如何在转换之前计算UIView的框架? [英] How to compute the frame of a UIView before the transform?
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问题描述
我有一个UIView
,我向它申请了CGAffineTransform
.我希望能够了解如果未应用转换的视图框架.
I have a UIView
and I apply to it a CGAffineTransform
. I would like to be able to know the frame of the view if the transform had not be applied.
我正在寻找一种(简单的)解决方案来处理变换为零变换"(不可逆)的情况.
I am looking for a (simple) solution that handles the case where the transform is the "zero-transform" (which is not invertible).
我认为以下内容不适用于零变换".
The following does not work for the "zero-transform", I guess.
CGRect result ;
CGAffineTransform transform = self.transform ;
result = CGRectApplyAffineTransform(self.frame, CGAffineTransformInvert(transform)) ;
return result ;
为什么?
我需要对动画执行此操作
Why?
I need to do this for an animation:
- 初始设置:我将
transform
设置为"0".插入了视图,但是所有元素的框架都像视图不在这里一样. - 最终设置:我计算所有元素的框架,这次我考虑了新视图.我将其
transform
设置为"1".
- initial settings: I set the
transform
"to 0". The view is inserted but the frames of all the elements do as if the view was not here. - final settings: I compute the frames of all my elements, and this time I take into account the new view. I set its
transform
"to 1".
我的变换是比例变换.
推荐答案
transform
不会影响center
或bounds
.
因此,您可以通过以下简单代码进行计算:
So, you can calculate it by this simple code:
CGPoint center = view.center;
CGSize size = view.bounds.size;
CGRect frameForTransformIdentity = CGRectMake(
center.x - size.width / 2,
center.y - size.height / 2,
size.width,
size.height
);
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