I trying take screenshot of camera vuforia. I using this code. Its perfect working on iPhone 7 (ios 11.3) and iPad Pro (ios 11.2). But this code not working on iPad 2 (ios 9.3.5), function returning valid UIImage, but it black.
static public func takeScreenshot() -> UIImage? {
let xCoord: Int = 0
let yCoord: Int = 0
let screen = UIScreen.main.bounds
let scale = UIScreen.main.scale
let width = screen.width * scale
let height = screen.height * scale
let dataLength: Int = Int(width) * Int(height) * 4
let pixels: UnsafeMutableRawPointer? = malloc(dataLength * MemoryLayout<GLubyte>.size)
glPixelStorei(GLenum(GL_PACK_ALIGNMENT), 4)
glReadPixels(GLint(xCoord), GLint(yCoord), GLsizei(width), GLsizei(height), GLenum(GL_RGBA), GLenum(GL_UNSIGNED_BYTE), pixels)
guard let pixelData: UnsafePointer = (UnsafeRawPointer(pixels)?.assumingMemoryBound(to: UInt8.self)) else { return nil }
let cfdata: CFData = CFDataCreate(kCFAllocatorDefault, pixelData, dataLength * MemoryLayout<GLubyte>.size)
let provider: CGDataProvider! = CGDataProvider(data: cfdata)
let colorspace = CGColorSpaceCreateDeviceRGB()
guard let iref = CGImage(width: Int(width),
height: Int(height),
bitsPerComponent: 8,
bitsPerPixel: 32,
bytesPerRow: Int(width)*4,
space: colorspace,
bitmapInfo: CGBitmapInfo.byteOrder32Big,
provider: provider,
decode: nil,
shouldInterpolate: false,
intent: CGColorRenderingIntent.defaultIntent) else { return nil }
UIGraphicsBeginImageContext(CGSize(width: CGFloat(width), height: CGFloat(height)))
if let cgcontext = UIGraphicsGetCurrentContext() {
cgcontext.setBlendMode(CGBlendMode.copy)
cgcontext.draw(iref, in: CGRect(x: CGFloat(0.0), y: CGFloat(0.0), width: CGFloat(width), height: CGFloat(height)))
let image: UIImage? = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image
}
return nil
}
UPDATE: i resolved this problem, need run function in opengl thread
