从旋转的UIImageView创建UIImage

我有一个UIImageView与它的图像.我已经通过将UIImageView的transform属性设置为CGAffineTransformMakeRotation(angle)来旋转图像,其中angle是以弧度表示的角度.

我想要能够创建另一个对应于我在视图中可以看到的旋转版本的UIImage.

我几乎在那里,通过旋转图像上下文我得到一个旋转的图像:

- (UIImage *) rotatedImageFromImageView: (UIImageView *) imageView
{
    UIImage *rotatedImage;

    // Get image width, height of the bounding rectangle
    CGRect boundingRect = [self getBoundingRectAfterRotation: imageView.bounds byAngle:angle];

    // Create a graphics context the size of the bounding rectangle
    UIGraphicsBeginImageContext(boundingRect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();

    // Rotate and translate the context
    CGAffineTransform ourTransform = CGAffineTransformIdentity;
    ourTransform = CGAffineTransformConcat(ourTransform, CGAffineTransformMakeRotation(angle));

    CGContextConcatCTM(context, ourTransform);

    // Draw the image into the context
    CGContextDrawImage(context, CGRectMake(0, 0, imageView.image.size.width, imageView.image.size.height), imageView.image.CGImage);

    // Get an image from the context
    rotatedImage = [UIImage imageWithCGImage: CGBitmapContextCreateImage(context)];

    // Clean up
    UIGraphicsEndImageContext();
    return rotatedImage;
 }

然而,图像不会绕其中心旋转.我已经尝试过各种变形,并将其与我的旋转连接,使其绕中心旋转,但无济于事.我错过了一个技巧吗?这是否可能,因为我旋转的上下文不是图像?

迫切需要让这项工作成为现实,任何帮助将不胜感激.

戴夫

编辑:我被问了几次我的boundingRect代码,所以这里是:

- (CGRect) getBoundingRectAfterRotation: (CGRect) rectangle byAngle: (CGFloat) angleOfRotation {
    // Calculate the width and height of the bounding rectangle using basic trig
    CGFloat newWidth = rectangle.size.width * fabs(cosf(angleOfRotation)) + rectangle.size.height * fabs(sinf(angleOfRotation));
    CGFloat newHeight = rectangle.size.height * fabs(cosf(angleOfRotation)) + rectangle.size.width * fabs(sinf(angleOfRotation));

    // Calculate the position of the origin
    CGFloat newX = rectangle.origin.x + ((rectangle.size.width - newWidth) / 2);
    CGFloat newY = rectangle.origin.y + ((rectangle.size.height - newHeight) / 2);

    // Return the rectangle
    return CGRectMake(newX, newY, newWidth, newHeight);
}
好的 – 最后我似乎已经做了.对正确性的任何意见将是有用的…需要一个平移,一个旋转,一个缩放和一个从图形直角位置偏移,使其工作.代码在这里:

CGAffineTransform transform = CGAffineTransformIdentity;
transform = CGAffineTransformTranslate(transform, boundingRect.size.width/2, boundingRect.size.height/2);
transform = CGAffineTransformRotate(transform, angle);
transform = CGAffineTransformScale(transform, 1.0, -1.0);

CGContextConcatCTM(context, transform);

// Draw the image into the context
CGContextDrawImage(context, CGRectMake(-imageView.image.size.width/2, -imageView.image.size.height/2, imageView.image.size.width, imageView.image.size.height), imageView.image.CGImage);

// Get an image from the context
rotatedImage = [UIImage imageWithCGImage: CGBitmapContextCreateImage(context)];
http://stackoverflow.com/questions/2856556/creating-a-uiimage-from-a-rotated-uiimageview

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