Image capture is distorted when using it for a CALayer - ios

Question

I am working on a photo taking app. The app's preview layer is set to take up exactly half of the screen using this code:
[_previewLayer setFrame:CGRectMake(0, 0, rootLayer.bounds.size.width, rootLayer.bounds.size.height/2)];
This looks perfect and there is no distortion at all while the user is viewing the camera's "preview" / what they are seeing while taking the picture.
However, once they actually take the photo, I create a sub layer and set it's frame property to my preview layer's property, and set the photo as the contents of the sub layer.
This does technically work. Once the user takes the photo, the photo shows up on the top half of the screen like it should.
The only problem is that the photo is distorted.
It looks stretched out, almost as if I'm taking a landscape photo.
Any help is greatly appreciated I am totally desperate on this and have not been able to fix it after working on it all day today.
Here is all of my view controller's code:
#import "MediaCaptureVC.h"
#interface MediaCaptureVC ()
#end
#implementation MediaCaptureVC
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
AVCaptureSession *session =[[AVCaptureSession alloc]init];
[session setSessionPreset:AVCaptureSessionPresetPhoto];
AVCaptureDevice *inputDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
NSError *error = [[NSError alloc]init];
AVCaptureDeviceInput *deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:inputDevice error:&error];
if([session canAddInput:deviceInput])
[session addInput:deviceInput];
_previewLayer = [[AVCaptureVideoPreviewLayer alloc]initWithSession:session];
[_previewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
CALayer *rootLayer = [[self view]layer];
[rootLayer setMasksToBounds:YES];
[_previewLayer setFrame:CGRectMake(0, 0, rootLayer.bounds.size.width, rootLayer.bounds.size.height/2)];
[rootLayer insertSublayer:_previewLayer atIndex:0];
_stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
[session addOutput:_stillImageOutput];
[session startRunning];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(UIImage*) rotate:(UIImage*) src andOrientation:(UIImageOrientation)orientation
{
UIGraphicsBeginImageContext(src.size);
CGContextRef context=(UIGraphicsGetCurrentContext());
if (orientation == UIImageOrientationRight) {
CGContextRotateCTM (context, 90/180*M_PI) ;
} else if (orientation == UIImageOrientationLeft) {
CGContextRotateCTM (context, -90/180*M_PI);
} else if (orientation == UIImageOrientationDown) {
// NOTHING
} else if (orientation == UIImageOrientationUp) {
CGContextRotateCTM (context, 90/180*M_PI);
}
[src drawAtPoint:CGPointMake(0, 0)];
UIImage *img=UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
-(IBAction)stillImageCapture {
AVCaptureConnection *videoConnection = nil;
for (AVCaptureConnection *connection in _stillImageOutput.connections){
for (AVCaptureInputPort *port in [connection inputPorts]){
if ([[port mediaType] isEqual:AVMediaTypeVideo]){
videoConnection = connection;
break;
}
}
if (videoConnection) {
break;
}
}
NSLog(#"about to request a capture from: %#", _stillImageOutput);
[_stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
if(imageDataSampleBuffer) {
NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
UIImage *image = [[UIImage alloc]initWithData:imageData];
image = [self rotate:image andOrientation:image.imageOrientation];
CALayer *subLayer = [CALayer layer];
CGImageRef imageRef = image.CGImage;
subLayer.contents = (id)[UIImage imageWithCGImage:imageRef].CGImage;
subLayer.frame = _previewLayer.frame;
CALayer *rootLayer = [[self view]layer];
[rootLayer setMasksToBounds:YES];
[subLayer setFrame:CGRectMake(0, 0, rootLayer.bounds.size.width, rootLayer.bounds.size.height/2)];
[_previewLayer addSublayer:subLayer];
NSLog(#"%#", subLayer.contents);
NSLog(#"Orientation: %d", image.imageOrientation);
}
}];
}
#end

Answer 1

Hi I hope this helps you -
The code seems more complex than it should be because most of the code is done on the CALayer level instead of the imageView / view level however I think the issue is that the proportion of the frame from the original capture to your mini viewport is different and this is distorting the UIImage in this statement :
[subLayer setFrame:CGRectMake(0, 0, rootLayer.bounds.size.width, rootLayer.bounds.size.height/2)];
What needs to be done is to capture the proportion of sublayer.frame and get the best size that will fit into the rootlayer or the Image view associated with it
I have some code before that does this : coded a subroutine before that handles the proportion (Note you will need to adjust the origin of the frame to get what you want!)
...
CGRect newbounds = [self figure_proportion:image to_fit_rect(rootLayer.frame)
if (newbounds.size.height < rootLayer.frame.size.height) {
rootLayer ..... (Code to adjust origin of image view frame)
-(CGRect) figure_proportion:(UIImage *) image2 to_fit_rect:(CGRect) rect {
CGSize image_size = image2.size;
CGRect newrect = rect;
float wfactor = image_size.width/ image_size.height;
float hfactor = image_size.height/ image_size.width;
if (image2.size.width > image2.size.height) {
newrect.size.width = rect.size.width;
newrect.size.height = (rect.size.width * hfactor);
}
else if (image2.size.height > image2.size.width) {
newrect.size.height = rect.size.height;
newrect.size.width = (rect.size.height * wfactor);
}
else {
newrect.size.width = rect.size.width;
newrect.size.height = newrect.size.width;
}
if (newrect.size.height > rect.size.height) {
newrect.size.height = rect.size.height;
newrect.size.width = (newrect.size.height* wfactor);
}
if (newrect.size.width > rect.size.width) {
newrect.size.width = rect.size.width;
newrect.size.height = (newrect.size.width* hfactor);
}
return(newrect);
}