Question


double angle = -15;
UIImage *image = [UIImage imageNamed:@"test.jpg"];
CGSize s = {image.size.width, image.size.height};
UIGraphicsBeginImageContext(s);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(ctx, 0,image.size.height);
CGContextScaleCTM(ctx, 1.0, -1.0);
CGContextRotateCTM(ctx, 2*M_PI*angle/360);
CGContextDrawImage(ctx,CGRectMake(0,0,image.size.width, image.size.height),image.CGImage);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

嗨，我不会在图像中心点旋转UIImage。我可以使用此代码旋转UIImage，但不能在中心点旋转。

请帮帮我。

Answer 1

使用核心动画。你可以说

UIView.layer.anchor = Point;

然后，使用CA框架执行轮换，它将围绕该锚点发生。

Answer 2

此代码可以使用但只能使用UIImageOrientation = 0，

// Move the origin to the middle of the image so we will rotate and scale around the center.
CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);

//Rotate the image context
CGContextRotateCTM(bitmap, rad(degrees));

// Now, draw the rotated/scaled image into the context
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]);

如何在图像中心旋转UIImage

2 个答案: