low level keyboard hook repeat keystrokes (unwanted) - c++

Question

my laptop space bar is broken and so I went on a venture to write a low level keyboard hook to disable it (As it insisted it was being pressed all the time) and change my full stop/period key into a new space bar.. that works fine but I have 2 issues.
1) The new space bar keystroke is sent twice, always - I don't know why
2) I'm trying to rewrite this hook to read alternative input and when I output that input to verify, it's doubled up in the output.
I'm not a strong c++ programmer nor am I a master if the Windows API so would love for a spot of guidance from you guys, if I may!
Code follows:-
#include<Windows.h>
#include <stdio.h>
#include <iostream>
using namespace std;
HHOOK hHook = NULL;
INPUT space[2];
bool sendingSpace=false;
void sendSpace()
{
cout << "Sending space\n";
space[0].type=INPUT_KEYBOARD;
space[0].ki.wVk=VK_SPACE;
space[0].ki.time=0;
space[1].type=INPUT_KEYBOARD;
space[1].ki.wVk=VK_SPACE;
space[1].ki.time=0;
space[1].ki.dwFlags=KEYEVENTF_KEYUP;
SendInput(2,space,sizeof(INPUT));
}
LRESULT CALLBACK MyLowLevelHook ( int nCode , WPARAM wParam , LPARAM lParam)
{
KBDLLHOOKSTRUCT* hs = (KBDLLHOOKSTRUCT*)lParam;
if(nCode <0)
return CallNextHookEx(hHook , nCode ,wParam , lParam);
switch(hs->vkCode)
{
case VK_SPACE:
if(!sendingSpace)
{
cout << "Ignoring space bar\n";
return 1;
}
else
{
return CallNextHookEx(hHook , nCode ,wParam , lParam);
}
break;
case VK_OEM_PERIOD:
sendingSpace=true;
sendSpace();
sendingSpace=false;
return 1;
break;
default:
cout << hs->vkCode << " ( " << (char)(hs->vkCode) << ")" << endl;
break;
}
return CallNextHookEx(hHook , nCode ,wParam , lParam);
}
int main()
{
//FreeConsole();
MSG msg;
hHook = SetWindowsHookEx(WH_KEYBOARD_LL, MyLowLevelHook , NULL,NULL);
while(!PeekMessage(&msg, NULL, 0, 0,PM_REMOVE)>0)
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
UnhookWindowsHookEx(hHook);
return 0;
}
P.S Im only using PeekMessage as a trial and error attempt to solve my issue!
Thanks in advance for any guidance, help or fingers pointing in the right direction!
Timmy.

Answer 1

The keyboard hook sees an event for a key being pressed and a key being released. The wParam argument of the hook callback contains WM_KEYDOWN on a key down, and WM_KEYUP on a key up.
In this case, you're not separating them both out, and are sending a space character every time the key is pressed and then released.
What you should really do is SendInput a KEYEVENTF_KEYDOWN when you see a WM_KEYDOWN and to a SendInput of a KEYEVENTF_KEYUP on seeing a WM_KEYUP.
The easiest way to accomplish this is to add a parameter to the sendSpace() function, so that it looks like:
void sendSpace(WPARAM param)
{
INPUT space;
cout << "Sending space " << (param == WM_KEYDOWN ? "Down" : "Up") << endl;
space.type = INPUT_KEYBOARD;
space.ki.wVk = VK_SPACE;
space.ki.time = 0;
space.ki.dwFlags = (param == WM_KEYDOWN) ? KEYEVENTF_KEYDOWN : KEYEVENTF_KEYUP;
SendInput(1, &space, sizeof INPUT);
}