PB9 - Listview - Lv_Keydown - Heap Problem

[Markus Saegesser]

Maybe I'm completely wrong, but I thought that's what filefind.bas in the samples directory does?

(select and then process an entry from the list)


----

by the way, if I test for %vk_return (which is caught when pressing [alt]+[return]) I neither get a
memory access violation nor a heap-error.

[Michael Mattias]

I want the user to select an item either with cursor up/down or the mouse and then accept the selection with double click or spacebar.

That's not what a listview control does. When you use the arrow keys, you HAVE selected that item (row), unless you pre-empt it on LVB_SELCHANGING... but that has a problem because now if you reject the change, you can't 'skip over' a row in the list with the keyboard.

Maybe you should look at using combobox with style read-only, or maybe CBS_DROPDOWNLIST; or even a listbox. Then the user has to take an affirmative action to select one of the items in that list. Then when you click (or press spacebar on) the button, you can read the combobox/listbox to find which item has been selected to perform your processing.

[Markus Saegesser]

Thanks Chris but....
unfortunately not - I get the same when I strip down the code even further to no array and and an empty listview.

BTW..
You don't need to mess with the lparam=pointer var code with 9x. There are new internal functions to deal with this. See the CB.NMCODE magic word under the "CB" topic of help.

Than again, I'm not a "DDT" guy...

Great, this one i could do without problems.

I think I'd do a DIALOG POST CBHNDL, %WM_CLOSE, %NULL, %NULL there, and pick up WM_CLOSE in the main dialog procedure to do my DIALOG END.

That way I'd know the rest of the notification messages associated with a 'key down' event will have been handled before I try ending the dialog.

Worth a try, anyway.

I tested this and ended in a sort of "%WM_CLOSE-Loop". Stupid me.
What I did afterwards was kind of this (compilable code):

#COMPILE EXE
#DIM ALL
 
'------------------------------------------------------------------------------
'   ** Includes **
'------------------------------------------------------------------------------
#INCLUDE "WIN32API.INC"
#INCLUDE "CommCtrl.inc"
'------------------------------------------------------------------------------
GLOBAL beenden AS LONG
GLOBAL hdlg AS LONG
'------------------------------------------------------------------------------
'   ** Main Application Entry Point **
'------------------------------------------------------------------------------
FUNCTION PBMAIN
    beenden = 0
    DIALOG NEW 0, "Dialog1",,,                        100, 100, TO hDlg
    CONTROL ADD BUTTON,  hDlg, 1000, "Button1", 15, 15, 50, 15, CALL cbBtn1
    CONTROL ADD LISTVIEW, hDlg, 1001, "", 15,35,65,50 CALL cbLv
    DIALOG SHOW MODAL hDlg, CALL cbDlg
END FUNCTION
'------------------------------------------------------------------------------
'   ** CallBacks **
'------------------------------------------------------------------------------
CALLBACK FUNCTION cbDlg
    IF beenden = 1 THEN
        beenden = 0
        DIALOG END hdlg
    END IF
END FUNCTION
'------------------------------------------------------------------------------
CALLBACK FUNCTION cbBtn1
    beenden = 1
END FUNCTION
'------------------------------------------------------------------------------
CALLBACK FUNCTION cbLv
    LOCAL kb     AS LV_KEYDOWN
    TYPE SET kb    = CB.NMHDR$(SIZEOF(kb))
         IF CB.NMCODE = %LVN_KEYDOWN AND beenden = 0 THEN
                IF kb.wvkey = %vk_space THEN
                        beenden = 1
                END IF
         END IF
END FUNCTION

but I still get an error when pressing the space bar (Memory Access Violation).

If I change %vk_space to %vk_a, there comes the "heap" thing again.

[Michael Mattias]

Assuming the stepping debugger kept running after that display...
I take that back, it's NOT a compiler/stepping debugger problem; it's actually a feature.

The stepping debugger returned a more detailed error message than would Windows.. which for this condition would simply exit on a code '0005' protection fault (attempt to access unowned memory). Not that that particular message is terribly useful to a beginning user, or maybe even the average user.

