为什么设置图层边界矩形的anchorPoint表现得如此奇怪？ [英] Why does setting the anchorPoint of the layer's bounds rectangle behave so strange?

问题描述

我尝试设置anchorPoint属性，以便通过定义良好的轴旋转视图。
但是：

I try to set the anchorPoint property, in order to rotate a view by a well defined axis. But:

myView.layer.anchorPoint = CGPointMake(myView.layer.anchorPoint.x - 1.0, myView.layer.anchorPoint.y);

Wenn我将其移动-1.0，它不仅会向左移动1个单位。相反，我的整个视图向右移动。

Wenn I shift it by -1.0, it will not just move 1 unit to left. Instead, my whole view moves by the width of the view to right.

那是什么坐标系？好像倒了。但是，单位也与例如myView.frame.size.width的单位不匹配？

What kind of coordinate system is that? It seems inverted. But also the units don't match with those of for example myView.frame.size.width ?

推荐答案

anchorPoint是标准化的在图层中的位置。也就是说，（0.0，0.0）是图层的左上角（在iPhone的翻转的UIView图层坐标系中），而（1.0，1.0）是图层的右下角。 （0.5，0.5）是图层的中间。这些位置与大小无关，因此也只是相对位置。

anchorPoint is a normalized position within your layer. That is, (0.0, 0.0) is the upper-left corner of your layer (in the iPhone's flipped UIView layer coordinate system) and (1.0, 1.0) is the lower-right corner. (0.5, 0.5) is the middle of your layer. These positions are size-independent, and thus merely relative locations.

这使得可以围绕该anchorPoint进行缩放，如果anchorPoint是绝对坐标，这将造成混淆

This makes it possible to scale about that anchorPoint, which would be confusing to do if anchorPoint was an absolute coordinate.

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