使用CGAffineTransform缩放并设置锚点 [英] Scale with CGAffineTransform and set the anchor

问题描述

如果我理解正确缩放 UIView 并使用 CGAffineTransform 将转换锚定到其中心。

If I understand correctly scaling a UIView with CGAffineTransform anchors the transformation to its center.

特别是：

self.frame = CGRectMake(0,0,100,100);
self.transform = CGAffineTransformMakeScale(2, 2);
NSLog(@"%f;%f;%f;%f", self.frame.origin.x, self.frame.origin.y, self.frame.size.width, self.frame.size.height); 

打印：

-50;-50;200;200

如何创建CGAffineTransform比例使用特定的锚点（比如0; 0）？

How do you create a CGAffineTransform scale that uses a specific anchor point (say 0;0)?

推荐答案

（a）

缩放然后翻译？

类似于：

CGAffineTransform t = CGAffineTransformMakeScale(2, 2);
t = CGAffineTransformTranslate(t, width/2, height/2);
self.transform = t;

（b）

设置锚点点（这可能是你真正想要的）

Set the anchor point (which is probably what you want really)

[self layer].anchorPoint = CGPointMake(0.0f, 0.0f);
self.transform = CGAffineTransformMakeScale(2, 2);

（c）

设置中心再次确保它在同一个地方？

Set the center again to make sure it's in the same place?

CGPoint center = self.center;
self.transform = CGAffineTransformMakeScale(2, 2);
self.center = center;

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