Announcement

**Michael Mattias** · 8 Apr 2008, 01:52 PM

want for when the user clicks the listview, that I can get the value of column 4 of the row they clicked and do something with that data

You can look for WM_NOTIFY/NM_CLICK. The selected item (row) is in NMITEMACTIVATE.iITem .. but only if the click occured where a selection occurs. (Full row select style on/off affects this).

Better (more reliable).....use Listview_HitTest against nmitemactivate.ptaction to know exactly where that click occurred.

OR.... if you want to do this on "change of selection" rather than on click .. eg, the user uses the arrow keys to navigate within the listview control (forget about the keyboard interface for a moment, did we?)......

Yes, you CAN use WM_NOTIFY/LVN_ITEMCHANGED... you are looking for a "state" change to LVIF_FOCUSED.. only one row is ever focused... and it not even need be in a selected state. (single- and multiple-selection listviews act differently).

(Just forget about Listview_GetNextITem, you don't need it at all).

MCM

**Shawn Anderson** · 8 Apr 2008, 02:14 PM

thanks, for now I just did this

Code:

        CASE %wm_notify
            udtNMListview = CBLPARAM
            SELECT CASE @udtNMListview.hdr.Code
                CASE %LVN_COLUMNCLICK
                    ' column heading is clicked
                    ' use later for sort?
                    
                CASE %nm_click
                    ' row clicked
                     lngIndex = ListView_GetNextItem( mainLV, - 1, %LVNI_SELECTED )
                     strName = LV_ReadItem( lngIndex, 3 )
                     retrieveRecord(strName)

            END SELECT

not as nice as what you suggested but I understand it enough so I can move on. The ability for keyboard selection is not necessary this time.
ListView needs a wrapper!

**Michael Mattias** · 8 Apr 2008, 03:12 PM

Code:

CASE %nm_click
                    ' row clicked

You were not paying attention, because IT AIN'T NECESSARILY SO!

Demo: Click on your listview control OUTSIDE the location of the rows.

Oops, huh?

Like your mama always told you, if it's worth doing, it's worth doing right.

This does Selected rather than focused, which is what I do with single-selection listviews:

Code:

#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
 END UNION
 %LVUNION = 1
#ENDIF
...

FUNCTION Window/DialogProc....

   LOCAL plvu AS LvUnion PTR

  SELECT CASE AS LONG wMsg 


         CASE %WM_NOTIFY
             plvu = lparam          ' always needed to do anything, whatever the control is.

             SELECT CASE AS LONG @plvu.nmhdr.idfrom
                  CASE %ID_LV      ' message from the listview 
                      SELECT CASE AS LONG @plvu.nmhdr.code 
                               CASE %LVN_ITEMCHANGED
                                   IF ISTRUE (@plvu.NMLV.uChanged AND %LVIF_STATE)  THEN 
                                        ' an item's state has changed
                                       ' Is that state change a selected/unselected state change?
                                       IF ISTRUE  (@plvu.nmlv.uNewState AND %LVIS_SELECTED)  THEN

                                       DO STUFF HERE

MCM

**Shawn Anderson** · 8 Apr 2008, 03:53 PM

that's true, but I'm pulling a value from the row.
If it is an empty string then I just ignore it.

Code:

FUNCTION  retrieveRecord(recordNumber AS STRING) AS LONG
    LOCAL sqlStatement AS STRING
    LOCAL errMsg AS STRING
    LOCAL d AS STRING
    LOCAL tST AS SYSTEMTIME

    IF recordNumber="" THEN EXIT FUNCTION

    sqlStatement = "select * from mainTable where quoteNumber="+recordNumber     
...... and so forth

no?

**Michael Mattias** · 8 Apr 2008, 05:55 PM

>If it is an empty string then I just ignore it.

You got me there.

I guess I'd forgotten how to program lazily^h^h^h^h^h^h like a Microsoft Visual Basic 'programmer'

Yes, I will have fries with that, thank you.

**BOB MECHLER** · 8 Apr 2008, 06:20 PM

For what it's worth, here is my wm_notify event handler. You may find some info here that is useful.

Code:

