UIImage Rotation自定义度 [英] UIImage Rotation custom degrees

问题描述

我一直在使用此示例中的代码来提供帮助，并且效果很好. http://www.platinumball.net /blog/2009/03/30/iphone-uiimage-rotation-and-mirroring/

I have been using the code in this sample to assist and this works well. http://www.platinumball.net/blog/2009/03/30/iphone-uiimage-rotation-and-mirroring/

我无法锻炼如何将自定义角度旋转0到& 360 ....

I cannot workout how to rotate by a custom amount of degrees between 0 & 360....

推荐答案

您将想要做与旋转中的帖子差不多的事情:

You'll want to do pretty much the same stuff as in that post does in rotate:

CGSize size = sizeOfImage;
UIGraphicsBeginImageContext(size);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextRotateCTM(ctx, angleInRadians);
CGContextDrawImage(ctx, (CGRect){{}, size}, image);

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;

除了旋转以外，您可能还需要平移CTM以补偿旋转中心.如果不想在旋转时裁剪图像的边缘，则应通过一些基本的触发来增加尺寸.

You might need to also translate the CTM in addition to rotating to compensate for the center of rotation. If you want to not crop the edges of the image when rotating, you should increase the size with some basic trig.

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