how to determine if a scrollbar exists (Listview)

[Bill Scharf]

Hello,

I am looking for a way to determine if a scrollbar exists on a listView control. I tried this:

LOCAL si AS SCROLLINFO
LOCAL retval, w, h AS LONG
              si.cbSize = SIZEOF(si)
              si.fMask  = %SIF_ALL
              retval= getscrollinfo(GetDlgItem(hdlg, %ID_ListView), %SB_HORZ,  si)

This did not work. I would think that if there is no scroll bar, then the "revtal" variable would be zero--but it is 1. Then I thought that maybe there is some variable in the scrollinfo structure that could be used. However, I found none. The nMax and nMin both have strange values although there is no scrollbar?!?
The next attempt was to see how long the rect of one of the listview's item is:

local rc as rect, hlv as long
              CONTROL HANDLE CBHNDL, %ID_LIstView TO hLV
              rc.nleft = %LVIR_BOUNDS
              SendMessage(hlv, %LVM_GETITEMRECT, 1, VARPTR(rc))

I thought if the rect's length is as wide as the controls's width, then that might signal no scrollbar. Oddly enough, it appears that when I combine both attempts then I see something that might work. The scrollinfo.nMax is just a pixel shorter than the rc.nright. So maybe:

IF scrollinfo.nMax + 1 = (rect.NRight - Rect.NLeft) then
  'there is no scrollbar
else
  'there is a scrollbar
end if

Does this make sense? Can somebody think of a better way of doing it?

I have thought of looping through all the columns to total the columns' widths and then comparing that do the size of the control; however, that seems like a guess and check idea that ignores any scrollbar data. Any comments or insight would be greatly appreciated?

[Michael Mattias]

Are you sure you can't learn whatever it is you are trying to learn without mucking about trying to figure out if the scrollbar is visible?

I mean, you can use Listview_Get[SUB]ItemRect for any row and/or column.. that is automatically adjusted for the presence/absence of a scrollbar.

???

For that matter, if ListView_GetItemRect does not return the same width or height as does GetClientRect(), you may assume the listview's vertical and/or horizontal scroll bars are in play. (I'm pretty sure of that, but you'll have to give it a try)

[Bill Scharf]

No, I am not sure. It turns out that my above assmption is wrong.

The greater and more complex underlying issue is back to a previous post about parallel scrolling listviews. If one listview has a horizontal scrollbar then windows automatically makes the veritcal scrollbar one row bigger. Let me show you this example:

#COMPILE EXE
#DIM ALL
#REGISTER ALL

%USEMACROS = 1
#INCLUDE "h:\source08\winapi\WIN32API.INC"
#INCLUDE "h:\source08\winapi\COMMCTRL.INC"

%ID_LVA_LV          = 100       ' Main listview identifier #1
%ID_LVB_LV          = 200       ' Main listview identifier #2
%IDTEST             = 300
GLOBAL hDlg, hDlgLv AS DWORD
GLOBAL h1, h2 AS LONG

'------------------------------------------------------------------------------
' Listview Subclass Procedure
' This subclass callback is for both listivews, despite the fact that they have
'      two different parent dialogs.
'------------------------------------------------------------------------------
CALLBACK FUNCTION ListView_SubclassProc
  STATIC sbUpdating AS BYTE
  STATIC ControlID, secondaryID, ControlHdlg, SecondaryHDLG, hctl, hctl2 AS LONG
  LOCAL i AS LONG
  LOCAL ms_lvi AS LV_ITEM

