我在滚动视图中使用此代码放大和缩小图像。但我不知道出了什么问题，因为放大不起作用？
const CGFloat kScrollObjHeight = 460.0;
const CGFloat kScrollObjWidth = 320.0;
const NSUInteger kNumImages = 32;
- (void)layoutScrollImages
{
UIImageView *view = nil;
NSArray *subviews = [scrollView1 subviews];
// reposition all image subviews in a horizontal serial fashion
CGFloat curXLoc = 0;
for (view in subviews)
{
if ([view isKindOfClass:[UIImageView class]] && view.tag > 0)
{
CGRect frame = view.frame;
frame.origin = CGPointMake(curXLoc, 0);
view.frame = frame;
curXLoc += (kScrollObjWidth);
}
}
// set the content size so it can be scrollable
[scrollView1 setContentSize:CGSizeMake((kNumImages * kScrollObjWidth), [scrollView1 bounds].size.height)];
}
- (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;
//imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"image0.jpg"]];
[scrollView1 addSubview:imageView];
[scrollView1 setContentSize:CGSizeMake(imageView.frame.size.width, imageView.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:@"page-%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
}
-(UIView *) viewForZoomingInScrollView:(UIScrollView *)scrollView {
return imageView;
}
how add below code for zooming with above code?
#define ZOOM_VIEW_TAG 100
#define ZOOM_STEP 1.5
@interface RootViewController (UtilityMethods)
- (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center;
@end
@implementation RootViewController
@synthesize imageScrollView, imageView;
- (void)loadView {
[super loadView];
// set the tag for the image view
[imageView setTag:ZOOM_VIEW_TAG];
// add gesture recognizers to the image view
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap:)];
UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTap:)];
UITapGestureRecognizer *twoFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTwoFingerTap:)];
[doubleTap setNumberOfTapsRequired:2];
[twoFingerTap setNumberOfTouchesRequired:2];
[imageView addGestureRecognizer:singleTap];
[imageView addGestureRecognizer:doubleTap];
[imageView addGestureRecognizer:twoFingerTap];
[singleTap release];
[doubleTap release];
[twoFingerTap release];
// calculate minimum scale to perfectly fit image width, and begin at that scale
float minimumScale = [imageScrollView frame].size.width / [imageView frame].size.width;
[imageScrollView setMinimumZoomScale:minimumScale];
[imageScrollView setZoomScale:minimumScale];
}
- (void)viewDidUnload {
self.imageScrollView = nil;
self.imageView = nil;
}
- (void)dealloc {
[imageScrollView release];
[imageView release];
[super dealloc];
}
#pragma mark UIScrollViewDelegate methods
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
return [imageScrollView viewWithTag:ZOOM_VIEW_TAG];
}
/************************************** NOTE **************************************/
/* The following delegate method works around a known bug in zoomToRect:animated: */
/* In the next release after 3.0 this workaround will no longer be necessary */
/**********************************************************************************/
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale {
[scrollView setZoomScale:scale+0.01 animated:NO];
[scrollView setZoomScale:scale animated:NO];
}
#pragma mark TapDetectingImageViewDelegate methods
- (void)handleSingleTap:(UIGestureRecognizer *)gestureRecognizer {
// single tap does nothing for now
}
- (void)handleDoubleTap:(UIGestureRecognizer *)gestureRecognizer {
// double tap zooms in
float newScale = [imageScrollView zoomScale] * ZOOM_STEP;
CGRect zoomRect = [self zoomRectForScale:newScale withCenter:[gestureRecognizer locationInView:gestureRecognizer.view]];
[imageScrollView zoomToRect:zoomRect animated:YES];
}
- (void)handleTwoFingerTap:(UIGestureRecognizer *)gestureRecognizer {
// two-finger tap zooms out
float newScale = [imageScrollView zoomScale] / ZOOM_STEP;
CGRect zoomRect = [self zoomRectForScale:newScale withCenter:[gestureRecognizer locationInView:gestureRecognizer.view]];
[imageScrollView zoomToRect:zoomRect animated:YES];
}
#pragma mark Utility methods
- (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 = [imageScrollView frame].size.height / scale;
zoomRect.size.width = [imageScrollView 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;
}
在上面的代码中如何在滚动视图中缩放图像？
答案 0 :(得分：0)
您可以使用捏合手势识别器进行放大/缩小。请检查以下链接：
How can I use pinch zoom(UIPinchGestureRecognizer) to change width of a UITextView?