CCheckListBox is giving me trouble!
Hulemannen -- elg2@nobipol.unit.no
Friday, August 02, 1996
Environment: VC++ 4.0,NT 3.51
Here's my problem:
- a dialog created with the dialog editor that also
contains a list box
- with class wizard I derived a memeber variable -
CListBox m_dlListBox -
in the class CMyDialog. I then changed it to a
CCheckListBox-class.
- in OnCreate I added this code:
CRect rect;
m_dlgListBox.GetItemRect(IDC_LIST, &rect);
int nRet = m_dlgListBox.Create(WS_CHILD |
WS_VISIBLE | LBS_STANDARD |
LBS_HASSTRINGS | LBS_OWNERDRAWFIXED
| LBS_OWNERDRAWVARIABLE ,
rect, this, IDC_LIST);
ASSERT(nRet != 0);
"GetItemRect(IDC_LIST, &rect);" causes the
following ASSERT failure in line 643 in
AFXWIN2.INL:
_AFXWIN_INLINE int CListBox::GetItemRect(int
nIndex, LPRECT lpRect) const
{ ASSERT(::IsWindow(m_hWnd)); return
(int)::SendMessage(m_hWnd, LB_GETITEMRECT, nIndex,
(LPARAM)lpRect); }
I have discovered that this function can only be
used after Create is called, but I need the
parameter 'rect' it passes to run Create correctly.
I can replace the second paramater 'rect' in Create
with CRect(0,0, 200,200) for example and then
I can see the list, although it isn't placed
correctly in the dialog and seems to be hiding
behind
text,buttons etc.
Passing NULL instead of 'rect' produces an error
and trying to read the listbox-position and size
from the dialog editor and passing these doesn't
produce produce satisfactory results.
--
Name: Steinar M. Elgsaeter (The Caveman)
E-mail: elg2@nobipol.unit.no
"The nice thing about C++ is that only your friends
can handle your private parts."
Benny -- blee@filenet.com
Tuesday, August 06, 1996
[Mini-digest: 8 responses]
Try to intercept it in OnInitDialog. That should do it.
Benny
----------
From: owner-mfc-l
To: mfcpro; mfc-l
Subject: CCheckListBox is giving me trouble!
Date: Friday, August 02, 1996 7:08PM
Environment: VC++ 4.0,NT 3.51
Here's my problem:
- a dialog created with the dialog editor that also
contains a list box
- with class wizard I derived a memeber variable -
CListBox m_dlListBox -
in the class CMyDialog. I then changed it to a
CCheckListBox-class.
- in OnCreate I added this code:
CRect rect;
m_dlgListBox.GetItemRect(IDC_LIST, &rect);
int nRet = m_dlgListBox.Create(WS_CHILD |
WS_VISIBLE | LBS_STANDARD |
LBS_HASSTRINGS | LBS_OWNERDRAWFIXED
| LBS_OWNERDRAWVARIABLE ,
rect, this, IDC_LIST);
ASSERT(nRet != 0);
"GetItemRect(IDC_LIST, &rect);" causes the
following ASSERT failure in line 643 in
AFXWIN2.INL:
_AFXWIN_INLINE int CListBox::GetItemRect(int
nIndex, LPRECT lpRect) const
{ ASSERT(::IsWindow(m_hWnd)); return
(int)::SendMessage(m_hWnd, LB_GETITEMRECT, nIndex,
(LPARAM)lpRect); }
I have discovered that this function can only be
used after Create is called, but I need the
parameter 'rect' it passes to run Create correctly.
I can replace the second paramater 'rect' in Create
with CRect(0,0, 200,200) for example and then
I can see the list, although it isn't placed
correctly in the dialog and seems to be hiding
behind
text,buttons etc.
Passing NULL instead of 'rect' produces an error
and trying to read the listbox-position and size
from the dialog editor and passing these doesn't
produce produce satisfactory results.
--
Name: Steinar M. Elgsaeter (The Caveman)
E-mail: elg2@nobipol.unit.no
"The nice thing about C++ is that only your friends
can handle your private parts."
-----From: "Greg Tighe"
Forget about calling Create()... that will only result in your having
two separate listbox controls in your dialog. Instead, try this:
m_dlgListBox.SubclassDlgItem (IDC_LIST, this);
This will subclass the listbox control to your CMyCCheckListBox
member variable. Make sure the 'Owner Draw:Fixed' attribute has been
chosen in the dialog editor for your listbox. The listbox should be
displayed with checkboxes to the left of each item.
-Greg Tighe
Applied Intelligent Systems, Inc.
Ann Arbor, MI
gdt@aisinc.com
-----From: Wolfgang Loch
Let the class wizard make a member variable m_List for your
listbox control and change the class name in (mydlg.h) from
CListBox to CCheckListBox.
So why do you want to Create() it ?
Wolfgang
--
/-------------------------------------------------\
| Wolgang Loch (Technical University of Ilmenau) |
| e-mail: Wolfgang.Loch@rz.TU-Ilmenenau.DE |
| www : http://www.rz.tu-ilmenau.de/~wolo |
\-------------------------------------------------/
-----From: mjmo@lubrizol.com
You are doing too much work. Let MFC do most of it. In the dialog editor, make
sure the listbox has these styles:
owner-draw fixed
Has Strings
NO SORT
Remove the Create from your OnCreate - the listbox will be created from your
dialog template, and MFC will attach it to your CCheckListBox variable (but not
until OnInitDialog). That's all you need to do.
