UIScrollView 的中心内容较小时
我有一个 UIImageView内的 UIScrollView，我用来缩放和滚动。如果滚动视图的图像/内容大于滚动视图，则一切正常。但是，当图像变得比滚动视图小时，它会粘附在滚动视图的左上角。我想保持它的中心，像照片应用程序。
当 UIScrollView变小的时候，有什么关于保持内容居中的想法或例子吗？
我正在使用 iPhone 3.0。
下面的代码几乎可以正常工作。如果我在达到最小缩放水平后捏它，图像就会返回到左上角。
- (void)loadView {
[super loadView];
// set up main scroll view
imageScrollView = [[UIScrollView alloc] initWithFrame:[[self view] bounds]];
[imageScrollView setBackgroundColor:[UIColor blackColor]];
[imageScrollView setDelegate:self];
[imageScrollView setBouncesZoom:YES];
[[self view] addSubview:imageScrollView];
UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"WeCanDoIt.png"]];
[imageView setTag:ZOOM_VIEW_TAG];
[imageScrollView setContentSize:[imageView frame].size];
[imageScrollView addSubview:imageView];
CGSize imageSize = imageView.image.size;
[imageView release];
CGSize maxSize = imageScrollView.frame.size;
CGFloat widthRatio = maxSize.width / imageSize.width;
CGFloat heightRatio = maxSize.height / imageSize.height;
CGFloat initialZoom = (widthRatio > heightRatio) ? heightRatio : widthRatio;
[imageScrollView setMinimumZoomScale:initialZoom];
[imageScrollView setZoomScale:1];
float topInset = (maxSize.height - imageSize.height) / 2.0;
float sideInset = (maxSize.width - imageSize.width) / 2.0;
if (topInset < 0.0) topInset = 0.0;
if (sideInset < 0.0) sideInset = 0.0;
[imageScrollView setContentInset:UIEdgeInsetsMake(topInset, sideInset, -topInset, -sideInset)];
}
- (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];
// END Bug workaround
CGSize maxSize = imageScrollView.frame.size;
CGSize viewSize = view.frame.size;
float topInset = (maxSize.height - viewSize.height) / 2.0;
float sideInset = (maxSize.width - viewSize.width) / 2.0;
if (topInset < 0.0) topInset = 0.0;
if (sideInset < 0.0) sideInset = 0.0;
[imageScrollView setContentInset:UIEdgeInsetsMake(topInset, sideInset, -topInset, -sideInset)];
}
最佳答案