As for what CAUSED this error condition, that's a horse of a different color. In general it would mean you have an invalid address somewhere, but not null, and not an array bound violation, both of which would have given you an "Error 9" message.

This may be related to your funky "end of program" logic.... e.g Windows is trying to process a notification message for a window which no longer exists.

[Chris Holbrook]

I think it is to do with loading the array. You appear to be referencing off the end of the array - ubound(texte) is the last element which you can reference.

[Michael Mattias]

(BTW: the error message you got there is definitely a compiler problem. That should never happen to you unless you call HeapFree() or DestroyHeap(), which I am guessing you are not doing a whole lot of).

[Michael Mattias]

 CASE %LVN_KEYDOWN
                SELECT CASE @kb.wVKEY
                    CASE %vk_space
                       MSGBOX strSel
                       DIALOG END hdlg
                       FUNCTION = 1

Just off the top of my head, I don't like DIALOG END on LVN_KEYDOWN 'in-line' like this, since I know more notification messages are coming in response to this user action.

I think I'd do a DIALOG POST CBHNDL, %WM_CLOSE, %NULL, %NULL there, and pick up WM_CLOSE in the main dialog procedure to do my DIALOG END.

That way I'd know the rest of the notification messages associated with a 'key down' event will have been handled before I try ending the dialog.

Worth a try, anyway.

BTW..

pNMLV = CB.LPARAM
        kb    = CB.LPARAM
        SELECT CASE @pNMLV.hdr.code

You don't need to mess with the lparam=pointer var code with 9x. There are new internal functions to deal with this. See the CB.NMCODE magic word under the "CB" topic of help.

Than again, I'm not a "DDT" guy...

MCM

[Markus Saegesser]

Here we go - that's the stripped down version i'm trying my luck with atm.

#COMPILE EXE
#DIM ALL
'------------------------------------------------------------------------------
'   Verhindert zuviel Ballast aus den CommCtrl.inc (wird benötigt für Listview-Callbacks)
'------------------------------------------------------------------------------
    %NOANIMATE         = 1  ' Animate control
    %NOBUTTON          = 1  ' Button
    %NOCOMBO           = 1  ' Combo box
    %NOCOMBOEX         = 1  ' ComboBoxEx
    %NODATETIMEPICK    = 1  ' Date/time picker
    %NODRAGLIST        = 1  ' Drag list control
    %NOEDIT            = 1  ' Edit control
    %NOFLATSBAPIS      = 1  ' Flat scroll bar
    %NOHEADER          = 1  ' Header control
    %NOHOTKEY          = 1  ' HotKey control
    %NOIMAGELIST       = 1  ' Image APIs
    %NOIPADDRESS       = 1  ' IP Address edit control
    %NOLIST            = 1  ' List box control
    %NOMENUHELP        = 1  ' Menu help
    %NOMONTHCAL        = 1  ' MonthCal
    %NOMUI             = 1  ' MUI
    %NONATIVEFONTCTL   = 1  ' Native Font control
    %NOPAGESCROLLER    = 1  ' Pager
    %NOPROGRESS        = 1  ' Progress control
    %NOREBAR           = 1  ' Rebar control
    %NOSTATUSBAR       = 1  ' Status bar
    %NOSYSLINK         = 1  ' SysLink
    %NOTABCONTROL      = 1  ' Tab control
    %NOTOOLBAR         = 1  ' Tool bar
    %NOTOOLTIPS        = 1  ' Tool tips
    %NOTRACKBAR        = 1  ' Track bar
    %NOTRACKMOUSEEVENT = 1  ' Track Mouse Event
    %NOTREEVIEW        = 1  ' TreeView
    %NOUPDOWN          = 1  ' Up Down arrow control