  SELECT CASE CBMSG

         CASE %WM_VSCROLL, %WM_MOUSEWHEEL , %WM_KEYFIRST TO %WM_KEYLAST, %WM_MOUSEFIRST TO %WM_MOUSELAST'Note HSCROLL is not needed
                    'the left ListView should not be allowed to scroll right
                    IF CBMSG = %WM_KEYDOWN AND CBWPARAM = %VK_RIGHT AND GetDlgCtrlID(CBHNDL) = %ID_LVA_LV THEN'
                        EXIT FUNCTION
                    END IF
                    ControlID   =IIF&(GetDlgCtrlID(CBHNDL) = %ID_LVA_LV, %ID_LVA_LV, %ID_LVB_LV)
                    secondaryID = IIF&(GetDlgCtrlID(CBHNDL) = %ID_LVA_LV, %ID_LVB_LV, %ID_LVA_LV)
                    ControlHdlg = IIF&(GetDlgCtrlID(CBHNDL) = %ID_LVA_LV, hDlgLv, hdlg)
                    SecondaryHDLG =  IIF&(GetDlgCtrlID(CBHNDL) = %ID_LVB_LV, hDlgLv, hdlg)
                    'post a custom message.  THis allows all the scrolling to complete
                    'without this, the scrolling will trigger before it is complete and you might be off by 1 row
                    PostMessage CBHNDL, %WM_USER + 401, 0, 0

         CASE %WM_USER + 401
             LOCAL rc1 AS RECT, rc2 AS RECT
             rc1.nLeft = %LVIR_BOUNDS
             CONTROL HANDLE ControlHdlg, ControlID TO hctl
             CONTROL HANDLE SecondaryHDLG, secondaryID TO hctl2
             'find how far down the initiating control is scrolled
             SendMessage hctl, %LVM_GETITEMRECT, 0, VARPTR(rc1)
             'find how far down the secondary control is
             rc2.nLeft = %LVIR_BOUNDS
             i=SendDlgItemMessage (SecondaryHDLG,secondaryID,%LVM_GETITEMRECT, 0, VARPTR(rc2))
             'scrolling the secondary control to where the initiating control is
             i=SendDlgItemMessage (SecondaryHDLG, secondaryID, %LVM_SCROLL, 0,rc2.nTop - rc1.nTop)
             'get the selected one from the initiating control and select the same one in the secondary control
              i=ListView_GetNextItem(hctl, -1, %LVNI_FOCUSED OR %LVNI_SELECTED)
              IF i > -1 THEN'select the other one
                            ms_lvi.stateMask = %LVIS_FOCUSED OR %LVIS_SELECTED
                            ms_lvi.state = %LVIS_FOCUSED OR %LVIS_SELECTED
                            SendMessage hctl2, %LVM_SETITEMSTATE, -1, VARPTR(ms_lvi)
                            SendMessage hctl2, %LVM_SETITEMSTATE, i, VARPTR(ms_lvi)
              END IF

         CASE %WM_DESTROY
              FUNCTION = CallWindowProc(GetWindowLong(CBHNDL, %GWL_USERDATA), CBHNDL, CBMSG, CBWPARAM, CBLPARAM)
              SetWindowLong CBHNDL, %GWL_WNDPROC, GetWindowLong(CBHNDL, %GWL_USERDATA)
              EXIT FUNCTION

  END SELECT

  FUNCTION = CallWindowProc(GetWindowLong(CBHNDL, %GWL_USERDATA), CBHNDL, CBMSG, CBWPARAM, CBLPARAM)
END FUNCTION

'------------------------------------------------------------------------------
' Main dialog callback procedure
'------------------------------------------------------------------------------
CALLBACK FUNCTION dlgMain
  LOCAL i AS LONG, lvi AS LV_ITEM, lvc AS LV_COLUMN, zText AS ASCIIZ * 1024, rc AS RECT

