CA - Visual Objects Hello World Example

TEXTBLOCK HELLOWIN.C  --  (c) Charles Petzold, 1992
/*--------------------------------------------------------
   HELLOWIN.C -- Displays "Hello, Windows" in client area
                 (c) Charles Petzold, 1992

   HELLOWIN.PRG - CA Visual Objects adaptation
                        John Forsberg, 1994
  --------------------------------------------------------*/


FUNCTION Start()

  STATIC szAppName := "HelloWin"            AS STRING
  LOCAL hWnd                                                      AS WORD
  LOCAL msg                                                         IS
_WINMSG
  LOCAL wndclass                                               IS
_WINWNDCLASS

  /* Parameters not received by VO */
  LOCAL hPrevinstance := _GetPrevInst()     AS WORD
  LOCAL hInstance          := _GetInst()               AS WORD
  LOCAL nCmdShow      := _GetCmdShow()  AS WORD

  IF hPrevInstance == 0

    wndclass.style         := _OR(CS_HREDRAW, CS_VREDRAW)
    wndclass.lpfnWndProc        := @WndProc()
    wndclass.cbClsExtra            := 0
    wndclass.cbWndExtra         := 0
    wndclass.hInstance              := hInstance
    wndclass.hIcon                      := LoadIcon (hInstance,
IDI_APPLICATION)
    wndclass.hCursor                 := LoadCursor (0, IDC_ARROW)
    wndclass.hbrBackground  := GetStockObject (WHITE_BRUSH)
    wndclass.lpszMenuName := ""
    wndclass.lpszClassName := szAppName

    RegisterClass (@wndclass)
  ENDIF

  hwnd := CreateWindow (szAppName, ;        // window class name
                 "The Hello Program", ;                        // window
caption
                 WS_OVERLAPPEDWINDOW, ;      // window style
                 CW_USEDEFAULT, ;                          // initial x
position
                 CW_USEDEFAULT, ;                          // initial y
position
                 CW_USEDEFAULT, ;                          // initial x
size
                 CW_USEDEFAULT, ;                          // initial y
size
                 0, ;
        // parent window handle
                 0, ;
        // window menu handle
                 hInstance, ;
// program instance handle
                NULL_PTR)                                            //
creation parameters

/*  Not in the book.  Add it if you prefer */
//  if hWnd = 0
//    return FALSE
//  endif

  ShowWindow (hwnd, nCmdShow)
  UpdateWindow (hwnd)

  WHILE (GetMessage (@msg, 0, 0, 0))
       TranslateMessage (@msg)
       DispatchMessage (@msg)
  END

  /* Not in the book.  Add it if you prefer */
  //  UnregisterClass ( szAppName, hInstance )
RETURN msg.wParam

FUNCTION WndProc (hwnd AS WORD, message AS WORD, wParam AS WORD, ;
                  lParam AS LONG) AS LONG  _WINCALL

     LOCAL hdc  AS WORD
     LOCAL ps   IS _WINPAINTSTRUCT
     LOCAL rect IS _WINRECT

     DO CASE
          CASE message == WM_PAINT
            hdc := BeginPaint (hwnd, @ps)

            GetClientRect (hwnd, @rect)

            DrawText (hdc, "Hello, Windows!", -1, @rect, ;
                      _OR(_OR(DT_SINGLELINE, DT_CENTER), DT_VCENTER))

            EndPaint (hwnd, @ps)
            RETURN 0L

          CASE message == WM_DESTROY
            PostQuitMessage (0)
            RETURN 0L

          ENDCASE

RETURN DefWindowProc (hwnd, message, wParam, lParam)