如何在具有正确图像大小和滚动的 UIScrollView 内将 UIImageView 旋转 90 度? [英] How to I rotate UIImageView by 90 degrees inside a UIScrollView with correct image size and scrolling?

问题描述

我在 UIScrollView 中的 UIImageView 中有一个图像.我想要做的是将此图像旋转 90 度，使其默认为横向，并设置图像的初始缩放，以便整个图像适合滚动视图，然后允许它放大到 100% 并返回再次缩小到最小缩放.

I have an image inside an UIImageView which is within a UIScrollView. What I want to do is rotate this image 90 degrees so that it is in landscape by default, and set the initial zoom of the image so that the entire image fits into the scrollview and then allow it to be zoomed up to 100% and back down to minimum zoom again.

这是我目前所拥有的:

self.imageView.transform = CGAffineTransformMakeRotation(-M_PI/2);

float minimumScale = scrollView.frame.size.width  / self.imageView.frame.size.width;  
scrollView.minimumZoomScale = minimumScale;  
scrollView.zoomScale = minimumScale;  


scrollView.contentSize = CGSizeMake(self.imageView.frame.size.height,self.imageView.frame.size.width);

问题是，如果我设置转换，滚动视图中不会显示任何内容.但是，如果我注释掉转换，除了图像不是我想要的横向方向之外，一切正常！

The problem is that if I set the transform, nothing shows up in the scrollview. However if I commented out the transform, everything works except the image is not in the landscape orientation that I want it to be!

如果我应用转换并删除设置 minimumZoomScale 和 zoomScale 属性的代码，则图像会以正确的方向显示，但是 zoomScale 不正确，并且似乎 contentSize 属性也未正确设置 - 因为不会向左/右方向滚动到图像的边缘，但会滚动到顶部和底部，但会超出边缘.

If I apply the transform and remove the code that sets the minimumZoomScale and zoomScale properties, then the image shows up in the correct orientation, however with the incorrect zoomScale and seems like the contentSize property isn't set correctly either - since the doesn't scroll to the edge of the image in the left/right direction, however does top and bottom but much over the edge.

注意:图片正在从 URL 加载

NB: image is being loaded from a URL

推荐答案

也许旋转图像本身符合您的需求:

Maybe rotating the image itself fits your needs:

 UIImage* rotateUIImage(const UIImage* src, float angleDegrees)  {   
    UIView* rotatedViewBox = [[UIView alloc] initWithFrame: CGRectMake(0, 0, src.size.width, src.size.height)];
    float angleRadians = angleDegrees * ((float)M_PI / 180.0f);
    CGAffineTransform t = CGAffineTransformMakeRotation(angleRadians);
    rotatedViewBox.transform = t;
    CGSize rotatedSize = rotatedViewBox.frame.size;
    [rotatedViewBox release];

    UIGraphicsBeginImageContext(rotatedSize);
    CGContextRef bitmap = UIGraphicsGetCurrentContext();
    CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);
    CGContextRotateCTM(bitmap, angleRadians);

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

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

    return newImage;
}

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