  SELECT CASE CBMSG

         CASE %WM_INITDIALOG
              ' Prepare example listview items...
              lvi.mask    = %LVIF_TEXT
              lvi.pszText = VARPTR(zText)
              FOR i = 1 TO 24
                  lvi.iItem = i-1
                  zText     = STR$(i)+":00 " + "Appointment"
                  CONTROL SEND CBHNDL, %ID_LVB_LV, %LVM_INSERTITEM, 0, VARPTR(lvi)
                  zText     = STR$(i)+":00"
                  CONTROL SEND hDlgLv, %ID_LVA_LV, %LVM_INSERTITEM, 0, VARPTR(lvi)
              NEXT i
            ' Set column info...
              GetClientRect GetDlgItem(CBHNDL, %ID_LVb_LV), rc
              zText       = "Employee2"
              lvc.mask    = %LVCF_WIDTH OR %LVCF_TEXT
              lvc.pszText = VARPTR(zText)
              lvc.cx      = rc.nRight-2
              CONTROL SEND CBHNDL, %ID_LVB_LV, %LVM_INSERTCOLUMN, 0, VARPTR(lvc)
              zText       = "Employee1"
              CONTROL SEND CBHNDL, %ID_LVB_LV, %LVM_INSERTCOLUMN, 0, VARPTR(lvc)
              zText       = "Time"
              CONTROL SEND hDlgLv, %ID_LVA_LV, %LVM_INSERTCOLUMN, 0, VARPTR(lvc)
               FOR i = 0 TO 24
                     ztext = "Another appt at" + STR$(i+1) + ":00"
                     ListView_SetitemText(h1, i, 1, ztext)
               NEXT i
              ' Subclass listviews
              SetWindowLong GetDlgItem(hDlgLv, %ID_LVA_LV), %GWL_USERDATA, SetWindowLong(GetDlgItem(hDlgLv, %ID_LVA_LV), %GWL_WNDPROC, CODEPTR(ListView_SubclassProc))
              SetWindowLong GetDlgItem(CBHNDL, %ID_LVB_LV), %GWL_USERDATA, SetWindowLong(GetDlgItem(CBHNDL, %ID_LVB_LV), %GWL_WNDPROC, CODEPTR(ListView_SubclassProc))

              
         CASE %WM_COMMAND
              ' Exit program...
              IF (CBCTL = %IDOK) AND (CBCTLMSG = %BN_CLICKED) THEN DIALOG END CBHNDL
              IF (CBCTL = %IDTEST) AND (CBCTLMSG = %BN_CLICKED) THEN
                  checkit(CBHNDL)
              END IF
         CASE %WM_SIZE
             'LOCAL dlgxx, dlgyy AS LONG
             'IF CBLPARAM<>%SIZE_MINIMIZED THEN
             '   DIALOG GET SIZE CBHNDL TO DlgXX, DlgYY
             '   CONTROL SET SIZE CBHNDL, %ID_LVB_LV  , dlgxx-20,129
             'end if
             

  END SELECT

END FUNCTION
'------------------------------------------------------------------------------
' Secondary callback procedure
'------------------------------------------------------------------------------
CALLBACK FUNCTION dlgMain2
      'subclassing this dialog's ListView could go here if you wanted...but why not put them in the same place
END FUNCTION

'------------------------------------------------------------------------------
' Program Start Point
'------------------------------------------------------------------------------


FUNCTION PBMAIN
  LOCAL lStyle AS LONG
  DIALOG NEW 0, "Parallel ListView Test", , , 250, 153, %DS_MODALFRAME OR %WS_CAPTION OR %WS_SYSMENU OR %WS_THICKFRAME OR %WS_POPUP TO hDlg
  DIALOG NEW hDlg, "", 0, 0, 65-2, 130-3-10, %WS_CHILD OR %WS_VISIBLE TO hDlgLv

  CONTROL ADD $WC_LISTVIEW, hDlgLv, %ID_LVA_LV, "", 0, 0, 75, 129,  %WS_CHILD OR %WS_VISIBLE OR _
                %WS_TABSTOP OR %LVS_REPORT OR %LVS_SHOWSELALWAYS OR %LVS_SINGLESEL, %WS_EX_LEFT OR _
                %WS_EX_CLIENTEDGE OR %WS_EX_RIGHTSCROLLBAR
  CONTROL ADD $WC_LISTVIEW, hDlg, %ID_LVB_LV, "", 64, 0, 125, 129,  %WS_CHILD OR %WS_VISIBLE OR _
                %WS_TABSTOP OR %LVS_REPORT OR %LVS_SHOWSELALWAYS OR %LVS_SINGLESEL, %WS_EX_LEFT OR _
                %WS_EX_CLIENTEDGE OR %WS_EX_RIGHTSCROLLBAR
  CONTROL HANDLE hDlgLv, %ID_LVa_LV TO h2
  CONTROL HANDLE hDlg, %ID_LVb_LV TO h1
  CONTROL ADD BUTTON, hDlg, %IDOK, "Exit", 100, 135, 50, 15
  CONTROL ADD BUTTON, hDlg, %IDtest, "test", 160, 135, 50, 15
  'The listviews lack style...so let's add styles
  '  This is done separately and after all controls are added just so I could play around with various styles
    lStyle = ListView_GetExtendedListViewStyle(h2)
    ListView_SetExtendedListViewStyle(h2, lStyle OR %LVS_EX_FULLROWSELECT _
        OR %LVS_EX_GRIDLINES)
    lStyle = ListView_GetExtendedListViewStyle(h1)
    ListView_SetExtendedListViewStyle(h1, lStyle OR %LVS_EX_FULLROWSELECT _
        OR %LVS_EX_GRIDLINES)

