UIImagePickerController doesn't fill screen

问题:

I'm adding a custom overlay to the UIImagePickerController and there is a persistant black bar at the bottom of the view. Here is my code to instantiate the controller.

- (UIImagePickerController *)imagePicker {
    if (_imagePicker) {
        return _imagePicker;
    }

    _imagePicker = [[UIImagePickerController alloc] init];
    _imagePicker.delegate = self;

    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
        _imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;

        _imagePicker.showsCameraControls = NO;

        _imagePicker.wantsFullScreenLayout = YES;
        _imagePicker.navigationBarHidden = YES;
        _imagePicker.toolbarHidden = YES;

    } else {
        _imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    }

    return _imagePicker;
}

The returned controller is displayed modally and works just fine (i.e. displays full screen) when I'm not hiding the camera controls.

---

Thanks to Ole's suggestion I got it working with this code:

// Resize the camera preview
        _imagePicker.cameraViewTransform = CGAffineTransformMakeScale(1.0, 1.03);

A 3% increase in height worked just fine. When I add my custom toolbar at the bottom of the screen there is no longer a visible black bar across the window.

回答1:

The camera's aspect ratio is 4:3 and the screen's aspect ratio is 3:2. So there is simply no way for the camera picture to fill the screen unless you're willing to crop is to 3:2. To do that, apply an appropriate scale transform.

回答2:

Scaling by a fixed value isn't a good idea... as I'm sure anyone who used the accepted answer here probably found out when the iPhone 5 came out.

Here's a code snippet to scale dynamically based on the screen resolution to eliminate the letter boxing.

// Device's screen size (ignoring rotation intentionally):
CGSize screenSize = [[UIScreen mainScreen] bounds].size;

// iOS is going to calculate a size which constrains the 4:3 aspect ratio
// to the screen size. We're basically mimicking that here to determine
// what size the system will likely display the image at on screen.
// NOTE: screenSize.width may seem odd in this calculation - but, remember,
// the devices only take 4:3 images when they are oriented *sideways*.
float cameraAspectRatio = 4.0 / 3.0;
float imageWidth = floorf(screenSize.width * cameraAspectRatio);
float scale = ceilf((screenSize.height / imageWidth) * 10.0) / 10.0;

self.ipc.cameraViewTransform = CGAffineTransformMakeScale(scale, scale);

回答3:

Hey I saw some people were still getting the black bar at the bottom after calculating the scale for the iPhone 5. I had this problem for a while but then I figured out you have to translate the view so it is in the middle of the screen and then apply the scale. Here is my code for doing those two things and it works for me!

    CGSize screenBounds = [UIScreen mainScreen].bounds.size;

    CGFloat cameraAspectRatio = 4.0f/3.0f;

    CGFloat camViewHeight = screenBounds.width * cameraAspectRatio;
    CGFloat scale = screenBounds.height / camViewHeight;

    m_imagePickerController.cameraViewTransform = CGAffineTransformMakeTranslation(0, (screenBounds.height - camViewHeight) / 2.0);
    m_imagePickerController.cameraViewTransform = CGAffineTransformScale(m_imagePickerController.cameraViewTransform, scale, scale);

回答4:

Transform it with this:

#define CAMERA_TRANSFORM                    1.12412

_picker.wantsFullScreenLayout = YES;
_picker.cameraViewTransform = CGAffineTransformScale(_picker.cameraViewTransform, CAMERA_TRANSFORM, CAMERA_TRANSFORM);

回答5:

From my experience on iOS 7, iphone 5S, to see the center of the picture into the full-screen preview you have to concatenate the transformations, not make them sequentially:

pickerController.cameraOverlayView = self.view;

CGSize screenSize = [[UIScreen mainScreen] bounds].size;   // 320 x 568

float scale = screenSize.height / screenSize.width*3/4;  // screen height divided by the pickerController height ... or:  568 / ( 320*4/3 )

CGAffineTransform translate=CGAffineTransformMakeTranslation(0,(screenSize.height - screenSize.width*4/3)*0.5);
CGAffineTransform fullScreen=CGAffineTransformMakeScale(scale, scale);
pickerController.cameraViewTransform =CGAffineTransformConcat(fullScreen, translate);

