Windows: swap keys (like ESC and Caps Lock) with a C-Sharp program

SwapKeys.cs

// vi: foldmarker={{{,}}} foldmethod=marker
//
// V0.3
//
using System;
using System.IO;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Windows.Forms;            // Use for Application.Run

using TQ84;

namespace TQ84 {

   public class SwapKeys {

     [DllImport("USER32.dll")]
      static extern short GetKeyState(int nVirtKey);

      private static Win32.INPUT[] inputs;
      private static int sizeOfInputs_1;

      public static void go() {

         inputs = new Win32.INPUT[1];

         inputs[0].type             = 1; // 1 = INPUT_KEYBOARD;
         inputs[0].U.ki.wScan       = 0;
         inputs[0].U.ki.dwFlags     =           0;
         inputs[0].U.ki.time        = (int)     0;
         inputs[0].U.ki.dwExtraInfo = (UIntPtr) 0;

         sizeOfInputs_1 = System.Runtime.InteropServices.Marshal.SizeOf(inputs[0]);

         if (GetKeyState((int) Win32.VirtualKey.CAPITAL) == 1) {
          //
          // V0.3: Caps Lock is pressed. Because this is probably not desired when
          // the application starts, we de-press Caps Lock here.
          // TODO: Should GetAsyncKeyState() be used?
          //
             inputs[0].U.ki.dwFlags = 0; // Win32.KEYEVENTF.KEYDOWN;
             replaceVKWith(Win32.VirtualKey.CAPITAL);

             inputs[0].U.ki.dwFlags = Win32.KEYEVENTF.KEYUP;
             replaceVKWith(Win32.VirtualKey.CAPITAL);
         }

         TQ84.Win32.Hook.KeyboardLL(keyboardEvent);
         Application.Run();
      }

      private static void replaceVKWith(Win32.VirtualKey vk) {
         inputs[0].U.ki.wVk = vk;
//       if (Win32.Hook.SendInput(1, inputs, System.Runtime.InteropServices.Marshal.SizeOf(inputs[0])) != 1)
         if (Win32.Hook.SendInput(1, inputs, sizeOfInputs_1) != 1)
         {
             Console.WriteLine("SendInput() did not return 1");
         }
      }

      public static bool keyboardEvent(IntPtr wParam, Win32.Hook.KBDLLHOOKSTRUCT kbd) {

          if (wParam == (IntPtr) 0x0101 /* WM_KEYUP */ || wParam == (IntPtr) 0x0105 /* WM_SYSKEYUP*/ ) {
              inputs[0].U.ki.dwFlags = Win32.KEYEVENTF.KEYUP;
          }
          else {
              inputs[0].U.ki.dwFlags = 0;
          }

          if (  ( kbd.flags & Win32.Hook.KBDLLHOOKSTRUCTFlags.LLKHF_INJECTED ) == 0 ) {

               if (kbd.vkCode == (uint) Win32.VirtualKey.CAPITAL) {
                   replaceVKWith(Win32.VirtualKey.ESCAPE);
                   return true;
               }

               if (kbd.vkCode == (uint) Win32.VirtualKey.ESCAPE) {
                   replaceVKWith(Win32.VirtualKey.CAPITAL);
                   return true;
               }

               if (kbd.vkCode == (uint) Win32.VirtualKey.RWIN) {
                   replaceVKWith(Win32.VirtualKey.LCONTROL);
                   Console.WriteLine("RWIN");
                   return true;
               }
           //
           //  V0.2: Removing this line seemed to generally improve typing speed and reduce Null pointer exception errors.
           //
           //  Console.WriteLine("scan: " + kbd.scanCode + ", vk = " + kbd.vkCode + ", wParam = " + wParam);
           //
               if (kbd.vkCode == (uint) Win32.VirtualKey.SNAPSHOT) { // Prt Scr
                  Win32.Hook.Stop();
                  Application.ExitThread();

                //  Never reached:
                    return true;
              }
           }

           return false;
      }
   }
}

Github repository cs-SwapKeys, path: /SwapKeys.cs

load-SwapKeys.ps1

load-SwapKeys.ps1 expects that the dependent Win32Hook.dll assembly was already created with create-assembly.ps1 (Event hooking with C#).

$assemblyPath = "$pwd/Win32-Hook/Win32Hook.dll"
[System.Reflection.Assembly]::LoadFile($assemblyPath);

$srcSwapKeys = get-content -raw swapKeys.cs

add-type                             `
  -typeDefinition       $srcSwapKeys `
  -referencedAssemblies              `
     System.Windows.Forms,           `
     $assemblyPath

[TQ84.SwapKeys]::go()

Github repository cs-SwapKeys, path: /load-SwapKeys.ps1

startAgain.bat

@cd %~dp0

:loop
   echo %time% >> started.at
   powershell -c . .\load-SwapKeys.ps1
goto loop

Github repository cs-SwapKeys, path: /startAgain.bat

install-autorun.ps1

The following PowerShell script adds the startAgain.bat batch file to the HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run registry key so that the keys are automatically remapped when the user logs on.

set-itemProperty                                      `
  HKCU:\Software\Microsoft\Windows\CurrentVersion\Run `
  swapKeys                                            `
 "$pwd\startAgain.bat"

Github repository cs-SwapKeys, path: /install-autorun.ps1

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