Disable Special Keys in Win App C#

Today, when I was planning to write an article on Grid View. I got a message from a very good friend of mine who is asking to disable the special keys(Windows Keys) in his application. When I start researching on it, I was thinking that it can be done using e.KeyChar but unfortunately, it is not showing any information about windows keys.

So in this post I will explain you, how can we disable the special keys (in our case windows keys) in C# Application.

1. Crete a c# windows application project
2. On the code behind of your default form add the following references

    using System.Diagnostics;
    using System.Runtime.InteropServices;

3. Now before the constructor of your form place the following code.

// Structure contain information about low-level keyboard input event
[StructLayout(LayoutKind.Sequential)]
private struct KBDLLHOOKSTRUCT {
  public Keys key;
  public int scanCode;
  public int flags;
  public int time;
  public IntPtr extra;
}

// System level functions to be used for hook and unhook keyboard input
private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam,
                                             IntPtr lParam);
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr SetWindowsHookEx(int id,
                                              LowLevelKeyboardProc callback,
                                              IntPtr hMod, uint dwThreadId);
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern bool UnhookWindowsHookEx(IntPtr hook);
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr CallNextHookEx(IntPtr hook, int nCode, IntPtr wp,
                                            IntPtr lp);
[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr GetModuleHandle(string name);
[DllImport("user32.dll", CharSet = CharSet.Auto)]
private static extern short GetAsyncKeyState(Keys key);

// Declaring Global objects
private IntPtr ptrHook;
private LowLevelKeyboardProc objKeyboardProcess;

4. Now add the following code on your constructor.

public Form1() {
  ProcessModule objCurrentModule =
      Process.GetCurrentProcess().MainModule;  // Get Current Module
  objKeyboardProcess = new LowLevelKeyboardProc(
      captureKey);  // Assign callback function each time keyboard process
  ptrHook = SetWindowsHookEx(
      13, objKeyboardProcess, GetModuleHandle(objCurrentModule.ModuleName),
      0);  // Setting Hook of Keyboard Process for current module

  InitializeComponent();
}

5. Now Implement the callback function

private IntPtr captureKey(int nCode, IntPtr wp, IntPtr lp) {
  if (nCode >= 0) {
    KBDLLHOOKSTRUCT objKeyInfo =
        (KBDLLHOOKSTRUCT)Marshal.PtrToStructure(lp, typeof(KBDLLHOOKSTRUCT));

    if (objKeyInfo.key == Keys.RWin ||
        objKeyInfo.key == Keys.LWin)  // Disabling Windows keys
    {
      return (IntPtr)1;
    }
  }
  return CallNextHookEx(ptrHook, nCode, wp, lp);
}

6. Now go to your designer class and replace your dispose method.

/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed;
/// otherwise, false.</param>
protected override void Dispose(bool disposing) {
  if (disposing && (components != null)) {
    components.Dispose();
  }
  if (ptrHook != IntPtr.Zero) {
    UnhookWindowsHookEx(ptrHook);
    ptrHook = IntPtr.Zero;
  }
  base.Dispose(disposing);
}

So, in this way we can stop the windows key operation till your application is running.You can find the VS 2008 Source code here.