'------------------------------------------------------------------------------
'   ** Includes **
'------------------------------------------------------------------------------
#INCLUDE "WIN32API.INC"
#INCLUDE "CommCtrl.inc"
'------------------------------------------------------------------------------
'------------------------------------------------------------------------------
'   ** Constants **
'------------------------------------------------------------------------------
%IDC_LABEL1   = 1001
%IDC_LISTVIEW = 1003
%IDC_BUTTON1  = 1004
'------------------------------------------------------------------------------
'------------------------------------------------------------------------------
'   ** Declarations **
'------------------------------------------------------------------------------
'------------------------------------------------------------------------------
'------------------------------------------------------------------------------
GLOBAL hDlg    AS DWORD
GLOBAL strSel  AS STRING
GLOBAL texte() AS STRING
'------------------------------------------------------------------------------
'   ** Main Application Entry Point **
'------------------------------------------------------------------------------
FUNCTION PBMAIN()
    CALL sprachen
    CALL fundstuecke
END FUNCTION
'------------------------------------------------------------------------------
FUNCTION fundstuecke AS LONG
    LOCAL i AS LONG
    DIALOG NEW 0, "Dialog1",,,                          326, 235,        TO hDlg
    CONTROL ADD LABEL,   hDlg, %IDC_LABEL1, "Label1",   10, 10, 165, 15
    CONTROL ADD LISTVIEW,hDlg, %IDC_LISTVIEW,"" ,       10, 70, 300, 90, CALL cbLv
    CONTROL ADD BUTTON,  hDlg, %IDC_BUTTON1, "Button1", 15, 200, 80, 15, CALL cbBtn1
    CONTROL SET FOCUS hDlg, %idc_listview

    ''listview füllen
    LISTVIEW INSERT COLUMN hDlg, %IDC_LISTVIEW, 1, "a", 120,0
    LISTVIEW INSERT COLUMN hDlg, %IDC_LISTVIEW, 2, "b", 50 ,0
    LISTVIEW INSERT COLUMN hDlg, %IDC_LISTVIEW, 3, "c", 180,0
    LISTVIEW INSERT COLUMN hDlg, %IDC_LISTVIEW, 4, "i", 1,0
    FOR i = 1 TO UBOUND(texte)
        IF TRIM$(texte(i + 7)) = "" THEN
            EXIT FOR
        END IF
        LISTVIEW INSERT ITEM hDlg, %IDC_Listview, 1,0, texte(i + 7)
        LISTVIEW SET TEXT hDlg, %IDC_Listview, 1,2 , texte(i + 7)
        LISTVIEW SET TEXT hDlg, %IDC_Listview, 1,3 , texte(i + 7)
        LISTVIEW SET TEXT hDlg, %IDC_Listview, 1,4 , STR$(i + 7)
    NEXT i
    DIALOG SHOW MODAL hDlg
    FUNCTION = 1
END FUNCTION

