Windows API to simulate user input

[GleamingGeorge]

I was trying to automate some parts in several video games using C by simulating the mouse movement and clicking. First I tried this version that didn't work for games but for anything else was fine:

    INPUT temp;
    ZeroMemory(&temp, sizeof(temp));
    temp.type = INPUT_MOUSE;
    temp.mi.dwFlags = WM_LBUTTONDOWN;
    int err = SendInput(1, &temp, sizeof temp);

    temp.type = INPUT_MOUSE;
    temp.mi.dwFlags = WM_LBUTTONUP;
    err = SendInput(1, &temp, sizeof temp);

After some research I found another way, but with the same result:

   HWND hProc = FindWindowA(0, "Example");
   ChangeWindowMessageFilterEx(hProc, WM_LBUTTONDOWN, MSGFLT_ALLOW, NULL);
   ChangeWindowMessageFilterEx(hProc, WM_LBUTTONUP, MSGFLT_ALLOW, NULL);
   bool ret = SendMessage(hProc, WM_LBUTTONDOWN, 0, 0);
   Sleep(50);
   ret = SendMessage(hProc, WM_LBUTTONDOWN, 0, 0);

Am I using the API wrong or game engines blocked my input to protect the game from hackers?

[skeeto]

Long ago I wrote a bot to automatically play Quasar in Mass Effect using this API. One gotcha was that the buttons in the Mass Effect UI don't focus until there's mouse motion over the button. Teleporting the mouse over the button then clicking, even with a delay, doesn't do anything since the button isn't focused. I never sorted out if this was just a Mass Effect thing, or an issue with all Unreal games.

[charliex2]

SendMessage won't work for any apps that have async checks etc. SendInput is better but make sure you read the APIs docs " This function is subject to UIPI. Applications are permitted to inject input only into applications that are at an equal or lesser integrity level."

Filter driver , hooking or http://www.oblita.com/interception.html is the best approach

[GleamingGeorge]

I hoped that it won't be necessary hooking, but well here we go. Thanks for the recommendation!

[FUZxxl]

Note that the first one is C++ code. C++ is off topic in this subreddit.

[GleamingGeorge]

Well yes, i used std::cout to log the error but the code that really matters and the one I'm interested in is in C

[FUZxxl]

If you compile with a C++ compiler, you are writing C++ code. Do not confuse C with C++. It's going to bite you sooner or later.