使用Http Post成功上传到服务器后图像变为水平

Question

我使用图像选择器捕获图像，当时图像处于其实际位置。但是在将其上传到服务器后，它变成了水平的。我不知道为什么会这样。

这是我的代码

    NSString *urlString = @"Url";
    NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
    [request setURL:[NSURL URLWithString:urlString]];
    [request setHTTPMethod:@"POST"];

    NSMutableData *body = [NSMutableData data];


    NSString *boundary = [NSString stringWithString:@"---------------------------14737809831466499882746641449"];
    NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary];
    [request addValue:contentType forHTTPHeaderField:@"Content-Type"];

    // file
    NSData *imageData = UIImageJPEGRepresentation(image.image, 90);

    [body appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
   // [body appendData:[[NSString stringWithString:@"Content-Disposition: attachment; name=\"user_photo\"; filename=\"photoes.jpg\"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];

    [body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"image\"; filename=\"%@.jpg\"\r\n",@"ImageNmae"] dataUsingEncoding:NSUTF8StringEncoding]];

    [body appendData:[[NSString stringWithString:@"Content-Type: application/octet-stream\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[NSData dataWithData:imageData]];
    [body appendData:[[NSString stringWithString:@"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];




    [body appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"desc\"\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithString:ImageDesc.text] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithString:@"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];

    // close form
    [body appendData:[[NSString stringWithFormat:@"--%@--\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    // set request body
    [request setHTTPBody:body];

    //return and test
    NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
    NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];

Answer 1

我发现这里的解决方案是代码。

- (UIImage *)scaleAndRotateImage:(UIImage *)image { // here we rotate the image in its orignel 
int kMaxResolution = 640; // Or whatever

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 = roundf(bounds.size.width / ratio);
    }
    else {
        bounds.size.height = kMaxResolution;
        bounds.size.width = roundf(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"];

}

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;
}

Answer 2

方向（在您的情况下是旋转）在图像的 exif 数据中。 您需要在 iOS 上预旋转图像或在服务器上后旋转它们。

在 iOS 上，您可以检查 UIImage 的 imageOrientation 属性。

您可以通过剪断该代码来获得转换（您需要设置大小或更改代码部分。大小可以是原始大小）：

- (CGAffineTransform)transformForOrientation:(CGSize)newSize {
    CGAffineTransform transform = CGAffineTransformIdentity;

    switch (self.imageOrientation) {
        case UIImageOrientationDown:           // EXIF = 3
        case UIImageOrientationDownMirrored:   // EXIF = 4
            transform = CGAffineTransformTranslate(transform, newSize.width, newSize.height);
            transform = CGAffineTransformRotate(transform, M_PI);
            break;

        case UIImageOrientationLeft:           // EXIF = 6
        case UIImageOrientationLeftMirrored:   // EXIF = 5
            transform = CGAffineTransformTranslate(transform, newSize.width, 0);
            transform = CGAffineTransformRotate(transform, M_PI_2);
            break;

        case UIImageOrientationRight:          // EXIF = 8
        case UIImageOrientationRightMirrored:  // EXIF = 7
            transform = CGAffineTransformTranslate(transform, 0, newSize.height);
            transform = CGAffineTransformRotate(transform, -M_PI_2);
            break;
    }

    switch (self.imageOrientation) {
        case UIImageOrientationUpMirrored:     // EXIF = 2
        case UIImageOrientationDownMirrored:   // EXIF = 4
            transform = CGAffineTransformTranslate(transform, newSize.width, 0);
            transform = CGAffineTransformScale(transform, -1, 1);
            break;

        case UIImageOrientationLeftMirrored:   // EXIF = 5
        case UIImageOrientationRightMirrored:  // EXIF = 7
            transform = CGAffineTransformTranslate(transform, newSize.height, 0);
            transform = CGAffineTransformScale(transform, -1, 1);
            break;
    }

    return transform;
}

当然，您需要以某种方式将转换应用于您的 UIImage。但我认为您会在有关 stackoverflow 的其他问题中发现这一点。也许开始here。

Answer 3

这是一个很好的媒体上传查询。

当您从设备捕获图像时，它会修复特定图像的方向。 假设您以横向模式捕获图像，并且当您使用 imageView 显示此图像时，它会以纵向模式显示，因为基本设备配置同时支持图像（横向和纵向），那么它可能会伪装成纵向，而实际存储在横向中。因此，当您在 UI (imageView) 中以纵向显示图像时，它会以横向方式保存在服务器上。 最后 1) 图像在设备上水平写入。 2) 由于应用程序的纵向模式处于活动状态，您已在 UI 上垂直显示它。 3) 但是当它被写入服务器时，它会采用它原来的模式（水平）。

因此，根据最佳建议，您应该在应用程序中以适当的模式显示媒体。

Answer 4

 NSData *imageData = UIImageJPEGRepresentation(image.image, 90);

90不是旋转角度吗？

阅读文档后编辑

 NSData *imageData = UIImageJPEGRepresentation(image.image, 90);

看起来 90 应该是 0.9。不过可能不是问题。