  DIALOG SHOW MODELESS hDlgLv CALL dlgMain2
  DIALOG SHOW MODAL hDlg CALL dlgMain
END FUNCTION


FUNCTION checkit(hdlg AS LONG) AS LONG
LOCAL si AS SCROLLINFO
LOCAL billstest, w, h, hlv, ww, hh AS LONG
LOCAL rc AS rect

              si.cbSize = SIZEOF(si)
              si.fMask  = %SIF_ALL
              billstest = getscrollinfo(GetDlgItem(hdlg, %ID_LVB_LV), %SB_HORZ,  si)
              SLEEP 1
              IF si.nmax = 0 AND si.nmin = 0 THEN
                        MSGBOX "no scroll bar"
              END IF
              CONTROL GET SIZE hdlg, %ID_LVB_LV TO w , h
              SLEEP 1
              CONTROL HANDLE hdlg, %ID_LVB_LV TO hLV
              'ListView_GetItemRect hlv&, 1, rc, %LVIR_BOUNDS
              rc.nleft = %LVIR_BOUNDS
              SendMessage(hlv, %LVM_GETITEMRECT, 1, VARPTR(rc))
               SLEEP 1
              DIALOG UNITS hdlg, w, h TO PIXELS ww, hh
              SLEEP 1
              'if si.nmax + 1 = (rc.nright-rc.Nleft) then
              '      msgbox "no scrollbar"
              'end if
              'if si.npage = si.NMax -1 then
              '      msgbox "no scrollbar"
              'end if
              IF (rc.nRight+20-rc.Nleft) > ww THEN
                    MSGBOX "scroll bar"
              END IF
END FUNCTION

If you compile this sample program then the right-hand side listview scrolls with the left-hand side listview--no problems. But obviously I have accounted for the scroll bar by making the "employee" listivew a bit longer. Now if you uncomment these lines:

             LOCAL dlgxx, dlgyy AS LONG
             IF CBLPARAM<>%SIZE_MINIMIZED THEN
                DIALOG GET SIZE CBHNDL TO DlgXX, DlgYY
                CONTROL SET SIZE CBHNDL, %ID_LVB_LV  , dlgxx-20,129
             END IF

then run the code again, you will see no scrollbar. I can now scroll the time listview down to "24:00" while on the same line the employee listview is at "23:00". I have thought of several senarios that might work to correct this, but each one has boiled down to working with the scrollbar or without the scrollbar.
As always, I am open to any ideas. I have a lot of work to do and am trying to get this fixed ASAP.



Right now (as you can see from the code above) I am exploring if the item's rect is bigger than the control's width. After lots of "guess and check" it appears that I have to adjust it by 20. On my VIsta Business machine this will work:
IF (ItemRect.nRight+20-ItemRect.Nleft) > widthOfControl THEN
MSGBOX "scroll bar"
END IF
That offset makes me think it might be theme or OS dependent, so I am not sure of this solution either.

Any other ideas or obvious holes in the logic?

[Eric Pearson]

Bill --

I spent well over an hour with your code, and I'm pretty confused.

To make it easier for other people to help you, I'd suggest making your variable and equate names more descriptive and consistent. For example...

CONTROL HANDLE hDlgLv, %ID_LVa_LV TO h2
CONTROL HANDLE hDlg, %ID_LVb_LV TO h1

A is 2 and B is 1? That makes it much more difficult to keep them straight. Maybe use A and B for everything, or better yet use Main and Child. Left and Right?

What does Lv mean?

hctl? hctl2?

If you make your source code more human-readable, more humans will be able to help you.

