Basic Keyboard Hooks

[Kantanomo]

First off this is obviously my first post on MPGH.net and i wanna post something actually contributory.

To create a Basic Keyboard hook you are going to need to understand basic C# and .NET basics.

To start make a new Windows Form project and name it whatever you want. Then go into the Forms Code and add the following namespaces

using System.IO;
using System****ntime.InteropServices;
using Microsoft.Win32;
using System.Diagnostics;

Now that you have those you want to add a new struct above your main form class.

    [StructLayout(LayoutKind.Sequential)]
    public struct KeyHook
    {
        public Keys key;
        public int Code;
        public int flags;
        public int time;
        public IntPtr extra;
    }

Now that you have a new struct you want to go into your forms class and add the following Fields.

        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);
        private IntPtr ptrHook;
        private LowLevelKeyboardProc objKeyboardProcess;

Now in your forms class add the following void

        private IntPtr captureKey(int nCode, IntPtr wp, IntPtr lp)
        {
            if (nCode >= 0)
            {
                KeyHook objKeyInfo = (KeyHook)Marshal.PtrToStructure(lp, typeof(KeyHook));
            }
            //this.TopMost = true;
            return CallNextHookEx(ptrHook, nCode, wp, lp);
        }

now into your forms main void default (Form1()) or

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

Now go to your Forms Designer.cs and add the name spaces

using System;

then in the designers Desposing() bool replace it with

        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {

                components.Dispose();
            }
            if (ptrHook != IntPtr.Zero)
            {
                UnhookWindowsHookEx(ptrHook);
                ptrHook = IntPtr.Zero;
            }
            base.Dispose(disposing);
        }

Now we have added the code to catch the keybaord hooks to use this to do functions or other stuff we go to the CaptureKey void

To Disable a Key's input you add the code

        private IntPtr captureKey(int nCode, IntPtr wp, IntPtr lp)
        {
            if (nCode >= 0)
            {
                KeyHook objKeyInfo = (KeyHook)Marshal.PtrToStructure(lp, typeof(KeyHook));
                if (objKeyInfo.key == /*Key to disable*/) 
                    return (IntPtr)1;
            }
            //this.TopMost = true;
            return CallNextHookEx(ptrHook, nCode, wp, lp);
        }

To have it do a function do

        private IntPtr captureKey(int nCode, IntPtr wp, IntPtr lp)
        {
            if (nCode >= 0)
            {
                KeyHook objKeyInfo = (KeyHook)Marshal.PtrToStructure(lp, typeof(KeyHook));
                //if (objKeyInfo.key == /*Key*/)
                      Application.Exit();
            }
            //this.TopMost = true;
            return CallNextHookEx(ptrHook, nCode, wp, lp);
        }

That is basic Keyboard Hooks, You can do many things with this code.

-Kantanomo leaving it short and sweet