iPhone - Mirroring back a picture taken from the f

问题:

When using the front camera of the iPhone 4 to take a picture, the taken picture is mirrored compared with what you see on the iPhone screen. How may I restore the "on screen" view of the UIImage (not the UIImageView), and be able to save it like this ?

I tried :

UIImage* transformedImage = [UIImage imageWithCGImage:pickedImage.CGImage scale:1.0 orientation:UIImageOrientationLeftMirrored];
UIImageWriteToSavedPhotosAlbum (transformedImage, self, @selector(photoSaved:didFinishSavingWithError:contextInfo:), nil);

then putting it on screen. It is nearly the same as seen on screen, but the saved image is distorted.

So... How may I restore the "on screen" view of the UIImage (not the UIImageView), and be able to save it like this ?

I also tried this way :

UIImage* pickedImage = [[info objectForKey:UIImagePickerControllerOriginalImage] retain];
UIImage* transformedImage;

CGSize imageSize = pickedImage.size;
UIGraphicsBeginImageContextWithOptions(imageSize, YES, 1.0);
GContextRef ctx = UIGraphicsGetCurrentContext();

CGContextRotateCTM(ctx, 3.14);  // rotate by 180°
CGContextScaleCTM(ctx, 1.0, -1.0); // flip vertical
CGContextDrawImage(ctx, CGRectMake(0.0, 0.0, imageSize.width, imageSize.height), pickedImage.CGImage);
transformedImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

But that just gives a black image.

回答1:

The best way is to draw the image into a new context.

CGSize imageSize = pickedImage.size;
UIGraphicsBeginImageContextWithOptions(imageSize, YES, 1.0);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(ctx, imageSize.width, 0.0);
CGContextScaleCTM(ctx, -1.0, 1.0);
CGContextDrawImage(ctx, pickedImage.CGImage, CGRectMake(0.0, 0.0, imageSize.width, imageSize.height));
UIImage *transformedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum (transformedImage, self, @selector(photoSaved:didFinishSavingWithError:contextInfo:), nil);

This was written out of memory and without aid of a compiler, please don't copy and paste...

回答2:

- (void)didTakePicture:(UIImage *)picture
{
    UIImage * flippedImage = [UIImage imageWithCGImage:picture.CGImage scale:picture.scale orientation:UIImageOrientationLeftMirrored];
    picture = flippedImage;
}

回答3:

I know this question was already answered, but the answer above didn't work for me so in case there are others...

UIImage *theImage = [info objectForKey:UIImagePickerControllerOriginalImage];
    if (picker.cameraDevice == UIImagePickerControllerCameraDeviceFront) {
        CGSize imageSize = theImage.size;
        UIGraphicsBeginImageContextWithOptions(imageSize, YES, 1.0);
        CGContextRef ctx = UIGraphicsGetCurrentContext();
        CGContextRotateCTM(ctx, M_PI/2);
        CGContextTranslateCTM(ctx, 0, -imageSize.width);
        CGContextScaleCTM(ctx, imageSize.height/imageSize.width, imageSize.width/imageSize.height);
        CGContextDrawImage(ctx, CGRectMake(0.0, 0.0, imageSize.width, imageSize.height), theImage.CGImage);
        UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
    }

and newImage is your new image with the up orientation

回答4:

Andrew Park's answer works great. This is Swift version.

func flipImage(image: UIImage!) -> UIImage! {
    let imageSize:CGSize = image.size;
    UIGraphicsBeginImageContextWithOptions(imageSize, true, 1.0);
    let ctx:CGContextRef = UIGraphicsGetCurrentContext()!;
    CGContextRotateCTM(ctx, CGFloat(M_PI/2.0));
    CGContextTranslateCTM(ctx, 0, -imageSize.width);
    CGContextScaleCTM(ctx, imageSize.height/imageSize.width, imageSize.width/imageSize.height);
    CGContextDrawImage(ctx, CGRectMake(0.0, 0.0, imageSize.width, imageSize.height), image.CGImage);
    let newImage:UIImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage
}

回答5:

You might want to mirror the image you get from the camera but what you originally get is correct. Take a picture with text to compare.

回答6:

A slightly simpler answer updated for Swift 3:

func flipImage(image: UIImage) -> UIImage {
    guard let cgImage = image.cgImage else {
        // Could not form CGImage from UIImage for some reason.
        // Return unflipped image
        return image
    }
    let flippedImage = UIImage(cgImage: cgImage, 
                               scale: image.scale, 
                               orientation: .leftMirrored)
    return flippedImage
}

回答7:

As the other answers, I had the same problem. But just flip the final image is only half the answer, because the preview image, displayed by the UIPickerController when you take a picture with the front camera, it's still inverted (mirrored).

Based in some codes from internet, I created a Pod to get this wanted behavior:

https://github.com/lucasecf/LEMirroredImagePicker

After installed, you just have to call this two lines of code together with your UIImagePickerController:

self.mirrorFrontPicker = [[LEMirroredImagePicker alloc] initWithImagePicker:pickerController];
[self.mirrorFrontPicker mirrorFrontCamera];

And thats it, simply as that. You can check for more informations in the README of the github link.

回答8:

I'd like to vote up @Lucas Eduardo , I have tried to integrate the component LEImagePickerController into my project as below:

- (void)onCamera:(id)sender {
    UIImagePickerController* imagePicker = [[UIImagePickerController alloc] init];
    imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
    imagePicker.cameraDevice = UIImagePickerControllerCameraDeviceFront;
    imagePicker.delegate = self;

    //cover the switch button at the top right corner, I just need user take photo with the front facing camera
    UIView* view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 40, 40)];
    view.center = CGPointMake(CGRectGetWidth(imagePicker.view.bounds) - CGRectGetWidth(view.bounds)/2, CGRectGetHeight(view.bounds)/2);
    view.backgroundColor = [UIColor blackColor];
    [imagePicker.view addSubview:view];

    LEMirroredImagePicker* mirrorFrontPicker = [[LEMirroredImagePicker alloc] initWithImagePicker:imagePicker];
    [mirrorFrontPicker mirrorFrontCamera];

    [self presentViewController:imagePicker animated:YES completion:nil];
}