#define _TEST
#ifdef _TEST
change_screen_size(3)
=inkey(0)
change_screen_size(1)
=inkey(0)
change_screen_size(2)
inkey(0)
change_screen_size(3)
#endif


funct change_screen_size
 LPARAMETERS tnSize
 if type('tnSize') != 'N'
    if type('tnSize') == "C"
       tnSize = val(tnSize)
    else
       tnSize = 2   
    endif
       
 endif   
 tnSize = iif(empty(tnSize), 0, tnSize)
 do case
 case tnSize == 1
      ChangeRes(640, 480)
 case tnSize == 2
      ChangeRes(800, 600)
 case tnSize == 3
      ChangeRes(1024, 768)
 endcase
return
*

FUNC ChangeRes
    LPARAMETERS tnWidth, tnHeight
    LOCAL lnWidth, lnHeight, lnModeNum, lcDevMode
    DECLARE INTEGER EnumDisplaySettings   IN Win32API ;
            STRING lpszDeviceName,;
            INTEGER iModeNum, ;
            STRING @lpDevMode
    DECLARE INTEGER ChangeDisplaySettings IN Win32API ;
            STRING @lpDevMode, ;
            INTEGER dwFlags
    lnModeNum  = 0
    lcDevMode  = REPLICATE(CHR(0), 156)
    lnWidth    = IIF(EMPTY(tnWidth), 800, tnWidth)
    lnHeight   = IIF(EMPTY(tnHeight), 600, tnHeight)
    DO WHILE EnumDisplaySettings(NULL, lnModeNum, @lcDevMode) <> 0
        lnModeNum = lnModeNum +1
    ENDDO
    lcDevMode = STUFF(lcDevMode,  41, 4, LongToStr(1572864))
    lcDevMode = STUFF(lcDevMode, 109, 4, LongToStr(tnWidth))   && Width
    lcDevMode = STUFF(lcDevMode, 113, 4, LongToStr(tnHeight))  && Height
    ChangeDisplaySettings(@lcDevMode, 1) && Change res
ENDFUNC
*---

FUNC LongToStr
    LPARAMETERS lnLongVal
    LOCAL lnCnt, lcRetStr
    lcRetStr = ''
    FOR lnCnt = 24 TO 0 STEP -8
        lcRetStr = CHR(INT(lnLongVal/(2^lnCnt))) + lcRetStr
        lnLongVal = MOD(lnLongVal, (2^lnCnt))
    NEXT
    RETURN lcRetStr
ENDFUNC
*---