cocoa-touch - UIImage 上传到休息服务器的方向会改变吗？

Question

相机拍照，上传到api成功，但图像方向会向左转。

NSData *data = [[[NSMutableData alloc] initWithData:imageData] autorelease];
NSString *path = [[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"] stringByAppendingPathComponent:@"file"];
BOOL _B = [data writeToFile:path atomically:YES];

if (!_B) {
    NSLog(@"write to file error!");
    return;
}
[request addFile:path forKey:@"photofile"];

为什么？

Answer 1

好的，我解决了这个问题。

- (UIImage *)fixOrientation:(UIImage *)aImage {

// No-op if the orientation is already correct
if (aImage.imageOrientation == UIImageOrientationUp) 
    return aImage;

// We need to calculate the proper transformation to make the image upright.
// We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
CGAffineTransform transform = CGAffineTransformIdentity;

switch (aImage.imageOrientation) {
    case UIImageOrientationDown:
    case UIImageOrientationDownMirrored:
        transform = CGAffineTransformTranslate(transform, aImage.size.width, aImage.size.height);
        transform = CGAffineTransformRotate(transform, M_PI);
        break;

    case UIImageOrientationLeft:
    case UIImageOrientationLeftMirrored:
        transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);
        transform = CGAffineTransformRotate(transform, M_PI_2);
        break;

    case UIImageOrientationRight:
    case UIImageOrientationRightMirrored:
        transform = CGAffineTransformTranslate(transform, 0, aImage.size.height);
        transform = CGAffineTransformRotate(transform, -M_PI_2);
        break;
    default:
        break;
}

switch (aImage.imageOrientation) {
    case UIImageOrientationUpMirrored:
    case UIImageOrientationDownMirrored:
        transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);
        transform = CGAffineTransformScale(transform, -1, 1);
        break;

    case UIImageOrientationLeftMirrored:
    case UIImageOrientationRightMirrored:
        transform = CGAffineTransformTranslate(transform, aImage.size.height, 0);
        transform = CGAffineTransformScale(transform, -1, 1);
        break;
    default:
        break;
}

// Now we draw the underlying CGImage into a new context, applying the transform
// calculated above.
CGContextRef ctx = CGBitmapContextCreate(NULL, aImage.size.width, aImage.size.height,
                                         CGImageGetBitsPerComponent(aImage.CGImage), 0,
                                         CGImageGetColorSpace(aImage.CGImage),
                                         CGImageGetBitmapInfo(aImage.CGImage));
CGContextConcatCTM(ctx, transform);
switch (aImage.imageOrientation) {
    case UIImageOrientationLeft:
    case UIImageOrientationLeftMirrored:
    case UIImageOrientationRight:
    case UIImageOrientationRightMirrored:
        // Grr...
        CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.height,aImage.size.width), aImage.CGImage);
        break;

    default:
        CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.width,aImage.size.height), aImage.CGImage);
        break;
}

// And now we just create a new UIImage from the drawing context
CGImageRef cgimg = CGBitmapContextCreateImage(ctx);
UIImage *img = [UIImage imageWithCGImage:cgimg];
CGContextRelease(ctx);
CGImageRelease(cgimg);
return img;

}