UIImage 大小（宽度和高度）在旋转后减小

Question

我正在根据比例值旋转 UIImage。我的 Scale 和 Rotation 运行良好，但问题是旋转 uiimage 后，图像大小（宽度和高度）正在减小。知道如何解决这个问题吗？
Image before Rotation

Image After Rotation

我正在使用的代码：

 UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0,self.image.size.width, self.image.size.height)];
    CGAffineTransform t = CGAffineTransformMakeRotation(self.lastContentOffset/5);
    rotatedViewBox.transform = t;
    CGSize rotatedSize = rotatedViewBox.frame.size;

    // Create the bitmap context
    UIGraphicsBeginImageContext(rotatedSize);
    CGContextRef bitmap = UIGraphicsGetCurrentContext();

    // 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, 5.0);

    // Now, draw the rotated/scaled image into the context
    CGContextScaleCTM(bitmap, 1.0, -1.0);
    CGContextDrawImage(bitmap, CGRectMake(-self.image.size.width/2 , -self.image.size.height/2 , self.image.size.width, self.image.size.height), \[self.rotatedImage CGImage\]);

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    self.rotatedImage = newImage;

Answer 1

假设您的图像大小为 HxH。旋转 45 度（M_PI/2 弧度）后，其大小将变为 sqrt(2)*H x sqrt(2)*H。所以你需要更大的上下文来适应旋转的图像。否则图片的边角会被切掉。此外，您将需要更大的UIImageView 以适应更大的图像。否则它将自动缩放到UIImageView 大小。