Iphone 缩小时将UIImageView居中显示在屏幕上
我在UIScrollView中有一个UIImageView。我希望用户可以缩放和导航图像 这是我的工作代码:Iphone 缩小时将UIImageView居中显示在屏幕上,iphone,uiscrollview,uiimageview,zooming,Iphone,Uiscrollview,Uiimageview,Zooming,我在UIScrollView中有一个UIImageView。我希望用户可以缩放和导航图像 这是我的工作代码: //img is the UIImageView //scroller is the UIScrollView - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView { return img; } - (void)viewDidLoad { [super viewDidLoad]; UIImag
//img is the UIImageView
//scroller is the UIScrollView
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
return img;
}
- (void)viewDidLoad {
[super viewDidLoad];
UIImage *image = [UIImage imageNamed:@"map_screen.png"];
img = [[UIImageView alloc] initWithImage:image];
scroller.delegate = self;
scroller.autoresizesSubviews = YES;
scroller.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
scroller.contentSize = img.frame.size;
scroller.scrollEnabled = YES;
scroller.directionalLockEnabled = NO;
scroller.userInteractionEnabled = YES;
CGSize ivsize = img.frame.size;
CGSize ssize = scroller.frame.size;
float scalex = ssize.width / ivsize.width;
float scaley = ssize.height / ivsize.height;
scroller.minimumZoomScale = fmin(1.0, fmax(scaley, scalex));
scroller.zoomScale = fmin(1.0, fmax(scalex, scaley));
[scroller addSubview:img];
img.userInteractionEnabled = YES;
}
所有的工作,但这发生了:最小的缩放是屏幕的高度。
我的图像的宽度大于高度,因此我希望最小缩放是宽度
如果我写
scroller.minimumZoomScale = fmin(1.0, scalex);
工作正常,但当用户缩小时,图像不在屏幕中央,而是在顶部
我试过这样的东西
CGPoint scrollCenter = [scroller center];
[img setCenter:CGPointMake(scrollCenter.x, scrollCenter.y)];
或
但是在这个解决方案中,图像不是完全可滚动的,如果我缩小,它会再次停留在屏幕顶部,但不是完全可见的
我能做些什么来修复它?当正在使用scrollViewDidZoom代理功能进行缩放时,您必须手动执行此操作。。。差不多
- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
// center the image as it becomes smaller than the size of the screen
CGSize boundsSize = scrollView.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;
}
-(无效)scrollViewDidZoom:(UIScrollView*)scrollView
{
//当图像小于屏幕尺寸时,将图像居中
CGSize boundsSize=scrollView.bounds.size;
CGRect frameToCenter=imageView.frame;
//水平居中
if(frameToCenter.size.width
巴斯蒂安答案的Swift 3.0版,更简洁一点:
func scrollViewDidZoom(_ scrollView: UIScrollView) {
// center the image as it becomes smaller than the size of the screen
let boundsSize = scrollView.bounds.size
var frameToCenter = imageView.frame
// center horizontally and vertically
let widthDiff = boundsSize.width - frameToCenter.size.width
let heightDiff = boundsSize.height - frameToCenter.size.height
frameToCenter.origin.x = (widthDiff > 0) ? widthDiff / 2 : 0;
frameToCenter.origin.y = (heightDiff > 0) ? heightDiff / 2 : 0;
imageView.frame = frameToCenter;
}
func scrollViewDidZoom(_ scrollView: UIScrollView) {
// center the image as it becomes smaller than the size of the screen
let boundsSize = scrollView.bounds.size
var frameToCenter = imageView.frame
// center horizontally and vertically
let widthDiff = boundsSize.width - frameToCenter.size.width
let heightDiff = boundsSize.height - frameToCenter.size.height
frameToCenter.origin.x = (widthDiff > 0) ? widthDiff / 2 : 0;
frameToCenter.origin.y = (heightDiff > 0) ? heightDiff / 2 : 0;
imageView.frame = frameToCenter;
}