回答6:

And here the answer in Swift.

let screenSize:CGSize = UIScreen.mainScreen().bounds.size

let ratio:CGFloat = 4.0 / 3.0
let cameraHeight:CGFloat = screenSize.width * ratio
let scale:CGFloat = screenSize.height / cameraHeight

let imag:UIImagePickerController = UIImagePickerController()
imag.cameraViewTransform = CGAffineTransformMakeTranslation(0, (screenSize.height - cameraHeight) / 2.0)
imag.cameraViewTransform = CGAffineTransformScale(imag.cameraViewTransform, scale, scale)

回答7:

This worked for me on iOS 10:

let screenSize = UIScreen.main.bounds.size
let cameraAspectRatio = CGFloat(4.0 / 3.0)
let cameraImageHeight = screenSize.width * cameraAspectRatio
let scale = screenSize.height / cameraImageHeight
imagePickerController.cameraViewTransform = CGAffineTransform(translationX: 0, y: (screenSize.height - cameraImageHeight)/2)
imagePickerController.cameraViewTransform = imagePickerController.cameraViewTransform.scaledBy(x: scale, y: scale)

回答8:

I used this method to calculate the scale.

// get the screen size
CGSize screenSize = [[UIScreen mainScreen] bounds].size;
// establish the height to width ratio of the camera
float heightRatio = 4.0f / 3.0f;
// calculate the height of the camera based on the screen width
float cameraHeight = screenSize.width * heightRatio;
// calculate the ratio that the camera height needs to be scaled by
float scale = screenSize.height / cameraHeight;
imagePicker.cameraViewTransform = CGAffineTransformMakeScale(scale, scale);

回答9:

my issue solved :)

//Camera is 426 * 320. Screen height is 568.  Multiply by 1.333 in 5 inch (iPhone5) to fill vertical

CGAffineTransform translate = CGAffineTransformMakeTranslation(0.0, 71.0); //This slots the preview exactly in the middle of the screen by moving it down 71 points
self.imagePickerController.cameraViewTransform = translate;

CGAffineTransform scale = CGAffineTransformScale(translate, 1.333333, 1.333333);
self.imagePickerController.cameraViewTransform = scale;

回答10:

Try use this code:

picker.wantsFullScreenLayout = YES;
CGAffineTransform translate = CGAffineTransformMakeTranslation(0.0, 71.0);
CGAffineTransform scale = CGAffineTransformScale(translate, 1.333333, 1.47);
picker.view.transform = scale;

回答11:

PickerViewController.m    
#define CAMERA_TRANSFORM  1.8

- (void)viewDidAppear:(BOOL)animated
{
 if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera])
    {
       // type = UIImagePickerControllerSourceTypeCamera;

        UIImagePickerController *picker = [[UIImagePickerController alloc] init];
        picker.allowsEditing = NO;
        picker.delegate   = self;
        picker.sourceType = UIImagePickerControllerSourceTypeCamera;
        picker.showsCameraControls=NO;
        picker.extendedLayoutIncludesOpaqueBars = YES;
        picker.cameraViewTransform = CGAffineTransformScale(picker.cameraViewTransform, CAMERA_TRANSFORM , CAMERA_TRANSFORM);

        [self presentViewController:picker animated:YES completion:nil];
    }else{

        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Message"
                                                        message:@"Device have no camera"
                                                       delegate:self
                                              cancelButtonTitle:@"OK"
                                              otherButtonTitles:nil];
        [alert show];
    }
}

回答12:

This is what works for me with Swift 4

let screenSize: CGSize = picker.view.safeAreaLayoutGuide.layoutFrame.size
let ratio: CGFloat = 4.0 / 3.0
let cameraHeight: CGFloat = screenSize.width * ratio
let scale: CGFloat = (screenSize.height + 80) / cameraHeight
picker.cameraViewTransform = picker.cameraViewTransform.scaledBy(x: scale, y: scale)