Function InstallHooks

src/lib/WindowCaptureControl.cpp:15–68

namespace OpenKneeboard::WindowCaptureControl {

Handles InstallHooks(HWND hwnd) {
  DWORD processID {};
  Handles ret {};

  auto threadID = GetWindowThreadProcessId(hwnd, &processID);
  if (processID == GetCurrentProcessId()) {
    dprint("Cowardly refusing to move my own mouse cursor.");
    return {};
  }
  if (!threadID) {
    dprint("Failed to find thread for window.");
    return {};
  }

  const auto hookPath = (RuntimeFiles::GetInstallationDirectory()
                         / RuntimeFiles::WINDOW_CAPTURE_HOOK_DLL)
                          .wstring();

  dprint(L"Loading hook library: {}", hookPath);

  ret.mLibrary.reset(LoadLibraryW(hookPath.c_str()));
  if (!ret.mLibrary) {
    dprint("Failed to load hook library: {}", GetLastError());
  }

  auto msgProc
    = GetProcAddress(ret.mLibrary.get(), "GetMsgProc_WindowCaptureHook");
  if (!msgProc) {
    dprint("Failed to find msgProc hook address: {}", GetLastError());
  }
  auto wndProc
    = GetProcAddress(ret.mLibrary.get(), "CallWndProc_WindowCaptureHook");
  if (!msgProc) {
    dprint("Failed to find wndProc hook address: {}", GetLastError());
  }

  ret.mMessageHook.reset(SetWindowsHookExW(
    WH_GETMESSAGE,
    reinterpret_cast<HOOKPROC>(msgProc),
    ret.mLibrary.get(),
    threadID));
  if (!ret.mMessageHook) {
    dprint("Failed to set WH_GETMESSAGE: {}", GetLastError());
  }
  ret.mWindowProcHook.reset(SetWindowsHookExW(
    WH_CALLWNDPROC,
    reinterpret_cast<HOOKPROC>(wndProc),
    ret.mLibrary.get(),
    threadID));
  if (!ret.mWindowProcHook) {
    dprint("Failed to set WH_CALLWNDPROC: {}", GetLastError());
  }
  return ret;
}

bool Handles::IsValid() const {
  return mLibrary && mMessageHook && mWindowProcHook;