C# Signature:

[DllImport("user32.dll")]
static extern bool GetAsyncKeyState(System.Windows.Forms.Keys vKey);

VB Signature:

    <DllImport("user32.dll")> _
    Public Shared Function GetAsyncKeyState(ByVal vKey As Int32) As Short
    End Function

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.

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 = "";

    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 == -32767))
            {
                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:

    [DllImport("user32.dll")]
    static extern ushort GetAsyncKeyState(int vKey);

    public static bool IsKeyPushedDown(System.Windows.Forms.Keys vKey) {
        return 0 != (GetAsyncKeyState((int)vKey) & 0x8000);
    }

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.

Please edit this page!

Do you have...

• helpful tips or sample code to share for using this API in managed code?
• corrections to the existing content?
• variations of the signature you want to share?
• additional languages you want to include?

Select "Edit This Page" on the right hand toolbar and edit it! Or add new pages containing supporting types needed for this API (structures, delegates, and more).