如何旋转UIImage

Question

我正在为iPad开发iOS应用程序.有没有办法旋转UIImage90º然后将其添加到UIImageView？我尝试了很多不同的代码,但都没有工作......

谢谢!

Answer 1

你可以UIImageView用以下方式自行调整

UIImageView *iv = [[UIImageView alloc] initWithImage:image];
iv.transform = CGAffineTransformMakeRotation(M_PI_2);

或者,如果您真的想要更改图像,可以使用此答案中的代码,它可以正常工作.

Answer 2

要旋转像素,您可以使用以下内容.这将创建一个带有旋转元数据的中间UIImage,并将其渲染到具有宽度/高度尺寸转换的图像上下文中.生成的图像旋转了像素(即底层的CGImage)

- (UIImage*)rotateUIImage:(UIImage*)sourceImage clockwise:(BOOL)clockwise
{
    CGSize size = sourceImage.size;
    UIGraphicsBeginImageContext(CGSizeMake(size.height, size.width));
    [[UIImage imageWithCGImage:[sourceImage CGImage] scale:1.0 orientation:clockwise ? UIImageOrientationRight : UIImageOrientationLeft] drawInRect:CGRectMake(0,0,size.height ,size.width)];
    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return newImage;
}

还可以为orientation参数传递其他可能的值,以实现180度旋转和翻转等.

Answer 3

这将以任何给定的度数旋转图像.

请注意,这也适用于2x和3x视网膜

- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees {
    CGFloat radians = DegreesToRadians(degrees);

    UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0, self.size.width, self.size.height)];
    CGAffineTransform t = CGAffineTransformMakeRotation(radians);
    rotatedViewBox.transform = t;
    CGSize rotatedSize = rotatedViewBox.frame.size;

    UIGraphicsBeginImageContextWithOptions(rotatedSize, NO, [[UIScreen mainScreen] scale]);
    CGContextRef bitmap = UIGraphicsGetCurrentContext();

    CGContextTranslateCTM(bitmap, rotatedSize.width / 2, rotatedSize.height / 2);

    CGContextRotateCTM(bitmap, radians);

    CGContextScaleCTM(bitmap, 1.0, -1.0);
    CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2 , self.size.width, self.size.height), self.CGImage );

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return newImage;
}

Answer 4

还有imageWithCIImage:scale:orientation,如果你想旋转UIImage不UIImageView

其中一个方向:

typedef enum {
   UIImageOrientationUp,
   UIImageOrientationDown,   // 180 deg rotation
   UIImageOrientationLeft,   // 90 deg CW
   UIImageOrientationRight,   // 90 deg CCW
   UIImageOrientationUpMirrored,    // vertical flip
   UIImageOrientationDownMirrored,  // horizontal flip
   UIImageOrientationLeftMirrored,  // 90 deg CW then perform horizontal flip
   UIImageOrientationRightMirrored, // 90 deg CCW then perform vertical flip
} UIImageOrientation;

Answer 5

以下是@ RyanG的Objective C代码的快速版本,作为UIImage的扩展:

extension UIImage {

    func rotate(byDegrees degree: Double) -> UIImage {
        let radians = CGFloat(degree*M_PI)/180.0 as CGFloat
        let rotatedViewBox = UIView(frame: CGRect(x: 0, y: 0, width: self.size.width, height: self.size.height))
        let t = CGAffineTransform(rotationAngle: radians)
        rotatedViewBox.transform = t
        let rotatedSize = rotatedViewBox.frame.size
        let scale = UIScreen.main.scale
        UIGraphicsBeginImageContextWithOptions(rotatedSize, false, scale)
        let bitmap = UIGraphicsGetCurrentContext()
        CGContextTranslateCTM(bitmap, rotatedSize.width / 2, rotatedSize.height / 2);

        bitmap!.rotate(by: radians);

        bitmap!.scaleBy(x: 1.0, y: -1.0);
        CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2 , self.size.width, self.size.height), self.CGImage );

        let newImage = UIGraphicsGetImageFromCurrentImageContext()

        return newImage
    }

}

用法是image.rotate(degree).