Alperen Veli Sezer Alperen Veli Sezer - 1 month ago 23
iOS Question

CGPointZero and CGContextDrawImage is unavailable

I couldn't convert CGContextDrawImage for swift 3 , I tried context.draw but it doesn't work. ıs there anyone can give me a feedback

Error screenshot


Code:

import UIKit

public struct Pixel {
public var value: UInt32

public var red: UInt8 {
get {
return UInt8(value & 0xFF)
}
set {
value = UInt32(newValue) | (value & 0xFFFFFF00)
}
}

public var green: UInt8 {
get {
return UInt8((value >> 8) & 0xFF)
}
set {
value = (UInt32(newValue) << 8) | (value & 0xFFFF00FF)
}
}

public var blue: UInt8 {
get {
return UInt8((value >> 16) & 0xFF)
}
set {
value = (UInt32(newValue) << 16) | (value & 0xFF00FFFF)
}
}

public var alpha: UInt8 {
get {
return UInt8((value >> 24) & 0xFF)
}
set {
value = (UInt32(newValue) << 24) | (value & 0x00FFFFFF)
}
}

public struct RGBAImage {
public var pixels: [Pixel]

public var width: Int
public var height: Int

public init?(image: UIImage) {
guard let cgImage = image.cgImage else { return nil }

// Redraw image for correct pixel format
let colorSpace = CGColorSpaceCreateDeviceRGB()

var bitmapInfo: UInt32 = CGBitmapInfo.byteOrder32Big.rawValue
bitmapInfo |= CGImageAlphaInfo.premultipliedLast.rawValue & CGBitmapInfo.alphaInfoMask.rawValue

width = Int(image.size.width)
height = Int(image.size.height)
let bytesPerRow = width * 4

let imageData = UnsafeMutablePointer<Pixel>.allocate(capacity: width * height)

guard let imageContext = CGContext(data: imageData, width: width, height: height, bitsPerComponent: 8, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo: bitmapInfo) else { return nil }
CGContextDrawImage(imageContext, CGRect(origin: CGPointZero, size: image.size), cgImage)

let bufferPointer = UnsafeMutableBufferPointer<Pixel>(start: imageData, count: width * height)
pixels = Array(bufferPointer)

imageData.deinitialize()
imageData.deallocate(capacity: width * height)
}

public func toUIImage() -> UIImage? {
let colorSpace = CGColorSpaceCreateDeviceRGB()
var bitmapInfo: UInt32 = CGBitmapInfo.byteOrder32Big.rawValue
bitmapInfo |= CGImageAlphaInfo.premultipliedLast.rawValue & CGBitmapInfo.alphaInfoMask.rawValue

let bytesPerRow = width * 4

let imageDataReference = UnsafeMutablePointer<Pixel>(mutating: pixels)
defer {
imageDataReference.deinitialize()
}
let imageContext = CGContext(data: imageDataReference, width: width, height: height, bitsPerComponent: 8, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo: bitmapInfo, releaseCallback: nil, releaseInfo: nil)

guard let cgImage = imageContext!.makeImage() else {return nil}
let image = UIImage(cgImage: cgImage)

return image
}

Answer

All CoreGraphics C functions were refactored to fit Swift style better:

Swift 2:

CGContextDrawImage(imageContext, CGRect(origin: CGPointZero, size: image.size), cgImage)

Swift 3:

imageContext.draw(cgImage, in: CGRect(origin: .zero, size: image.size))

P.S. .zero can be used instead of CGPoint.zero because it's type is inferred implicitly.

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