parser.swift

class Page {
    var layers: [Layer] = []
    
    init?(data: Data) {
        let header = String(bytes: data[0...32], encoding: .utf8)!.last!
        
        let input = InputStream(data: data[43...])
        
        input.open()
        
        let bufferSize = 4
        let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: bufferSize)
        let _ = input.read(buffer, maxLength: bufferSize)
        let numberOfLayers = buffer.toUInt32()
        
        self.layers = (0..<numberOfLayers).map { _ in
            let _ = input.read(buffer, maxLength: bufferSize)
            let numberOfLines = buffer.toUInt32()
            
            return Layer(lines: (0..<numberOfLines).map { _ in
                let _ = input.read(buffer, maxLength: bufferSize)
                let brush = buffer.toUInt32()
                
                let _ = input.read(buffer, maxLength: bufferSize)
                let color = buffer.toUInt32()
                
                // padding
                let _ = input.read(buffer, maxLength: bufferSize)
                
                let _ = input.read(buffer, maxLength: bufferSize)
                let baseBrushSize = buffer.toFloat32()
                
                // padding (this 5 is a *barf*)
                if header == "5" {
                    let _ = input.read(buffer, maxLength: bufferSize)
                }
                
                let _ = input.read(buffer, maxLength: bufferSize)
                let numberOfPoints = buffer.toUInt32()
                
                return Line(brush: brush, color: color, baseBrushSize: baseBrushSize, points: (0..<numberOfPoints).map { _ in
                    let _ = input.read(buffer, maxLength: bufferSize)
                    let x = buffer.toFloat32()
                    
                    let _ = input.read(buffer, maxLength: bufferSize)
                    let y = buffer.toFloat32()
                    
                    let _ = input.read(buffer, maxLength: bufferSize)
                    let speed = buffer.toFloat32()
                    
                    let _ = input.read(buffer, maxLength: bufferSize)
                    let direction = buffer.toFloat32()
                    
                    let _ = input.read(buffer, maxLength: bufferSize)
                    let width = buffer.toFloat32()
                    
                    let _ = input.read(buffer, maxLength: bufferSize)
                    let pressure = buffer.toFloat32()
                    
                    return Point(point: CGPoint(x: CGFloat(x), y: CGFloat(y)),
                                 speed: speed,
                                 direction: direction,
                                 width: width,
                                 pressure: pressure)
                })
            })
        }
    }
}