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Disable Special Keys in Win App C#

30 Aug

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: }

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.

Referenced by: http://geekswithblogs.net/aghausman/archive/2009/04/26/disable-special-keys-in-win-app-c.aspx
// ------------ Code ----------------------- 
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace WindowsKeyPressed 
{
    public partial class Form1 : Form
    {
        // 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; 

        public Form1()
        {
            ProcessModule objCurrentModule = Process.GetCurrentProcess().MainModule;
            objKeyboardProcess = new LowLevelKeyboardProc(captureKey);
            ptrHook = SetWindowsHookEx(13, objKeyboardProcess, GetModuleHandle(objCurrentModule.ModuleName), 0);


            InitializeComponent();
        }

        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);
        }


        
        private void Form1_KeyPress(object sender, KeyPressEventArgs e)
        {
            MessageBox.Show(e.KeyChar.ToString());
        }


    }

For Disable Art + Tab

// 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;

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

            // Disabling Windows keys 

            if (objKeyInfo.key == Keys.RWin || objKeyInfo.key == Keys.LWin || objKeyInfo.key == Keys.Tab && HasAltModifier(objKeyInfo.flags) || objKeyInfo.key == Keys.Escape && (ModifierKeys & Keys.Control) == Keys.Control)     
            {
                return (IntPtr)1; // if 0 is returned then All the above keys will be enabled
            }
        }
        return CallNextHookEx(ptrHook, nCode, wp, lp);
    }

    bool HasAltModifier(int flags)
    {
        return (flags & 0x20) == 0x20;
    }

    /* Code to Disable WinKey, Alt+Tab, Ctrl+Esc Ends Here */

http://stackoverflow.com/questions/3213606/how-to-suppress-task-switch-keys-winkey-alt-tab-alt-esc-ctrl-esc-using-low
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8 Comments

Posted by on August 30, 2011 in C#, Window Application

 

8 responses to “Disable Special Keys in Win App C#

  1. nigel

    January 29, 2012 at 1:25 AM

    i would like to call release the keys. how do i do this ?

     
    • sochinda

      February 4, 2012 at 3:01 PM

      I don’t understand what you want, please tell more detail. I will help you if I know.

       
      • nigel

        February 4, 2012 at 11:00 PM

        I wanted to ENABLE Special Keys in Win App C# but i figured it out. Never mind.

        Thanks.

         
  2. Rahul

    February 1, 2012 at 9:35 PM

    Thank You very much dear…That Worked and helped me a lot.

     
  3. Ravi Trimurthulu

    April 7, 2013 at 4:10 PM

    thank u ………

     
  4. mohit garg

    May 8, 2013 at 9:27 AM

    intptr doesno exist in designer form

     
  5. mohit garg

    May 8, 2013 at 9:29 AM

    pls do tell

     
  6. sochinda

    May 8, 2013 at 10:54 AM

    Did you import these file into your code:
    ————————————————————
    using System.Diagnostics;
    using System.Runtime.InteropServices;
    ————————————————————

     

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