TListView detecting ESC or unchanged editing

I am trying to subclass the WindowProc of TListView to detect ESC key press after editing TListView caption (if user cancels editing). ListViewWndProc is getting called clearly, but the code parameter which is supposed to detect that never gets LVN_ENDLABELEDIT value. Why the commented part never gets called? I cannot see the error, it should be happening.

WindowProc

TListView

TListView

TWndMethod OldWndProc;

//---------------------------------------------------------------------------

__fastcall TForm1::TForm1(TComponent* Owner) : TForm(Owner)
{
OldWndProc = ListView1->WindowProc;
ListView1->WindowProc = ListViewWndProc;
}

//---------------------------------------------------------------------------

void __fastcall TForm1::ListViewWndProc(TMessage &Message)
{
if (Message.Msg == CN_NOTIFY)
{
LPNMHDR pnmh = reinterpret_cast<LPNMHDR>(Message.LParam);

if (pnmh->code == LVN_ENDLABELEDIT) // UPDATE: if LVN_ENDLABELEDIT is replaced with 4294967120 it works
{

// !!! THE FOLLOWING NEVER HAPPENS !!!

// UPDATE: Looks like LVN_ENDLABELEDIT is incorrectly defined in C++ Builder 2010
// if LVN_ENDLABELEDIT is replaced with 4294967120 the code works

LV_DISPINFO *pdi = reinterpret_cast<LV_DISPINFO*>(Message.LParam);
if (pdi->item.pszText == NULL)
{
Edit1->Text = "Cancelled";
return;
}
}
}

OldWndProc(Message);
}

//---------------------------------------------------------------------------

void __fastcall TForm1::ListView1Editing(TObject *Sender, TListItem *Item, bool &AllowEdit)
{
Edit1->Text = "Editing";
}

//---------------------------------------------------------------------------

void __fastcall TForm1::ListView1Edited(TObject *Sender, TListItem *Item, UnicodeString &S)
{
Edit1->Text = "Done";
}


Edit1->Text = LVN_ENDLABELEDIT;

4294967190

4294967120

2 Answers
2

In C++, the value of LVN_ENDLABELEDEDIT depends on the project's TCHAR_Mapping, which can be changed in the Project Settings via the "_TCHAR maps to" configuration item. By default, _TCHAR is set to wchar_t in C++Builder 2009 and later, unless you migrate a project from an earlier version, in which case it is char by default instead.

LVN_ENDLABELEDEDIT

"_TCHAR maps to"

_TCHAR

wchar_t

char

LVN_ENDLABELEDIT is a macro that maps to LVN_ENDLABELEDITA (4294967190) when _TCHAR is char, and to LVN_ENDLABELEDITW (4294967120) when _TCHAR is wchar_t.

LVN_ENDLABELEDIT

LVN_ENDLABELEDITA

_TCHAR

char

LVN_ENDLABELEDITW

_TCHAR

wchar_t

Checking for both constants LVN_ENDLABELEDEDITA and LVN_ENDLABELEDEDITW, like it is done in the Delphi source code, should be OK.

LVN_ENDLABELEDEDITA

LVN_ENDLABELEDEDITW

void __fastcall TForm1::ListViewWndProc(TMessage &Message)
{
if (Message.Msg == CN_NOTIFY)
{
LPNMHDR pnmh = reinterpret_cast<LPNMHDR>(Message.LParam);

if ((pnmh->code == LVN_ENDLABELEDITA) || (pnmh->code == LVN_ENDLABELEDITW))
{
LV_DISPINFO *pdi = reinterpret_cast<LV_DISPINFO*>(Message.LParam);
if (pdi->item.pszText == NULL)
{
Edit1->Text = "Cancelled";
return;
}
}
}

OldWndProc(Message);
}


LVN_ENDLABELEDITA

pdi->item

LVITEMA

item.pszText

char*

LVN_ENDLABELEDITW

pdi->item

LVITEMW

item.pszText

wchar_t*

pszText

TListView

LVN_ENDLABELEDITW

LVN_ENDLABELEDIT

4294967120

LVN_ENDLABELEDITW

In case anybody else gets here looking for a solution in Delphi, I have just translated Kerem D's code:

constructor TForm1.Create(_Owner: TComponent);
begin
inherited;
OldWndProc = ListView1.WindowProc;
ListView1.WindowProc = ListViewWndProc;
end;

procedure TForm1.ListViewWndProc(var _Message: TMessage);
var
LvDispInfo: PLVDispInfo; // declared in CommCtrl
Code: Integer;
begin
if _Message.Msg = CN_NOTIFY then begin
Code := PNMHdr(_Message.lParam).Code;
if (Code = LVN_ENDLABELEDITA) or (Code = LVN_ENDLABELEDITW) then begin
LvDispInfo := PLVDispInfo(_Message.lParam);
if LvDispInfo.Item.pszText = nil then begin
Edit1.Text := 'Cancelled';
Exit; //==>
end;
end;
end;
OldWndProc(_Message);
end;


It works for me in Delphi 6 to 10.2 (used in GExperts)

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