CGPoint分配错误

Question

我的代码：

CGFloat scaleFactor = newSize.width / oldSize.width;
CGFloat newCenterX = center_.x * scaleFactor;
CGFloat newCenterY = center_.y * scaleFactor;

CGPoint newCenter = CGPointMake(newCenterX, newCenterY);
//newCenter.x = newCenterX;
//newCenter.y = newCenterY;

CGFloat newRaduis = raduis_ * scaleFactor;
newCenter.y += newSize.height - ceilf(scaleFactor) * oldSize.height;
NSLog(@"Convertion from %@ to %@", NSStringFromCGSize(oldSize), NSStringFromCGSize(newSize));
NSLog(@"old center = %@, old radius = %f", NSStringFromCGPoint(center_), raduis_);
NSLog(@"new center = %@, new radius = %f", NSStringFromCGPoint(newCenter), newRaduis);
NSLog(@"new center x = %f, new center y = %f", newCenterX, newCenterY);

和输出：

2012-09-14 14:18:35.027 TestApp[425:4b93] Convertion from {1080, 1920} to {320, 415}
2012-09-14 14:18:35.031 TestApp[425:4b93] old center = {246, 822}, old radius = 20.000000
2012-09-14 14:18:35.033 TestApp[425:4b93] new center = {73, -1261}, new radius = 5.925926
2012-09-14 14:18:35.035 TestApp[425:4b93] new center x = 73, new center y = 244

在输出中-新中心= {73，-1261}，新半径= 5.925926。为什么中心y值为负值？我做错了什么？

提前感谢您的帮助

Answer 1

错误是由于您的行造成的

newCenter.y += newSize.height - ceilf(scaleFactor) * oldSize.height;

• scaleFactor是关于1.
• newSize.height的，所以0.2962等于ceilf(scaleFactor)是415，oldSize.height是1920，所以415 - 1*1920是-1505，而newCenter.y += -1505使newCenter.y从<代码>D17更改为<代码>D18=code

因此，在这一行之后，newCenter.y是-1261似乎是合法的。