ios - 旋转 UIImage 的问题 - IOS/Swift

Question

为了旋转 UIImage，我使用了一个从互联网上下载的扩展。在那里，旋转是有效的，但有一些有线行为。

这是扩展代码

import UIKit

extension UIImage {

    public func imageRotatedByDegrees(degrees: CGFloat, flip: Bool) -> UIImage {

        let radiansToDegrees: (CGFloat) -> CGFloat = {
            return $0 * (180.0 / CGFloat(M_PI));
        }
        let degreesToRadians: (CGFloat) -> CGFloat = {
            return $0 / 180.0 * CGFloat(M_PI);
        }

        // calculate the size of the rotated view's containing box for our drawing space
        let rotatedViewBox = UIView(frame: CGRect(origin: CGPointZero, size: size));
        let t = CGAffineTransformMakeRotation(degreesToRadians(degrees));
        rotatedViewBox.transform = t;
        let rotatedSize = rotatedViewBox.frame.size

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

        // Move the origin to the middle of the image so we will rotate and scale around the center.
        CGContextTranslateCTM(bitmap, rotatedSize.width / 2.0, rotatedSize.height / 2.0);

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

        // Now, draw the rotated/scaled image into the context
        var yFlip: CGFloat;

        if(flip){
            yFlip = CGFloat(-1.0);
        } else {
            yFlip = CGFloat(1.0);
        }

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

        let newImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();

        return newImage;
    }
}

这就是我调用扩展方法并将返回的图像设置到 ImageView 的方式。 ImageView 的“contentMode”属性设置为“缩放以填充”

currentPagePreviewImageVew.image = currentPagePreviewImageVew.image!.imageRotatedByDegrees(90, flip: false);

这是按下旋转按钮之前的样子

这是在按下旋转按钮一次之后。(看到图像没有旋转但是它的大小已经改变)

这是图像旋转 90 度时的情况。(这里是在图像旋转之后，但如上图所示，当图像处于 0 度和 180 度时其他 View 会被拉伸(stretch) (2))

谁能告诉我我的代码有什么问题，如果有更好的解决方案请告诉我。任何帮助将不胜感激。

已编辑: 拉伸(stretch) View 是因为约​​束问题。我通过对 ImageView 上方的工具栏设置高度约束来解决它。但还是找不到第一次的事情的答案。

Answer 1

    func flipImageVertical(originalImage: UIImage) -> UIImage
    {
        let tempImageView:UIImageView = UIImageView(image: originalImage)
        UIGraphicsBeginImageContext(tempImageView.frame.size)
        let context:CGContextRef = UIGraphicsGetCurrentContext()!
        let flipVertical:CGAffineTransform = CGAffineTransformMake(1,0,0,-1,0,tempImageView.frame.size.height)
        CGContextConcatCTM(context, flipVertical)
        tempImageView.layer .renderInContext(context)

        let flippedImage:UIImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return flippedImage
    }

    func flipImageHorizontal(originalImage: UIImage) -> UIImage
    {
        let tempImageView:UIImageView = UIImageView(image: originalImage)
        UIGraphicsBeginImageContext(tempImageView.frame.size)
        let context:CGContextRef = UIGraphicsGetCurrentContext()!
        let flipHorizontal:CGAffineTransform = CGAffineTransformMake(-1,0,0,1,tempImageView.frame.size.width,0)

        CGContextConcatCTM(context, flipHorizontal)
        tempImageView.layer .renderInContext(context)

        let flippedImage:UIImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return flippedImage
    }