旋轉UIImage的問題 - IOS / Swift

Question

為了旋轉UIImage，我使用了從互聯網上下載的擴展程序。 在那里，旋轉工作但有一些有線行為。

這是擴展代碼

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;
    }
}

這就是我調用擴展方法並將返回的圖像設置為圖像視圖的方法。 圖像視圖的'contentMode'屬性設置為'Scale to Fill'

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

這是按下旋轉按鈕之前的樣子

這是在按下旋轉按鈕一次之后（參見圖像未旋轉但尺寸已更改）

這是當圖像旋轉90度時（圖像旋轉后，如圖所示，當圖像處於0和180度時，其他視圖會被拉伸，如上面的屏幕（2））

有人可以告訴我我的代碼有什么問題，如果有更好的解決方案，請告訴我。 任何幫助將受到高度贊賞。

編輯：拉伸視圖是因為存在約束問題。 我通過在imageview上方的工具欄上設置一個高度約束來解決它。 但仍然無法找到第一次的答案。

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
    }

Answer 2

你必須試試這個：

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

        // 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(CGFloat(toRadian(degrees)))
        rotatedViewBox.transform = t
        let rotatedSize = rotatedViewBox.frame.size

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

        CGContextSetAllowsAntialiasing(bitmap, true)
        CGContextSetShouldAntialias(bitmap, true)
        CGContextSetInterpolationQuality(bitmap, CGInterpolationQuality.High)

        // 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, CGFloat(toRadian(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
    }

然后使用此方法來滿足您的新大小：

extension UIImage {
    public func resizeImage(newSize:CGSize) -> UIImage {

        let newRect = CGRectIntegral(CGRectMake(0, 0, newSize.width, newSize.height))
        let imageRef:CGImageRef = self.CGImage!

        UIGraphicsBeginImageContextWithOptions(newSize, false, 0)
        let context:CGContextRef = UIGraphicsGetCurrentContext()!

        // Set the quality level to use when rescaling
        CGContextSetInterpolationQuality(context, CGInterpolationQuality.High)
        CGContextSetAllowsAntialiasing(context, true)
        CGContextSetShouldAntialias(context, true)

        let flipVertical:CGAffineTransform = CGAffineTransformMake(1, 0, 0, -1, 0, newSize.height)

        CGContextConcatCTM(context, flipVertical)
        // Draw into the context; this scales the image
        CGContextDrawImage(context, newRect, imageRef)

        // Get the resized image from the context and a UIImage
        let newImage:UIImage = UIImage(CGImage: CGBitmapContextCreateImage(context)!)

        UIGraphicsEndImageContext();
        return newImage
    }
}

Answer 3

我使用下面的擴展，它工作正常。 實際上這很快 。

import UIKit

extension UIImage {

    public func rotateImageByDegrees(_ degrees: CGFloat) -> UIImage {

        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: CGPoint.zero, size: self.size))
        let t = CGAffineTransform(rotationAngle: 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.
        bitmap?.translateBy(x: rotatedSize.width / 2.0, y: rotatedSize.height / 2.0);

        // Rotate the image context
        bitmap?.rotate(by: degreesToRadians(degrees));

        // Now, draw the rotated/scaled image into the context
        bitmap?.scaleBy(x: 1.0, y: -1.0)
        bitmap?.draw(self.cgImage!, in: CGRect(x: -self.size.width / 2, y: -self.size.height / 2, width: self.size.width, height: self.size.height))

        let cgimage:CGImage  = bitmap!.makeImage()!
        return UIImage(cgImage: cgimage)
    }
}

所有其他事情都與問題中的相同。