    CASE %WM_NOTIFY
        SELECT CASE CBCTL
          CASE 1005 '%RPTLISTVIEW
             CONTROL HANDLE CBHNDL, %RPTLISTVIEW TO hctrl&
             my_LpLvNm = CBLPARAM
             SELECT CASE @my_LpLvNm.hdr.code
               CASE %NM_DBLCLK
                 I = ListView_GetNextItem(BYVAL hctrl&, -1, %LVNI_SELECTED)
                 IF I > -1 THEN
                   GETLISTVIEWSELECT = I
                   NEW_FLAG = 0
                   MAC_WINPOS(idlg&)
                   ShowWindow idlg&, %SW_SHOW
                   DIALOG END CBHNDL,2 'simulate LOAD query
                 END IF
               CASE %NM_CLICK
                 I = ListView_GetNextItem(BYVAL hctrl&, -1, %LVNI_SELECTED)
                 IF I > -1 THEN
                   GETLISTVIEWSELECT = I
                 ELSEIF I = -1 THEN
                   tLVI.iSubItem = 0
                   tLVI.iItem    = 0
                   tLVI.STATE    = %LVIS_FOCUSED OR %LVIS_SELECTED
                   tLVI.stateMask = %LVIS_FOCUSED OR %LVIS_SELECTED
                   CONTROL SEND CBHNDL,CBCTL, %LVM_SETITEMSTATE, 0&, VARPTR(tLVI) 'don't highlight first row. Make them select
                   tLVI.STATE = 0
                   tLVI.stateMask = 0
                   I = ListView_GetNextItem(BYVAL hctrl&, -1, %LVNI_SELECTED)
                   GETLISTVIEWSELECT = I
                 END IF
               CASE %LVN_COLUMNCLICK
                 LV_COLUMNID = @my_LpLvNm.iSubItem
                 SELECT CASE PARSE$(FDA(LV_COLUMNID + 1),",",2)
                   CASE "C"
                     CDIRECTION = NOT CDIRECTION
                     IF CDIRECTION THEN
                       sortdir$ = "ascending"
                     ELSE
                       sortdir$ = "descending"
                     END IF
                   CASE "N"
                     NDIRECTION = NOT NDIRECTION
                     IF NDIRECTION THEN
                       sortdir$ = "ascending"
                     ELSE
                       sortdir$ = "descending"
                     END IF
                   CASE "D"
                     DDIRECTION = NOT DDIRECTION
                     IF DDIRECTION THEN
                       sortdir$ = "ascending"
                     ELSE
                       sortdir$ = "descending"
                     END IF
                 END SELECT
                 CONTROL SET TEXT CBHNDL,1006,"Sorting..."
                 ListView_SortItems(@my_LpLvNm.hdr.hwndFrom, CODEPTR(CompareFunc), my_LpLvNm)
                 CONTROL SET TEXT CBHNDL,1006,"Sorted " + sortdir$ + " by " + PARSE$(FDA(LV_COLUMNID + 1),",",1)
                 FixLParam(@my_LpLvNm.hdr.hwndFrom)
                 VKEY = 21
             END SELECT
             kp = CBLPARAM
             SELECT CASE @kp.hdr.code
               CASE %LVN_KEYDOWN
                 SELECT CASE @kp.wVKEY
                   CASE %VK_ADD
                     I = ListView_GetNextItem(BYVAL hctrl&, -1, %LVNI_SELECTED)
                     IF I > -1 THEN
                       GETLISTVIEWSELECT = I
                       MAC_WINPOS(idlg&)
                       ShowWindow idlg&, %SW_SHOW
                       DIALOG END CBHNDL,2 'simulate LOAD query
                     END IF
                   CASE %VK_DOWN
                     I = ListView_GetNextItem(BYVAL hctrl&, -1, %LVNI_SELECTED)
                     IF I > -1 THEN
                       GETLISTVIEWSELECT = I
                     END IF
                   CASE %VK_UP
                     I = ListView_GetNextItem(BYVAL hctrl&, -1, %LVNI_SELECTED)
                     IF I > -1 THEN
                       GETLISTVIEWSELECT = I
                     END IF
                 END SELECT
             END SELECT
        END SELECT

**Shawn Anderson** · 8 Apr 2008, 06:23 PM

like a Microsoft Visual Basic 'programmer'

AHHH! Cuts me to the quick man! CUTS ME TO THE QUICK! Ouch!

yeah I know

Thanks everyone.

**Cliff Nichols** · 8 Apr 2008, 08:19 PM

like a Microsoft Visual Basic 'programmer'

MCM...don't forget we were "lulled" into it, not knowing any better

The good part is, the ones that see the light, start wondering "Why do I do this?...How does it REALLY work? and more importantly WHY?

Maybe rare breeds, but rare breeds are what makes computing so great

**Michael Mattias** · 9 Apr 2008, 09:05 AM

For whatever it's worth, here are some functions I use.

The "get selection" gets the FIRST selected item, so it's only useful with single-select listviews. The "set" also sets the focused status, so while it will work with both single- and multi-select listviews, you need to be aware the focused item changes when you use it with a multi-select listview.

Code:

' Get the first selected row of a listview
FUNCTION ListView_GetSelection (BYVAL hWnd AS LONG) AS LONG
  FUNCTION = SendMessage(hWnd, %LVM_GETNEXTITEM, -1, %LVNI_SELECTED)
END FUNCTION
'selected status of a listview row to true 
FUNCTION ListView_SetSelection (BYVAL hWnd AS LONG, BYVAL Rowno AS LONG) AS LONG
  ListView_SetItemState hWnd, RowNo, &hFFFFFFFF, (%LVIS_SELECTED OR %LVIS_FOCUSED)
END FUNCTION

Yes, you could convert these to MACROs pretty easily, but these were created before MACROS were supported by the compilers, and if it ain't broke.....

MCM

**Michael Mattias** · 9 Apr 2008, 09:42 AM

As long as it seems to be "listview day..."

Here's an edited and commented version of the NM_CLICK processing I use to determine the row and column of a click on a listview control ..