'------------------------------------------------------------------------------
'   ** CallBacks **
'------------------------------------------------------------------------------
CALLBACK FUNCTION cbBtn1
    DIALOG END hDlg
    FUNCTION = 1
END FUNCTION
'------------------------------------------------------------------------------
CALLBACK FUNCTION cbLv AS LONG
    LOCAL pNMLV  AS NM_LISTVIEW PTR
    LOCAL kb     AS LV_KEYDOWN PTR
        pNMLV = CB.LPARAM
        kb    = CB.LPARAM
        SELECT CASE @pNMLV.hdr.code
            CASE %LVN_ITEMCHANGED
                IF ISTRUE @pNMLV.uCHANGED AND ISTRUE %LVIS_SELECTED THEN
                    IF ISTRUE (@pNMLV.uNewState AND %LVIS_SELECTED) THEN
                        IF @pNMLV.iItem > -1 THEN
                            LISTVIEW GET TEXT CB.HNDL, %IDC_Listview, @pNMLV.iItem+1, 1 TO strSel
                            FUNCTION = 1
                        END IF
                    END IF
                END IF
            CASE %NM_DBLCLK
                MSGBOX strSel
                DIALOG END hdlg
                FUNCTION = 1
            CASE %LVN_KEYDOWN
                SELECT CASE @kb.wVKEY
                    CASE %vk_space
                       MSGBOX strSel
                       DIALOG END hdlg
                       FUNCTION = 1
                END SELECT
        END SELECT
END FUNCTION
'------------------------------------------------------------------------------
SUB sprachen
    DIM texte(100)
        texte(8) = "Fundstücke...: "
        texte(9) = "Bitte nur Ziffern von 0 bis "
        texte(10) = "Falsche Eingabe"
        texte(11) = "User nicht gefunden"
        texte(12) = "Nicht gefunden: "
        texte(13) = "(extern)"
        texte(14) = "Tel: "
        texte(15) = "Büro: "
        texte(16) = "Geräte-Nr: "
        texte(17) = "IP-Adresse: "
        texte(18) = "Angemeldet"
        texte(19) = "Nicht angemeldet"
        texte(20) = "letzte Anmeldung: "
        texte(21) = "Telefax: "
        texte(22) = "E-Mail Stellvertreter: "
        texte(23) = "Termin-Details: "
        texte(24) = "Start: "
        texte(25) = "Ende: "
        texte(26) = "Ort: "
        texte(27) = "Optionen"
        texte(28) = "Na&chricht senden"
        texte(29) = "Wer gehört zur selben &Abteilung"
        texte(30) = "Die nächsten 20 &Termine anzeigen"
        texte(31) = "Nachrichten-Typ"
        texte(32) = "&NetSend an: "
        texte(33) = "E-&Mail an: "
        texte(34) = "SMS an: "
        texte(35) = "O&K"
        texte(36) = "s&enden"
        texte(37) = "Wirklich senden?"
        texte(38) = "Nachricht"
        texte(39) = "Nachricht von:"
        texte(40) = "Anmeldestatus wird geprüft, " & $CRLF & "bitte warten"
        texte(41) = "Name"
        texte(42) = "UserID"
        texte(43) = "Abteilung"
END SUB

[Chris Holbrook]

oh. How about showing compileable code?

[Markus Saegesser]

I don't hope so. At least it doesn't do anything i've written -there's no dialog callback in my code.

[Chris Holbrook]

You are closing the DIALOG hDlg here but you only show code for the control callback. Is it possible that the dialog's WM_DESTROY handler is doing something untoward, or even something after the dialog is closed?

[Markus Saegesser]

Hi everyone

I run into a problem with my callback function for the listview control.

I want the user to select an item either with cursor up/down or the mouse and then accept the selection with double click or spacebar. After that, the selection is processed in another sub.

Selection part works ok (thanks, MCM). So does the DBLCLK. But when I close the dialog in the %LVN_KEYDOWN-Part, i get the following message in the output window

HEAP: Free Heap block 1a48bf0 modified at 1a48cc0 after it was freed<0A>

I'm quite certain it must be something with the pointer, but this is fairly new stuff for me.

CALLBACK FUNCTION cbLv AS LONG
    LOCAL pNMLV  AS NM_LISTVIEW PTR
    LOCAL kb     AS LV_KEYDOWN PTR

        pNMLV = CB.LPARAM
        kb    = CB.LPARAM

        SELECT CASE @pNMLV.hdr.code
            CASE %LVN_ITEMCHANGED
                IF ISTRUE @pNMLV.uCHANGED AND ISTRUE %LVIS_SELECTED THEN
                    IF ISTRUE (@pNMLV.uNewState AND %LVIS_SELECTED) THEN
                        IF @pNMLV.iItem > -1 THEN
                            LISTVIEW GET TEXT CB.HNDL, %IDC_Listview, @pNMLV.iItem+1, 1 TO strSel
                            FUNCTION = 1
                        END IF
                    END IF
                END IF
            CASE %NM_DBLCLK
                MSGBOX strSel
                DIALOG END hdlg
                FUNCTION = 1
            CASE %LVN_KEYDOWN
                SELECT CASE @kb.wVKEY
                    CASE %vk_space
                       MSGBOX strSel
                       DIALOG END hdlg
                       FUNCTION = 1
                END SELECT
        END SELECT
END FUNCTION

This occurs only when debugging, not when running the compiled version - but i'm sure the problem exists there as well.

Best regards,
Markus