上传后iOS UIImagePickerController结果图像方向

问题描述

我正在 iOS 3.1.3 iPhone 上测试我的 iPhone 应用程序.我正在使用 UIImagePickerController 选择/捕获图像:

I am testing my iPhone application on an iOS 3.1.3 iPhone. I am selecting/capturing an image using a UIImagePickerController:

UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
[imagePicker setSourceType:UIImagePickerControllerSourceTypeCamera];
[imagePicker setDelegate:self];
[self.navigationController presentModalViewController:imagePicker animated:YES];
[imagePicker release];



- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    self.image = [info objectForKey:UIImagePickerControllerOriginalImage];
    imageView.image = self.image;
    [self.navigationController dismissModalViewControllerAnimated:YES];
    submitButton.enabled = YES;
}

然后我会在某个时候使用 ASI 类将其发送到我的 Web 服务器:

I then at some point send it to my web server using the ASI classes:

ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:[NSURL URLWithString:@"http://example.com/myscript.php"]];
[request setDelegate:self];
[request setStringEncoding:NSUTF8StringEncoding];
[request setShouldContinueWhenAppEntersBackground:YES];
//other post keys/values
[request setFile:UIImageJPEGRepresentation(self.image, 100.0f) withFileName:[NSString stringWithFormat:@"%d.jpg", [[NSDate date] timeIntervalSinceNow]] andContentType:@"image/jpg" forKey:@"imageFile"];
[request startAsynchronous];

问题:当我拿着 iphone 横向拍照时，图像会上传到服务器，它看起来就像你所期望的那样.手持手机纵向拍照时，图像会被上传并以旋转 90 度的方式查看.

the problem: when i take a picture with the iphone while holding it landscape, the image gets uploaded to the server and it viewed like you would expect. when taking a picture holding the phone in portrait, the image is uploaded and viewed as it had been rotated 90 degrees.

我的应用程序设置为仅在纵向模式下工作(颠倒和常规).

my application is set to only work in portrait modes(upsidedown and regular).

如何让图片在上传后始终显示正确的方向?

How can i make the image always show the correct orientation after uploading?

在 UIImageView 中显示的图像似乎是正确的(在拍照后直接显示)，但在服务器上查看则不然.

the image appears to be correct as displayed in an UIImageView(directly after taking the picture), but viewing on the server says otherwise.

推荐答案

一个 UIImage 有一个属性 imageOrientation，它指示 UIImageView 和其他 UIImage 消费者旋转原始图像数据.这个标志很有可能被保存到上传的 jpeg 图像中的 exif 数据中，但是您用来查看它的程序不支持该标志.

A UIImage has a property imageOrientation, which instructs the UIImageView and other UIImage consumers to rotate the raw image data. There's a good chance that this flag is being saved to the exif data in the uploaded jpeg image, but the program you use to view it is not honoring that flag.

要旋转 UIImage 以在上传时正确显示，您可以使用这样的类别:

To rotate the UIImage to display properly when uploaded, you can use a category like this:

UIImage+fixOrientation.h

@interface UIImage (fixOrientation)

- (UIImage *)fixOrientation;

@end

UIImage+fixOrientation.m

@implementation UIImage (fixOrientation)

- (UIImage *)fixOrientation {

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

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

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

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

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

        case UIImageOrientationLeftMirrored:
        case UIImageOrientationRightMirrored:
            transform = CGAffineTransformTranslate(transform, self.size.height, 0);
            transform = CGAffineTransformScale(transform, -1, 1);
            break;
        case UIImageOrientationUp:
        case UIImageOrientationDown:
        case UIImageOrientationLeft:
        case UIImageOrientationRight:
            break;
    }

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

        default:
            CGContextDrawImage(ctx, CGRectMake(0,0,self.size.width,self.size.height), self.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;
}

@end