dejix dejix - 2 months ago 62
Swift Question

How use CGContextDrawImage in Swift 3?

I have an

UIImage
extension that uses
CGContextDrawImage
.
It simply rotate a
UIImage
.
I updated to Xcode8 and Swift3 and cant figure out how to use
CGContextDrawImage
.

I got error on CGContextDrawImage.


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


My code is :

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


And whole extension :

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 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

In Swift 3, many functions for CGContext are imported as an instance method of CGContext, the property name CGImage has renamed to cgImage. And CGRectMake is removed.

Try this:

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

(Hope ! would be safe for your usage.)

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

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