iOS UIImagePickerController上传后的结果图像方向 [英] iOS UIImagePickerController result image orientation after upload

问题描述

我在iOS 3.1.3 iPhone上测试我的iPhone应用程式。我使用 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;
}

然后我在某些时候使用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拍照时，图像上传到服务器，它看起来像你所期望的。

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只在纵向模式下工作

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?

推荐答案

UIImage有一个属性 imageOrientation ，它指示UIImageView和其他UIImage用户旋转原始图像数据。这个标志很有可能被保存到上传的jpeg图片中的exif数据，但是你用来查看它的程序并不遵守这个标志。

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.

旋转UIImage以在上传时正确显示，您可以使用如下类别：

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

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