如何在一点旋转CALayer [英] how to rotate CALayer at one point

问题描述

如何在一个选定点旋转CALayer。

how to rotate CALayer at one selected point.

推荐答案

CATransform3D transform = CATransform3DIdentity;
transform = CATransform3DTranslate(transform, rotationPoint.x-center.x, rotationPoint.y-center.y, 0.0);
transform = CATransform3DRotate(transform, rotationAngle, 0.0, 0.0, -1.0);
transform = CATransform3DTranslate(transform, center.x-rotationPoint.x, center.y-rotationPoint.y, 0.0);

其中中心是图层的中心， rotationAngle 以弧度为单位（正为逆时针方向）， rotationPoint 是您想要旋转的点。 center 和 rotationPoint 位于包含视图的坐标空间中。

Where center is the center of your layer, rotationAngle is in radians (positive is counterclockwise), and rotationPoint is the point about which you wish to rotate. center and rotationPoint are in the coordinate space of the containing view.

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