UIView中的BezierPath旋转 [英] BezierPath Rotation in a UIView

问题描述

我正在绘制一个BezierPath on Touch事件。现在我必须使用Gesture方法在同一位置旋转Bezier Path。但问题是，轮换后它的位置会发生变化。它看起来像下面的图像..我该如何解决这个问题？

I am drawing a BezierPath on Touch event. Now I have to rotate that Bezier Path on the same location using Gesture Method. But problem is, after rotation its position become change. Its look like the following image.. How can I fix this?

上图是原始图像。
与我分享您的想法..
提前致谢

The Upper image is the original image. Share your ideas with me.. Thanks in advance

推荐答案

在 Apple文档。

applyTransform：
使用指定的仿射变换矩阵转换路径中的所有点。

applyTransform: Transforms all points in the path using the specified affine transform matrix.

- (void)applyTransform:(CGAffineTransform)transform

我没试过这个。但是这里是如何从链接中旋转 NSBezierPath rotate-nsbezierpath-objects 。尝试在 UIBezierPath 上使用类似的方法。

I haven't tried this. But here is how to rotate a NSBezierPath from the link rotating-nsbezierpath-objects. Try to use the similar approach on UIBezierPath.

- (NSBezierPath*)rotatedPath:(CGFloat)angle aboutPoint:(NSPoint)cp
{
// return a rotated copy of the receiver. The origin is taken as point <cp> relative to the original path.
// angle is a value in radians

if( angle == 0.0 )
  return self;
else
{
  NSBezierPath* copy = [self copy];

  NSAffineTransform* xfm = RotationTransform( angle, cp );
  [copy transformUsingAffineTransform:xfm];

  return [copy autorelease];
}
}

使用：

NSAffineTransform *RotationTransform(const CGFloat angle, const NSPoint cp)
{
// return a transform that will cause a rotation about the point given at the angle given

NSAffineTransform* xfm = [NSAffineTransform transform];
[xfm translateXBy:cp.x yBy:cp.y];
[xfm rotateByRadians:angle];
[xfm translateXBy:-cp.x yBy:-cp.y];

return xfm;
}

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