bits and bytes

So what does SendInput API do?

SendInput API is a helper function to simulate keyboard and mouse inputs. It’s an ideal function to insert characters into a password which otherwise is not possible. Here is what MSDN says about this function…

“The SendInput function inserts the events in the INPUT structures serially into the keyboard or mouse input stream. These events are not interspersed with other keyboard or mouse input events inserted either by the user (with the keyboard or mouse) or by calls to keybd_event, mouse_event, or other calls to SendInput.”

Here is a simple and basic function which sends a given text to a foreground window (my earlier function was crap so I replaced it with this new one that works for all texts, haven’t tried out with foreign keyboards though)…

BOOL SendText( LPCSTR lpctszText )
{
   vector< INPUT > EventQueue;

   char Buff[120] = {0};
   GetLocaleInfo(LOCALE_USER_DEFAULT, LOCALE_ILANGUAGE, Buff, sizeof(Buff));
   HKL hKeyboardLayout = ::LoadKeyboardLayout( Buff, KLF_ACTIVATE );

   const int Len = strlen( lpctszText );
   for( int Index = 0; Index < Len; ++Index )
   {
      INPUT Event = { 0 };

      const SHORT Vk = VkKeyScanEx(lpctszText[Index], hKeyboardLayout);
      const UINT VKey = ::MapVirtualKey( LOBYTE( Vk ), 0 );

      if( HIBYTE( Vk ) == 1 ) // Check if shift key needs to be pressed for this key
      {
          // Press shift key
          ::ZeroMemory( &Event, sizeof( Event ));
          Event.type = INPUT_KEYBOARD;
          Event.ki.dwFlags = KEYEVENTF_SCANCODE;
          Event.ki.wScan = ::MapVirtualKey( VK_LSHIFT, 0 );
          EventQueue.push_back( Event );
      }

      // Keydown
      ::ZeroMemory( &Event, sizeof( Event ));
      Event.type = INPUT_KEYBOARD;
      Event.ki.dwFlags = KEYEVENTF_SCANCODE;
      Event.ki.wScan = VKey;
      EventQueue.push_back( Event );

      // Keyup
      ::ZeroMemory( &Event, sizeof( Event ));
      Event.type = INPUT_KEYBOARD;
      Event.ki.dwFlags = KEYEVENTF_SCANCODE | KEYEVENTF_KEYUP;
      Event.ki.wScan = VKey;
      EventQueue.push_back( Event );

      if( HIBYTE( Vk ) == 1 )// Release if previouly pressed
      {
           // Release shift key
          ::ZeroMemory( &Event, sizeof( Event ));
          Event.type = INPUT_KEYBOARD;
          Event.ki.dwFlags = KEYEVENTF_SCANCODE| KEYEVENTF_KEYUP;
          Event.ki.wScan = ::MapVirtualKey( VK_LSHIFT, 0 );
          EventQueue.push_back( Event );
      }
   }// End for

   if( hKeyboardLayout )
   {
       UnloadKeyboardLayout( hKeyboardLayout );
   }

   return ::SendInput( EventQueue.size(), &EventQueue[0], sizeof( INPUT ));
}