片左右镜像翻转,平面镜顺时针旋转
这其中的规律能否不用switch 而用rawValue来表示,待明天来继续研究
- (IBAction)btnClicked:(id)sender { UIImage * image = _imageView.image; _imageView.image = nil; //逆时针 UIImageOrientation orientation = image.imageOrientation; switch (orientation) { case UIImageOrientationUp: orientation = UIImageOrientationLeft; break; case UIImageOrientationLeft: orientation = UIImageOrientationDown; break; case UIImageOrientationDown: orientation = UIImageOrientationRight; break; case UIImageOrientationRight: orientation = UIImageOrientationUp; break; default: break; } _imageView.image = [self image:image rotation:orientation];}- (UIImage *)image:(UIImage *)image rotation:(UIImageOrientation)orientation{ long double rotate = 0.0; CGRect rect; float translateX = 0; float translateY = 0; float scaleX = 1.0; float scaleY = 1.0; switch (orientation) { case UIImageOrientationLeft: rotate = M_PI_2; rect = CGRectMake(0, 0, image.size.height, image.size.width); translateX = 0; translateY = -rect.size.width; scaleY = rect.size.width/rect.size.height; scaleX = rect.size.height/rect.size.width; break; case UIImageOrientationRight: rotate = 3 * M_PI_2; rect = CGRectMake(0, 0, image.size.height, image.size.width); translateX = -rect.size.height; translateY = 0; scaleY = rect.size.width/rect.size.height; scaleX = rect.size.height/rect.size.width; break; case UIImageOrientationDown: rotate = M_PI; rect = CGRectMake(0, 0, image.size.width, image.size.height); translateX = -rect.size.width; translateY = -rect.size.height; break; default: rotate = 0.0; rect = CGRectMake(0, 0, image.size.width, image.size.height); translateX = 0; translateY = 0; break; } UIGraphicsBeginImageContext(rect.size); CGContextRef context = UIGraphicsGetCurrentContext(); //做CTM变换 CGContextTranslateCTM(context, 0.0, rect.size.height); CGContextScaleCTM(context, 1.0, -1.0); CGContextRotateCTM(context, rotate); CGContextTranslateCTM(context, translateX, translateY); CGContextScaleCTM(context, scaleX, scaleY); //绘制图片 CGContextDrawImage(context, CGRectMake(0, 0, rect.size.width, rect.size.height), image.CGImage); UIImage *newPic = UIGraphicsGetImageFromCurrentImageContext(); return newPic;}