如何将UIImage和图像数据旋转90度

Question

我有一个包含图像的UIImageView.用户可以点击将UIImageView中的图像保存到磁盘.

我想这样做,以便用户可以单击旋转UIImageView并在视图中旋转UImage,以便在保存图像时保持新的旋转.

在我有的时候

- (IBAction)rotateImage:(id)sender {

float degrees = 90; //the value in degrees
self.imagePreview.transform = CGAffineTransformMakeRotation(degrees * M_PI/180);

}

有人能指出我关于保持当前轮换的正确方向.

谢谢

Answer 1

我的旧应用程序中有这样的代码.但是这个代码可以简化,因为你不需要在非90度的角度上旋转它.

Objective-C的

@implementation UIImage (Rotation)

- (UIImage *)imageRotatedOnDegrees:(CGFloat)degrees
{
  // Follow ing code can only rotate images on 90, 180, 270.. degrees.
  CGFloat roundedDegrees = (CGFloat)(round(degrees / 90.0) * 90.0);
  BOOL sameOrientationType = ((NSInteger)roundedDegrees) % 180 == 0;
  CGFloat radians = M_PI * roundedDegrees / 180.0;
  CGSize newSize = sameOrientationType ? self.size : CGSizeMake(self.size.height, self.size.width);

  UIGraphicsBeginImageContext(newSize);
  CGContextRef ctx = UIGraphicsGetCurrentContext();
  CGImageRef cgImage = self.CGImage;
  if (ctx == NULL || cgImage == NULL) {
    UIGraphicsEndImageContext();
    return self;
  }

  CGContextTranslateCTM(ctx, newSize.width / 2.0, newSize.height / 2.0);
  CGContextRotateCTM(ctx, radians);
  CGContextScaleCTM(ctx, 1, -1);
  CGPoint origin = CGPointMake(-(self.size.width / 2.0), -(self.size.height / 2.0));
  CGRect rect = CGRectZero;
  rect.origin = origin;
  rect.size = self.size;
  CGContextDrawImage(ctx, rect, cgImage);
  UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  return image ?: self;
}

@end

迅速

extension UIImage {

  func imageRotated(on degrees: CGFloat) -> UIImage {
    // Following code can only rotate images on 90, 180, 270.. degrees.
    let degrees = round(degrees / 90) * 90
    let sameOrientationType = Int(degrees) % 180 == 0
    let radians = CGFloat.pi * degrees / CGFloat(180)
    let newSize = sameOrientationType ? size : CGSize(width: size.height, height: size.width)

    UIGraphicsBeginImageContext(newSize)
    defer {
      UIGraphicsEndImageContext()
    }

    guard let ctx = UIGraphicsGetCurrentContext(), let cgImage = cgImage else {
      return self
    }

    ctx.translateBy(x: newSize.width / 2, y: newSize.height / 2)
    ctx.rotate(by: radians)
    ctx.scaleBy(x: 1, y: -1)
    let origin = CGPoint(x: -(size.width / 2), y: -(size.height / 2))
    let rect = CGRect(origin: origin, size: size)
    ctx.draw(cgImage, in: rect)
    let image = UIGraphicsGetImageFromCurrentImageContext()
    return image ?? self
  }

}

Answer 2

这将按任何给定的弧度旋转图像.

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 3

self.imageview.transform = CGAffineTransformMakeRotation(M_PI/2);