Question

我有一个围绕其中心旋转的UIImageView：

imageHorizon.layer.anchorPoint = CGPointMake(0.5, 0.5);
imageHorizon.transform = CGAffineTransformRotate(imageHorizon.transform, angleToRotate*(CGFloat)(M_PI/180));

有时我也会将此图像向左或向右移动，然后再次旋转。我想一直保持旋转中心在同一点（实际上是超视图的中心）。我怎么能这样做？

欢呼声，

Answer 1

self.imgView.layer.anchorPoint = CGPointMake(0.0,1.0);
self.imgView.layer.position = CGPointMake(100,200.0);
CGAffineTransform cgaRotateHr = CGAffineTransformMakeRotation(-(3.141/4));
[self.imgView setTransform:cgaRotateHr];

Answer 2

这是一个较旧的问题，但其他解决方案对我来说效果不佳，所以我想出了另一个解决方案：

旋转图像基本上只是应用平移的正常旋转，确保旋转后要旋转的点仍然在同一点。要做到这一点，在旋转之前计算图像中的位置CGPoint，在旋转之后获得位置，并将差值作为图像上的平移应用，将其“捕捉”到正确的位置。这是我一直在使用的代码：

请记住，翻译应该通过CGAffineTransform应用，而不是移动.center，因为翻译需要相对于旋转，CGAffineTransformTranslate（）负责处理。

// Note: self is the superview of _imageView

// Get the rotation point
CGPoint rotationPointInSelf = self.center; // or whatever point you want to rotate around
CGPoint rotationPointInImage = [_imageView convertPoint:rotationPointInSelf fromView:self];

// Rotate the image
_imageView.transform = CGAffineTransformRotate(_imageView.transform, angle);

// Get the new location of the rotation point
CGPoint newRotationPointInImage = [_imageView convertPoint:rotationPointInSelf fromView:self];

// Calculate the difference between the point's old position and its new one
CGPoint translation = CGPointMake(rotationPointInImage.x - newRotationPointInImage.x, rotationPointInImage.y - newRotationPointInImage.y);

// Move the image so the point is back in it's old location
_imageView.transform = CGAffineTransformTranslate(_imageView.transform, -translation.x, -translation.y);

Answer 3

您可以将图像作为另一个视图的子视图，然后旋转超级视图以获得该效果。另一种方法是按照docs。

中的描述设置anchorPoint属性

Answer 4

我使用此代码围绕点（0,0）旋转。也许它可以帮助你弄清楚如何激活你想要的东西。

    float width = self.view.frame.size.width;
    float height = self.view.frame.size.height;

    CGRect frame_smallView = CGRectMake(-width, -height, width, height);
    UIView *smallView = [[UIView alloc] initWithFrame:frame_smallView];
    smallView.backgroundColor = darkGrayColor;

    // Select x and y between 0.0-1.0. 
    // The default is (0.5f,0.5f) that is the center of the layer
    // (1.0f,1.0f) is the right bottom corner
    smallView.layer.anchorPoint = CGPointMake(1.0f, 1.0f);

    // Rotate around this point
    smallView.layer.position = CGPointMake(0, 0);

    [self.view insertSubview:smallView belowSubview:self.navBar];

    [UIView animateWithDuration:1
                     animations:^{
                         smallView.transform = CGAffineTransformMakeRotation(M_PI);
                     }
                     completion:^(BOOL finished){
                         [self.navigationController popViewControllerAnimated:NO];
                     }];

围绕任意点旋转UIImageView

4 个答案: