Retreives a buffer containing all keys state

KeyboardState.cs

using System;
using System.Runtime.InteropServices;

namespace System.Input
{
    public class KeyboardState
    {
        [DllImport("user32.dll")]
        private static extern int GetKeyboardState(byte[] buffer);

        [DllImport("user32.dll")]
        private static extern short GetKeyState(int key);

        public static readonly int MaxKeyCode = 0xFF;
        public static readonly int MinKeyCode = 0x00;

        private byte[] _buffer;

        public byte this[int index]
        {
            get
            {
                if (index < MinKeyCode || index >= MaxKeyCode) throw new ArgumentOutOfRangeException(nameof(index));

                return _buffer[index];
            }
        }

        public byte this[VirtualKeyCode virtualKeyCode]
        {
            get
            {
                return this[(int)virtualKeyCode];
            }
        }

        public KeyboardState()
        {
            _buffer = new byte[MaxKeyCode];
            Update();
        }

        public bool IsPressed(int index)
        {
            if (index < MinKeyCode || index >= MaxKeyCode) throw new ArgumentOutOfRangeException(nameof(index));

            // a key is pressed when it's least significant bit is set
            return (_buffer[index] & (1 << 7)) != 0;
        }

        public bool IsPressed(VirtualKeyCode virtualKeyCode)
        {
            int index = (int)virtualKeyCode;

            if (index < MinKeyCode || index >= MaxKeyCode) throw new ArgumentOutOfRangeException(nameof(index));

            return (_buffer[index] & (1 << 7)) != 0;
        }

        public bool IsToggled(int index)
        {
            if (index < MinKeyCode || index >= MaxKeyCode) throw new ArgumentOutOfRangeException(nameof(index));

            // a key is pressed when it's most significant bit is set
            return (_buffer[index] & (1 << 0)) != 0;
        }

        public bool IsToggled(VirtualKeyCode virtualKeyCode)
        {
            int index = (int)virtualKeyCode;

            if (index < MinKeyCode || index >= MaxKeyCode) throw new ArgumentOutOfRangeException(nameof(index));

            return (_buffer[index] & (1 << 0)) != 0;
        }

        public void Update()
        {
            // invalidates this thread keyboardstate when not called from an ui thread
            GetKeyState(0);
            GetKeyboardState(_buffer);
        }
    }
}