UIScrollView minimumZoomScale
@property(nonatomic) float minimumZoomScale
Discussion of [UIScrollView minimumZoomScale]
This value determines how small the content can be scaled. The default value is 1.0
UIScrollView minimumZoomScale 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 minimumZoomScale].
- (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 minimumZoomScale 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
}