修改鼠标移动的问题

Question

i'm playing around with windows hooks at the moment. I set up a global low level mouse hook and i want to invert the mousemovement. For this i had several aproaches (i hope this is right, my english isn't very good, sorry). The first one was to modify the lParam parameter and forward it with the CallNextHookEx function:

LRESULT CALLBACK MouseInvertProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    MSLLHOOKSTRUCT* ms = NULL;
    int dx = 0; //delta x
    int dy = 0; //delta y
    if(nCode == HC_ACTION)
    {
        if(wParam == WM_MOUSEMOVE)
        {
            ms = (MSLLHOOKSTRUCT*)lParam;
            dx = ms->pt.x - g_oldMousePos.x;
            dy = ms->pt.y - g_oldMousePos.y;
            ms->pt.x = ms->pt.x - 2 * dx;
            ms->pt.y = ms->pt.y - 2 * dy;
            GetCursorPos(&g_oldMousePos);

            return CallNextHookEx(g_MouseInvertHook,nCode,wParam, (LPARAM)ms);          
        }
        else
            return CallNextHookEx(g_MouseInvertHook, nCode, wParam, lParam);
    }
    return CallNextHookEx(g_MouseInvertHook, nCode, wParam, lParam);            
}

But this has no effect at all. Does someone know why?
The second try was to provide an input with the modified mousecoordinates:

LRESULT CALLBACK MouseInvertProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    MSLLHOOKSTRUCT* ms = NULL;
    int dx = 0; //delta x
    int dy = 0; //delta y
    if(nCode == HC_ACTION)
    {
        if(wParam == WM_MOUSEMOVE)
        {
            ms = (MSLLHOOKSTRUCT*)lParam;
            dx = ms->pt.x - g_oldMousePos.x;
            dy = ms->pt.y - g_oldMousePos.y;
            ms->pt.x = ms->pt.x - 2 * dx;
            ms->pt.y = ms->pt.y - 2 * dy;
            GetCursorPos(&g_oldMousePos);

            if(!g_artificialma) //g_artificialma is true when i created a artificial mouse input.
            {
                g_artificialma = true;
                mouse_event(MOUSEEVENTF_MOVE | MOUSEEVENTF_ABSOLUTE, ms->pt.x, ms->pt.y, NULL, NULL);
                return 1;                           
            }
            else
            {               
                g_artificialma = false;
                return CallNextHookEx(g_MouseInvertHook, nCode, wParam, lParam);
            }           
        }
        else
            return CallNextHookEx(g_MouseInvertHook, nCode, wParam, lParam);
    }
    return CallNextHookEx(g_MouseInvertHook, nCode, wParam, lParam);
}           

With the g_artificialma variable i wanted to prevent an endless loop, because the hookproc is called when i call mouse_event.
But this way i made my mouse stuck in the top left corner of my screen.

The last try was to simply call the SetCursorPos function:

LRESULT CALLBACK MouseInvertProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    MSLLHOOKSTRUCT* ms = NULL;
    int dx = 0; //delta x
    int dy = 0; //delta y
    if(nCode == HC_ACTION)
    {
        if(wParam == WM_MOUSEMOVE)
        {
            ms = (MSLLHOOKSTRUCT*)lParam;
            dx = ms->pt.x - g_oldMousePos.x;
            dy = ms->pt.y - g_oldMousePos.y;
            ms->pt.x = ms->pt.x - 2 * dx;
            ms->pt.y = ms->pt.y - 2 * dy;
            GetCursorPos(&g_oldMousePos);

            SetCursorPos(ms->pt.x, ms->pt.y);                       
        }
        else
            return CallNextHookEx(g_MouseInvertHook, nCode, wParam, lParam);
    }
    return CallNextHookEx(g_MouseInvertHook, nCode, wParam, lParam);            
}

This worked fine, but in 3d applications for example this caused a weird mouse movement
and i think this way is really ugly, because i block other hooks installed by other applications.

So do you have any suggestions to solve that in a well working and clean way (maybe without windows hooks)?

Answer 1

Your 'last try' code has no effect at all in my test :

#define _WIN32_WINNT 0x0501

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

HHOOK g_MouseInvertHook;
POINT g_oldMousePos;
LRESULT CALLBACK MouseInvertProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    MSLLHOOKSTRUCT* ms = NULL;
    int dx = 0; //delta x
    int dy = 0; //delta y
    if(nCode == HC_ACTION)
    {
        if(wParam == WM_MOUSEMOVE)
        {
            ms = (MSLLHOOKSTRUCT*)lParam;
            dx = ms->pt.x - g_oldMousePos.x;
            dy = ms->pt.y - g_oldMousePos.y;
            ms->pt.x = ms->pt.x - 2 * dx;
            ms->pt.y = ms->pt.y - 2 * dy;
            GetCursorPos(&g_oldMousePos);

            SetCursorPos(ms->pt.x, ms->pt.y);                       
        }
        else
            return CallNextHookEx(g_MouseInvertHook, nCode, wParam, lParam);
    }
    return CallNextHookEx(g_MouseInvertHook, nCode, wParam, lParam);            
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
  GetCursorPos(&g_oldMousePos);
  g_MouseInvertHook = SetWindowsHookEx(WH_MOUSE_LL, MouseInvertProc, hInstance, 0);
  MSG msg;
  while(GetMessage(&msg, NULL, 0, 0))
  {
    TranslateMessage(&msg);
    DispatchMessage(&msg);
  }
  return msg.wParam;
}

Could you make a small example of an application (like mine) that uses just that function of yours and give the result you are describing ?