DDT SourceCode

[Lance Edmonds]

CONTROL ADD SCROLLBAR syntax does allow you to specify a callback, but the callback is not able to be utilized.

Instead, you intercept %WM_VSCROLL (for %SBS_VERT controls) or %WM_HSCROLL (for %SBS_HORZ) controls in the dialog callback, just like you would do with normal applications

#COMPILE EXE
#INCLUDE "WIN32API.INC"
 
%SBSTEPS = 9 ' 9 unique STEP positions in the scrollbar
%ID_SCROLL = 102
 
CALLBACK FUNCTION DlgCallback
    STATIC SI AS SCROLLINFO
      
    SELECT CASE CBMSG
        CASE %WM_INITDIALOG
            SI.cbSize = LEN(SI)
            SI.fMask  = %SIF_ALL
            SI.nMin   = 1
            SI.nMax   = 10 * %SBSTEPS ' 10 * 9 = 90 possible positions (1 to 90)
            SI.nPage  = (SI.nMax - SI.nMin) / %SBSTEPS
            SI.nPos   = (SI.nMax - SI.nMin) \ 2
            CONTROL SEND CBHNDL, %ID_SCROLL, %SBM_SETSCROLLINFO, %FALSE, VARPTR(SI)
 
        CASE %WM_COMMAND
            IF CBCTLMSG = %BN_CLICKED THEN
                MSGBOX "You clicked a button! (Button ID=" & STR$(CBCTL) & ")"
                DIALOG END CBHNDL, 1
            END IF
  
        CASE %WM_VSCROLL
            SELECT CASE LOWRD(CBWPARAM)
                CASE %SB_LINEDOWN
                    INCR SI.nPos
                CASE %SB_PAGEDOWN
                    SI.nPos = SI.nPos + Si.nPage
                CASE %SB_LINEUP
                    DECR SI.nPos 
                CASE %SB_PAGEUP
                    SI.nPos = SI.nPos - Si.nPage
                CASE %SB_THUMBPOSITION, %SB_THUMBTRACK
                    SI.nPos = HIWRD(CBWPARAM)
                CASE ELSE
                    EXIT FUNCTION
            END SELECT
 
            ' Ensure range is correct
            SI.nPos = MAX&(Si.nMin, MIN&(SI.nPos, Si.nMax - Si.nPage + 1))
 
            ' Update the scroll bar
            Si.fMask = %SIF_POS
            CONTROL SEND CBHNDL, %ID_SCROLL, %SBM_SETSCROLLINFO, %TRUE, VARPTR(Si)
            FUNCTION = 1
    END SELECT
END FUNCTION
 
FUNCTION PBMAIN
    DIM hdlg AS LONG
    DIALOG NEW 0, "SCROLLBAR Test By Lance Edmonds",,, 200, 100, %WS_SYSMENU OR %WS_CAPTION TO hDlg
    CONTROL ADD BUTTON, hDlg, 100, "Button 1", 10, 10, 50, 14
    CONTROL ADD BUTTON, hDlg, 101, "Button 2", 10, 31, 50, 14
    CONTROL ADD SCROLLBAR, hDlg, %ID_SCROLL, "", 190, 0, 10, 100, %SBS_VERT OR %SBS_RIGHTALIGN
    DIALOG SHOW MODAL hDlg CALL DlgCallback
END FUNCTION

* Posted to the Source Code forum too.

------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Paul Dwyer]

Lance,

Thanks for the info, I looked up the API functions and I get the idea however I can't seem to use it like this"

Control Add ScrollBar, hfrm_ByteMaster&,  %HSCR_BYTEMARKER,  "", 72, 14, 154, 8, %WS_CHILD Or %WS_VISIBLE Or %SBS_HORZ  Call HSCR_BYTEMARKER

Can't I use it lake the other "ADD CONTROL" functions with the CALL statement? This help file gap is most inconvenient as the scrollbar looks to work differently from the others !!

There was almost no code doing a search, just a few tantalising tips



------------------
Paul Dwyer
Network Engineer
Aussie in Tokyo

[Lance Edmonds]

The actual CONTROL ADD SCROLLBAR statement is the same as the other CONTROL ADD statements:

CONTROL ADD SCROLLBAR, hDlg, id, text$, x, y, xx, yy, style, exstyle

Your callback will receive standard %WM_VSCROLL or %WM_HSCROLL messages. From that point, you need to use the SetScrollInfo() and GetScrollInfo() API's to set and get the scroll bar information as with conventional scrollbars. Just remember to use the %SB_CTL flag, since a DDT SCROLLBAR is a child control, rather than "part of the dialog".

Search the BBS for "SetScrollInfo" and you should find some example code.


------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Paul Dwyer]

Does anyone have any source code for a DDT scroll bar? There seems to be a large hole in my PB6 help file.

Apparently you can use:

Control Add Scrollbar

but then what??

Thanks

PS, Lance, is it my imagination or is the PB website been slower over the last couple of weeks?


------------------
Paul Dwyer
Network Engineer
Aussie in Tokyo