera then before uploading image generate Image Thumbnail in original orientation by this:

- (UIImage *)generatePhotoThumbnail:(UIImage *)image 
{
    //int kMaxResolution = 320; 

    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 = bounds.size.width / ratio; 
     } 
     else
     { 
     bounds.size.height = kMaxResolution; 
     bounds.size.width = 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"]; 
            break;
    } 

    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;

}

after this u get a correct image and then upload that image. I hope this will solve your issue.

Step1: capture image from camera.

Step2: Generate photoThumbnail by following method

Step3: Then upload the resultant image.

you will get correct image

回答2:

This worked for me when using images from the the Photo library.

ALAssetRepresentation *rep = [_asset defaultRepresentation];
CGImageRef iref = [rep fullResolutionImage];
UIImage* img = [UIImage imageWithCGImage:iref scale:1.f orientation:UIImageOrientationUp]

Note: _asset is an instance of ALAsset.

来源：https://stackoverflow.com/questions/14231552/uploading-image-on-server-receiving-rotated-image