Using the Scroll-Bar Range and Position

You can initialize the current value and range of a scroll bar to non-default values by sending the SBCDATA structure with class-specific data for a call to WinCreateWindow:

    #define ID_SCROLL_BAR 1

    SBCDATA sbcd;
    HWND hwndScroll,hwndClient;

    /* Set up scroll-bar control data.                     */
    sbcd.posFirst = 200;
    sbcd.posLast  = 400;
    sbcd.posThumb = 300;

    /* Create the scroll bar.                              */
    hwndScroll = WinCreateWindow(hwndClient,
        WC_SCROLLBAR,
        (PSZ) NULL,
        SBS_VERT | WS_VISIBLE,
        10, 10,
        20, 100,
        hwndClient,
        HWND_TOP,
        ID_SCROLL_BAR,
        &sbcd,                     /* Class-specific data  */
        NULL);

    /* Set the scroll-bar value and range. */

    WinSendMsg(hwndScroll, SBM_SETSCROLLBAR,
        (MPARAM)300,
        MPFROM2SHORT(200, 400));

You can read a scroll-bar value by sending it an SBM_QUERYPOS message:

    USHORT usSliderPos;

    /* Read the scroll-bar value. */
    usSliderPos = (USHORT) WinSendMsg(hwndScroll,
        SBM_QUERYPOS, (MPARAM) NULL, (MPARAM) NULL);

Similarly, you can set a scroll-bar value by sending an SBM_SETPOS message:

    /* Set the vertical scroll-bar value. */
    WinSendMsg(hwndScroll, SBM_SETPOS, (MPARAM)300, (MPARAM) NULL);

You can read a scroll-bar range by sending it an SBM_QUERYRANGE message:

    MRESULT mr;
    USHORT  usMinimum, usMaximum;

    /* Read the vertical scroll-bar range.                               */
    mr = WinSendMsg(hwndScroll, SBM_QUERYRANGE, (MPARAM) NULL, (MPARAM) NULL);

    usMinimum = SHORT1FROMMR(mr);            /* minimum in the low word  */
    usMaximum = SHORT2FROMMR(mr);            /* maximum in the high word */