UIScrollView maximumZoomScale
@property(nonatomic) float maximumZoomScale
Discussion of [UIScrollView maximumZoomScale]
This value determines how large the content can be scaled. It must be greater than the minimum zoom scale for zooming to be enabled. The default value is 1.0.
UIScrollView maximumZoomScale example.
- (id)initWithFrame:(CGRect)frame {
if (self = [super initWithFrame:frame]) {
self.autoresizesSubviews = YES;
self.showsVerticalScrollIndicator = YES;
self.showsHorizontalScrollIndicator = NO;
self.bouncesZoom = YES;
self.alwaysBounceVertical = YES;
self.delegate = self;
self.minimumZoomScale = kMinimumZoomScale;
self.maximumZoomScale = kMaximumZoomScale;
}
return self;
}
if (self = [super initWithFrame:frame]) {
self.autoresizesSubviews = YES;
self.showsVerticalScrollIndicator = YES;
self.showsHorizontalScrollIndicator = NO;
self.bouncesZoom = YES;
self.alwaysBounceVertical = YES;
self.delegate = self;
self.minimumZoomScale = kMinimumZoomScale;
self.maximumZoomScale = kMaximumZoomScale;
}
return self;
}
Example of [UIScrollView maximumZoomScale].
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)aScrollView {
return contentView;
}
- (void)scrollViewDidEndZooming:(UIScrollView *)aScrollView withView:(UIView *)view atScale:(float)scale {
CGFloat oldZoomScale = contentView.zoomScale;
CGSize size = self.bounds.size;
// Figure out where the scroll view was centered so that we can
// fix up its offset after adjusting the scaling
CGPoint contentCenter = self.contentOffset;
contentCenter.x += size.width / (oldZoomScale * scale) / 2;
contentCenter.y += size.height / (oldZoomScale * scale) / 2;
CGFloat newZoomScale = scale * oldZoomScale;
newZoomScale = MAX(newZoomScale, kMinimumZoomscale);
newZoomScale = MIN(newZoomScale, kMaximumZoomscale);
// Set the scroll view's zoom scale back to 1 and adjust its minimum and maximum
// to allow the expected amount of zooming.
self.zoomScale = 1.0;
self.minimumZoomScale = kMinimumZoomScale / newZoomScale;
self.maximumZoomScale = kMaximumZoomScale / newZoomScale;
// Tell the contentView about its new scale. My contentView.zoomScale setter method
// calls setNeedsDisplay, but you could also call it here
contentView.zoomScale = newZoomScale;
// My ContentView class overrides sizeThatFits to give its expected size with
// zoomScale taken into account
CGRect newContentSize = [contentView sizeThatFits];
// update the content view's frame and the scroll view's contentSize with the new size
contentView.frame = CGRectMake(0, 0, newContentSize.width, newContentSize.height);
self.contentSize = newContentSize;
// Figure out the new contentOffset so that the contentView doesn't appear to move
CGPoint newContentOffset = CGPointMake(contentCenter.x - size.width / newZoomScale / 2,
contentCenter.y - size.height / newZoomScale / 2);
newContentOffset.x = MIN(newContentOffset.x, newContentSize.width - size.width);
newContentOffset.x = MAX(0, newContentOffset.x);
newContentOffset.y = MIN(newContentOffset.y, newContentSize.height - .size.height);
newContentOffset.y = MAX(0, newContentOffset.y);
[self setContentOffset:newContentOffset animated:NO];
}
return contentView;
}
- (void)scrollViewDidEndZooming:(UIScrollView *)aScrollView withView:(UIView *)view atScale:(float)scale {
CGFloat oldZoomScale = contentView.zoomScale;
CGSize size = self.bounds.size;
// Figure out where the scroll view was centered so that we can
// fix up its offset after adjusting the scaling
CGPoint contentCenter = self.contentOffset;
contentCenter.x += size.width / (oldZoomScale * scale) / 2;
contentCenter.y += size.height / (oldZoomScale * scale) / 2;
CGFloat newZoomScale = scale * oldZoomScale;
newZoomScale = MAX(newZoomScale, kMinimumZoomscale);
newZoomScale = MIN(newZoomScale, kMaximumZoomscale);
// Set the scroll view's zoom scale back to 1 and adjust its minimum and maximum
// to allow the expected amount of zooming.
