获取UIScrollView内容的可见rect [英] Getting the visible rect of an UIScrollView's content

问题描述

如何查找屏幕上实际可见的显示视图内容的rect（CGRect）。

How can I go about finding out the rect (CGRect) of the content of a displayed view that is actually visible on screen.

myScrollView.bounds

上面的代码在没有缩放时工作，但只要你允许缩放，它会以1以外的缩放比例中断。

The code above works when there's no zooming, but as soon as you allow zooming, it breaks at zoom scales other than 1.

为了澄清，我想要一个CGRect，其中包含相对于内容的滚动视图内容的可见区域。 （即如果它是缩放比例2，则rect的大小将是滚动视图大小的一半，如果它在缩放比例为0.5时，它将是双倍。）

To clarify, I want a CGRect that contains the visible area of the scroll view's content, relative to the content. (ie. if it's a zoom scale 2, the rect's size will be half of the scroll view's size, if it's at zoom scale 0.5, it'll be double.)

推荐答案

回答我自己的问题，主要是感谢Jim Dovey的答案，这个答案并没有完全解决问题，但给了我答案的基础：

Answering my own question, mostly thanks to Jim Dovey's answer, which didn't quite do the trick, but gave me the base for my answer:

CGRect visibleRect;
visibleRect.origin = scrollView.contentOffset;
visibleRect.size = scrollView.bounds.size;

float theScale = 1.0 / scale;
visibleRect.origin.x *= theScale;
visibleRect.origin.y *= theScale;
visibleRect.size.width *= theScale;
visibleRect.size.height *= theScale;

主要区别在于visibleRect的大小应该是 scrollView。 bounds.size ，而不是 scrollView.contentSize 这是内容视图的大小。还简化了数学，并没有完全看到 isless（）的使用，这会在代码更大时破坏代码。

The main difference is that the size of the visibleRect ought to be scrollView.bounds.size, rather than scrollView.contentSize which is the size of the content view. Also simplified the math a bit, and didn't quite see the use for the isless() which would break the code whenever it's greater.

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