I agree with MCM: I don't think you need to detect the scroll bar. That's a hack. If you straighten out the main code, the problem will disappear.

-- Eric

[Michael Mattias]

I synched up a couple of listviews HORIZONTALLY by subclassing and catching WM_HSCROLL. Never even thought about scrollbars.

I would think you could do the same catching WM_VSCROLL.

[Dominic Mitchell]

Use the following code to check if scrollbars are visible in a window:

IF (GetWindowLong(hWndListView, %GWL_STYLE) AND %WS_VSCROLL) THEN
  ' Vertical scrollbar is visible
END IF  

IF (GetWindowLong(hWndListView, %GWL_STYLE) AND %WS_HSCROLL) THEN
  ' Horizontal scrollbar is visible
END IF

[Dominic Mitchell]

You can also use the GetScrollBarInfo function.

[Bill Scharf]

Thank you all for your help.
Eric-
I am sorry my code example was not in very good style. I admit it is very bad. This is just a sample quickly through together because the real app is about 10,000 lines. The "1" and "2" notation was to denote which listview was the originator of the message. The "2" was the listview which needed to get the same message. The "A" and "B" were to denote which listviews were which. The "A" is on the left and "B" on the right. "LV" means listview. "hctl" is what I (and I thought many others?) used for "handle of the control." I thought this was like 'hdlg' was common for the handle of the dialog. I appreciate your help and your time.

MCM-
As for synching to listviews using only the WM_VSCROLL command, this will fail to keep the listviews lined up if
1. The listviews have a different amount of rows OR
2. The listviews have the same number of rows, but one listview has a horizontal scrollbar and one does not.
My problem is that the listview columns for the left-most listview are user-controlled. The user could have 1 or 50. So the user may have a scrollbar or not.

Dominic-
I have tried the GetScrollBarInfo function and had no success. Maybe I don't know what to look for...? I have tried:

local si as SCROLLINFO
x= getscrollinfo(GetDlgItem(hdlg, %ID_LISVIEW), %SB_HORZ,  si)

I test "x" and it is "1" every time. So I test si.nMax and si.nMin and I cannot determine anything to denote "no scrollbar." Then I think I went insane and started tying to find relationships between the scrollinfo structure, the width of the control, and the rect of the listview item. That is how I ended up with this:

              IF (RectOfListViewItem.nRight+20-RectOfListViewItem.Nleft) > Width of control THEN
                    MSGBOX "scroll bar"
              END IF

Anyway, I will look into (GetWindowLong(hWndListView, %GWL_STYLE) AND %WS_HSCROLL) and I thank you very much.

My thought was that detecting a scrollbar would allow me to resize the listview to account for that extra line of scrolling that windows adds. After hours and hours I have found another way around this, but it is a bad hack. I will post that separately.

[Bill Scharf]

Ok, this is is NOT a great solution, but does work. THe problem was that listview B (the one with a horizontal scrollbar) could scroll down another line. This is corrected if a message is sent to listview A. This is any message for which the subclassing procedure is trapping. So, I send an empty %WM_MOUSEMOVE to listView A and then the listview corrects itself. Here are the changes in the subclassing procedure:

CALLBACK FUNCTION ListView_SubclassProc
  STATIC sbUpdating AS BYTE
  STATIC ControlID, secondaryID, ControlHdlg, SecondaryHDLG, hctl, hctl2, correctIt AS LONG
  LOCAL i AS LONG
  LOCAL ms_lvi AS LV_ITEM

