Swift3中如何使用CGContextDrawImage？

Question

我有一个使用 CGContextDrawImage 的 UIImage 扩展。它只是旋转一个UIImage。我更新到 Xcode8 和 Swift3，但不知道如何使用 CGContextDrawImage。

我在 CGContextDrawImage 上遇到错误。

"Cannot convert value of type "CGImage.Type to expected argument type 'CGImage?'"

我的代码是：

CGContextDrawImage(bitmap, CGRectMake(-size.width / 2, -size.height / 2, size.width, size.height), CGImage)

和整个扩展：

extension UIImage {
public func imageRotatedByDegrees(degrees: CGFloat, flip: Bool) -> UIImage {
    let radiansToDegrees: (CGFloat) -> CGFloat = {
        return [=12=] * (180.0 / CGFloat(M_PI))
    }
    let degreesToRadians: (CGFloat) -> CGFloat = {
        return [=12=] / 180.0 * CGFloat(M_PI)
    }

    // calculate the size of the rotated view's containing box for our drawing space
    let rectZero = CGPoint(dictionaryRepresentation: CGRect.zero as! CFDictionary)
    let rotatedViewBox = UIView(frame: CGRect(origin: rectZero!, size: 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
    var yFlip: CGFloat

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

    bitmap!.scaleBy(x: yFlip, y: -1.0)

    CGContextDrawImage(bitmap, CGRectMake(-size.width / 2, -size.height / 2, size.width, size.height), CGImage)

    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage!
}
}

Answer 1

在Swift3中，CGContext的很多函数作为CGContext的实例方法导入，属性名称CGImage已重命名为cgImage。 CGRectMake 被删除。

试试这个：

    bitmap!.draw(cgImage!, in: CGRect(x: -size.width / 2, y: -size.height / 2, width: size.width, height: size.height))

（希望 ! 对您的使用是安全的。）

func draw(CGImage, in: CGRect, byTiling: Bool)

Swift3中如何使用CGContextDrawImage？

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