我旋转我的视图CGAffineTransform
[view setTransform:newTransform];
应用变换后,帧值保持不变,但如何找到该帧的“旋转”或变换值?
(source: informit.com http://www.informit.com/content/images/art_sadun_affine/elementLinks/sadun_fig02.png)
我想要旋转框架边缘的精确坐标,即a、b、c、d点。
要记住的一件事是,变换会更改坐标系,因此您需要能够在父“视图”和子(变换后)视图之间进行转换。此外,变换保留变换对象的中心,但不保留任何其他坐标。所以你需要根据中心来计算。您需要几个帮助者。 (我从 Erica Sadun 的书 Core iOS Developer's Cookbook 中得到了以下大部分方法)。
我通常将它们添加为 UIView 上的类别。
为了将孩子的坐标转换为父母的坐标,您需要类似的东西:
// helper to get pre transform frame
-(CGRect)originalFrame {
CGAffineTransform currentTransform = self.transform;
self.transform = CGAffineTransformIdentity;
CGRect originalFrame = self.frame;
self.transform = currentTransform;
return originalFrame;
}
// helper to get point offset from center
-(CGPoint)centerOffset:(CGPoint)thePoint {
return CGPointMake(thePoint.x - self.center.x, thePoint.y - self.center.y);
}
// helper to get point back relative to center
-(CGPoint)pointRelativeToCenter:(CGPoint)thePoint {
return CGPointMake(thePoint.x + self.center.x, thePoint.y + self.center.y);
}
// helper to get point relative to transformed coords
-(CGPoint)newPointInView:(CGPoint)thePoint {
// get offset from center
CGPoint offset = [self centerOffset:thePoint];
// get transformed point
CGPoint transformedPoint = CGPointApplyAffineTransform(offset, self.transform);
// make relative to center
return [self pointRelativeToCenter:transformedPoint];
}
// now get your corners
-(CGPoint)newTopLeft {
CGRect frame = [self originalFrame];
return [self newPointInView:frame.origin];
}
-(CGPoint)newTopRight {
CGRect frame = [self originalFrame];
CGPoint point = frame.origin;
point.x += frame.size.width;
return [self newPointInView:point];
}
-(CGPoint)newBottomLeft {
CGRect frame = [self originalFrame];
CGPoint point = frame.origin;
point.y += frame.size.height;
return [self newPointInView:point];
}
-(CGPoint)newBottomRight {
CGRect frame = [self originalFrame];
CGPoint point = frame.origin;
point.x += frame.size.width;
point.y += frame.size.height;
return [self newPointInView:point];
}
Swift 4
extension UIView {
/// Helper to get pre transform frame
var originalFrame: CGRect {
let currentTransform = transform
transform = .identity
let originalFrame = frame
transform = currentTransform
return originalFrame
}
/// Helper to get point offset from center
func centerOffset(_ point: CGPoint) -> CGPoint {
return CGPoint(x: point.x - center.x, y: point.y - center.y)
}
/// Helper to get point back relative to center
func pointRelativeToCenter(_ point: CGPoint) -> CGPoint {
return CGPoint(x: point.x + center.x, y: point.y + center.y)
}
/// Helper to get point relative to transformed coords
func newPointInView(_ point: CGPoint) -> CGPoint {
// get offset from center
let offset = centerOffset(point)
// get transformed point
let transformedPoint = offset.applying(transform)
// make relative to center
return pointRelativeToCenter(transformedPoint)
}
var newTopLeft: CGPoint {
return newPointInView(originalFrame.origin)
}
var newTopRight: CGPoint {
var point = originalFrame.origin
point.x += originalFrame.width
return newPointInView(point)
}
var newBottomLeft: CGPoint {
var point = originalFrame.origin
point.y += originalFrame.height
return newPointInView(point)
}
var newBottomRight: CGPoint {
var point = originalFrame.origin
point.x += originalFrame.width
point.y += originalFrame.height
return newPointInView(point)
}
}
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