  SELECT CASE CBMSG

         CASE %WM_VSCROLL, %WM_MOUSEWHEEL , %WM_KEYFIRST TO %WM_KEYLAST, %WM_MOUSEFIRST TO %WM_MOUSELAST'Note HSCROLL is not needed
                    'the left ListView should not be allowed to scroll right
                    IF CBMSG = %WM_KEYDOWN AND CBWPARAM = %VK_RIGHT AND GetDlgCtrlID(CBHNDL) = %ID_LVA_LV THEN'
                        EXIT FUNCTION
                    END IF
                    ControlID   =IIF&(GetDlgCtrlID(CBHNDL) = %ID_LVA_LV, %ID_LVA_LV, %ID_LVB_LV)
                    secondaryID = IIF&(GetDlgCtrlID(CBHNDL) = %ID_LVA_LV, %ID_LVB_LV, %ID_LVA_LV)
                    ControlHdlg = IIF&(GetDlgCtrlID(CBHNDL) = %ID_LVA_LV, hDlgLv, hdlg)
                    SecondaryHDLG =  IIF&(GetDlgCtrlID(CBHNDL) = %ID_LVB_LV, hDlgLv, hdlg)
                    'post a custom message.  THis allows all the scrolling to complete
                    'without this, the scrolling will trigger before it is complete and you might be off by 1 row
                    PostMessage CBHNDL, %WM_USER + 401, 0, 0
                    debugprint ("cbmsg=" + STR$(CBMSG))
'*************Hack Starts here**********************
'I could have specified messages about selecting, scrolling, etc, but it seems 
'to catch everything if I just look for mousemove.
                    IF CBMSG <> %WM_MOUSEMOVE THEN
                        correctIt = 1
                    ELSE
                        correctIt = 0
                    END IF

         CASE %WM_USER + 401
             LOCAL rc1 AS RECT, rc2 AS RECT
             rc1.nLeft = %LVIR_BOUNDS
             CONTROL HANDLE ControlHdlg, ControlID TO hctl
             CONTROL HANDLE SecondaryHDLG, secondaryID TO hctl2
             'find how far down the initiating control is scrolled
             SendMessage hctl, %LVM_GETITEMRECT, 0, VARPTR(rc1)
             'find how far down the secondary control is
             rc2.nLeft = %LVIR_BOUNDS
             i=SendDlgItemMessage (SecondaryHDLG,secondaryID,%LVM_GETITEMRECT, 0, VARPTR(rc2))
             'scrolling the secondary control to where the initiating control is
             i=SendDlgItemMessage (SecondaryHDLG, secondaryID, %LVM_SCROLL, 0,rc2.nTop - rc1.nTop)
             'get the sel0ected one from the initiating control and select the same one in the secondary control
              i=ListView_GetNextItem(hctl, -1, %LVNI_FOCUSED OR %LVNI_SELECTED)
              IF i > -1 THEN'select the other one
                            ms_lvi.stateMask = %LVIS_FOCUSED OR %LVIS_SELECTED
                            ms_lvi.state = %LVIS_FOCUSED OR %LVIS_SELECTED
                            SendMessage hctl2, %LVM_SETITEMSTATE, -1, VARPTR(ms_lvi)
                            SendMessage hctl2, %LVM_SETITEMSTATE, i, VARPTR(ms_lvi)
              END IF
'***********Core of the Hack is here********************
              IF ControlID = %ID_LVB_LV AND CORRECTIT=1 THEN
'now we send a message to listview "A" so that everything will line up once again.
                    sendmessage hctl2, %WM_MOUSEMOVE, 0, 0
              END IF

         CASE %WM_DESTROY
              FUNCTION = CallWindowProc(GetWindowLong(CBHNDL, %GWL_USERDATA), CBHNDL, CBMSG, CBWPARAM, CBLPARAM)
              SetWindowLong CBHNDL, %GWL_WNDPROC, GetWindowLong(CBHNDL, %GWL_USERDATA)
              EXIT FUNCTION

  END SELECT

  FUNCTION = CallWindowProc(GetWindowLong(CBHNDL, %GWL_USERDATA), CBHNDL, CBMSG, CBWPARAM, CBLPARAM)
END FUNCTION

[Michael Mattias]

As for synching to listviews using only the WM_VSCROLL command, this will fail to keep the listviews lined up if
1. The listviews have a different amount of rows OR
2. The listviews have the same number of rows, but one listview has a horizontal scrollbar and one does not.

Huh?

If the two listview controls have different numbers of items (rows), they cannot be synched; at some point one listview is simply going to run out of rows.

And as long as you synch to the TOP row the presence of a horizontal scrollbar is moot... and why you'd even have a horizontal scrollbar in this case is a mystery.

Wait a minute...why are you using two separate listview controls instead of one listview control with more subitems (columns)?

I must be missing something.


