Scaling UIImageView inside UIScrollView with maintaining the rotation - iphone

Question

I have a problem in scaling the uiimageview which is placed inside the uiscrollview. I have googled and checked all the questions related to my problem in StackOverflow as well. I tried all the answers that are posted in the StackOverflow also. Nothing worked for me.
First I am placing the uiimageview inside uiscrollview in nib file and I am taking the image from Camera roll and filling the image view. Then I am using uirotationgesturerecognizer to rotate the image.
Here is the code that I am trying to do.
- (void)viewDidLoad
{
[super viewDidLoad];
NSLog(#"%#",[[UIDevice currentDevice] model]);
// Do any additional setup after loading the view, typically from a nib.
self.imagePicker = [[[UIImagePickerController alloc] init] autorelease];
self.picChosenImageView.layer.shouldRasterize = YES;
self.picChosenImageView.layer.rasterizationScale = [UIScreen mainScreen].scale;
self.picChosenImageView.layer.contents = (id)[UIImage imageNamed:#"test"].CGImage;
self.picChosenImageView.layer.shadowColor = [UIColor blackColor].CGColor;
self.picChosenImageView.layer.shadowOpacity = 0.8f;
self.picChosenImageView.layer.shadowRadius = 8;
self.picChosenImageView.layer.shadowPath = [UIBezierPath bezierPathWithRect:self.picChosenImageView.bounds].CGPath;
UIRotationGestureRecognizer *rotationRecognizer = [[[UIRotationGestureRecognizer alloc]initWithTarget:self
action:#selector(handleRotate:)] autorelease];
rotationRecognizer.delegate = self;
[self.picChosenImageView addGestureRecognizer:rotationRecognizer];
self.containerView.delegate = self;
self.containerView.contentSize = self.picChosenImageView.layer.frame.size;
self.containerView.maximumZoomScale = 4.0f;
self.containerView.minimumZoomScale = 1.0f;
angle = 0.0f;
useRotation = 0.0;
isRotationStarted=FALSE;
isZoomingStarted = FALSE;
}
-(void)lockZoom
{
maximumZoomScale = self.containerView.maximumZoomScale;
minimumZoomScale = self.containerView.minimumZoomScale;
self.containerView.maximumZoomScale = 1.0;
self.containerView.minimumZoomScale = 1.0;
self.containerView.clipsToBounds = false;
self.containerView.scrollEnabled = false;
}
-(void)unlockZoom
{
self.containerView.maximumZoomScale = maximumZoomScale;
self.containerView.minimumZoomScale = minimumZoomScale;
self.containerView.clipsToBounds = true;
self.containerView.scrollEnabled = true;
}
#pragma mark - ScrollView delegate methods
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.picChosenImageView;
}
- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
CGRect frame = self.picChosenImageView.frame;
frame.origin = CGPointZero;
self.picChosenImageView.frame = frame;
//self.picChosenImageView.transform = prevTransform;
}
-(void) scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view
{
if(!isZoomingStarted)
{
self.picChosenImageView.transform = CGAffineTransformRotate(self.picChosenImageView.transform, angle);
NSLog(#"The zooming started");
isZoomingStarted = TRUE;
CGSize contentSize = self.containerView.bounds.size;
CGRect contentFrame = self.containerView.bounds;
NSLog(#"frame on start: %#", NSStringFromCGRect(contentFrame));
NSLog(#"size on start: %#", NSStringFromCGSize(contentSize));
//prevTransform = self.picChosenImageView.transform;
}
}
-(void) scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale
{
if(isZoomingStarted)
{
self.picChosenImageView.transform = CGAffineTransformRotate(self.picChosenImageView.transform, angle);
isZoomingStarted = FALSE;
CGSize contentSize = self.containerView.contentSize;
CGRect contentFrame = self.containerView.bounds;
NSLog(#"frame on end: %#", NSStringFromCGRect(contentFrame));
NSLog(#"size on end: %#", NSStringFromCGSize(contentSize));
}
}
#pragma mark - GestureRecognizer methods
- (void) handleRotate:(UIRotationGestureRecognizer *)recognizer
{
if(isZoomingStarted == FALSE)
{
if([recognizer state] == UIGestureRecognizerStateBegan)
{
angle = 0.0f;
[self lockZoom];
}
useRotation+= recognizer.rotation;
while( useRotation < -M_PI )
{
useRotation += M_PI*2;
}
while( useRotation > M_PI )
{
useRotation -= M_PI*2;
}
NSLog(#"The rotated value is %f",RADIANS_TO_DEGREES(useRotation));
self.picChosenImageView.transform = CGAffineTransformRotate([self.picChosenImageView transform],
recognizer.rotation);
[recognizer setRotation:0];
if([recognizer state] == UIGestureRecognizerStateEnded)
{
angle = useRotation;
useRotation = 0.0f;
isRotationStarted = FALSE;
self.containerView.hidden = NO;
//prevTransform = self.picChosenImageView.transform;
[self unlockZoom];
}
}
}
My problem is, I am able to successfully do a zoom in and zoom out. I am able to rotate the uiimageview as I wanted to. After rotating the uiimageview to a certain angle, and when I am trying to zoom in, the imageview gets back to the original position (rotate itself back to zero degree) and then the zooming happens. I want to retain the rotation and also zoom. I tried saving the previous transform and assign in back scrollDidzoom and scrollDidBegin delegate methods. None worked. Please help me to spot my mistake which I am overlooking.

Answer 1

try using CGAffineTransformScale instead of just resizing the frame for zooming:
anImage.transform = CGAffineTransformScale(anImage.transform, 2.0, 2.0);
changing the transform for scaling might fix your rotation issue.
hope this helps.

Answer 2

I had the same problem. UIScrollView is taking control over UIImageView and it is using transform without rotation.
So I do not give image reference to scroll and I have added UIPinchGestureRecognizer for scaling.
func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView? {
return nil
}
Dragging is still working :)
// viewDidLoad
var pinchGestureRecognizer = UIPinchGestureRecognizer(target: self, action: #selector(pinchRecogniezed))
scrollView.addGestureRecognizer(pinchGestureRecognizer)
func pinchRecogniezed(sender: UIPinchGestureRecognizer) {
if sender.state == .Began || sender.state == .Changed {
let scale = sender.scale
imageView.transform = CGAffineTransformScale(imageView.transform, scale, scale)
sender.scale = 1
}
}