[英]UIimageView rotate around a center point of another UIImageView
[英]rotate UIImageView around an arbitrary point
我有一個UIImageView,它圍繞其中心旋轉:
imageHorizon.layer.anchorPoint = CGPointMake(0.5, 0.5);
imageHorizon.transform = CGAffineTransformRotate(imageHorizon.transform, angleToRotate*(CGFloat)(M_PI/180));
有時我還會將此圖像向左或向右移動,然后再次旋轉。 我想一直將旋轉中心保持在同一點(實際上是超級視圖的中心)。 我怎樣才能做到這一點 ?
干杯,
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];
這是一個比較老的問題,但是其他解決方案對我來說效果不佳,因此我想出了另一個解決方案:
旋轉圖像本質上只是應用了平移的普通旋轉,請確保要旋轉的點在旋轉后仍位於同一點。 為此,請在旋轉之前計算圖像中位置的CGPoint,在旋轉之后獲取位置,然后將差異作為平移應用於圖像,將其“捕捉”到正確的位置。 這是我一直在使用的代碼:
請記住,應通過CGAffineTransform而不是移動.center來應用平移,因為平移將需要相對於旋轉,而CGAffineTransformTranslate()會解決這一問題。
// 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);
您可以使圖像成為另一個視圖的子視圖,然后旋轉超級視圖以獲得該效果。 另一種方法是按照docs中的說明設置anchorPoint
屬性。
我正在使用此代碼圍繞點(0,0)旋轉。 也許它可以幫助您弄清楚如何激活想要的東西。
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];
}];
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