[Source] Aprenda fazer CrossHair em C++

#include <windows.h>
#include <iostream>
#include <math.h>
using namespace std;

bool crosshairon=false;
HDC ragedc = NULL;
int crosshairsize=0;
int cx=0;
int cy=0;

void CrossThread(void)
**
while(1)
**
if(GetAsyncKeyState(VK_NUMPAD0)&1)
**
crosshairon=!crosshairon;
ragedc = GetDC(HWND_DESKTOP);
cx=GetSystemMetrics(SM_CXSCREEN)/2-((crosshairsize-1)/2);
cy=GetSystemMetrics(SM_CYSCREEN)/2-((crosshairsize-1)/2);
**
Sleep(1);
**
**

int main()
**
cout<<"Crosshair size in pixels:\n";
cin>>crosshairsize;
if(crosshairsize%2==0)
**
crosshairsize+=1;
**
system("cls");
cout<<"Press numpad0 to toggle the crosshair on and off\n";
CreateThread(0,0,(LPTHREAD_START_ROUTINE)CrossThread,0,0,0);
while(1)
**
if(crosshairon==true)
**
for(int i=0;i<crosshairsize;i++)
**
SetPixel(ragedc, cx+i, cy+((crosshairsize-1)/2), RGB(255,0,0));
SetPixel(ragedc, cx+((crosshairsize-1)/2), cy+i, RGB(0,0,255));
**

if(crosshairon==false)

for(int i=1;i<crosshairsize;i++)
**
SetPixel(ragedc, cx+i, cy+((crosshairsize-1)/2), RGB(0,0,0));
SetPixel(ragedc, cx+((crosshairsize-1)/2), cy+i, RGB(0,0,0));
**
**
Sleep(33);
**
**