A service that displays an icon in the system tray

Download demo executable - 7 Kb

Download source files - 13 Kb

IconService is a Win32 console app that displays an icon in the system tray. The service can be installed/removed from the prompt: "IconService -install" , "IconService -remove", and started from the control panel (the "Services" icon). In order to display something from a service you must allow it to interact with the desktop. This can be done by specifying the SERVICE_INTERACTIVE_PROCESS switch when creating the service:

schService = CreateService(
            schSCManager,               // SCManager database
            TEXT(SZSERVICENAME),        // name of service
            TEXT(SZSERVICEDISPLAYNAME), // name to display
            SERVICE_ALL_ACCESS,         // desired access
            SERVICE_WIN32_OWN_PROCESS | SERVICE_INTERACTIVE_PROCESS ,  // service type
            SERVICE_DEMAND_START,       // start type
            SERVICE_ERROR_NORMAL,       // error control type
            szPath,                     // service's binary
            NULL,                       // no load ordering group
            NULL,                       // no tag identifier
            TEXT(SZDEPENDENCIES),       // dependencies
            NULL,                       // LocalSystem account
            NULL);                      // no password

ServiceStart creates an event used later for stopping the service, and a thread that is responsible for the icon's parent. Here I use an old trick to prevent the dialog from appearing in the task bar. First I create a modeless dialog with the WS_VISIBLE not checked:

HWND hwnd = CreateDialog(NULL, MAKEINTRESOURCE(IDD_DIALOG1), NULL, NULL);

and than I create the icon's parent:

DialogBox(NULL, MAKEINTRESOURCE(IDD_DIALOG1), hwnd, DialogProc);

To hide this one:

SetWindowPos(hwndDlg, NULL, -10,-10,0,0, SWP_NOZORDER|SWP_NOMOVE);

The DialogProc is quite simple. It creates the icon, and on RBCLK it displays a menu to stop the service. ServiceStop sets the event created by ServiceStart and deletes the icon.

The heart of the service is in the ServiceStart function. So if you want your service to actually do something after creating the icon, replace the WaitForSingleObject with something else.