How to initialise CVPixelBufferRef in Swift - swift

Question

We used to initialize CVPixelBufferRef like below.
CVPixelBufferRef pxbuffer = NULL;
But in Swift we can not use NULL, so we tried following but of course XCODE want us to have it initalized to use it
let pxbuffer: CVPixelBufferRef
but how ?
In Obj_C we were creating buffer like this, but as I was trying to explain above when converting to Swift I have been stopped at first line.
CVPixelBufferRef pxbuffer = NULL;
CVPixelBufferCreate(kCFAllocatorDefault, picGenislik,
frameHeight, kCVPixelFormatType_32ARGB, (__bridge CFDictionaryRef) options,
&pxbuffer);

Answer 1

Use CVPixelBufferCreate(_:_:_:_:_:_:) to create the object
Adding some demo code, hope this helps you. Also do read Using Legacy C APIs with Swift
var keyCallBack: CFDictionaryKeyCallBacks
var valueCallBacks: CFDictionaryValueCallBacks
var empty: CFDictionaryRef = CFDictionaryCreate(kCFAllocatorDefault, nil, nil, 0, &keyCallBack, &valueCallBacks)
var attributes = CFDictionaryCreateMutable(kCFAllocatorDefault,
1,
&keyCallBack,
&valueCallBacks);
var iOSurfacePropertiesKey = kCVPixelBufferIOSurfacePropertiesKey
withUnsafePointer(&iOSurfacePropertiesKey) { unsafePointer in
CFDictionarySetValue(attributes, unsafePointer, empty)
}
var width = 10
var height = 12
var pixelBuffer: CVPixelBufferRef? = nil
var status: CVReturn = CVPixelBufferCreate(kCFAllocatorDefault, width, height, kCVPixelFormatType_32BGRA, attributes, &pixelBuffer)

Answer 2

Here is another way to do it (Swift 3):
var pixelBuffer: UnsafeMutablePointer<CVPixelBuffer?>!
if pixelBuffer == nil {
pixelBuffer = UnsafeMutablePointer<CVPixelBuffer?>.allocate(capacity: MemoryLayout<CVPixelBuffer?>.size)
}
CVPixelBufferCreate(kCFAllocatorDefault, width, height, kCVPixelFormatType_32BGRA, attributes, pixelBuffer)
and then you can access the buffer object like this:
pixelBuffer.pointee
EDIT:
pixelBuffer = UnsafeMutablePointer<CVPixelBuffer?>.allocate(capacity: MemoryLayout<CVPixelBuffer?>.size)
Creates a memory leak if you don't manually deallocate the pointer when you're done with it, to avoid this change your code to the following:
var pixelBuffer : CVPixelBuffer? = nil
CVPixelBufferCreate(kCFAllocatorDefault, cgimg.width, cgimg.height, kCVPixelFormatType_32BGRA, nil, &pixelBuffer)

Answer 3

func getCVPixelBuffer(_ image: CGImage) -> CVPixelBuffer? {
let imageWidth = Int(image.width)
let imageHeight = Int(image.height)
let attributes : [NSObject:AnyObject] = [
kCVPixelBufferCGImageCompatibilityKey : true as AnyObject,
kCVPixelBufferCGBitmapContextCompatibilityKey : true as AnyObject
]
var pxbuffer: CVPixelBuffer? = nil
CVPixelBufferCreate(kCFAllocatorDefault,
imageWidth,
imageHeight,
kCVPixelFormatType_32ARGB,
attributes as CFDictionary?,
&pxbuffer)
if let _pxbuffer = pxbuffer {
let flags = CVPixelBufferLockFlags(rawValue: 0)
CVPixelBufferLockBaseAddress(_pxbuffer, flags)
let pxdata = CVPixelBufferGetBaseAddress(_pxbuffer)
let rgbColorSpace = CGColorSpaceCreateDeviceRGB();
let context = CGContext(data: pxdata,
width: imageWidth,
height: imageHeight,
bitsPerComponent: 8,
bytesPerRow: CVPixelBufferGetBytesPerRow(_pxbuffer),
space: rgbColorSpace,
bitmapInfo: CGImageAlphaInfo.premultipliedFirst.rawValue)
if let _context = context {
_context.draw(image, in: CGRect.init(x: 0, y: 0, width: imageWidth, height: imageHeight))
}
else {
CVPixelBufferUnlockBaseAddress(_pxbuffer, flags);
return nil
}
CVPixelBufferUnlockBaseAddress(_pxbuffer, flags);
return _pxbuffer;
}
return nil
}