如何在一个选定的点旋转CALayer。
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);
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.
bounds
, position
in superlayer and anchorPoint
. anchorPoint
has relative coordinates and points to an anchorPoint
. Your sublayer will rotate around this anchorPoint
; For example, to rotate a sublayer on its superview top center point around sublayer's bottom center, use this code:
// 1
let rect = CGRect(x: 0,
y: 0,
width: 20,
height: 20)
let path = UIBezierPath(rect: rect)
let sublayer = CAShapeLayer()
sublayer.fillColor = UIColor.green.cgColor
sublayer.path = path.cgPath
superlayer.addSublayer(sublayer)
// 2
sublayer.bounds = rect
sublayer.position = CGPoint(x: superlayer.bounds.size.width/2, y: 0)
sublayer.anchorPoint = CGPoint(x: 0.5, y: 1)
// 3
let rotationAnimation = CABasicAnimation(keyPath: "transform.rotation.z")
rotationAnimation.toValue = 2*CGFloat.pi
rotationAnimation.duration = 3
rotationAnimation.fillMode = kCAFillModeForwards
rotationAnimation.isRemovedOnCompletion = false
sublayer.add(rotationAnimation, forKey: nil)
Check out the CA documentation here .
You want to set the transform to a CATransform3DRotate, for example:
CATransform3D current = myLayer.transform;
myLayer.transform = CATransform3DRotate(current, DEGREES_TO_RADIANS(20), 0, 1.0, 0);
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