Besides the fact that you do not need to create the list box, I see two other
things in your code:
* There is no window handle for the control until after Create is
called. So calling GetItemRect before Create will ASSERT, as you found out.
But of course, that's no longer a problem because the rectangle from the dialog
template will be used.
* You are specifying both LBS_OWNERDRAWFIXED and LBS_OWNERDRAWVARIABLE,
which I believe are mutually exclusive. One will probably override the other,
but I'm not sure which.
Mike Morel
Mushroom Software
mmorel@mushroomsoft.com
MFC For Yourself at http://www.mushroomsoft.com/mushroom
-----From: Gordon Weakliem
I think you're trying to use a list box in a dialog, but handle it with your
owner draw class. What I usually do in these cases is put a static control
where the owner drawn control goes, then take the static's dimensions for my
control. What it seems like you're doing is creating a secong list box on
top of the one created when the dialog resource is created. I'm guessing
the way your code is written, you'll get two list boxes showing up in Spy++.
The reason taking units from Resource Studio is that RS deals in dialog
units, not pixels. Check out GetDialogBaseUnits for details.
> int nRet = m_dlgListBox.Create(WS_CHILD |
>WS_VISIBLE | LBS_STANDARD |
> LBS_HASSTRINGS | LBS_OWNERDRAWFIXED
>| LBS_OWNERDRAWVARIABLE ,
> rect, this, IDC_LIST);
On a side note, I don't understand why your list box is LBS_OWNERDRAWFIXED
and LBS_OWNERDRAWVARIABLE. These styles are mutually exclusive; either the
items are all the same size, or they aren't.
Gordon Weakliem
gweakl@metronet.com
-----From: "Frederic Steppe"
What a mess ...
You don't have to create a control defined in a dialog template, it will be
done for you.
Of course GetItemRect doesn't work, there is no control yet !
By the way, what are you trying to do ???
If you REALLY have to move the control from its original location, you can do
it in OnInitDialog (the control will exist at that time).
Frederic Steppe (frederics@msn.com)
-----From: "petter.hesselberg"
In the original question, Steinar M. Elgsaeter (aka The Caveman) attempts
to call GetItemRect on a listbox that has not yet been created. This MFC
function
is a wrapper for sending the message LB_GETITEMRECT to the listbox;
since the listbox does not yet exist, no dice.
You say that you need this rect size (which will, in fact, be the size of a
single
item in the listbox) to do your m_dlgListBox.Create properly. Actually, you
can create it any size you want, and then use MoveWindow to set the actual
position.
And, by the way, OnInitDialog is generally the best place to do this sort of
stuff.
At that point, all the controls you drew in the dialog editor will actually
have been
created.
Your code has a couple of other problems, though. To begin with, using IDC_LIST
as the first parameter to the GetItemRect call is meaningless. This parameter
is an index into the list box, not a control ID. At any rate, a CCheckListBox
is normally
LBS_OWNERDRAWFIXED, unless you want to handle the drawing yourself.
Since it is LBS_OWNERDRAWFIXED, IDC_LIST is as good as any other index,
so in this case, you'd actually get away with it -- by pure luck.
You attempt to create a listbox which combines LBS_OWNERDRAWVARIABLE
and LBS_OWNERDRAWFIXED styles -- these styles are not compatible.
You have drawn a listbox in the dialog editor. Why do you want to create another
one? That way, you will end up with two listboxes. What you want to do is to
subclass
the existing one; in this case, it will retain the position you gave it in the
dialog
editor.
You should be wary of overriding variables generated by ClassWizard. It may or
may not be safe in this case, but as a general rule, if I can't select a class
in the
ClassWizard's dialog box, I forego the Wizard on this point, define a variable
for the
control by hand, and use the control's CWnd::SubClass() method in OnInitDialog.
FYI, the coordinates used by the dialog editor are dialog units.
For more information on dialog units, check out CDialog::MapDialogUnits and
all the Win32 API functions referenced there.
I don't want to discourage you, but it seems to me that you have only vague
ideas about what you're doing. I happen to think that MFC and ClassWizard are
fine and useful tools, but you do need to have at least a rudimentary
understanding
of MFC, the underlying Windows API and the generated code. If you don't, you
will
consistently be led into the kind of quagmire you're in here. Unless you're
prepared
to invest a significant amount of time and effort, you'd be better off sticking
with Visual Basic.
Regards,
Petter Hesselberg
Andersen Consulting
-----From: Mats Manhav
You don't need to call create at all for doing this.
Assume the listbox in the dialog template has the following id IDC_LIST.
Declare the variable as before. Make sure that it has the style Owner drawn
fixed.
Then in the CYourDialog::OnInitDialog()
do the following
m_dlgListBox.SubclassDlgItem(IDC_LIST, this);
and the listbox will be a CCheckListBox!
You see, the listbox is already created by having it in the dialog template.
--
==========================================================================
Mats Mеnhav (Mats Manhav for 7-bit people)
email:manhav@connectum.skurup.se WWW: http://connectum.skurup.se/~manhav
FAX: (int) 46 (0) 414 243 05 Phone: (int) 46 (0) 414 243 05
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