仅将 CGAffineTransform 的缩放组件应用于 UIView [英] Applying just the scale component of a CGAffineTransform to a UIView

问题描述

我有一个 UIView，它应用了各种缩放和旋转 CGAffineTransforms，以响应触摸屏手势.

当缩放操作完成时，我想将视图的边界调整到新的大小，然后让视图以 1.0 的比例重新绘制自己，同时保持变换的所有其他组件相同.

要调整视图的边界，我正在使用:

self.myView.bounds = CGRectApplyAffineTransform(self.myView.bounds, self.myView.transform);

要撤消"缩放变换，我正在尝试:

self.myView.transform = CGAffineTransformConcat(self.myView.transform, CGAffineTransformMakeScale(1, 1));

然后调用 [myView setNeedsDisplay] 让视图重绘自身.

然而，这不会产生预期的结果，当应用旋转变换时，上面的代码似乎也导致应用了横向平移变换.

仅撤消"缩放变换并使视图以 1:1 重绘而所有其他变换保持不变的最简洁方法是什么?

解决方案

将您的比例值保存在一个变量中，然后尝试将 CGAffineTransformMakeScale(1, 1) 更改为

CGAffineTransformMakeScale(1/totalScaleWidth, 1/totalScaleHeight)

I have a UIView to which various scale and rotation CGAffineTransforms have been applied, in response to touch screen gestures.

When a scale operation completes, I want to adjust the bounds of the view to the new size, then have view to re-draw itself at a scale of 1.0, while keeping all other components of the transform the same.

To adjust the bounds of the view, I'm using:

self.myView.bounds = CGRectApplyAffineTransform(self.myView.bounds, self.myView.transform);

To "undo" the scale transform, I'm trying this:

self.myView.transform = CGAffineTransformConcat(self.myView.transform, CGAffineTransformMakeScale(1, 1));

then calling [myView setNeedsDisplay] to get the view to redraw itself.

However this does not produce the desired results and when a rotate transform is applied, the above code seems to cause what looks like a sideways translation transform to be applied too.

What's the cleanest way to "undo" just a scale transform and have the view redraw at 1:1 with all other transforms remaining intact?

解决方案

Save your scale values in a variable and then, try changing CGAffineTransformMakeScale(1, 1) into

CGAffineTransformMakeScale(1/totalScaleWidth, 1/totalScaleHeight)

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