C# Signature:
[DllImport("user32.dll")]
static extern bool GetKeyboardState(byte [] lpKeyState);
VB Signature:
<DllImport("user32.dll")> _
Private Shared Function GetKeyboardState(ByVal keyState() As Byte) As Boolean
End Function
'or...
Private Declare Function GetKeyboardState Lib "user32" (ByVal keyState() As Byte) As Boolean
Notes:
None.
Tips & Tricks:
Please add some!
Sample Code:
C#:
using System;
using System.Runtime.InteropServices;
using System.ComponentModel;
namespace PInvokeSample {
public static class Keyboard {
public static int GetKeyState(){
byte[] keys = new byte[256];
//Get pressed keys
if(!NativeMethods.GetKeyboardState(keys)){
int err = Marshal.GetLastWin32Error();
throw new Win32Exception(err);
}
for(int i = 0; i < 256; i++){
byte key = keys[i];
//Logical 'and' so we can drop the low-order bit for toggled keys, else that key will appear with the value 1!
if((key & 0x80) != 0){
//This is just for a short demo, you may want this to return
//multiple keys!
return (int)key;
}
}
return -1;
}
}
}
using System;
using System.Runtime.InteropServices;
namespace PInvokeSample {
internal static class NativeMethods {
[DllImport("User32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern bool GetKeyboardState(byte[] lpKeyState);
}
}
VB:
Imports System.Runtime.InteropServices
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Me.Text = "Caps:" & NativeMethods.CapsLockState.ToString
Me.Text &= ", Num: " & NativeMethods.NumLockState.ToString
Me.Text &= ", Scroll: " & NativeMethods.ScrollLockState.ToString
End Sub
End Class
Public Class NativeMethods
Private Shared keyState() As Byte
<DllImport("user32.dll")> _
Private Shared Function GetKeyboardState(ByVal keyState() As Byte) As Boolean
End Function
Private Shared Sub Update()
keyState = New Byte(256) {}
Dim result As Boolean = GetKeyboardState(keyState)
' Check for error:
If result = False Then
Debug.WriteLine("GetKeyBoardState error: " & Marshal.GetLastWin32Error)
Throw New Exception("GetKeyBoardState error: " & Marshal.GetLastWin32Error)
End If
End Sub
Public Enum LightState
Off
[On]
End Enum
' Example - the keyboard lights...
Public Shared ReadOnly Property CapsLockState() As LightState
Get
Update()
Dim isOn As Boolean = (keyState(Keys.CapsLock) = 1)
Return IIf(isOn, LightState.On, LightState.Off)
End Get
End Property
Public Shared ReadOnly Property NumLockState() As LightState
Get
Update()
Dim isOn As Boolean = (keyState(Keys.NumLock) = 1)
Return IIf(isOn, LightState.On, LightState.Off)
End Get
End Property
Public Shared ReadOnly Property ScrollLockState() As LightState
Get
Update()
Dim isOn As Boolean = (keyState(Keys.Scroll) = 1)
Return IIf(isOn, LightState.On, LightState.Off)
End Get
End Property
End Class
Alternative Managed API:
using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Text;
namespace PInvoke.Net
{
public class Keyboard
{
[DllImport( "user32.dll" )]
static extern short GetKeyState( VirtualKeyStates nVirtKey );
public static bool IsKeyPressed( VirtualKeyStates testKey )
{
bool keyPressed = false;
short result = GetKeyState( testKey );
switch( result )
{
case 0:
// Not pressed and not toggled on.
keyPressed = false;
break;
case 1:
// Not pressed, but toggled on
keyPressed = false;
break;
default:
// Pressed (and may be toggled on)
keyPressed = true;
break;
}
return keyPressed;
}
public enum VirtualKeyStates : int
{
VK_LBUTTON = 0x01,
VK_RBUTTON = 0x02,
VK_CANCEL = 0x03,
VK_MBUTTON = 0x04,
//
VK_XBUTTON1 = 0x05,
