C# Signature:
[DllImport("user32.dll")]
static extern short GetAsyncKeyState(System.Windows.Forms.Keys vKey);
VB.NET Signature:
<DllImport("user32.dll")> _
Shared Function GetAsyncKeyState(ByVal vKey As System.Windows.Forms.Keys) As Short
End Function
VB Signature:
Declare Function GetAsyncKeyState Lib "user32" (ByVal vkey As Integer) As Short
User-Defined Constants:
http://msdn.microsoft.com/en-us/library/windows/desktop/dd375731(v=vs.85).aspx
User-Defined Types:
None.
Notes:
None.
Tips & Tricks:
This could be a good keylogger (= yeah !
Or for hotkeys and such. This works even if the window isn't focused.
This works not for keyboard only, for mouse also (VK_RBUTTON, VK_LBUTTON).
C# Sample Code:
// this is import of libraries
[DllImport("User32.dll")]
private static extern short GetAsyncKeyState(System.Windows.Forms.Keys vKey); // Keys enumeration
[DllImport("User32.dll")]
private static extern short GetAsyncKeyState(System.Int32 vKey);
string keyBuffer = string.Empty;
private void timer1_Tick(object sender, EventArgs e)
{
timer1.Interval = 3;
foreach (System.Int32 i in Enum.GetValues(typeof(Keys)))
{
int x = GetAsyncKeyState(i);
if ((x == 1) || (x == Int16.MinValue)) //Use constants (0x8000 and -32768 is Int16.MaxValue)
{
keyBuffer += Enum.GetName(typeof(Keys), i) + " ";//this is WinAPI listener of the keys
}
}
if (keyBuffer != "")
{
// replacing of unreadable keys
keyBuffer = keyBuffer.Replace("Space", "_");
keyBuffer = keyBuffer.Replace("Delete", "_Del_");
keyBuffer = keyBuffer.Replace("LShiftKey", "_SHIFT_");
keyBuffer = keyBuffer.Replace("ShiftKey", "");
keyBuffer = keyBuffer.Replace("OemQuotes", "!");
keyBuffer = keyBuffer.Replace("Oemcomma", "?");
keyBuffer = keyBuffer.Replace("D8", "á");
keyBuffer = keyBuffer.Replace("D2", "ě");
keyBuffer = keyBuffer.Replace("D3", "š");
keyBuffer = keyBuffer.Replace("D4", "č");
keyBuffer = keyBuffer.Replace("D5", "ř");
keyBuffer = keyBuffer.Replace("D6", "ž");
keyBuffer = keyBuffer.Replace("D7", "ý");
keyBuffer = keyBuffer.Replace("D9", "í");
keyBuffer = keyBuffer.Replace("D0", "é");
keyBuffer = keyBuffer.Replace("Back", "<==");
keyBuffer = keyBuffer.Replace("LButton", "");
keyBuffer = keyBuffer.Replace("RButton", "");
keyBuffer = keyBuffer.Replace("NumPad", "");
keyBuffer = keyBuffer.Replace("OemPeriod", ".");
keyBuffer = keyBuffer.Replace("OemSemicolon", "ů");
keyBuffer = keyBuffer.Replace("Oem4", "/");
keyBuffer = keyBuffer.Replace("LControlKey", "");
keyBuffer = keyBuffer.Replace("ControlKey", "_CTRL_");
keyBuffer = keyBuffer.Replace("Enter", "");
keyBuffer = keyBuffer.Replace("Shift", "____SHIFT___");
keyBuffer = keyBuffer.ToLower();
keyBuffer = keyBuffer.Replace(" ", "");
textBox1.Text = keyBuffer;
}
}
C# Sample Code 2:
[DllImport("user32.dll")]
static extern ushort GetAsyncKeyState(int vKey);
public static bool IsKeyPushedDown(System.Windows.Forms.Keys vKey) {
return 0 != (GetAsyncKeyState((int)vKey) & 0x8000);
}
VB.NET Sample Code:
Imports System.Runtime.InteropServices
Public Class Form1
<DllImport("user32.dll")> _
Shared Function GetAsyncKeyState(ByVal vKey As System.Windows.Forms.Keys) As Short
End Function
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
If GetAsyncKeyState(Keys.Return) <> 0 Then
TextBox1.Text = "Enter pressed now"
Else
TextBox1.Text = "Enter not pressed now Hacked by pl4st1cf4c3"
End If
End Sub
End Class
Alternative Managed API:
The ManagedWindowsApi project (http://mwinapi.sourceforge.net) provides a KeyboardKey class to detect keyboard state and synthesize keyboard events.
Windows Input Simulator
An open source managed .NET wrapper written in C# is available on Codeplex at http://inputsimulator.codeplex.com/. It has all of these definitions complete with documented code comments and can be used to determine key states as well. Thanks to all the contributors at pinvoke.
