All posts tagged 'isable-Special-Keys-in-Win-App-C'

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

        1: using System.Diagnostics;       2: using System.Runtime.InteropServices;  

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

       1: // Structure contain information about low-level keyboard input event       2: [StructLayout(LayoutKind.Sequential)]       3: private struct KBDLLHOOKSTRUCT       4: {       5:     public Keys key;       6:     public int scanCode;       7:     public int flags;       8:     public int time;       9:     public IntPtr extra;      10: }      11:        12: //System level functions to be used for hook and unhook keyboard input      13: private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);      14: [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]      15: private static extern IntPtr SetWindowsHookEx(int id, LowLevelKeyboardProc callback, IntPtr hMod, uint dwThreadId);      16: [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]      17: private static extern bool UnhookWindowsHookEx(IntPtr hook);      18: [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]      19: private static extern IntPtr CallNextHookEx(IntPtr hook, int nCode, IntPtr wp, IntPtr lp);      20: [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]      21: private static extern IntPtr GetModuleHandle(string name);      22: [DllImport("user32.dll", CharSet = CharSet.Auto)]      23: private static extern short GetAsyncKeyState(Keys key);      24:        25:        26: //Declaring Global objects      27: private IntPtr ptrHook;      28: private LowLevelKeyboardProc objKeyboardProcess;   

4. Now add the following code on your constructor.

       1: public Form1()       2: {       3:     ProcessModule objCurrentModule = Process.GetCurrentProcess().MainModule; //Get Current Module       4:     objKeyboardProcess = new LowLevelKeyboardProc(captureKey); //Assign callback function each time keyboard process       5:     ptrHook = SetWindowsHookEx(13, objKeyboardProcess, GetModuleHandle(objCurrentModule.ModuleName), 0); //Setting Hook of Keyboard Process for current module       6:         7:         8:     InitializeComponent();       9: }  

5. Now Implement the callback function

       1: private IntPtr captureKey(int nCode, IntPtr wp, IntPtr lp)       2: {       3:     if (nCode >= 0)       4:     {       5:         KBDLLHOOKSTRUCT objKeyInfo = (KBDLLHOOKSTRUCT)Marshal.PtrToStructure(lp, typeof(KBDLLHOOKSTRUCT));       6:         7:         if (objKeyInfo.key == Keys.RWin || objKeyInfo.key == Keys.LWin) // Disabling Windows keys       8:         {       9:             return (IntPtr)1;      10:         }      11:     }      12:     return CallNextHookEx(ptrHook, nCode, wp, lp);      13: }  

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

       1: /// <summary>       2: /// Clean up any resources being used.       3: /// </summary>       4: /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>       5: protected override void Dispose(bool disposing)       6: {       7:     if (disposing && (components != null))       8:     {       9:        10:         components.Dispose();      11:     }      12:     if (ptrHook != IntPtr.Zero)      13:     {      14:         UnhookWindowsHookEx(ptrHook);      15:         ptrHook = IntPtr.Zero;      16:     }      17:     base.Dispose(disposing);      18: }  