VK_XBUTTON2 = 0x06,
//
VK_BACK = 0x08,
VK_TAB = 0x09,
//
VK_CLEAR = 0x0C,
VK_RETURN = 0x0D,
//
VK_SHIFT = 0x10,
VK_CONTROL = 0x11,
VK_MENU = 0x12,
VK_PAUSE = 0x13,
VK_CAPITAL = 0x14,
//
VK_KANA = 0x15,
VK_HANGEUL = 0x15, /* old name - should be here for compatibility */
VK_HANGUL = 0x15,
VK_JUNJA = 0x17,
VK_FINAL = 0x18,
VK_HANJA = 0x19,
VK_KANJI = 0x19,
//
VK_ESCAPE = 0x1B,
//
VK_CONVERT = 0x1C,
VK_NONCONVERT = 0x1D,
VK_ACCEPT = 0x1E,
VK_MODECHANGE = 0x1F,
//
VK_SPACE = 0x20,
VK_PRIOR = 0x21,
VK_NEXT = 0x22,
VK_END = 0x23,
VK_HOME = 0x24,
VK_LEFT = 0x25,
VK_UP = 0x26,
VK_RIGHT = 0x27,
VK_DOWN = 0x28,
VK_SELECT = 0x29,
VK_PRINT = 0x2A,
VK_EXECUTE = 0x2B,
VK_SNAPSHOT = 0x2C,
VK_INSERT = 0x2D,
VK_DELETE = 0x2E,
VK_HELP = 0x2F,
//
VK_LWIN = 0x5B,
VK_RWIN = 0x5C,
VK_APPS = 0x5D,
//
VK_SLEEP = 0x5F,
//
VK_NUMPAD0 = 0x60,
VK_NUMPAD1 = 0x61,
VK_NUMPAD2 = 0x62,
VK_NUMPAD3 = 0x63,
VK_NUMPAD4 = 0x64,
VK_NUMPAD5 = 0x65,
VK_NUMPAD6 = 0x66,
VK_NUMPAD7 = 0x67,
VK_NUMPAD8 = 0x68,
VK_NUMPAD9 = 0x69,
VK_MULTIPLY = 0x6A,
VK_ADD = 0x6B,
VK_SEPARATOR = 0x6C,
VK_SUBTRACT = 0x6D,
VK_DECIMAL = 0x6E,
VK_DIVIDE = 0x6F,
VK_F1 = 0x70,
VK_F2 = 0x71,
VK_F3 = 0x72,
VK_F4 = 0x73,
VK_F5 = 0x74,
VK_F6 = 0x75,
VK_F7 = 0x76,
VK_F8 = 0x77,
VK_F9 = 0x78,
VK_F10 = 0x79,
VK_F11 = 0x7A,
VK_F12 = 0x7B,
VK_F13 = 0x7C,
VK_F14 = 0x7D,
VK_F15 = 0x7E,
VK_F16 = 0x7F,
VK_F17 = 0x80,
VK_F18 = 0x81,
VK_F19 = 0x82,
VK_F20 = 0x83,
VK_F21 = 0x84,
VK_F22 = 0x85,
VK_F23 = 0x86,
VK_F24 = 0x87,
//
VK_NUMLOCK = 0x90,
VK_SCROLL = 0x91,
//
VK_OEM_NEC_EQUAL = 0x92, // '=' key on numpad
//
VK_OEM_FJ_JISHO = 0x92, // 'Dictionary' key
VK_OEM_FJ_MASSHOU = 0x93, // 'Unregister word' key
VK_OEM_FJ_TOUROKU = 0x94, // 'Register word' key
VK_OEM_FJ_LOYA = 0x95, // 'Left OYAYUBI' key
VK_OEM_FJ_ROYA = 0x96, // 'Right OYAYUBI' key
//
VK_LSHIFT = 0xA0,
VK_RSHIFT = 0xA1,
VK_LCONTROL = 0xA2,
VK_RCONTROL = 0xA3,
VK_LMENU = 0xA4,
VK_RMENU = 0xA5,
//
VK_BROWSER_BACK = 0xA6,
VK_BROWSER_FORWARD = 0xA7,
VK_BROWSER_REFRESH = 0xA8,
VK_BROWSER_STOP = 0xA9,
VK_BROWSER_SEARCH = 0xAA,
VK_BROWSER_FAVORITES = 0xAB,
VK_BROWSER_HOME = 0xAC,
//
VK_VOLUME_MUTE = 0xAD,
VK_VOLUME_DOWN = 0xAE,
VK_VOLUME_UP = 0xAF,
VK_MEDIA_NEXT_TRACK = 0xB0,
VK_MEDIA_PREV_TRACK = 0xB1,
VK_MEDIA_STOP = 0xB2,
VK_MEDIA_PLAY_PAUSE = 0xB3,
VK_LAUNCH_MAIL = 0xB4,
VK_LAUNCH_MEDIA_SELECT = 0xB5,
VK_LAUNCH_APP1 = 0xB6,
VK_LAUNCH_APP2 = 0xB7,
//
VK_OEM_1 = 0xBA, // ';:' for US
VK_OEM_PLUS = 0xBB, // '+' any country
VK_OEM_COMMA = 0xBC, // ',' any country
VK_OEM_MINUS = 0xBD, // '-' any country
VK_OEM_PERIOD = 0xBE, // '.' any country
VK_OEM_2 = 0xBF, // '/?' for US
VK_OEM_3 = 0xC0, // '`~' for US
//
VK_OEM_4 = 0xDB, // '[{' for US
VK_OEM_5 = 0xDC, // '\|' for US
VK_OEM_6 = 0xDD, // ']}' for US
VK_OEM_7 = 0xDE, // ''"' for US
VK_OEM_8 = 0xDF,
//
VK_OEM_AX = 0xE1, // 'AX' key on Japanese AX kbd
VK_OEM_102 = 0xE2, // "<>" or "\|" on RT 102-key kbd.
VK_ICO_HELP = 0xE3, // Help key on ICO
VK_ICO_00 = 0xE4, // 00 key on ICO
//
VK_PROCESSKEY = 0xE5,
//
VK_ICO_CLEAR = 0xE6,
//
VK_PACKET = 0xE7,
//
VK_OEM_RESET = 0xE9,
VK_OEM_JUMP = 0xEA,
VK_OEM_PA1 = 0xEB,
VK_OEM_PA2 = 0xEC,
VK_OEM_PA3 = 0xED,
VK_OEM_WSCTRL = 0xEE,
VK_OEM_CUSEL = 0xEF,
VK_OEM_ATTN = 0xF0,
VK_OEM_FINISH = 0xF1,
VK_OEM_COPY = 0xF2,
VK_OEM_AUTO = 0xF3,
VK_OEM_ENLW = 0xF4,
VK_OEM_BACKTAB = 0xF5,
//
VK_ATTN = 0xF6,
VK_CRSEL = 0xF7,
VK_EXSEL = 0xF8,
VK_EREOF = 0xF9,
VK_PLAY = 0xFA,
VK_ZOOM = 0xFB,
VK_NONAME = 0xFC,
VK_PA1 = 0xFD,
VK_OEM_CLEAR = 0xFE
}
}
}
