计算UIScrollView的minimumZoomScale
我有一个要加载到图像视图中的图像，并将minimumZoomScale和zoomScale设置为类似于aspectFill的比例，我按如下方式计算：
// configure the map image scroll view
iImageSize = CGSizeMake(iImageView.bounds.size.width, iImageView.bounds.size.height);
iScrollView.minimumZoomScale = iScrollView.bounds.size.height / iImageSize.height;
iScrollView.maximumZoomScale = 2;
iScrollView.zoomScale = iScrollView.minimumZoomScale;
iScrollView.contentOffset = CGPointMake(0, 0);
iScrollView.clipsToBounds = YES;iScrollView大小为450 x 320px，iImageSize为1600 x 1960px。
手工计算minimumZoomScale : 450 /1960年= 0.22959184。系统会改为确定0.234693885 (？)。
但是为了让窗口适应450px的空间，这两个数字都不起作用(！)。我手动尝试，发现0.207是正确的数字(这将转换为图像高度为2174XP，或者UIScrollView高度为406px)。
参考信息: UIScrollview屏幕为450px，即480px减去状态栏高度(10)，减去UITabBar高度(20)
关于这种不端行为有什么线索吗？
回答 2
Stack Overflow用户
发布于 2015-06-10 02:23:19
我不确定你是否仍然有这个问题，但对我来说，规模正好相反。我需要计算minimumZoomScale = 1，我需要计算maximumZoomScale。
代码如下：
[self.imageView setImage:image];
// Makes the content size the same size as the imageView size.
// Since the image size and the scroll view size should be the same, the scroll view shouldn't scroll, only bounce.
self.scrollView.contentSize = self.imageView.frame.size;
// despite what tutorials say, the scale actually goes from one (image sized to fit screen) to max (image at actual resolution)
CGRect scrollViewFrame = self.scrollView.frame;
CGFloat minScale = 1;
// max is calculated by finding the max ratio factor of the image size to the scroll view size (which will change based on the device)
CGFloat scaleWidth = image.size.width / scrollViewFrame.size.width;
CGFloat scaleHeight = image.size.height / scrollViewFrame.size.height;
self.scrollView.maximumZoomScale = MAX(scaleWidth, scaleHeight);
self.scrollView.minimumZoomScale = minScale;
// ensure we are zoomed out fully
self.scrollView.zoomScale = minScale;Stack Overflow用户
发布于 2010-10-06 18:39:31
对于简单的放大/缩小，我通常使用以下代码。minimumZoomScale= 1将初始缩放设置为当前图像大小。我已经给出了maximumZoomScale = 10，它可以从图像大小和容器帧大小的实际比率中计算出来。
[scrollView addSubview: iImageView];
scrollView.contentSize = iImageView.frame.size;
scrollView.minimumZoomScale = 1.0;
scrollView.maximumZoomScale = 10;
[iImageView setFrame:CGRectMake(0, 0, 450, 320)];
[scrollView scrollRectToVisible:iImageView.frame animated:YES];https://stackoverflow.com/questions/3869779
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