self.zoomScale = 1.0;
self.minimumZoomScale = kMinimumZoomScale / newZoomScale;
self.maximumZoomScale = kMaximumZoomScale / newZoomScale;
// Tell the contentView about its new scale. My contentView.zoomScale setter method
// calls setNeedsDisplay, but you could also call it here
contentView.zoomScale = newZoomScale;
// My ContentView class overrides sizeThatFits to give its expected size with
// zoomScale taken into account
CGRect newContentSize = [contentView sizeThatFits];
// update the content view's frame and the scroll view's contentSize with the new size
contentView.frame = CGRectMake(0, 0, newContentSize.width, newContentSize.height);
self.contentSize = newContentSize;
// Figure out the new contentOffset so that the contentView doesn't appear to move
CGPoint newContentOffset = CGPointMake(contentCenter.x - size.width / newZoomScale / 2,
contentCenter.y - size.height / newZoomScale / 2);
newContentOffset.x = MIN(newContentOffset.x, newContentSize.width - size.width);
newContentOffset.x = MAX(0, newContentOffset.x);
newContentOffset.y = MIN(newContentOffset.y, newContentSize.height - .size.height);
newContentOffset.y = MAX(0, newContentOffset.y);
[self setContentOffset:newContentOffset animated:NO];
}
UIScrollView maximumZoomScale example.
- (void)viewDidLoad
{
self.view.backgroundColor = [UIColor viewFlipsideBackgroundColor];
// 1. setup the scrollview for multiple images and add it to the view controller
//
// note: the following can be done in Interface Builder, but we show this in code for clarity
[scrollView1 setBackgroundColor:[UIColor blackColor]];
[scrollView1 setCanCancelContentTouches:NO];
scrollView1.indicatorStyle = UIScrollViewIndicatorStyleWhite;
scrollView1.clipsToBounds = YES; // default is NO, we want to restrict drawing within our scrollview
scrollView1.scrollEnabled = YES;
scroll1ImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"image0.jpg"]];
[scrollView1 addSubview:scroll1ImageView];
[scrollView1 setContentSize:CGSizeMake(scroll1ImageView.frame.size.width, scroll1ImageView.frame.size.height)];
scrollView1.minimumZoomScale = 1;
scrollView1.maximumZoomScale = 3;
scrollView1.delegate = self;
[scrollView1 setScrollEnabled:YES];
// pagingEnabled property default is NO, if set the scroller will stop or snap at each photo
// if you want free-flowing scroll, don't set this property.
scrollView1.pagingEnabled = YES;
// load all the images from our bundle and add them to the scroll view
NSUInteger i;
for (i = 1; i <= kNumImages; i++)
{
NSString *imageName = [NSString stringWithFormat:@"image%d.jpg", i];
UIImage *image = [UIImage imageNamed:imageName];
UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
// setup each frame to a default height and width, it will be properly placed when we call "updateScrollList"
CGRect rect = imageView.frame;
rect.size.height = kScrollObjHeight;
rect.size.width = kScrollObjWidth;
imageView.frame = rect;
imageView.tag = i; // tag our images for later use when we place them in serial fashion
[scrollView1 addSubview:imageView];
[imageView release];
}
[self layoutScrollImages]; // now place the photos in serial layout within the scrollview
}
{
self.view.backgroundColor = [UIColor viewFlipsideBackgroundColor];
// 1. setup the scrollview for multiple images and add it to the view controller
//
// note: the following can be done in Interface Builder, but we show this in code for clarity
[scrollView1 setBackgroundColor:[UIColor blackColor]];
[scrollView1 setCanCancelContentTouches:NO];
scrollView1.indicatorStyle = UIScrollViewIndicatorStyleWhite;
scrollView1.clipsToBounds = YES; // default is NO, we want to restrict drawing within our scrollview
scrollView1.scrollEnabled = YES;
scroll1ImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"image0.jpg"]];
[scrollView1 addSubview:scroll1ImageView];
[scrollView1 setContentSize:CGSizeMake(scroll1ImageView.frame.size.width, scroll1ImageView.frame.size.height)];
scrollView1.minimumZoomScale = 1;
scrollView1.maximumZoomScale = 3;
scrollView1.delegate = self;
[scrollView1 setScrollEnabled:YES];
// pagingEnabled property default is NO, if set the scroller will stop or snap at each photo
// if you want free-flowing scroll, don't set this property.
scrollView1.pagingEnabled = YES;
// load all the images from our bundle and add them to the scroll view
NSUInteger i;
for (i = 1; i <= kNumImages; i++)
{
NSString *imageName = [NSString stringWithFormat:@"image%d.jpg", i];
UIImage *image = [UIImage imageNamed:imageName];
UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
// setup each frame to a default height and width, it will be properly placed when we call "updateScrollList"
CGRect rect = imageView.frame;
rect.size.height = kScrollObjHeight;
rect.size.width = kScrollObjWidth;
imageView.frame = rect;
imageView.tag = i; // tag our images for later use when we place them in serial fashion
[scrollView1 addSubview:imageView];
[imageView release];
}
[self layoutScrollImages]; // now place the photos in serial layout within the scrollview
}