I'm trying to create a screenshot application using windows service, that can capture complete screen at regular time intervals. To get started with, I took basic window service example (http://code.msdn.microsoft.com/windowsdesktop/CppWindowsService-cacf4948) and included screenshot utility class in the project and called the capture function in the onStart method of sample windows service. However, I got blank screen shots. Later I realized that windows service runs in different session and hence the screenshots are blank.
S, I decoupled the screenshot utility class and made it as a seperate project and generated a .exe out of it (which is capable of writing logs to a file where ever needed). This time, I used createProcessWithLogonW function to call the executable, so that it will run the exe in specified user domain than the default service session. The following is the code snippet I have been using.
void CSampleService::StartProcess()
{
DWORD dwSize; HANDLE hToken=NULL;
LPVOID lpvEnv; PROCESS_INFORMATION pi = {0};
STARTUPINFO si = {0};
WCHAR szUserProfile[256] = L"";
si.cb = sizeof(STARTUPINFO);
if (!CreateEnvironmentBlock(&lpvEnv, hToken, TRUE))
{
logger::Wlog(logger::fileName,"CreateEnvironmentBlock Error");
}
dwSize = sizeof(szUserProfile)/sizeof(WCHAR);
GetUserProfileDirectory(hToken, szUserProfile, &dwSize);
CreateProcessWithLogonW(L"admin", L"MyDomain",L"mypassword",
LOGON_WITH_PROFILE, NULL, L"C:\\Temp\\application.exe",
CREATE_UNICODE_ENVIRONMENT, lpvEnv, NULL, &si, &pi);
DestroyEnvironmentBlock(lpvEnv);
CloseHandle(hToken);
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
WaitForSingleObject(pi.hProcess, INFINITE);
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
}
I have no errors from the logs i got. when the services get initiated, it gives a warning of interactive service trying to show a message. When I click that, I received a black screenshot again. I know that there are many things involved here, I just gave a high level view of what I'm doing. Also, i'm pretty new to windows programming. Any kind of help is appreciated.
