_PROGRAMMER'S BOOKSHELF COLUMN_
by Andrew Schulman


Example 1: A simple Windows program, SYSTRES.C, consists of 
little more than the OkMsgBox() function from Petzold's Programming
Windows.

/*  SYSTRES.C -- System Resources
Borland C++:    
bcc -W systres.c
rc systres.exe */

#include <windows.h>

/* undocumented Windows call: KERNEL.138 */
extern DWORD FAR PASCAL GetHeapSpaces(WORD hModule);
void heap_info(char *module, WORD *pfree, WORD *ptotal, WORD *ppercent)
{
    DWORD info = GetHeapSpaces(GetModuleHandle(module));
    *pfree = LOWORD(info);
    *ptotal = HIWORD(info);
    *ppercent = (WORD) ((((DWORD) *pfree) * 100L) / ((DWORD) *ptotal));
}

#define PROGMAN_EXE     "progman.exe"
#define PROGMAN_CLASS   "Progman"
#define HELP_ABOUT      0x387       // subject to change!!!

// run the Program Manager Help menu About... box
void progmgr_aboutbox(void)
{
    WORD progmgr;
    // use class name ("Progman"), not window title ("Program Manager"):
    // see Richter, Windows 3: A Developer's Guide, p.80
    if (! (progmgr = FindWindow(PROGMAN_CLASS, 0)))
    {
        // WinExec() is async: equivalent of spawn() P_NOWAIT
        WinExec(PROGMAN_EXE, SW_SHOWMINIMIZED);
        if (! (progmgr = FindWindow(PROGMAN_CLASS, 0)))
            return; // couldn't find or load Program Manager
    }
    // use PostMessage instead of SendMessage so we run async
    PostMessage(progmgr, WM_COMMAND, HELP_ABOUT, 0L);
}
// from Petzold, Programming Windows, p. 441
void OkMsgBox(char *szCaption, char *szFormat, ...)
{
    char szBuffer[256] ;
    char *pArguments ;
    pArguments = (char *) &szFormat + sizeof szFormat ;
    wvsprintf(szBuffer, szFormat, pArguments) ; // changed from vsprintf
    MessageBox(NULL, szBuffer, szCaption, MB_OK) ;
}
int PASCAL WinMain(HANDLE hInstance, HANDLE hPrevInstance, LPSTR lpszCmdLine, 
                                                                 int nCmdShow)
{
    WORD user_free, user_total, user_percent;
    WORD gdi_free, gdi_total, gdi_percent;
    heap_info("USER", &user_free, &user_total, &user_percent);
    heap_info("GDI",  &gdi_free,  &gdi_total, &gdi_percent);
    progmgr_aboutbox();
    OkMsgBox("System Resources",
        "USER heap: %u bytes free out of %u (%u%% free)\n"
        "GDI heap: %u bytes free out of %u (%u%% free)\n"
        "Free system resources: %u%%\n",
            user_free, user_total, user_percent,
            gdi_free, gdi_total, gdi_percent,
            min(user_percent, gdi_percent));
}





Example 2: The same utility as in Example 1, but this time written with
the Realizer BASIC development environment for Windows.

' SYSTRES.RLZ -- System Resources
' run-time dynamic linking to Windows API
external "kernel" func GetHeapSpaces (word) as dword
external "kernel" func GetModuleHandle(pointer) as word
external "user" func FindWindow(pointer, pointer) as word
external "user" proc PostMessage(word, word, word, dword)

func get_free(modname)
    heap_space = GetHeapSpaces(GetModuleHandle(modname))
    free = heap_space mod 65536         ' LOWORD
    total = Floor(heap_space / 65536)   ' HIWORD
    percent = 100 * free / total
    Print #1; modname, "heap: ", free, " bytes free out of ", total;
    Print #1; " (", percent, "%)"
    return percent
end func

WM_COMMAND = 273     ' 111h (yuk! no hex!)
HELP_ABOUT = 903     ' 387h

' pull down Program Manager Help About... box
progmgr = FindWindow("Progman", Pointer(0))
if progmgr = 0 then 
    Shell "progman", _Minimize
    progmgr = FindWindow("Progman", Pointer(0))
end if
PostMessage(progmgr, WM_COMMAND, HELP_ABOUT, 0)

LogNew(1; "System Resources")
user_percent = get_free("USER")
gdi_percent = get_free("GDI")
Print #1; "System Resources: ", min(user_percent, gdi_percent), "% free"
LogControl(_Show)




Example 3: "hello world!" using the Oriel graphical batch language

{ HELLO.ORL -- "hello world" for Oriel }

UseCaption("Hello")
SetMenu("&File", IGNORE, "E&xit", Do_Exit, ENDPOPUP)
UseFont("Roman", 0, 24, BOLD, NOITALIC, NOUNDERLINE, 64, 0, 0)
DrawText(10, 10, "Hello world!")
WaitInput()
Do_Exit:
    End