Code:

 LOCAL plvu AS LVUNION PTR             ' <<<< LVUNION IN PRIOR POST ABOVE 
 LOCAL hti  AS AS LVHITTESTINFO        ' <<< IN COMMCTRL.INC

 SELECT CASE AS LONG wMSg   (or "CBMSG" for DDT'ers) 
  
    CASE  %WM_NOTIFY                                ' a message from one of the Common Controls  
         SELECT CASE AS LONG @pvlu.nmhdr.idFrom     ' which control is WM_NOTIFY from?
              CASE %ID_LISTVIEW
                 ' Ok, it's from that listview, now what is the specific notification? 
                  SELECT CASE  AS LONG @plvu.nmhdr.code 
              
                               CASE %NM_CLICK   ' returns NMIA
                                       ' hti.pt  = @plvu.nmia.ptAction              ' get real click pos
                                       ' above only valid with common controls 4.71 or higher.

                                       ' for generic, works regardless of Common Controls version:
                                       GetCursorPos        hti.pt
                                       ScreenToClient      hWnd, hti.pt

                                      ' test the point:
                                      iHit = Listview_SubItemHitTest (@plvu.nmhdr.hWndFrom, hti)
                                      ' and decide if I'm on the item:
                                      ' NOWHERE=in control client area, but not on any item
                                      IF ISTRUE (hti.flags AND %LVHT_NOWHERE) THEN
                                         Do whatever you do when user clicks not on a row
                                      ELSEIF ISTRUE (hti.flags AND %LVHT_ONITEM) THEN
                                          ROW (item)       ==> hti.iTem
                                          COLUMN (subitem) ==> hti.iSubITem but ONLY with CC version 4.70+
                                          'but doc also says iSubItem is always zero when hit testing
                                          'so I'm not sure exactly what you get here. 
                                          ' but I usually don't care about which subitem* 
                                      ......

A little extra doc from SDK re hit testing.....

'You can test for LVHT_ONITEM to determine whether a specified position is over a list-view item. This value is a bitwise-OR operation on LVHT_ONITEMICON, LVHT_ONITEMLABEL, and LVHT_ONITEMSTATEICON.

Again, this is for testing CLICKS... but - especially when using a single-select listview - it may be more advantageous to intercept the LVIS_SELECTED state changes posted above than testing specifically for mouse clicks... remember the listview control WILL process the up and down arrow keys if the listview control has the keyboard focus, and will move the focused item (and selection, if single select) up and down one row as you use them. IIRC, with multi-select listview, the arrow keys do not set the selection, but do set the focused item... you then toggle the selected status of the currently-focused row with <spacebar>.

* There is a (subjective) nice demo of processing DOUBLE clicks at Listview with Multiple Checkbox Columns Demo 2-20-05. The doc for NM_DBLCLK then says you CAN get sub-item (column) reliably with Listview_SubItemHitTest.

MCM
PS: In case you can't tell, the listview control is one of my favorites.

**Roberto Condorelli** · 10 Apr 2008, 05:11 PM

Marvelous, fantastic...
It was simpler than I thought.
Have modified the code that had inserted in the post (Listview with Multiple Checkbox Columns Demo 2-20-05.) to manage the single clik (the double click should be very simple!)
Have you seen that the things can be resolved in very simple way without so many complications of planning??
Now that I have understood the mechanism I believe (I hope) not to have big problems.
Still thanks
Roberto

' Global.bas
'*****************************
.
.
UNION LvUnion
NMHDR AS NMHDR
NMLV AS NMLISTVIEW
NMIA AS NMITEMACTIVATE
LVDI AS LV_DISPINFO
LVCD AS NMLVCUSTOMDRAW
NMTTDI AS NMTTDISPINFO
END UNION

' Main file
.
CALLBACK FUNCTION xxxxxxxxxx()
LOCAL plvu AS LvUnion PTR
LOCAL iSelRow AS LONG, iSelCol AS LONG

LOCAL lvNm AS NM_LISTVIEW PTR
STATIC zText AS ASCIIZ * 256
STATIC l_Testo AS STRING

SELECT CASE AS LONG CBMSG
CASE %WM_NOTIFY
plvu = CBLPARAM
SELECT CASE AS LONG @plvu.nmhdr.idfrom
CASE %IDC_SYSLISTVIEW32

SELECT CASE AS LONG @plVU.nmhdr.code
CASE %NM_CLICK
iSelRow = @plvu.nmia.iItem
iSelCol = @plvu.nmia.iSubItem
IF iSelRow >= 0 THEN ' if something is selected
' Column 0 = the identify of the user to retrieve the data in the database
ListView_getITemText @plvu.nmhdr.hwndFrom, iSelRow, 1, zText, SIZEOF(zText) ' Surname
l_Testo= zText
ListView_getITemText @plvu.nmhdr.hwndFrom, iSelRow, 2, zText, SIZEOF(zText) ' Name
l_Testo=l_Testo & " " & zText
CONTROL SET TEXT h_frmAnagrafeOUT, %lbl_Info, l_Testo ' Fill the label with the informations
.
.

Announcement

ListView select row

ListView select row

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