I am trying to create a CGContext in swift. It compiles but throws an error at runtime.
let colorSpace:CGColorSpace = CGColorSpaceCreateDeviceRGB()
let context:CGContext = CGBitmapContextCreate(nil, 20, 20, 8, 0, colorSpace, CGBitmapInfo.AlphaInfoMask)
CGColorSpaceRelease(colorSpace);
....
And the error is:
Error: CGBitmapContextCreate: unsupported parameter combination: 8 integer bits/component; 32 bits/pixel; 3-component color space; unrecognized; 96 bytes/row.
fatal error: Can't unwrap Optional.None
Just in case somebody is running into the same problem. The snippet below finally works.
let colorSpace:CGColorSpace = CGColorSpaceCreateDeviceRGB()
let bitmapInfo = CGBitmapInfo(CGImageAlphaInfo.PremultipliedLast.rawValue)
let context = CGBitmapContextCreate(nil, UInt(rect.size.width), UInt(rect.size.height), 8, 0, colorSpace, bitmapInfo)
It generates a 32 bit RGBA context in swift
Updated for Swift 3:
let colorSpace = CGColorSpaceCreateDeviceRGB()
let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedLast.rawValue)
guard let context = CGContext.init(data: nil, width: Int(size.width), height: Int(size.height), bitsPerComponent: Int(bitsPerComponent), bytesPerRow: Int(bytesPerRow), space: colorSpace, bitmapInfo: UInt32(bitmapInfo.rawValue)) else {
// cannot create context - handle error
}
In Swift 2.1 one can access the fields properly, and even OR them together:
let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.PremultipliedFirst.rawValue | CGBitmapInfo.ByteOrder32Little.rawValue)
let context = CGBitmapContextCreate(baseAddress, width, height, 8,
bytesPerRow, colorSpace, bitmapInfo.rawValue);
Whole lot of 'rawValue' going on :)
You don't even need to separate out the bitmapInfo, and can do a one-liner:
let context = CGBitmapContextCreate(baseAddress, width, height, 8,
bytesPerRow, colorSpace, CGImageAlphaInfo.PremultipliedFirst.rawValue | CGBitmapInfo.ByteOrder32Little.rawValue
Updated for Swift 5:
let colorSpace:CGColorSpace = CGColorSpaceCreateDeviceRGB()
let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedLast.rawValue)
let context = CGContext(data: nil, width: UInt(rect.size.width), height: UInt(rect.size.height), bitsPerComponent: 8, bytesPerRow: 0, space: colorSpace, bitmapInfo: bitmapInfo.rawValue)
where rect has height and width
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With