MCM

[Bill Scharf]

MCM-

Thank you for your reponse. I will try to start from the beginning and give a quick overview:
1. I was given a project with many requires, among which are:
A. Use a listview as a grid-type control
B. No third-party tools or controls are allowed--only that which is in PB
C. The first column is time and the rest of the columns represent employees.
D. There can be 1 to 50 columns for employees.
E. The user must be able to scroll through the employee columns horizontally, but the time column must stay on the screen. I refer to this as the time column being "frozen" desipite the horizontal scrolling of the other columns.

2. Issues to overcome
A. There are no other PB controls that seem to be of any help.
B. To "freeze" the time column, I could try a few different approaches:
i. Constantly change the first column visible to be the time column. This does not work well as it will scroll a little, then jump.
ii. Use two different listviews with the same amount of lines and try to keep them synched vertically. This seemed to have no big draw-backs.
iii. Use dynamically changing labels. The labels could change as the employee listview scrolls. The problem is that the label itself cannot scroll.
C. In going with option ii above, I synched them vertically. It worked well, but not perfectly. The problem exists when one listview has a scrollbar and the other does not.

I think I need to stop here and try to draw a picture with words. Picture two listviews are the same size and shape. They are right beside each other. Each one is perfectly full. They have no scollbars, but are 1 pixel away in either direction from getting a scrollbar. Now make the column in listview #1 a pixel wider. Instantly you have a horizontal scrollbar. That scrollbar now covers up the bottom row of listview #1. That is where the problem is. Now, to see the bottom row, you must scroll down one row--but if you scroll down, then listview one is out of synch with listview 2.

The idea was that when a scrollbar exists, make the listview itself a row bigger, so that this cannot happen. Then the listviews will appear to always be the same size, and when a scrollbar appears, it will look like it is appearing underneath the listview instead of on the bottom row of the listview.

Does this make more sense? This time of the year is a lot of long hours, so my brian may be a little fried.

[Dave Biggs]

Listview with movable vertical and horizontal splitter windows

You might find some usefull ideas here..

http://www.powerbasic.com/support/pbforums/showthread.php?t=24702

[Michael Mattias]

You can also do it by making the employee listview control minus the built-in horizontal scrollbar, and adding a separate horizontal scrollbar UNDERNEATH that control.

Scroll the employee listview horizontally (Listview_Scroll) in response to notification messages from the standlone scrollbar, and vertically in response to scroll notifications from the time listview control.

I think the picture looks like

TIME     SMITH    JONES     BROWN   GREEN   JOHNSON   WILSON .....
8:00          X
9:00                    X
10:00  
.....
             >[ Scrollbar to scroll employees horizontally                           ]<

[Dominic Mitchell]

I have tried the GetScrollBarInfo function and had no success. Maybe I don't know what to look for...? I have tried:

local si as SCROLLINFO
x= getscrollinfo(GetDlgItem(hdlg, %ID_LISVIEW), %SB_HORZ,  si)

GetScrollInfo <> GetScrollBarInfo

[Bill Scharf]

Thank you all for your suggestions. I have spent days searching the PB forums on this project and would have pulled my hair out otherwise. I think MCM's separate scrollbar idea is good as well. The issue still exists though--when should the listview control have a scroll bar and when should it not. Our users would not want a scrollbar there which did nothing. I would still have to find a way to show/hide it when needed.

Dominic
I am sorry for mistyping "getscrollinfo." I did use that function and could not figure out how to tell when no scrollbar exists. The function always returns 1 with or without a scrollbar, and I could not find any member of the si structure that could help. Do you know how to tell if a scrollbar exists from what is returned by GetScrollInfo?

[Cliff Nichols]

The back of my mind tells me this is like syncing 2 listviews in VB in the days of ole'

(Look out when a glimmer from the darkness of the back of my mind comes to light)

If I remember right, then vbnet.mvps.org might be what you need to port to PB

[Dominic Mitchell]

I will have a look at your code later if I find the time.

I am sorry for mistyping "getscrollinfo." I did use that function and could not figure out how to tell when
no scrollbar exists. The function always returns 1 with or without a scrollbar, and I could not find any
member of the si structure that could help. Do you know how to tell if a scrollbar exists from what
is returned by GetScrollInfo?

