围绕其左上角旋转矩形 [英] Rotate Rectangle Around Its Upper Left Corner

问题描述

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使用以下内容：

  panGestureRecognizer.view.transform = CGAffineTransformRotate（panGestureRecognizer.view.transform，（M_PI * angle）/ 180）; 
  

但是这个矩形有一个大的循环。有什么翻译我需要做的，以使其发挥作用？

解决方案

你只需要设置定位点： https://developer.apple.com/library/mac/#documentation/graphicsimaging/reference/CALayer_class/Introduction/Introduction.html#//apple_ref/occ/instp/CALayer/anchorPoint

  panGestureRecognizer.view.layer.anchorPoint = CGPointMake（0.0，0.0）; 
  

进一步阅读：对于更高级的内容，您可以尝试一些提示这里详细介绍矩阵转换： https://stackoverflow.com/a/8536553/563381

Simply trying to rotate a rectangle around it's origin, or its upper left corner like so:

Am using the following:

panGestureRecognizer.view.transform = CGAffineTransformRotate(panGestureRecognizer.view.transform, (M_PI * angle) / 180);

But the rectangle is sort of rotating in a big loop. Is there some sort of translation I need to do to get this to work?

解决方案

You just need to set the anchor point: https://developer.apple.com/library/mac/#documentation/graphicsimaging/reference/CALayer_class/Introduction/Introduction.html#//apple_ref/occ/instp/CALayer/anchorPoint

panGestureRecognizer.view.layer.anchorPoint = CGPointMake(0.0, 0.0);

Further Reading: For more advanced stuff you could try some of the tips detailed here for matrix transformations: https://stackoverflow.com/a/8536553/563381

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