UIScroll view for comic App - cocoa-touch

Question

I´m working on an ipad app for a comic but i can´t get my scroll view to work. I need it to do:
Pinch zoom
Rotation
Double tap and move by comic strip
Here´s an example of what i want to get http://vimeo.com/16073699 (Second 35 +-)
Right now i have pinch zoom but i can get the scroll view to rotate and center image.
Here´s my controller code:
#define ZOOM_VIEW_TAG 100
#define ZOOM_STEP 2
#define PAGE_TIME 10
- (void)viewDidLoad{
[super loadView];
self.myImage.image = [UIImage imageNamed:#"Tira01.jpg"];
[self.myImage setTag:ZOOM_VIEW_TAG];
UISwipeGestureRecognizer *recognizer;
recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(Tap)];
[(UITapGestureRecognizer *)recognizer setNumberOfTouchesRequired:1];
[(UITapGestureRecognizer *)drecognizer setNumberOfTapsRequired:1];
[[self myImage] addGestureRecognizer:recognizer];
[recognizer release];
self.drecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleDoubleTap:)];
[(UITapGestureRecognizer *)drecognizer setNumberOfTouchesRequired:1];
[(UITapGestureRecognizer *)drecognizer setNumberOfTapsRequired:2];
[[self myImage] addGestureRecognizer:drecognizer];
[drecognizer release];
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
return [myScrollView viewWithTag:ZOOM_VIEW_TAG];
}
- (void)handleDoubleTap:(UIGestureRecognizer *)gestureRecognizer {
UIInterfaceOrientation currentOrientation = [[UIDevice currentDevice] orientation];
if(!self.zoomed)
{
// double tap zooms in
float newScale = [self.myScrollView zoomScale] * ZOOM_STEP;
CGRect zoomRect = [self zoomRectForScale:newScale withCenter:[gestureRecognizer locationInView:gestureRecognizer.view]];
[self.myScrollView zoomToRect:zoomRect animated:YES];
self.zoomed = YES;
}
else {
float newScale = [self.myScrollView zoomScale] / ZOOM_STEP;
CGRect zoomRect = [self zoomRectForScale:newScale withCenter:[gestureRecognizer locationInView:gestureRecognizer.view]];
[self.myScrollView zoomToRect:zoomRect animated:YES];
self.zoomed = NO;
}
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation{
return YES;
}
- (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center {
CGRect zoomRect;
// the zoom rect is in the content view's coordinates.
// At a zoom scale of 1.0, it would be the size of the imageScrollView's bounds.
// As the zoom scale decreases, so more content is visible, the size of the rect grows.
zoomRect.size.height = [self.myScrollView frame].size.height / scale;
zoomRect.size.width = [self.myScrollView frame].size.width / scale;
// choose an origin so as to get the right center.
zoomRect.origin.x = center.x - (zoomRect.size.width / 2.0);
zoomRect.origin.y = center.y - (zoomRect.size.height / 2.0);
return zoomRect;
}
In interface builder i have:
-> UIView(ScaleToFill mode)
--> UIScrollView (ScaleToFill mode)
---> UIImageView (AspectFit mode)
I don´t know what i´m doing wrong but i´m going crazy with that :(

Answer 1

Regarding the UIScrollView centering the content, I might be wrong here, but the UIScrollView doesn't automatically do that.
In my app i'm manually doing it by actually moving the content in the scrollView so that it is centered.
Just as a quick explanation for the code below, if the content (image) frame is smaller than the bounds of the scroll view, then adjust the position of the content horizontally and vertically.
The code below is from my class derived from UIScrollView. If you're using the default UIScrollView, you can use this code in the parent UIView.
- (void)layoutSubviews
{
[super layoutSubviews];
if (![self centersContent])
{
return;
}
// center the image as it becomes smaller than the size of the screen
CGSize boundsSize = self.bounds.size;
CGRect frameToCenter = imageView.frame;
// center horizontally
if (frameToCenter.size.width < boundsSize.width)
frameToCenter.origin.x = (boundsSize.width - frameToCenter.size.width) / 2;
else
frameToCenter.origin.x = 0;
// center vertically
if (frameToCenter.size.height < boundsSize.height)
frameToCenter.origin.y = (boundsSize.height - frameToCenter.size.height) / 2;
else
frameToCenter.origin.y = 0;
imageView.frame = frameToCenter;
}