Why are you using GetScrollInfo? This function is not what you want to use to determine the visible state
of scrollbars.
Either Check the window style as shown previously, or use the GetScrollBarInfo function.
For example,

  LOCAL tsbi        AS SCROLLBARINFO
  LOCAL hWndList    AS DWORD
  LOCAL fVert       AS LONG
  LOCAL fHorz       AS LONG
  
  hWndList = GetDlgItem(hWndParent, %IDC_FORM1_LISTVIEW1)

  tsbi.cbSize = SIZEOF(tsbi)
  GetScrollBarInfo hWndList, %OBJID_HSCROLL, tsbi
  fHorz = ((tsbi.rgstate(0) AND %STATE_SYSTEM_INVISIBLE) <> %STATE_SYSTEM_INVISIBLE)
  GetScrollBarInfo hWndList, %OBJID_VSCROLL, tsbi
  fVert = ((tsbi.rgstate(0) AND %STATE_SYSTEM_INVISIBLE) <> %STATE_SYSTEM_INVISIBLE)
  
  MSGBOX "horz,vert:" + FORMAT$(fHorz) + "," + FORMAT$(fVert)

[Michael Mattias]

when should the listview control have a scroll bar and when should it not. Our users would not want a scrollbar there which did nothing. I would still have to find a way to show/hide it when needed.

You just hide the separate scrollbar control if the total width of the data columns (add 'em up!) is less than the client width of the employee listview control.

You know this when you insert the columns. If they resize the listview control just check again on WM_SIZE. (not that I can envision a user-resizeable child control for this application). If they resize the entire window and you adjust that control's width to fit, just check the column widths again.

[Bill Scharf]

Thank you all. I am truly grateful! I have multiple options now. Thank you thank you! I will report back with which solution works best for our app.

[Michael Mattias]

One other thing I forgot... if your user resizes the columns of the employee listview by dragging the divider in the header control, you'll have to detect that to see if the total column widths are now greater/less than the control width so you can hide or show the separate scrollbar control.

Here's some code to get you started.

I think you will want to detect "HDN_ENDTRACK" only instead of HDN_TRACK, since if the user is dragging the divider he can't be using the scrollbar at the same time so showing/hiding the scrollbar can be done when he finishes dragging.

#IF NOT %DEF(%LVUNION)
 UNION LvUnion
    NMHDR  AS NMHDR
    NMLV   AS NMLISTVIEW
    NMIA   AS NMITEMACTIVATE
    LVDI   AS LV_DISPINFO
    LVCD   AS NMLVCUSTOMDRAW
    NMLVK  AS NMLVKEYDOWN
    NMTVDI AS TV_DISPINFO
    NMTV   AS NM_TREEVIEW
    ' NOTE NEXT IS NOT THE SAME AS NMHDR.
    HEADER AS NMHEADER
 END UNION
 %LVUNION = 1
#ENDIF

FUNCTION DlgProc .....


LOCAL pLVU AS LVUNION PTR 

   SELECT CASE AS LONG uMSG 


     CASE %WM_NOTIFY
         pLVU =  lparam 

         IF @plvu.nmhdr.idFrom = %ID_HEADER THEN
              SELECT CASE AS LONG @plvu.nmhdr.code
                  CASE %HDN_TRACK   ' pNMHEader
                      STDOUT "HDN_TRACK NOTFICATION FROM HEADER iTiem =" & FORMAT$(@pLVU.header.iItem)
                      ' item is always the item on the left of the divider
                      ' check out cxy, I should see it shirink and grow
                      IF (@[email protected] AND %HDI_WIDTH) THEN
                          STDOUT "Cxy=" & FORMAT$(@[email protected])
                          ' return the new width of column iItem here.
                      END IF
                      ' set the listview column to match the header...
                      'IF @plvu.HEADER.iItem = 0  THEN
                          Listview_SetColumnWidth GetDlgITem(hWnd, %ID_LV), @plvu.HEADER.iItem, @[email protected]
                     ' END IF
                      ' WORKS PERFECTLY! for column zero
                      ' also seems to be working for all columns.

             ......

MCM